DEVICES, SYSTEMS, AND METHODS FOR DELIVERING, POSITIONING, AND SECURING POLYMER DEPOTS IN SITU

TECHNICAL FIELD

The present technology relates to implants for controlled, sustained release of therapeutic agents in vivo.

BACKGROUND OF THE INVENTION

Implantable systems for the controlled release of therapeutic agents offer advantages over other drug delivery methods, such as oral or parenteral methods. Devices comprised of biocompatible and/or biodegradable polymers and therapeutic agents can be implanted in clinically desirable anatomic locations, thereby providing localized delivery of select agents. This localized delivery enables a substantial proportion of the agent to reach the intended target and undesirable systemic side effects can be avoided. However, these systems often suffer from a lack of a true controlled release mechanism in that they typically provide a burst release of drug upon contact with surrounding physiologic fluids followed by a residual release of drug.

In order to improve drug release in certain polymer carriers, hydrophilic polymers, such as polysorbate, have been added to these carriers as wetting agents to accelerate or to enhance drug release from biocompatible polymers such polyethylene glycol (PEG) in oral formulations (Akbari, J., et al., ADV. PHARM. BULL., 2015, 5(3): 435-441). However, these formulations are intended to provide an immediate release of a hydrophobic drug into a hydrophilic environment (the in vivo physiologic fluid), where a substantial portion of the entire drug payload is immediately or aggressively released, not a variable or sustained controlled release.

While these drug release kinetics may be desirable in some clinical applications, a controlled, sustained release of a therapeutic agent can be of clinical benefit in certain circumstances. In particular, it may be desirable to implant a biodegradable carrier holding a large dose of a therapeutic agent for a controlled, sustained release over time. This may have particular value when the carrier loaded with therapeutic agent is implanted in conjunction with an interventional or surgical procedure and, optionally, alongside or as part of an implantable medical device.

Thus, a need exists for biocompatible implantable systems capable of providing a highly controlled release of drug.

SUMMARY

The present technology relates to implants for controlled release of a therapeutic agent to treat a medical condition and associated systems and methods. In particular, the present technology relates to implants for local, sustained release of a therapeutic agent at a surgical or interventional site and associated systems and methods.

The subject technology is illustrated, for example, according to various aspects described below, including with reference to FIGS. 1-97C. Various examples of aspects of the subject technology are described as numbered clauses (1, 2, 3, etc.) for convenience. These are provided as examples and do not limit the subject technology.

1. A depot for the treatment of postoperative pain via sustained, controlled release of an analgesic, comprising:

- a therapeutic region comprising the analgesic; and
- a control region comprising a bioresorbable polymer and a releasing agent mixed with the polymer, wherein the releasing agent is configured to dissolve when the depot is placed in vivo to form diffusion openings in the control region,
- wherein the depot includes a first notch at a first side of the depot and a second notch at a second side of the depot, the second side being opposite the first side and/or angled relative to the first side about a periphery of the depot, and
- wherein the depot is configured to be implanted at a treatment site in vivo and, while implanted, release the analgesic at the treatment site for no less than 3 days.

2. The depot of any one of the preceding clauses, wherein each of the first notch and the second notch are configured to receive and support a suture.

3. The depot of any one of the preceding clauses, wherein the first and second notches are configured such that a suture may be wrapped at least one time around the depot and secured within each of the first and second notches, thereby securing the suture at a first location along at least one dimension of the depot.

4. The depot of any one of the preceding clauses, wherein the first and second notches are configured such that a suture may be wrapped to engage with each of the first and second notches, thereby securing the suture at a first location along at least one dimension of the depot.

5. The depot of any one of the preceding clauses, wherein the depot is configured to be secured, via a suture extending along the depot and through the first and second notches, to a suprapatellar region of an intracapsular space of the knee.

6. The depot of any one of the preceding clauses, wherein the depot is configured to be secured, via a suture extending along the depot and through the first and second notches, to one or both gutter regions of an intracapsular space of the knee.

7. The depot of any one of the preceding clauses, wherein each of the first notch and the second notch extend through all or a portion of a thickness of the depot.

8. The depot of any one of the preceding clauses, wherein each of the first notch and the second notch extend through all or a portion of a thickness of the control region.

9. The depot of any one of the preceding clauses, wherein each of the first notch and the second notch extend through all or a portion of a thickness of the therapeutic region.

10. The depot of any one of the preceding clauses, further comprising an integrated suture, wherein the integrated suture is preloaded onto the depot.

11. The depot of any one of the preceding clauses, further comprising an integrated suture, wherein the integrated suture is preloaded onto the first and second notches of the depot.

12. The depot of any one of the preceding clauses, further comprising a fixation portion comprising a bioeresorbable polymer and not including any therapeutic agent at least prior to implantation, wherein each of the first notch and the second notch extend through all or a portion of a thickness of the fixation portion and do not extend through one or both of the control region and the therapeutic region.

13. The depot of any one of the preceding clauses, wherein the first side is generally parallel to the second side.

14. The depot of any one of the preceding clauses, wherein the first side is generally perpendicular to the second side.

15. The depot of any one of the preceding clauses, further comprising a third notch and a fourth notch.

16. The depot of any one of the preceding clauses, wherein the third notch is at a third side of the depot and the fourth notch is at a fourth side of the depot, the fourth side being opposite the third side and/or angled relative to the third side about the periphery of the depot.

17. The depot of any one of the preceding clauses, wherein the first, second, third, and fourth sides are either generally parallel or angled relative to one another.

18. The depot of any one of the preceding clauses, wherein each of the first, second, third, and fourth notches are configured to receive and support a suture.

19. The depot of any one of the preceding clauses, wherein each of the third notch and the fourth notch extend through all or a portion of a thickness of the depot.

20. The depot of any one of the preceding clauses, wherein each of the third notch and the fourth notch extend through all or a portion of a thickness of the control region.

21. The depot of any one of the preceding clauses, wherein each of the third notch and the fourth notch extend through all or a portion of a thickness of the therapeutic region.

22. The depot of any one of the preceding clauses, further comprising a fixation portion comprising a bioeresorbable polymer and not including any therapeutic agent at least prior to implantation, wherein each of the third notch and the fourth notch extend through all or a portion of a thickness of the fixation portion and do not extend through one or both of the control region and the therapeutic region.

23. The depot of any one of the preceding clauses, wherein the first side is generally parallel to the second side, and the third side is generally parallel to the fourth side.

24. The depot of any one of the preceding clauses, wherein the depot is generally square-shaped.

25. The depot of any one of the preceding clauses, wherein the depot is generally rectangular.

26. The depot of any one of the preceding clauses, wherein the control region comprises a first control region at a first side of the therapeutic region, and a second control region at a second side of the therapeutic region, opposite the first side such that the therapeutic region is sandwiched between the first and second control regions.

27. The depot of any one of the preceding clauses, wherein the control region does not comprise any analgesic prior to implantation, and wherein the therapeutic region further comprises a bioresorbable polymer and a releasing agent.

28. The depot of any one of the preceding clauses, wherein the analgesic comprises at least 50% by weight of the depot.

29. The depot of any one of the preceding clauses, wherein the depot is configured to be positioned within a knee joint.

30. The depot of any one of the preceding clauses, wherein the depot is configured to be positioned within a knee joint but not alongside any articulating surface of the knee joint.

31. The depot of any one of the preceding clauses, wherein the fixation portion is configured to secure the depot at the treatment site for no less than 3 days but no more than 30 days.

32. A method comprising:

- securing a depot to an intracapsular portion of the knee, the depot comprising any one of the depots of the preceding clauses.

33. The method of any one of the preceding clauses, wherein securing the depot includes wrapping a suture around an axis of the depot through and between the first and second notches.

34. The method of any one of the preceding clauses, wherein securing the depot includes (a) wrapping a suture around a first axis of the depot through and between the first and second notches, and (b) wrapping the suture around a second axis of the depot through and between the third and fourth notches.

35. The method of any one of the preceding clauses, wherein securing the depot includes (a) wrapping a suture around a first axis of the depot through and between the first and second notches, (b) wrapping the suture around a second axis of the depot through and between the second and third notches, and (c) securing the suture to intracapsular tissue of the knee joint.

36. The method of any one of the preceding clauses, wherein the depot is a first depot, the method further comprising securing a second depot to the first depot, wherein securing the second depot comprises wrapping a suture around an axis of the first depot through and between the first and second notches, and then wrapping the suture around an axis of the second depot through and between notches of the second depot.

37. The method of any one of the preceding clauses, wherein securing the depot includes securing a suture to intracapsular tissue of the knee joint, wrapping the suture around an axis of the depot through and between the first and second notches, and pulling on the suture to ferry the wrapped depot into a suprapatellar region, a left gutter region, or a right gutter region.

38. The method of any one of the preceding clauses, wherein securing the depot includes securing a suture to a bone of the knee joint, wrapping the suture around an axis of the depot through and between the first and second notches, and pulling on the suture to ferry the wrapped depot into a treatment site within or adjacent the knee joint.

39. A depot assembly for the controlled, sustained release of a therapeutic agent, comprising:

- a depot comprising:
  - a therapeutic region comprising the therapeutic agent; and
  - a control region at least partially surrounding the therapeutic region, the control region comprising a bioresorbable polymer and a releasing agent mixed with the polymer, wherein the releasing agent is configured to dissolve when the depot is placed in vivo to form diffusion openings in the control region;
  - wherein the depot is configured to be implanted at a treatment site in vivo and, while implanted, release the therapeutic agent at the treatment site for a period of time not less than 3 days; and
- a fixation portion carried by the depot.

40. The depot assembly of any one of the preceding clauses, wherein the fixation portion is configured to facilitate attachment to anatomical features at the treatment site.

41. The depot assembly of any one of the preceding clauses, wherein the fixation portion comprises structural features configured to directly engage the anatomical features.

42. The depot assembly of any one of the preceding clauses, wherein the structural features comprise one or more of: a tab, a ridge, a hook, a barb, a protrusion, or a notch.

43. The depot assembly of any one of the preceding clauses, wherein the fixation portion comprises structural features configured to engage with a separate fixation device.

44. The depot assembly of any one of the preceding clauses, wherein the structural features comprise one or more of: a hole, a loop, a grommet, an eyelet, a channel, or a hook.

45. The depot assembly of any one of the preceding clauses, wherein the structural features comprise one or more of: a tab, a protrusion, or a ridge.

46. The depot assembly of any one of the preceding clauses, wherein the fixation device is configured to couple a plurality of depots together.

47. The depot assembly of any one of the preceding clauses, wherein the fixation device comprises one or more of: a suture, a yarn, or a staple.

48. The depot assembly of any one of the preceding clauses, wherein the fixation portion comprises a bioresorbable polymer.

49. The depot assembly of any one of the preceding clauses, wherein the fixation portion is formed of the same bioresorbable polymer as the control region.

50. The depot assembly of any one of the preceding clauses, wherein the fixation portion is formed of the same bioresorbable polymer as is included in the therapeutic region.

51. The depot assembly of any one of the preceding clauses, wherein the fixation portion comprises a margin extending laterally away from one or more edges of the depot.

52. The depot assembly of any one of the preceding clauses, wherein the fixation portion extends circumferentially around a perimeter of the depot.

53. The depot assembly of any one of the preceding clauses, wherein the fixation portion is radiopaque.

54. The depot assembly of any one of the preceding clauses, wherein the fixation portion comprises a region of the depot that does not include any therapeutic agent.

55. The depot assembly of any one of the preceding clauses, wherein the fixation portion is structurally integrated with or overlaps the depot.

56. The depot assembly of any one of the preceding clauses, wherein the fixation portion is discrete from the depot and attached thereto.

57. The depot assembly of any one of the preceding clauses, wherein the fixation portion comprises an elongate tubular member extending along one side of the depot.

58. The depot assembly of any one of the preceding clauses, wherein the tubular member defines a lumen extending therethrough.

59. The depot assembly of any one of the preceding clauses, wherein the lumen is filled with fluid or gas.

60. The depot assembly of any one of the preceding clauses, further comprising a hydrogel positioned within the lumen that is configured to expand in the presence of physiologic fluid, thereby expanding the tubular member.

61. The depot assembly of any one of the preceding clauses, wherein the fixation portion comprises a second elongate tubular member extending along a second side of the depot.

62. The depot assembly of any one of the preceding clauses, wherein the fixation portion comprises a plurality of protrusions extending over at least one surface of the depot.

63. The depot assembly of any one of the preceding clauses, wherein the fixation portion comprises a plurality of protrusions extending over at least two opposing surfaces of the depot.

64. The depot assembly of any one of the preceding clauses, wherein the fixation portion comprises a plurality of ridges extending circumferentially around the depot.

65. The depot assembly of any one of the preceding clauses, wherein the fixation portion comprises a portion of the depot having an increased thickness and configured to receive a fixation device therethrough.

66. The depot assembly of any one of the preceding clauses, wherein the fixation portion comprises an adhesive material disposed over at least a portion of the depot.

67. The depot assembly of any one of the preceding clauses, wherein the adhesive material comprises at least one of: hook-and-loop fasteners, epoxy, silicone, a cyanoacrylate, a mussel byssus adhesive, or a fibrin-based adhesive.

68. The depot assembly of any one of the preceding clauses, wherein the adhesive material is disposed over a tab extending from one edge of the depot.

69. The depot assembly of any one of the preceding clauses, wherein the tab on which the adhesive material is disposed is devoid of therapeutic agent.

70. The depot assembly of any one of the preceding clauses, wherein the fixation portion comprises an anchor element configured to be implanted into tissue at a treatment site, and wherein the depot is coupled to the fixation portion via a tether.

71. The depot assembly of any one of the preceding clauses, wherein the anchor element comprises one or more of: ridges, barbs, teeth, or threads.

72. The depot assembly of any one of the preceding clauses, further comprising a plurality of depots coupled to the anchor element via one or more tethers.

73. The depot assembly of any one of the preceding clauses, wherein the tether comprises one or more of: a suture, a yarn, or a polymeric thread.

74. The depot assembly of any one of the preceding clauses, wherein the fixation portion comprises one or more wings projecting away from the depot.

75. The depot assembly of any one of the preceding clauses, wherein the depot is substantially planar, or semi-cylindrical, or bent, or ridged.

76. The depot assembly of any one of the preceding clauses, wherein the wings are substantially planar, or semi-cylindrical, or bent, or ridged.

77. The depot assembly of any one of the preceding clauses, wherein the fixation portion comprises a plurality of recesses configured to receive a tether therethrough.

78. The depot assembly of any one of the preceding clauses, wherein the recesses comprise at least a first and a second recess formed in opposing sides of the depot.

79. The depot assembly of any one of the preceding clauses, wherein the recesses are configured to receive a suture therethrough.

80. The depot assembly of any one of the preceding clauses, wherein the recesses further comprise third and fourth recesses formed on opposing sides of the depot.

81. The depot assembly of any one of the preceding clauses, wherein the first and second recesses are aligned along a first axis and the third and fourth recesses are aligned along a second axis substantially perpendicular to the first.

82. The depot assembly of any one of the preceding clauses, wherein the depot has an upper surface, a lower surface, and a thinnest side surface extending therebetween, and wherein the recesses are formed in the side surface.

83. The depot assembly of any one of the preceding clauses, wherein the depot has substantially circular or elliptical upper surface and lower surface, and a thinnest side surface extending therebetween, and wherein recesses are formed in the side surface.

84. The depot assembly of any one of the preceding clauses, wherein the fixation portion comprises a receptacle configured to house one or more depots therein.

85. The depot assembly of any one of the preceding clauses, wherein the receptacle comprises a mesh bag.

86. The depot assembly of any one of the preceding clauses, wherein the receptacle is biodegradable.

87. The depot assembly of any one of the preceding clauses, wherein the receptacle comprises a plurality of separate compartments.

88. The depot assembly of any one of the preceding clauses, further comprising a depot disposed within each of the separate compartments.

89. The depot assembly of any one of the preceding clauses, wherein the receptacle is configured to be secured to the treatment site via one or more separate fixation devices.

90. The depot assembly of any one of the preceding clauses, wherein the fixation portion comprises a notch or detent configured to facilitate bending of the depot for placement at the treatment site.

91. The depot assembly of any one of the preceding clauses, wherein the fixation portion comprises a shoulder region of the depot having a greater cross-sectional dimension than a non-shoulder region, the shoulder region configured to engage with a pusher to be advanced through a delivery shaft.

92. The depot assembly of any one of the preceding clauses, wherein the fixation portion comprises a protrusion configured to interlock with a corresponding recess of an adjacent depot assembly.

93. The depot assembly of any one of the preceding clauses, wherein the fixation portion comprises a recess configured to interlock with a corresponding protrusion of an adjacent depot assembly.

94. The depot assembly of any one of the preceding clauses, wherein the fixation portion comprises a ridge extending circumferentially around a long axis of the depot.

95. The depot assembly of any one of the preceding clauses, wherein the fixation portion comprises a plurality of ridges extending circumferentially around a long axis of the depot, the plurality of ridges extending substantially parallel to one another.

96. The depot assembly of the preceding clauses, wherein the ridge defines a projection angled with respect to a long axis of the depot, such that when the ridge engages tissue at a treatment site, the ridge provides greater resistance to proximal movement than to distal movement.

97. The depot assembly of the preceding clauses, wherein the depot comprises an interior void configured to removably receive a portion of a delivery shaft therein.

BRIEF DESCRIPTION OF THE DRAWINGS

Many aspects of the present disclosure can be better understood with reference to the following drawings. The components in the drawings are not necessarily to scale. Instead, emphasis is placed on illustrating clearly the principles of the present disclosure.

FIG. 1 depicts the release of bupivacaine hydrochloride over time from a Xaracoll® sponge.

FIG. 2 is an isometric view of a depot configured in accordance with the present technology.

FIG. 3 depicts the release profile over time of one or more depots of the present technology.

FIG. 4 is an isometric view of a depot in accordance with some embodiments of the present technology.

FIG. 5 is an isometric view of a depot in accordance with some embodiments of the present technology.

FIG. 6 is a cross-sectional view of a depot in accordance with some embodiments of the present technology.

FIG. 7 is a cross-sectional view of a depot in accordance with some embodiments of the present technology.

FIG. 8 is a cross-sectional view of a depot in accordance with some embodiments of the present technology.

FIG. 9A is an isometric view of a depot in accordance with some embodiments of the present technology.

FIG. 9B is a cross-sectional view of the depot shown in FIG. 9A.

FIG. 10 is a cross-sectional view of a depot in accordance with some embodiments of the present technology.

FIG. 11 is a cross-sectional view of a depot in accordance with some embodiments of the present technology.

FIG. 12 is a cross-sectional view of a depot in accordance with some embodiments of the present technology.

FIG. 13 is an isometric view of a depot in accordance with some embodiments of the present technology.

FIGS. 14A-H are depots having different cross-sectional areas and shapes in accordance with the present technology.

FIG. 15 depicts the maximum flexural load of an implant over time from testing performed on implant samples submerged in buffered solution.

FIGS. 16A-16E depict various depot embodiments including a barrier region in accordance with the technology.

FIG. 17 is a schematic representation of core acidification of the prior art.

FIG. 18 is a scanning electron microscope image of a polymer tablet of the prior art after 20 days of degradation.

FIG. 19A is a schematic representation of the degradation of the depots of the present technology.

FIGS. 19B and 19C are scanning electron microscope (“SEM”) images of cross-sections of depots of the present technology at different timepoints during degradation.

FIG. 20 is a perspective view of a depot in accordance with some embodiments of the present technology.

FIG. 21 is cross-sectional view of a depot in accordance with some embodiments of the present technology.

FIG. 22 is cross-sectional view of a depot in accordance with some embodiments of the present technology.

FIG. 23 is cross-sectional view of a depot in accordance with some embodiments of the present technology.

FIG. 24A is a perspective view of a depot in accordance with some embodiments of the present technology.

FIG. 24B is cross-sectional view of the depot shown in FIG. 24A taken along line B-B.

FIG. 24C is cross-sectional view of the depot shown in FIG. 24A taken along line C-C.

FIG. 24D is a perspective view of a depot in accordance with some embodiments of the present technology.

FIG. 25 is a perspective view of a depot in accordance with some embodiments of the present technology.

FIG. 26 is a perspective view of a depot in accordance with some embodiments of the present technology.

FIG. 27 is a perspective view of a depot in accordance with some embodiments of the present technology.

FIG. 28 is a perspective view of a depot in accordance with some embodiments of the present technology.

FIG. 29A is a side cross-sectional view of a depot in accordance with some embodiments of the present technology.

FIG. 29B is a cross-sectional view of the depot shown in FIG. 29A taken along line B-B.

FIG. 30 is a side cross-sectional view of a depot in accordance with some embodiments of the present technology.

FIG. 31 is a side cross-sectional view of a depot in accordance with some embodiments of the present technology.

FIG. 32 is a perspective view of a depot in accordance with some embodiments of the present technology.

FIG. 33 is a side cross-sectional view of a depot in accordance with some embodiments of the present technology.

FIG. 34 is a side cross-sectional view of a depot in accordance with some embodiments of the present technology.

FIG. 35 is a side cross-sectional view of a depot in accordance with some embodiments of the present technology.

FIG. 36A is a side cross-sectional view of a depot in accordance with some embodiments of the present technology.

FIG. 36B is a cross-sectional view of the depot shown in FIG. 36A taken along line B-B.

FIG. 36C is a side cross-sectional view of a depot in accordance with some embodiments of the present technology.

FIG. 36D is a side cross-sectional view of a depot in accordance with some embodiments of the present technology.

FIG. 37A is a side cross-sectional view of a depot in accordance with some embodiments of the present technology.

FIG. 37B depicts example release profiles over time of the depot shown in FIG. 37A.

FIG. 38A is a side cross-sectional view of a depot in accordance with some embodiments of the present technology.

FIG. 38B depicts example release profiles over time of the depot shown in FIG. 38A.

FIG. 39A is a side cross-sectional view of a depot in accordance with some embodiments of the present technology.

FIG. 39B depicts example release profiles over time of the depot shown in FIG. 39A.

FIG. 40A is a perspective view of a depot in accordance with some embodiments of the present technology.

FIG. 40B is a perspective view of a depot in accordance with some embodiments of the present technology.

FIG. 41A is a side view of a depot in a straightened state in accordance with some embodiments of the present technology.

FIG. 41B is a side view of the depot shown in FIG. 41A in a curved state.

FIG. 42A is a side view of a depot in a straightened state in accordance with some embodiments of the present technology.

FIG. 42B is a side view of the depot shown in FIG. 42A in a curved state.

FIG. 43A is a perspective view of a depot in a straightened state in accordance with some embodiments of the present technology.

FIG. 43B is cross-sectional view of the depot shown in FIG. 43A taken along line B-B.

FIG. 43C is a side view of the depot shown in FIG. 43A in a curved state.

FIG. 44 is a side view of a depot deployed at a target site in a body in accordance with some embodiments of the present technology.

FIG. 45 is a side view of a depot deployed at a target site in a body in accordance with some embodiments of the present technology.

FIG. 46 is a side view of a depot in accordance with some embodiments of the present technology.

FIG. 47 is a side view of a depot in accordance with some embodiments of the present technology.

FIGS. 48A and 48B are perspective views of depots in accordance with some embodiments of the present technology.

FIG. 49A-C are perspective, top, and side views, respectively, of a depot in accordance with some embodiments of the present technology.

FIG. 50A is an end view of a depot in a curled state in accordance with some embodiments of the present technology.

FIG. 50B is a side view of the depot shown in FIG. 50A in an uncurled state.

FIG. 51 illustrates a plurality of depots in accordance with some embodiments of the present technology.

FIG. 52A is an end view of a plurality of depots in accordance with some embodiments of the present technology.

FIG. 52B is a side view of the depots shown in FIG. 52A.

FIG. 52C illustrates a method of manufacturing the depots shown in FIGS. 52A and 52B.

FIG. 53 depicts the in vitro release profile for the depots as described in Example 1, in accordance with the present technology.

FIG. 54 depicts the in vitro release profile for the depots as described in Example 2A, in accordance with the present technology.

FIG. 55 depicts the in vitro release profile for the depots as described in Example 2B, in accordance with the present technology.

FIG. 56 depicts the in vitro release profile for the depots as described in Example 3, in accordance with the present technology.

FIG. 57A shows the in vivo blood plasma bupivacaine concentration over time for a rabbit implanted with the depots as described in Example 4, in accordance with the present technology.

FIG. 57B depicts the in vitro release profile over time for the sample depots as described in Example 4, in accordance with the present technology.

FIG. 57C shows the in vivo blood plasma bupivacaine concentration over time for a rabbit implanted with the depots as described in Example 4, in accordance with the present technology.

FIG. 57D depicts the in vitro release profile over time of the sample depots as described in Example 4, in accordance with the present technology.

FIG. 58 shows the in vivo blood plasma bupivacaine concentration over time for a canine implanted with the depots as described in Example 5, in accordance with the present technology.

FIG. 59A shows the in vivo blood plasma bupivacaine concentration over time for a sheep implanted with the depots as described in Example 6, in accordance with the present technology.

FIG. 59B shows the in vivo synovial bupivacaine concentration over time for a sheep implanted with the depots as described in Example 6, in accordance with the present technology.

FIG. 59C is a plot depicting the blood plasma bupivacaine concentration versus the synovial bupivacaine concentration over time for a sheep implanted with the depots as described in Example 6, in accordance with the present technology.

FIGS. 60A and 60B illustrate common locations within a patient that may be sites where surgery is conducted and locations where the depot can be administered.

FIG. 61 is a table showing common surgical procedures for which the depots of the present technology may be utilized for treating postoperative pain. FIG. 61 also shows nerve targets and anatomical access/placement associated with the different surgeries.

FIGS. 62A-62C are anterior, lateral, and medial views of a human knee, showing the location of the nerves innervating the knee.

FIG. 63A is a splayed view of a human knee exposing the intracapsular space and identifying potential locations for positioning one or more depots.

FIG. 63B is a splayed view of a human knee exposing the intracapsular space and showing several depots positioned within for treating postoperative pain.

FIGS. 64A and 64B show anterior and posterior, extracapsular views of a human knee, showing the location of the nerves innervating the knee at an extracapsular location.

FIG. 65 is an anterior view of a partially splayed human knee, showing an extracapsular space and showing several depots of the present technology positioned at the extracapsular space for treating postoperative pain.

FIG. 66A is a depot assembly including a fixation portion configured in accordance with embodiments of the present technology.

FIG. 66B is an enlarged view of the depot assembly shown in FIG. 66A.

FIGS. 67A and 67B illustrate a method of manufacturing the depot assembly shown in FIGS. 66A and 66B in accordance with embodiments of the present technology.

FIG. 68 is a depot assembly including a fixation portion in accordance with embodiments of the present technology.

FIG. 69 is a depot assembly including a fixation portion engaged with a suture in accordance with embodiments of the present technology.

FIG. 70 is another embodiment of a depot assembly including a fixation portion engaged with a suture in accordance with the present technology.

FIG. 71 is another embodiment of a depot assembly including a fixation portion in accordance with the present technology.

FIG. 72 is another embodiment of a depot assembly including a fixation portion in accordance with the present technology.

FIGS. 73A and 73B are top and side views, respectively, of a depot assembly affixed to a treatment site in accordance with embodiments of the present technology.

FIG. 74A shows a depot assembly positioned within a delivery system configured in accordance with embodiments of the present technology.

FIG. 74B is an enlarged, cross-sectional view of a portion of the delivery device shown in FIG. 74A.

FIGS. 75-77B illustrate examples of a depot assembly positioned at a treatment site in accordance with embodiments of the present technology.

FIG. 78 is another embodiment of a depot assembly including a fixation portion in accordance with the present technology.

FIG. 79A illustrates depot assemblies having fixation portions.

FIG. 79B is an enlarged view of the fixation portion of the depot assembly shown in FIG. 79A.

FIG. 80 illustrates a variety of depot assemblies having fixation portions in accordance with embodiments of the present technology.

FIGS. 81A-81D illustrate plan, side, end, and perspective views, respectively, of another embodiment of a depot assembly including a fixation portion in accordance with the present technology.

FIG. 82 illustrates a plurality of depots disposed within a delivery receptacle in accordance with embodiments of the present technology.

FIG. 83 illustrates a system including a plurality of depot assemblies coupled together in accordance with embodiments of the present technology.

FIG. 84 illustrates another embodiment of a system including a plurality of depot assemblies coupled together in accordance with the present technology.

FIG. 85 illustrates another embodiment of a system including a plurality of depot assemblies coupled together in accordance with the present technology.

FIG. 86 illustrates another embodiment of a system including a plurality of depot assemblies coupled together in accordance with the present technology.

FIG. 87 illustrates another embodiment of a system including a plurality of depot assemblies coupled together in accordance with the present technology.

FIG. 88 illustrates another embodiment of a system including a plurality of depot assemblies coupled together in accordance with the present technology.

FIG. 89 illustrates another embodiment of a depot assembly including a fixation portion in accordance with the present technology.

FIGS. 90A and 90B illustrate additional embodiments of depot assemblies having fixation portions in accordance with the present technology.

FIG. 91A illustrates a depot assembly having fixation portions coupled to sutures in accordance with the present technology.

FIG. 91B illustrates the depot assembly of FIG. 91A after placement at a treatment site.

FIGS. 92A and 92B illustrate top and side views, respectively, of a coiled depot assembly in a constrained state in accordance with embodiments of the present technology.

FIG. 92C illustrates a side view of the coiled depot assembly shown in FIGS. 92A and 92B in an unconstrained state.

FIG. 92D illustrates delivery of the coiled depot assembly shown in FIGS. 92A-92C using a delivery device.

FIG. 93A illustrates a side cross-sectional view of a depot assembly having a fixation portion in accordance with embodiments of the present technology.

FIG. 93B illustrates a side cross-sectional view of a portion of a system for delivering the depot assembly of FIG. 93A.

FIG. 93C illustrates example placement of the depot assembly of FIG. 93A at a treatment site in the intracapsular space.

FIG. 94A illustrates a side cross-sectional view of a depot assembly having a fixation portion in accordance with embodiments of the present technology.

FIG. 94B illustrates a side cross-sectional view of a portion of a system for delivering the depot assembly of FIG. 94A.

FIGS. 95A-95C illustrate steps of securing a depot at a treatment site in accordance with embodiments of the present technology.

FIGS. 96A-96B illustrate steps of delivering a depot to a treatment site in accordance with embodiments of the present technology.

FIGS. 97A-97C illustrate steps of delivering a depot to a treatment site in accordance with embodiments of the present technology.

DETAILED DESCRIPTION

The present technology relates to implantable depots for the sustained, controlled release of therapeutic agents, and associated devices, systems, and methods of use. Examples of the depots of the present technology and associated release kinetics are described below with reference to FIGS. 2-52C and Section I. Selected examples of the depots of the present technology and associated release profiles are described below with reference to FIGS. 53-59C and Section II. Selected devices, systems, and methods for using the depots of the present technology for treating postoperative pain associated with orthopedic surgery are described below with reference to FIGS. 60A-65 and Section II. Selected devices, systems, and methods for using the depots of the present technology for treating postoperative pain associated with other surgeries are described below at Section IV. Selected systems and methods for delivering and/or fixing depots at or adjacent to treatment sites are described below with reference to FIGS. 66A-97C and Section V.

I. Examples of Depots of the Present Technology

As noted previously, prior art drug delivery systems often suffer from a lack of a true controlled release mechanism in that they typically provide a burst of drug upon contact with surrounding physiologic fluids followed by a residual release of drug. For example, FIG. 1 shows an example prior art biodegradable polymer-based delivery system, in which the drug concentration in plasma peaked within 15 hours of implantation, thereby illustrating a duration of effect that is inadequate.

Disclosed herein are implantable depots and associated devices, systems, and methods for treating (i.e., preventing, reducing, and/or eliminating) postoperative pain via sustained, controlled release of a therapeutic agent while the depot is implanted at a treatment site in vivo. Many embodiments of the present technology comprise one or more depots configured to be implanted at or near a surgical site of a patient to treat pain following a surgery. While implanted in vivo, the depot(s) are configured to release a therapeutic agent (such as an analgesic) to the surgical site in a controlled, prescribed manner for at least 3 days following implantation.

As used herein, a “depot” comprises a composition configured to administer at least one therapeutic agent to a treatment site in the body of a patient in a controlled, sustained manner. The depot also comprises the therapeutic agent itself. A depot may comprise a physical structure or carrier to configured to perform or enhance one or more functions related to treatment, such as facilitating implantation and/or retention in a treatment site (e.g., tissue at the intracapsular and/or extracapsular space of a knee joint), modulating the release profile of the therapeutic agent (e.g., creating a two-phase release profile), increasing release towards a treatment site, reducing release away from a treatment site, or combinations thereof. In some embodiments, a “depot” includes but is not limited to films, sheets, strips, ribbons, capsules, coatings, matrices, wafers, pills, pellets, or other pharmaceutical delivery apparatus or a combination thereof. Moreover, as used herein, “depot” may refer to a single depot, or may refer to multiple depots. As an example, the statement “The depot may be configured to release 2 g of therapeutic agent to a treatment site” describes (a) a single depot that is configured to release 2 g of therapeutic agent to a treatment site, and (b) a plurality of depots that collectively are configured to release 2 g of therapeutic agent to a treatment site.

FIG. 2 is an isometric view of an implantable depot 100 in accordance with several embodiments of the present technology. The depot 100 may be a thin, multi-layered polymer film configured to be implanted at a treatment site comprising a therapeutic region 200 containing a therapeutic agent (such as an analgesic), and a control region 300 configured to regulate the release of the therapeutic agent from the depot 100 in a controlled and sustained manner. The depot 100 may include a high therapeutic payload of the therapeutic agent, especially as compared to other known films of equal thickness or polymer weight percentage, while exhibiting mechanical properties (e.g., flexural strength) sufficient to withstand storage, handling, implantation, and/or retention in the treatment site. For example, in some embodiments, the depot 100 comprises at least 50% by weight of the therapeutic agent.

The control region 300 may comprise at least one bioresorbable polymer and at least one releasing agent mixed with the polymer, and the therapeutic region 200 may comprise at least one bioresorbable polymer and at least one releasing agent mixed with the polymer and the therapeutic agent. The control region 300 may optionally include a therapeutic agent, or the control region 300 may include no therapeutic agent at all. The therapeutic region 200 may optionally include no releasing agent at all. The releasing agent in the control region 300 may be the same or may be different from the releasing agent in the therapeutic region 200. The bioresorbable polymer in the control region 300 may be the same or may be different from the bioresorbable polymer in the therapeutic region 200. As detailed below, in some embodiments the therapeutic region 200 and/or the control region 300 may have different constituents and/or formulations.

When exposed to a fluid (e.g., physiologic fluid), the releasing agent can have a dissolution rate that is faster than the degradation rate of the bioresorbable polymer. Accordingly, when a fluid contacts the depot 100 (e.g., after implantation of the depot 100 in a treatment site), the releasing agent dissolves within the surrounding polymer of the control region 300 and/or therapeutic region 200 faster than the polymer degrades. As the releasing agent dissolves, the space vacated by the dissolved releasing agent forms diffusion openings (e.g., channels, voids, pores, etc.) in the surrounding polymer region. The formation of diffusion openings may enhance the release of therapeutic agent from the polymer region and into the surrounding physiologic fluid. In some embodiments, the release rate of the therapeutic agent is higher when there are diffusion openings in the polymer region, compared to when there are no diffusion openings in the polymer region.

The concentration and type of releasing agent, among other parameters, can be selected to regulate the release of the therapeutic agent from the therapeutic region 200 and/or through the control region 300 into the surrounding fluid at a controlled dosage rate over a desired period of time. For example, a higher concentration of releasing agent may increase the release rate of the therapeutic agent, while a lower concentration of releasing agent may decrease the release rate of the therapeutic agent. The therapeutic region 200 may comprise a different concentration and/or type of releasing agent than the control region 300, or may comprise the same concentration and/or type of releasing agent.

The position and/or geometry of the control region 300 can be configured to modulate the release profile of the therapeutic agent from the therapeutic region 200. As shown in FIG. 2, at least a portion of the control region 300 may be disposed on or adjacent the therapeutic region 200 such that, when the depot 100 is initially positioned in vivo, the control region 300 is between at least a portion of the therapeutic region 200 and physiologic fluids at the treatment site. For example, the control region 300 can cover all or a portion of one or more surfaces of the therapeutic region 200. When the depot 100 is exposed to physiologic fluids, the therapeutic agent elutes from the exposed surfaces of the therapeutic region 200 and through the control region 300 by way of the diffusion openings created by dissolution of the releasing agent. In general, the therapeutic agent elutes from the exposed surfaces of the therapeutic region 200 at a faster (e.g., greater) rate than through the control region 300. As a result, the control region 300 prolongs the release of the therapeutic agent from the therapeutic region 200 to provide for longer release times and regulates the dosage rate, e.g., to provide the desired degree of pain relief and avoid complications related to overdosing.

The depot of the present technology is configured to release a therapeutic agent in a highly controlled, predetermined manner that is specifically tailored to the medical condition being treated and the therapeutic agent used. As described in greater detail below in Section II, the release kinetics of the depots may be customized for a particular application by varying one or more aspects of the depot's composition and/or structure, such as the shape and/or size of the depot, therapeutic region 200, and/or control region 300; the exposed surface area of the therapeutic region 200; the type of polymer (in the therapeutic region 200 and/or in the control region 300); the weight percentage of the therapeutic agent, the polymer, and/or the releasing agent (within a particular region or generally throughout the depot 100); and the composition of the therapeutic region 200 and the control region 300.

As shown in FIG. 3, in many embodiments the depot 100 (or a system of depots 100) is configured to release a disproportionately larger volume of a therapeutic agent per day for a first period of time than for a longer second period of time. In some embodiments, the depot 100 (or a system of depots 100) is configured to release the therapeutic agent for at least 14 days post-implantation (or post-immersion in a fluid), where a controlled burst of about 20% to about 50% of the therapeutic agent payload is released in the first 3-5 days, and at least 80% of the remaining therapeutic agent payload is released at a slower rate over the last 10-11 days. In some embodiments, at least 90% of the therapeutic agent payload is released by the end of 14 days.

A two-stage, second-order release profile—such as that shown in FIG. 3—may be especially beneficial in the context of treating pain resulting from a total knee arthroplasty (“TKA”). TKA patients typically experience the greatest pain within the first 1-3 days following surgery (clinically referred to as “acute pain”) with increasingly less pain over the next 7-10 days (clinically referred to as “subacute pain”). The acute period often overlaps or coincides with the patient's inpatient care (usually 1-3 days), and the subacute period generally begins when the patient is discharged and returns home. The two-stage, second-order release profile shown in FIG. 3 is also beneficial for other surgical applications, such as other orthopedic applications (e.g., ligament repair/replacement and other damage to the knee, shoulder, ankle, etc.) or non-orthopedic surgical applications. Excessive pain following any surgery may extend inpatient care, cause psychological distress, increase opioid consumption, and/or impair patient participation in physical therapy, any of which may prolong the patient's recovery and/or mitigate the extent of recovery. Pain relief during the subacute period may be particularly complicated to manage, as patient compliance with the prescribed pain management regimen drops off when patients transition from an inpatient to home environment.

To address the foregoing challenges in post-surgical pain management, the depot 100 (or depot system comprising multiple depots 100) of the present technology may have a release profile tailored to meet the pain management needs specific to the acute and subacute periods. For example, to address the greater acute pain that occurs immediately following surgery, the depot 100 may be configured to release the therapeutic agent at a faster rate for the first 3-5 days after implantation (as shown in FIG. 3) compared to a subsequent period of 9-11 days. In some embodiments, the depot 100 may deliver a local anesthetic at a rate of from about 150 mg/day to about 400 mg/day during this first, acute period. To address the diminishing pain during the subacute period, the depot 100 may be configured to release the therapeutic agent at a slower rate for the remaining 9-11 days. In some embodiments, the depot 100 may deliver a local anesthetic at a rate of from about 50 mg/day to about 250 mg/day during this second, subacute period. In some embodiments, the rate of release continuously decreases throughout the first period and/or the second period.

The release profile of the depot 100 may be tuned to release a therapeutic agent for other durations and/or at other release rates by adjusting the structure, composition, and the process by which the depot is manufactured. For example, in some embodiments the depot 100 may be configured to release the therapeutic agent at a constant rate throughout the entire duration of release. In particular embodiments, the depot 100 may be configured to release the therapeutic agent at a constant rate for a first period of time and at a non-constant rate for a second period of time (which may occur before or after the first period of time).

In some embodiments, the depot 100 is configured to release no more than 20%, no more than 25%, no more than 30%, no more than 35%, no more than 40%, no more than 45%, no more than 50%, no more than 55%, no more than 60%, no more than 65%, or no more than 70% of the therapeutic agent in the first day, 2 days, 3 days, 4 days, 5 days, 6 days, 8 days, 9 days, 10 days, 11 days, 12 days, or 13 days of the duration of release, and wherein at least 75%, at least 80%, at least 85%, at least 90%, at least 95%, or 100% of the remaining therapeutic agent is released in the remaining days of the duration of release. The intended duration of release may be at least 1 day, at least 2 days, at least 3 days, at least 4 days, at least 5 days, at least 6 days, at least 7 days, at least 8 days, at least 9 days, at least 10 days, at least 11 days, at least 12 days, at least 13 days, at least 14 days, at least 15 days, at least 16 days, at least 17 days, at least 18 days, at least 19 days, at least 20 days, at least 21 days, at least 22 days, at least 23 days, at least 24 days, at least 25 days, at least 26 days, at least 27 days, at least 28 days, at least 29 days, or at least 30 days.

In some embodiments, the depot 100 is configured to release at least 70%, at least 75%, at least 80%, at least 85%, at least 90%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100% of the therapeutic agent in the depot 100 within the intended duration of treatment. The intended duration of treatment may be at least 1 day, at least 2 days, at least 3 days, at least 4 days, at least 5 days, at least 6 days, at least 7 days, at least 8 days, at least 9 days, at least 10 days, at least 11 days, at least 12 days, at least 13 days, at least 14 days, at least 15 days, at least 16 days, at least 17 days, at least 18 days, at least 19 days, at least 20 days, at least 21 days, at least 22 days, at least 23 days, at least 24 days, at least 25 days, at least 26 days, at least 27 days, at least 28 days, at least 29 days, at least 30 days, at least 40 days, at least 50 days, at least 60 days, at least 70 days, at least 90 days, at least 100 days, at least 200 days, at least 300 days, or at least 365 days.

In some embodiments, the depot 100 is configured to release from about 50 mg/day to about 600 mg/day, 100 mg/day to about 500 mg/day, or from about 100 mg/day to about 400 mg/day, or from about 100 mg/day to about 300 mg/day of the therapeutic agent to the treatment site. In general, the release rate can be selected to deliver the desired dosage to provide the extent of pain relief needed at a given time after the surgical procedure, control toxicity, and deliver the therapeutic agent for a sufficient period of time for pain relief.

In some embodiments, the depot 100 is configured to release from about 50 mg/day to about 600 mg/day, from about 100 mg/day to about 500 mg/day, or from about 100 mg/day to about 400 mg/day, or from about 100 mg/day to about 300 mg/day of the therapeutic agent to the treatment site within a first period of release. The depot 100 can further be configured to release from about 500 mg/day to about 600 mg/day, about 100 mg/day to about 500 mg/day, or from about 100 mg/day to about 400 mg/day, or from about 100 mg/day to about 300 mg/day of the therapeutic agent to the treatment site within a second period of release. The release rate during the first period may be the same as, different than, less than, or greater than the release rate during the second period. Moreover, the first period may be longer or shorter than the second period. The first period may occur before or after the second period.

In some embodiments, the depot 100 is configured to release no more than 50 mg, no more than 100 mg, no more than 150 mg, no more than 200 mg, no more than 250 mg, no more than 300 mg, no more than 350 mg, no more than 400 mg, no more than 450 mg, no more than 500 mg, no more than 600 mg, no more than 700 mg, no more than 800 mg, no more than 900 mg, no more than 1000 mg, at least 10 mg, at least 20 mg, at least 30 mg, at least 40 mg, at least 50 mg, at least 60 mg, at least 70 mg, at least 80 mg, at least 90 mg, at least 100 mg, at least 110 mg, at least 120 mg, at least 130 mg, at least 140 mg, at least 150 mg, at least 160 mg, at least 170 mg, at least 180 mg, at least 190 mg, at least 200 mg, at least 210 mg, at least 220 mg, at least 230 mg, at least 240 mg, at least 250 mg, at least 260 mg, at least 270 mg, at least 280 mg, at least 290 mg, or at least 300 mg of the therapeutic agent within any day of a first period of release. This may be useful for providing different degrees of pain relief at different times after the surgical procedure, and it may also be useful to control toxicity. In such embodiments, the depot 100 may be configured to release no more than 50 mg, no more than 100 mg, no more than 150 mg, no more than 200 mg, no more than 250 mg, no more than 300 mg, no more than 350 mg, no more than 400 mg, no more than 450 mg, no more than 500 mg, no more than 600 mg, no more than 700 mg, no more than 800 mg, no more than 900 mg, no more than 1000 mg, at least 10 mg, at least 20 mg, at least 30 mg, at least 40 mg, at least 50 mg, at least 60 mg, at least 70 mg, at least 80 mg, at least 90 mg, at least 100 mg, at least 110 mg, at least 120 mg, at least 130 mg, at least 140 mg, at least 150 mg, at least 160 mg, at least 170 mg, at least 180 mg, at least 190 mg, at least 200 mg, at least 210 mg, at least 220 mg, at least 230 mg, at least 240 mg, at least 250 mg, at least 260 mg, at least 270 mg, at least 280 mg, at least 290 mg, or at least 300 mg of the therapeutic agent within any day of a second period of release. The first period of release and/or the second period of release may be 1 day, 2 days, 3 days, 4 days, 5 days, 6 days, 7 days, 8 days, 9 days, 10 days, 11 days, 12 days, 13 days, 14 days, 15 days, 16 days, 17 days, 18 days, 19 days, 20 days, 21 days, 22 days, 23 days, 24 days, 25 days, 26 days, 27 days, 28 days, 29 days, or 30 days. The depot 100 may be configured to release the therapeutic agent at a first rate during the first period and at a second rate during the second period. The first rate may be the same as, different than, less than, or greater than the second rate. In some embodiments, the first rate is at least 2-fold, 3-fold, 4-old, 5-fold, 6-fold, 7-fold, 8-fold, 9-fold, or 10-fold greater than the second rate, or vice versa. Moreover, the first period may be longer or shorter than the second period. The first period may come before or after the second period.

In some embodiments, the depot 100 is configured to release the therapeutic agent at a treatment site in vivo and/or in the presence of one or more fluids for no less than 1 day, no less than 2 days, no less than 3 days, no less than 4 days, no less than 5 days, no less than 6 days, no less than 7 days, no less than 8 days, no less than 9 days, no less than 10 days, no less than 11 days, no less than 12 days, no less than 13 days, no less than 14 days, no less than 15 days, no less than 16 days, no less than 17 days, no less than 18 days, no less than 19 days, no less than 20 days, no less than 21 days, no less than 22 days, no less than 23 days, no less than 24 days, no less than 25 days, no less than 26 days, no less than 27 days, no less than 28 days, no less than 29 days, no less than 30 days, no less than 40 days, no less than 50 days, no less than 60 days, no less than 70 days, no less than 90 days, no less than 100 days, no less than 200 days, no less than 300 days, or no less than 365 days.

The release kinetics of the depots of the present technology may be tuned for a particular application by varying one or more aspects of the depot's structure and/or composition, such as the exposed surface area of the therapeutic region 200, the porosity of the control region 300 during and after dissolution of the releasing agent, the concentration of the therapeutic agent in the therapeutic region, the post-manufacturing properties of the polymer, the structural integrity of the depots to avoid a sudden release of the therapeutic agent, the relative thicknesses of the therapeutic region 200 compared to the control region 300, and other properties of the depots. Several embodiments of depots of the present technology combine one or more of these properties in a manner that produces exceptional two-phase release profiles in animal studies that significantly outperform existing injectable or implantable systems, while also overcoming the shortcomings of disclosed prophetic devices. For example, several embodiments have exhibited two-phase release profiles that deliver an adequate mass of therapeutic agent to treat pain associated with joint replacement surgery or other applications over a 14-day period while maintaining sufficient structural integrity to withstand the forces of a joint to avoid a sudden release of too much therapeutic agent. This surprising result enables depots of the present technology to at least reduce, if not replace, opioids and/or enhance other existing pain relief systems for orthopedic surgical applications, non-orthopedic surgical applications, and for other applications (e.g., oncological).

For example, the release profile can be tuned by, at least in part, controlling the amount of exposed surface area of the therapeutic region 200 because depots having a therapeutic region 200 covered only partially by a control region 300 (see, for example, FIGS. 2, 4-8, and 13) will generally release a higher proportion of the total payload over a shorter period of time as compared to embodiments where the therapeutic region 200 is completely encapsulated by the control region 300 (see, for example, FIGS. 9A-12). More specifically, depot designs having a therapeutic region 200 with exposed surfaces will typically release the therapeutic agent at a high, substantially linear rate for a first period of time and then at a lower, substantially linear rate for a second period of time. Alternatively, depot designs having a therapeutic region 200 with surfaces that are substantially covered by one or more control regions 300 may achieve a zero-order release such that the release of the payload of therapeutic agent is at substantially the same rate.

As shown in FIG. 4, in some embodiments the depot 100 may comprise a multi-layer polymer film having a therapeutic region 200 and first and second control regions 300a, 300b positioned at opposite surfaces 100a, 100b of the therapeutic region 200. The depot 100 may be in the form of a flexible, rectangular strip having a length L, a width W, and a height H (or thickness). In some embodiments, the depot 100 has (a) a length L of from about 5-40 mm, about 10-30 mm, about 15-20 mm, about 20-35 mm, about 20-30 mm, about 20-25 mm, about 26-30 mm, about 5 mm, about 10 mm, about 11 mm, about 12 mm, about 13 mm, about 14 mm, about 15 mm, about 16 mm, about 17 mm, about 18 mm, about 19 mm about 20 mm, about 21 mm, about 22 mm, about 23 mm, about 24 mm, about 25 mm, about 26 mm, about 27 mm, about 28 mm, about 29 mm, about 30 mm, about 10-15 mm, about 12-16 mm, about 15-20 mm, about 21-23 mm, about 22-24 mm, about 23-25 mm, about 24-26 mm, about 25-27 mm, about 26-28 mm, about 27-29 mm, or about 28-30 mm, (b) a width W of from about 5-40 mm, about 10-30 mm, about 15-20 mm, about 20-35 mm, about 20-30 mm, about 20-25 mm, about 26-30 mm, about 5 mm, about 10 mm, about 11 mm, about 12 mm, about 13 mm, about 14 mm, about 15 mm, about 16 mm, about 17 mm, about 18 mm, about 19 mm about 20 mm, about 21 mm, about 22 mm, about 23 mm, about 24 mm, about 25 mm, about 26 mm, about 27 mm, about 28 mm, about 29 mm, about 30 mm, about 10-15 mm, about 12-16 mm, about 15-20 mm, about 21-23 mm, about 22-24 mm, about 23-25 mm, about 24-26 mm, about 25-27 mm, about 26-28 mm, about 27-29 mm, or about 28-30 mm (c) a height H of from about 0.4 mm to about 4 mm, about 1 mm to about 3 mm, about 1 mm to about 2 mm, at least 0.4 mm, at least 0.5 mm, at least 0.6 mm, at least 0.7 mm, at least 0.8 mm, at least 0.9 mm, at least 1 mm, at least 1.2 mm, at least 1.4 mm, at least 1.5 mm, at least 1.6 mm, at least 1.7 mm, at least 1.8 mm, at least 2 mm, at least about 3 mm, no more than 0.5 mm, no more than 0.6 mm, no more than 0.7 mm, no more than 0.8 mm, no more than 0.9 mm, etc.). In some embodiments, the depot 100 may have other shapes and/or dimensions, such as those detailed below

Additionally, some embodiments of the depot shown in FIG. 4 are configured such that a thickness of the control regions 300a and 300b, either individually or collectively, is less than or equal to 1/10 of a thickness of the therapeutic region 200. The thickness of the control regions 300a and 300b, either individually or collectively, can further be no more than 1/12.5, 1/15, 1/17.5, 1/20, 1/22.5, 1/25, 1/30, 1/40, 1/50, 1/75, or 1/100 of the thickness of the therapeutic region 200. In those embodiments with multiple sub-control regions, one or more of the sub-control regions may individually be less than or equal to 1/10, 1/12.5, 1/15, 1/17.5, 1/20, 1/22.5, 1/25, 1/27.5, 1/30, 1/32.5, 1/35, 1/37.5, 1/40, 1/42.5, 1/45, 1/47.5, 1/50, 1/55, 1/60, 1/65, 1/70, 1/75, 1/80, 1/85, 1/90, 1/95, or 1/100 of a thickness of the therapeutic region. In those embodiments where the control region comprises a single control region, the control region may have a thickness that is less than or equal to 1/10, 1/12.5, 1/15, 1/17.5, 1/20, 1/22.5, 1/25, 1/27.5, 1/30, 1/32.5, 1/35, 1/37.5, 1/40, 1/42.5, 1/45, 1/47.5, 1/50, 1/55, 1/60, 1/65, 1/70, 1/75, 1/80, 1/85, 1/90, 1/95, or 1/100 of a thickness of the therapeutic region. In those embodiments with multiple sub-control regions, one or more of the sub-control regions may individually be less than or equal to 1/10, 1/12.5, 1/15, 1/17.5, 1/20, 1/22.5, 1/25, 1/27.5, 1/30, 1/32.5, 1/35, 1/37.5, 1/40, 1/42.5, 1/45, 1/47.5, 1/50, 1/55, 1/60, 1/65, 1/70, 1/75, 1/80, 1/85, 1/90, 1/95, or 1/100 of a thickness of the depot. In those embodiments where the control region comprises a single control region, the control region may have a thickness that is less than or equal to 1/10, 1/12.5, 1/15, 1/17.5, 1/20, 1/22.5, 1/25, 1/27.5, 1/30, 1/32.5, 1/35, 1/37.5, 1/40, 1/42.5, 1/45, 1/47.5, 1/50, 1/55, 1/60, 1/65, 1/70, 1/75, 1/80, 1/85, 1/90, 1/95, or 1/100 of a thickness of the depot.

The control regions 300a, 300b may only cover a portion of the therapeutic region 200 such that a portion of each of the lateral surfaces (e.g., sidewall) of the therapeutic region 200 is exposed to physiologic fluids immediately upon implantation of the depot 100 in vivo. When the depot 100 is exposed to physiologic fluids (or any similar fluid in an in vitro setting), the therapeutic agent will elute from the exposed surfaces 202 (in addition to through the control regions 300a, 300b), such that the therapeutic agent is released faster than if the therapeutic region 200 had no exposed regions. As such, the surface area of the exposed surfaces 202 may be tailored to provide an initial, controlled burst, followed by a tapering release (for example, similar to that shown at FIG. 3). The initial, more aggressive release of the therapeutic agent is slowed in part by the control regions 300a, 300b that initially reduce the surface area of the therapeutic region 200 exposed to the fluids. Unlike the depots 100 of the present technology, many conventional drug-eluting technologies provide an initial, uncontrolled burst release of drug when exposed to physiologic fluids. Several embodiments of depots of the present technology not only enable enough therapeutic agent to be implanted for several days' or weeks' worth of dosage to achieve a sustained, durable, in vivo pharmacological treatment, but they also release the therapeutic agent as prescribed and thereby prevent a substantial portion of the entire payload being released in an uncontrolled manner that could potentially result in complications to the patient and/or reduce the remaining payload such that there is not enough therapeutic agent remaining in the depot to deliver a therapeutic amount for the remaining duration of release.

In some embodiments, the depot 100 shown in FIG. 4 is configured such that about 20% to about 50% of the analgesic is released in the first about 3 days to about 5 days of the 14 days, and wherein at least 80% of the remaining analgesic is released in the last about 9 days to about 11 days of the 14 days. This release profile provides higher dosages of the therapeutic agent during the acute period after surgery compared to the subacute period. In some embodiments, the depot 100 shown in FIG. 4 is configured to release about 100 mg to about 500 mg of analgesic to the treatment site per day, and in some cases no more than 400 mg or no more than 300 mg of analgesic per day within the first 3 days of implantation and no more than 200 mg per day in the remaining days.

Several embodiments of the depot 100 shown in FIG. 4 are also configured to maintain their structural integrity even after a substantial portion of the releasing agent has eluted from the depot 100. As the releasing agent(s) dissolves and therapeutic agent(s) elutes, the functional mechanical aspects of the depot 100 may change over time. Such mechanical aspects include structural integrity, flexural strength, tensile strength, or other mechanical characteristics of the depot. If a depot 100 experiences too much degradation too fast, it may fail mechanically and release an undesirable burst of therapeutic agent into the body. Several embodiments of depots 100 shown in FIG. 4 are loaded with enough therapeutic agent to deliver 100 mg to 500 mg of the therapeutic agent per day while still being able to maintain its structural integrity such that depot remains largely intact up to at least 14 days after implantation. A depot can be sufficiently intact, for example, if it does not fracture into multiple component pieces with two or more of the resulting pieces being at least 5% of the previous size of the depot. Alternatively, or additionally, a depot can be considered to be sufficiently intact if the release rate of the therapeutic agent does not increase by more than a factor of three as compared to the release rate of therapeutic agent in a control depot submerged in a buffered solution.

The therapeutic agent can be at least 50%-95% by weight of the total weight of the depot 100 before implantation, or 55%-85% by weight of the total weight of the depot 100 before implantation, or 60%-75% by weight of the total weight of the depot 100 before implantation. Likewise, the polymer may be no more than 5%-50% by weight of the total weight of the depot 100 before implantation, or 10%-50% by weight of the total weight of the depot 100 before implantation, or 15%-45% by weight of the total weight of the depot 100 before implantation, or 20%-40% by weight of the total weight of the depot 100 before implantation, or no more than 25%, no more than 30%, no more than 35%, or no more than 40%. The ratio of the mass of the therapeutic agent in the depot 100 to the mass of the polymer in the depot 100 can be at least 16:1, 15:1, 14:1, 13:1, 12:1, 11:1, 10:1, 9:1, 8:1, 7:1, 6:1, 5:1, 4:1, 3:1, or 2:1.

Several embodiments of the depot 100 shown in FIG. 4 having one or more combinations of the parameters described in the preceding paragraphs have provided exceptional results in animal studies as described herein. For example, a depot 100 was configured such that (a) the thickness of the control regions 300a-b were each or collectively less than or equal to 1/50 of the thickness of the therapeutic region 200, (b) the mass of therapeutic agent payload was sufficient to release about 100 mg to about 500 mg of analgesic to the treatment site per day, and (c) the structural integrity was such that the depot remained largely intact for at least 14 days after implantation. These embodiments were able to release about 20% to about 50% of the analgesic payload in the first about 3 days to about 5 days of the 14 days, and then release at least 80% of the remaining analgesic payload in the last about 9 days to about 11 days of the 14 days. This was unexpected because, at least in part, (a) providing such a large payload of therapeutic agent in the therapeutic region was expected to cause the depot 100 fail mechanically on or before 14 days post-implant, and (b) no disclosed devices had achieved a release profile wherein about 20% to about 50% of the analgesic was released in the first about 3 days to about 5 days of the 14 days, and then at least 80% of the remaining analgesic was released in the last about 9 days to about 11 days of the 14 days.

In some embodiments, one or more control regions 300 of the depot 100 may comprise two or more sub-control regions. For example, as shown in FIG. 5, the depot 100 may have a first control region 300a and a second control region 300b, each of which comprises first and second sub-control regions 302a, 302b and 302c, 302d, respectively. The first and second control regions 300a, 300b and/or one, some or all of the sub-control regions 302a-302d may have the same or different amounts of releasing agent, the same or different concentrations of releasing agent, the same or different releasing agents, the same or different amounts of polymer, the same or different polymers, the same or different polymer to releasing agent ratios, and/or the same or different thicknesses. In some embodiments, the concentration of the releasing agent in the individual outer control sub-regions 302a, 302d is less than the concentration of the releasing agent in the individual inner control sub-regions 302b, 302c such that the outer portion of the collective control region will elute the therapeutic agent more slowly than the inner portion of the collective control region. In some embodiments, the concentration of the releasing agent in the individual outer control sub-regions 302a, 302d is greater than the concentration of the releasing agent in the individual inner control sub-regions 302b, 302c. In those embodiments where the control region includes more than two sub-regions, the concentration of releasing agent per sub-region or layer may increase, decrease, or remain constant as the sub-control regions are farther away from the therapeutic region 200.

In certain embodiments, the outer control sub-regions include at least 5% by weight of the releasing agent, at least 10% by weight of the releasing agent, at least 15% by weight of the releasing agent, at least 20% by weight of the releasing agent, at least 25% by weight of the releasing agent, at least 30% by weight of the releasing agent, at least 35% by weight of the releasing agent, at least 40% by weight of the releasing agent, at least 45% by weight of the releasing agent, or at least 50% by weight of the releasing agent. In some embodiments, the inner control sub-regions include at least 5% by weight of the releasing agent, at least 10% by weight of the releasing agent, at least 15% by weight of the releasing agent, at least 20% by weight of the releasing agent, at least 25% by weight of the releasing agent, at least 30% by weight of the releasing agent, at least 35% by weight of the releasing agent, at least 40% by weight of the releasing agent, at least 45% by weight of the releasing agent, or at least 50% by weight of the releasing agent. In some embodiments, the outer control sub-regions may include a first amount of the releasing agent and the inner control sub-regions may include a second amount of the releasing agent, where the second amount is at least 200%, at least 300%, at least 400%, or at least 500% greater than the first amount.

FIGS. 6-8 show depot embodiments having a plurality of alternating therapeutic regions 200 and control regions 300 in accordance with the present technology. The depot 100 may have two or more control regions 300 and/or sub-regions 302 (e.g., 2, 3, 4, 5, 6, 7, 8, 9, 10, 20, etc.), and the depot 100 may have one or more therapeutic regions 200 and/or sub-regions 202 (e.g., 1, 2, 3, 4, 5, 6, 7, 10, 15, 20, etc.) surrounded by at least one control region 300 and/or sub-region 302. In some embodiments, each of the therapeutic regions 200 may comprise a single layer and/or each of the control regions 300 may comprise a single layer. In some embodiments, one, some, or all of the therapeutic regions 200 may comprise multiple layers and/or one, some, or all of the control regions 300 may comprise multiple layers. In some embodiments, for example as shown in FIGS. 6 and 7, two or more sub-regions 302a-b (FIG. 6) and 302a-b and 302c-d (FIG. 7) may be adjacent to each other between sub-regions 202 of the therapeutic region 200. Moreover, one or more of the individual control regions 300 and/or one or more of the therapeutic regions 200 may have the same or different amounts and/or types of releasing agent, and one or more of the therapeutic regions may have the same or different amounts and/or types of therapeutic agent.

The embodiments shown in FIGS. 6-8 may be beneficial where the therapeutic region comprises a large payload of the therapeutic agent (e.g., equivalent to many days, weeks or months of dosage). These embodiments may be beneficial because, with such a large payload, should the therapeutic region 200 be exposed to the body abruptly, the entire payload may be released prematurely, subjecting the patient to an abnormally and undesirably high dose of the therapeutic agent. For example, if the integrity of the control region 300 were compromised, the patient may be exposed in vivo to the therapeutic agent at a higher rate than intended, potentially resulting in a clinical complication. Particularly with respect to the administration of local anesthetics (e.g., bupivacaine, ropivacaine, etc.), manufacturing guidelines recommend no more than 400 mg should be administered within a 24-hour period. However, multiple studies have demonstrated that doses higher than 400 mg from extended release products are safe due to their slower release over an extended period of time. Regardless, in the event that a control region 300 is compromised, it is desirable for the patient to be subjected only to a fraction of the total payload, whereby the fraction to which the patient is exposed if prematurely released would be within safety margins for the particular therapeutic agent. The structural integrity of the control regions 300, as well as that of the therapeutic region(s) 200, is an important property for depots with large masses of therapeutic agents that are to be delivered over a long period of time.

To address this concern, in some embodiments of the present technology, the depot 100 may comprise multiple therapeutic regions 200 separated by one or more control regions 300 (for example, as shown in FIGS. 6-8). Such a configuration allows the therapeutic agent in each therapeutic region 200 (which carries a fraction of the total payload), to be individually sequestered. In the event a particular control region is compromised, only the fractional payload corresponding to the therapeutic region associated with the compromised control region would prematurely release. For example, in some of the foregoing embodiments, the total payload of the depot 100 may be at least 100 mg, at least 150 mg, at least 200 mg, at least 300 mg, at least 400 mg, at least 500 mg, at least 600 mg, at least 700 mg, at least 800 mg, at least 900 mg, or at least 1000 mg of therapeutic agent, such as an analgesic (e.g., bupivacaine, ropivacaine, etc.). Likewise, in some embodiments the fractional payload of each therapeutic region or sub-region may be up to 1%, up to 5%, up to 10%, up to 15%, up to 20%, up to 25%, up to 30%, up to 40%, up to 50%, up to 60%, up to 70%, up to 80%, up to 90%, or up to 100% of the total payload contained within the depot 100. As a result, if any single sub-region 202 of the therapeutic region 200 is compromised, it can release only a proportionate fraction of the total payload of the depot.

In some embodiments, each of the therapeutic regions and each of the control regions is a micro-thin layer, i.e., having a layer thickness that is less than 1 mm. In some embodiments, the depot comprises from about 2 to about 100 therapeutic regions, or from about 2 to about 50 therapeutic regions, or from about 2 to about 10 therapeutic regions.

FIGS. 9A-11 show some aspects of the present technology in which the depots 100 may have one or more therapeutic regions 200 completely enclosed or surrounded by one or more control regions 300. In contrast to the previously described embodiments, at least one therapeutic region of such fully-enclosed embodiments does not have any exposed surface area. For example, as shown in FIGS. 9A and 9B, in some embodiments the depot 100 may comprise a therapeutic region 200 surrounded or fully-enclosed by a control region 300 such that no portion of the therapeutic region 200 is exposed through the control region 300. As a result, the control region 300 substantially prevents contact between the therapeutic agent and physiologic fluids, thereby preventing an uncontrolled, burst release of the therapeutic agent when implanted. Over time, the releasing agent imbedded in the polymer of the control region 300 contacts physiologic fluids and dissolves, thereby forming diffusion openings in the control region. The combination of the restriction imposed by the control region and the diffusion openings formed by dissolution of the releasing agent enables a controlled release of the therapeutic agent from the depot over the course of several days, weeks, or months. Although the depot 100 is shown as a rectangular, thin film in FIGS. 9A and 9B, in other embodiments the depot 100 may have other shapes, sizes, or forms.

FIG. 10 illustrates a depot 100 having a therapeutic region 200 fully-enclosed by a control region 300 having a first control region 300a and a second control region 300b. As depicted in FIG. 10, in some embodiments the therapeutic region 200 may be sandwiched between the first control region 300a and the second control region 300b, and the first and second control regions 300a-b may be bonded via heat compression around the therapeutic region 200 to enclose the therapeutic region 200 therebetween. In certain embodiments, a bioresorbable polymer may be wrapped around the entire depot and sealed on the top or bottom surface creating a control region structure similar to that depicted in FIG. 9A. The outer portion of the first and second control regions 300a-b may be incorporated as the final wrapped layer to seal the edges. Additionally, the first and second control regions 300a-b can be integrally formed with each other using dip coating and/or spray coating techniques, such as dipping the therapeutic region 200 in a solution of the control region material or spraying a solution of control region material onto the surfaces of the therapeutic region 200.

In FIG. 10, the first control region 300a can have first and second sub-regions 302a-b, and the second control region 300b can have first and second sub-regions 302c-d. The first control region 300a can define a top control region member, and the first and second sub-regions 302a-b can comprise a first top control layer and a second top control layer, respectively. The second control region 300b can define a bottom control region member, and the first and second sub-regions 302c-d can comprise a first bottom control layer and a second bottom control layer, respectively. The first and second top/bottom control layers can be any variation of the first and second control sub-regions discussed above with reference to FIG. 5. In addition, the first top control layer of the top control region member may have the same or different properties (e.g., thickness, polymer, releasing agent, concentration of releasing agent, total amount of releasing agent, polymer to releasing agent ratio, etc.) as the first bottom control layer of the bottom control region member. Similarly, the second top control layer of the top control region member may have the same or different properties as the second bottom control layer of the bottom control region member. Variations in the loading and construction of the layers may be designed into the depot 100 to achieve a release profile or kinetics that suits the objectives of the intended therapy. In other embodiments, the first control region 300a and/or the second control region 300b has a single layer.

FIG. 11 shows some embodiments in which the depot 100 may have a therapeutic region 200 fully-enclosed by a control region 300 having different sub-region configurations. The depot 100 of FIG. 11 includes a first control region 300a and a second control region 300b that together fully enclose the therapeutic region 200. In contrast to the depot 100 shown in FIG. 10, the first control region 300a has an outer top control region 301a with first and second top sub-control regions 302a and 302b, respectively, and an inner top control region 301b with first and second top layers 303a and 303b. The first and second top layers 303a-b are over only the top surface of the therapeutic region 200, while the first and second top sub-control regions 302a-b cover a portion of the lateral surfaces of the therapeutic region 200 and the inner top control region 301b. The second control region 300b has an outer bottom control region 301c with first and second bottom sub-control regions 302c and 302d, respectively, and an inner bottom control region 301d with first and second bottom layers 303d and 303e, respectively. As such, when the depot 100 is positioned at the treatment site in vivo, the outer top and bottom control regions 301a and 301c are between: (a) the therapeutic region 200 and the inner top and bottom control regions 301b and 301d, respectively, and (b) physiologic fluids at the treatment site. In certain embodiments, such as that shown in FIG. 11, one or more of the outer top/bottom control regions 301a/301c may comprise one or more control sub-regions, and one or more inner top/bottom control regions 301b/301d may include one or more control sub-regions.

FIG. 12 shows a cross-section of a spherical depot 100 in accordance with several embodiments of the present technology having a plurality of alternating therapeutic regions 200 and control regions 300 in accordance with the present technology. The depot 100 may have two or more control regions 300 (e.g., 2, 3, 4, 5, 6, 7, 8, 9, 10, 20, etc.), and the depot may have one or more therapeutic regions 200 (e.g., 1, 2, 3, 4, 5, 6, 7, 10, 15, 20, etc.) surrounded by at least one control region 300. In some embodiments, each of the therapeutic regions 200 may comprise a single layer and/or each of the control regions 300 may comprise a single layer. In some embodiments, one, some, or all of the therapeutic regions 200 may comprise multiple layers and/or one, some, or all of the control regions 300 may comprise multiple layers. Moreover, one or more of the individual control regions 200 and/or one or more of the therapeutic regions 300 may have the same or different amounts and/or types of releasing agent, and one or more of the therapeutic regions 200 may have the same or different amounts and/or types of therapeutic agent.

FIG. 13 shows a depot 100 in accordance with several embodiments of the present technology having a therapeutic region 200 enclosed on the top and bottom surfaces as well as two of the four lateral surfaces by a control region 300. This configuration is expected to release the therapeutic agent more slowly, at least initially, compared to a depot with the same dimensions and fully exposed lateral surfaces (see, e.g., the depot 100 shown in FIG. 4).

The release kinetics of the depots of the present technology may also be tuned for a particular application by varying the shape and size of the depot 100. Depending on the therapeutic dosage needs, anatomical targets, etc., the depot 100 can be different sizes, shapes, and forms for implantation and/or injection in the body by a clinical practitioner. The shape, size, and form of the depot 100 should be selected to allow for ease in positioning the depot at the target tissue site, and to reduce the likelihood of, or altogether prevent, the depot from moving after implantation or injection. This may be especially true for depots being positioned within a joint (such as a knee joint), wherein the depot is a flexible solid that is structurally capable of being handled by a clinician during the normal course of a surgery without breaking into multiple pieces and/or losing its general shape. Additionally, the depot may be configured to be placed in the knee of a patient and release the analgesic in vivo for up to 7 days without breaking into multiple pieces.

Some of the form factors producible from the depot 100 or to be used adjunctive to the depot for implantation and fixation into the body include: strips, ribbons, hooks, rods, tubes, patches, corkscrew-formed ribbons, partial or full rings, nails, screws, tacks, rivets, threads, tapes, woven forms, t-shaped anchors, staples, discs, pillows, balloons, braids, tapered forms, wedge forms, chisel forms, castellated forms, stent structures, suture buttresses, coil springs, sponges, capsules, coatings, matrices, wafers, sheets, strips, ribbons, pills, and pellets.

The depot 100 may also be processed into a component of the form factors mentioned in the previous paragraph. For example, the depot could be rolled and incorporated into tubes, screws, tacks, or the like. In the case of woven embodiments, the depot may be incorporated into a multi-layer woven film/braid/mesh wherein some of the filaments used are not the inventive device. In one example, the depot is interwoven with Dacron, polyethylene or the like. For the sake of clarity, any form factor corresponding to the depot of the present technology, including those where only a portion or fragment of the form factor incorporates the depot, may be referred to herein as a “depot.”

As shown in the cross-sectional views of FIGS. 14A-14H, in various embodiments, the depot 100 can be shaped like a sphere, a cylinder such as a rod or fiber, a flat surface such as a disc, film, ribbon, strip or sheet, a paste, a slab, microparticles, nanoparticles, pellets, mesh or the like. FIG. 14A shows a rectilinear depot 100. FIG. 14B shows a circular depot 100. FIG. shows a triangular depot 100. FIG. 14D show cross-like depot 100, FIG. 14E shows a star-like depot 100, and FIG. 14F shows a toroidal depot 100. FIG. 14G shows a spheroid depot 100, and FIG. 14H shows a cylindrical depot 100. The shape of the depot 100 can be selected according to the anatomy to fit within a given space and provide the desired fixation and flexibility properties. This is because the fit, fixation and flexibility of the depot may enhance the ease of implanting the depot, ensure delivery of the therapeutic agent to the target site, and prolong the durability of the implant in dynamic implant sites.

In various embodiments, the depot can be different sizes, for example, the depot may be a length of from about 0.4 mm to 100 mm and have a diameter or thickness of from about 0.01 to about 5 mm. In various embodiments, the depot may have a layer thickness of from about 0.005 to 5.0 mm, such as, for example, from 0.05 to 2.0 mm. In some embodiments, the shape may be a rectangular or square sheet having a ratio of width to thickness in the range of 20 or greater, 25 or greater, 30 or greater, 35 or greater, 40 or greater, 45 or greater, or 50 or greater.

In some embodiments, a thickness of the control region (a single sub-control region or all sub-control regions combined) is less than or equal to 1/10, 1/12.5, 1/15, 1/17.5, 1/20, 1/22.5, 1/25, 1/27.5, 1/30, 1/32.5, 1/35, 1/37.5, 1/40, 1/42.5, 1/45, 1/47.5, 1/50, 1/55, 1/60, 1/65, 1/70, 1/75, 1/80, 1/85, 1/90, 1/95, or 1/100 of a thickness of the therapeutic region. In those embodiments with multiple sub-control regions, one or more of the sub-control regions may individually be less than or equal to 1/10, 1/12.5, 1/15, 1/17.5, 1/20, 1/22.5, 1/25, 1/27.5, 1/30, 1/32.5, 1/35, 1/37.5, 1/40, 1/42.5, 1/45, 1/47.5, 1/50, 1/55, 1/60, 1/65, 1/70, 1/75, 1/80, 1/85, 1/90, 1/95, or 1/100 of a thickness of the therapeutic region. In those embodiments where the control region comprises a single control region, the control region may have a thickness that is less than or equal to 1/10, 1/12.5, 1/15, 1/17.5, 1/20, 1/22.5, 1/25, 1/27.5, 1/30, 1/32.5, 1/35, 1/37.5, 1/40, 1/42.5, 1/45, 1/47.5, 1/50, 1/55, 1/60, 1/65, 1/70, 1/75, 1/80, 1/85, 1/90, 1/95, or 1/100 of a thickness of the therapeutic region. In those embodiments with multiple sub-control regions, one or more of the sub-control regions may individually be less than or equal to 1/10, 1/12.5, 1/15, 1/17.5, 1/20, 1/22.5, 1/25, 1/27.5, 1/30, 1/32.5, 1/35, 1/37.5, 1/40, 1/42.5, 1/45, 1/47.5, 1/50, 1/55, 1/60, 1/65, 1/70, 1/75, 1/80, 1/85, 1/90, 1/95, or 1/100 of a thickness of the depot. In those embodiments where the control region comprises a single control region, the control region may have a thickness that is less than or equal to 1/10, 1/12.5, 1/15, 1/17.5, 1/20, 1/22.5, 1/25, 1/27.5, 1/30, 1/32.5, 1/35, 1/37.5, 1/40, 1/42.5, 1/45, 1/47.5, 1/50, 1/55, 1/60, 1/65, 1/70, 1/75, 1/80, 1/85, 1/90, 1/95, or 1/100 of a thickness of the depot.

In some embodiments, the depot 100 has a width and a thickness, and a ratio of the width to the thickness is 21 or greater. In some embodiments, the ratio is 22 or greater, 23 or greater, 24 or greater, 25 or greater, 26 or greater, 27 or greater, 28 or greater, 29 or greater, 30 or greater, 35 or greater, 40 or greater, 45 or greater, or 50 or greater.

In some embodiments, the depot 100 has a surface area and a volume, and a ratio of the surface area to volume is at least 1, at least 1.5, at least 2, at least 2.5, or at least 3.

In any of the foregoing embodiments shown and described above with respect to FIGS. 2-14H, dissolution of the releasing agent(s) and elution of the therapeutic agent(s) can change functional mechanical aspects of the depot 100 over time. Such mechanical aspects include structural integrity, flexural strength, tensile strength, or other mechanical characteristics of the depot 100. In some instances, undesirable degradation of the depot 100, such as premature degradation, can cause mechanical failure of the depot 100 and a corresponding undesirable burst release of therapeutic agent into the body. Accordingly, it can be beneficial for the depot 100 to maintain sufficient flexural strength and/or mechanical integrity in vivo for at least a predetermined period of time or until a predetermined proportion of therapeutic agent has been released from the depot 100. The depot 100 can be considered to maintain its structural integrity if the depot 100 remains largely intact with only partial or gradual reduction due to elution of therapeutic agent or dissolution of the control layers or releasing agent. The depot 100 can be considered to lose its structural integrity if it separates (e.g., fractures) into multiple component pieces, for example, with two or more of the resulting pieces being at least 5% of the previous size of the depot 100. Alternatively, or additionally, the depot 100 can be considered to lose its structural integrity if the release rate of the therapeutic agent increases by more than a factor of three as compared to the release rate of therapeutic agent in a control depot submerged in a buffered solution.

In some embodiments, the depot 100 is configured to maintain its structural integrity in vivo for at least a predetermined length of time. For example, the depot 100 can be configured to maintain its structural integrity in vivo for at least 1 day, at least 2 days, at least 3 days, at least 4 days, at least 5 days, at least 6 days, at least 7 days, at least 8 days, at least 9 days, at least 10 days, at least 11 days, at least 12 days, at least 13 days, at least 14 days, at least 15 days, at least 16 days, at least 17 days, at least 18 days, at least 19 days, at least 20 days, at least 21 days, at least 22 days, at least 23 days, at least 24 days, at least 25 days, at least 26 days, at least 27 days, at least 28 days, at least 29 days, or at least 30 days, at least 40 days, at least 50 days, at least 60 days, at least 70 days, at least 90 days, at least 100 days, at least 200 days, at least 300 days, or at least 365 days.

In some embodiments, the depot 100 is configured to maintain its structural integrity in vivo until at least a predetermined proportion of therapeutic agent payload has been released from the depot. For example, the depot 100 can be configured to maintain its structural integrity in vivo until at least 5% by weight of the original payload has been released, at least 10% by weight of the original payload has been released, at least 15% by weight of the original payload has been released, at least 20% by weight of the original payload has been released, at least 25% by weight of the original payload has been released, at least 30% by weight of the original payload has been released, at least 35% by weight of the original payload has been released, at least 40% by weight of the original payload has been released, at least 45% by weight of the original payload has been released, at least 50% by weight of the original payload has been released, at least 55% by weight of the original payload has been released, at least 60% by weight of the original payload has been released, at least 65% by weight of the original payload has been released, at least 70% by weight of the original payload has been released, at least 75% by weight of the original payload has been released, at least 80% by weight of the original payload has been released, at least 85% by weight of the original payload has been released, at least 90% by weight of the original payload has been released, or until at least 95% by weight of the original payload has been released.

One aspect of the structural integrity of the depot 100 when it is in vivo can be quantified using a bend test, such as a three-point bend test that measures flexural properties including the flexural strength and/or maximum flexural stress sustained by a specimen before breaking. Such a bend test may represent (e.g., simulate) the forces that the depot 100 will encounter in vivo in an anatomical joint (e.g., a knee joint). In one example, a depot can be subjected to a three-point bend test based on ASTM-D790-17, “Standard Test Methods for Flexural Properties of Unreinforced and Reinforced Plastics and Electrical Insulating Materials.” The text of this standard is hereby incorporated by reference in its entirety. The depot 100 may be suspended in a medium configured to simulate in vivo conditions, for example a phosphate buffered saline (PBS) at approximately 37° C. The bend test may be performed after different time periods of submersion in the medium to evaluate changes in the flexural strength of the depot 100 over time in simulated in vivo conditions.

Table 1 shows the maximum flexural load sustained by four different samples of the depot 100 at different time periods following submersion in the medium as measured using a three-point bend test with maximum deflection set at 2.13 mm. The values in Table 1 reflect measurements made from two instances of each of the listed samples. FIG. 15 is a graph illustrating these values plotted graphically and fitted with trendlines. In each of these four samples, the depot 100 includes a therapeutic region 200 surrounded by upper and lower control regions 300a-b as shown and described above with reference to FIG. 4 or 5. The therapeutic region 200 has exposed lateral surfaces 202 between the first and second control regions 300a-b. The depots 100 each have lateral dimensions of approximately 2.5 cm by 1.5 cm, with a thickness of approximately 1 mm.

Sample 1 is a depot having a therapeutic region with a ratio by weight of releasing agent to polymer to therapeutic agent of 0.5:10:20. The polymer in this sample is P(DL)GACL with a PDLLA:PGA:PCL ratio of 6:3:1, the releasing agent is Tween 20, and the therapeutic agent is bupivacaine hydrochloride. In this sample, the depot includes a first control region 300a comprising a single control layer over the upper surface of the therapeutic region 200 and a second control region 300b comprising single control layer over the lower surface of the therapeutic region 200, as shown and described above with reference to FIG. 4. Each control region 300a-b individually has a ratio of releasing agent to polymer of 5:10.

Sample 2 is a depot having a therapeutic region 200 with a ratio by weight of releasing agent to polymer to therapeutic agent of 1:10:20. The polymer in this sample is PLGA with a PLA:PGA ratio of 1:1, the releasing agent is Tween 20, and the therapeutic agent is bupivacaine hydrochloride. Similar to Sample 1, the depot of Sample 2 includes a control region 300 comprising a first control region 300a with a single control layer over the upper surface of the therapeutic region 200 and a second control region 300b comprising a single control layer over the lower surface of the therapeutic region 200, as shown and described above with reference to FIG. 4. Each control region 300a-b individually has a ratio of releasing agent to polymer of 5:10.

Sample 3 is a depot having therapeutic region 200 with a ratio by weight of releasing agent to polymer to therapeutic agent of 5:10:20. The polymer in this sample is P(DL)GACL with a PDLLA:PGA:PCL ratio of 6:3:1, the releasing agent is Tween 20, and the therapeutic agent is bupivacaine hydrochloride. In this sample, the depot includes a control region 300 comprising a first control region 300a with two sub-control regions 302a-b over the upper surface of the therapeutic region 200, and a second control region 300b with two sub-control regions 302c-d, as shown and described above with reference to FIG. 5. Each of the inner sub-control regions 302b and 302c contacts the surface of the therapeutic region 200 and has a ratio of releasing agent to polymer of 5:10, and each of the outer sub-control regions 302a and 302d has a ratio of releasing agent to polymer of 1:10. The depot of Sample 3, therefore, includes a total of four sub-control regions.

Sample 4 is a depot having a therapeutic region 200 with a ratio by weight of releasing agent to polymer to therapeutic agent of 5:10:20. The polymer in this sample is PLGA with a PLA:PGA ratio of 1:1, the releasing agent is Tween 20, and the therapeutic agent is bupivacaine hydrochloride. As with Sample 3, the depot of Sample 4 includes a control region 300 having first and second control region 300a-b that each have two sub-control regions 302a-b and 302c-d, respectively, as shown and described with respect to FIG. 5. The depot of Sample 4 according also has a total of four sub-control regions 302a-d, two over the upper surface of the therapeutic region 200 and two over the lower surface of the therapeutic region 200. The inner of the sub-control regions 302b and 302c has a ratio of releasing agent to polymer of 5:10, and the outer of the sub-control regions 302a and 302d has a ratio of releasing agent to polymer of 1:10.

TABLE 1

Depot Sample
Day 0
Day 1
Day 3
Day 7
Day 14
Day 28

Sample 1:
No break
5.553N
2.903N
0.569N
1.263N
Not tested

P(DL)GACL 6:3:1

1.25 lbf
0.0653 lbf
0.134 lbf
0.284 lbf

2 control layers

Sample 2:
5.623N
5.447N
4.623N
1.386N
Not tested
Not tested

PLGA 1:1
1.264 lbf
1.22 lbf
1.04 lbf
0.312 lbf

2 control layers

Sample 3:
No break
5.474N
Not tested
2.430N
0.605N
Sample

P(DL)GACL 6:3:1

1.23 lbf

0.546 lbf
0.136 lbf
degraded

4 control layers

Sample 4:
No break
6.763N
Not tested
1.816N
0.869N
Sample

PLGA 1:1

1.52 lbf

0.408 lbf
0.195 lbf
degraded

4 control layers

As shown in Table 1, all samples were intact and maintained sufficient structural integrity after 14 days of being suspended in the medium to withstand a bending force before fracturing. Although the maximum load tolerated by each sample decreased over time, the flexural strength of these samples at 14 days was sufficient to maintain the structural integrity desired for implantation in an active joint, such as the knee or shoulder. As shown above, for two of the samples tested at 28 days, the samples had degraded such that the test could not be performed because the sample was no longer structurally intact. In such instances, it may be desirable to configure the depots such that all or substantially all the therapeutic agent payload has been released from the depot prior to its degradation and loss of structural integrity.

In this series of experiments summarized in Table 1, the sample depots are generally flexible at Day 0 before submersion in PBS. Following submersion, the flexural strength of the depots decreased such that the depots became more brittle with time. Yet, at 7-14 days, the depots were still sufficiently functionally intact. Without being bound by theory, it is believed that after the therapeutic agent has eluted, the depots gradually become an empty polymer matrix. For example, after 14-28 days in the solution, the depots may weigh only approximately 30% of their starting weight before submersion in the PBS. At this lower weight and in the porous state, the depots may be more brittle, with lower flexural strength and less resistance to bending loads.

As noted above, it can be advantageous for the depots 100 to maintain their structural integrity and flexural strength even while they gradually degrade as the therapeutic agent payload releases into the body. In some embodiments, the depot 100 can be configured such that, in in vitro testing utilizing a three-point bend test, the flexural strength of the depot 100 decreases by no more than 95%, no more than 90%, no more than 85%, no more than 80%, no more than 75%, no more than 70%, no more than 65%, no more than 60%, no more than 55%, no more than 50%, no more than 45%, no more than 40%, no more than 35%, no more than 30%, no more than 25%, no more than 20%, no more than 15%, no more than 10%, or no more than 5% after being submerged in PBS for a predetermined period of time. In various embodiments, the predetermined period of time that the depot 100 is submerged in PBS before being subjected to the three-point bend test is 1 day, 2 days, 3 days, 4 days, 5 days, 6 days, 7 days, 8 days, 9 days, 10 days, 11 days, 12 days, 13 days, 14 days, 15 days, 16 days, 17 days, 18 days, 19 days, 20 days, after 21 days, after 22 days, 23 days, 24 days, 25 days, 26 days, 27 days, 28 days, or more. In at least some embodiments, the change in flexural strength of the depot 100 can be measured between day 0 (e.g., before submersion in the PBS) and a subsequent time after some period of submersion in PBS. In other embodiments, the change in flexural strength of the depot 100 can be measured between day 1 (e.g., after 24 hours of submersion in PBS) and a subsequent time following longer submersion in PBS.

In some embodiments, the depot 100 can be configured such that, in in vitro testing utilizing a three-point bend test, the flexural strength of the depot 100 decreases by no more than 95%, no more than 90%, no more than 85%, no more than 80%, no more than 75%, no more than 70%, no more than 65%, no more than 60%, no more than 55%, no more than 50%, no more than 45%, no more than 40%, no more than 35%, no more than 30%, no more than 25%, no more than 20%, no more than 15%, no more than 10%, or no more than 5% over the time period in which a predetermined percentage of the initial therapeutic agent payload is released while the depot 100 is submerged in PBS. In various embodiments, the predetermined percentage of payload released when the depot 100 is submerged in PBS before being subjected to the three-point bend test is about 5%, about 10%, about 15%, about 20%, about 25%, about 30%, about 35%, about 40%, about 45%, about 50%, about 55%, about 60%, about 65%, about 70%, about 75%, about 80%, about t 85%, about 90%, or about 95%. As noted above, in at least some embodiments, the change in flexural strength of the depot 100 can be measured between day 0 (prior to submersion in PBS) or day 1 (after 24 hours of submersion in PBS) and a subsequent following longer submersion in PBS.

In some embodiments, the depot 100 has (a) lateral dimensions of about 1.0-3.0 cm, (b) a thickness of about 0.5-2.5 mm, and (c) a payload of therapeutic agent sufficient to release about 100 mg to about 500 mg of therapeutic agent per day for up to 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, or 20 days, and the depot 100 is configured to remain sufficiently mechanically intact to provide sustained, controlled release of therapeutic agent for at least 7 days. Such embodiments of the depot 100 can comprise the therapeutic region 200 with a therapeutic agent and the control region 300. The control region 300 can have first and second control regions 300a-b, such as those shown and described above with reference to FIGS. 4-13, and the control region 300 comprises a bioresorbable polymer and a releasing agent mixed with the bioresorbable polymer. The releasing agent is configured to dissolve when the depot 100 is placed in vivo to form diffusion openings in the control region 300. The depot 100 is further configured such that, following submersion of the depot 100 in a buffer solution for seven days, the flexural strength of the depot 100 decreases by no more than 75%, or by no more than 70%, or by no more than 65%, or by no more than 60%, or by no more than 55%, or by no more than 50%, or by no more than 45%

In some embodiments, the depot 100 has (a) lateral dimensions of about 1.0-3.0 cm, (b) a thickness of about 0.5-2.5 mm, and (c) a payload of therapeutic agent sufficient to release about 100 mg to about 500 mg of therapeutic agent per day for up to 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, or 20 days, and the depot 100 is configured to remain sufficiently mechanically intact to provide sustained, controlled release of therapeutic agent for at least 7 days. Such embodiments of the depot 100 can comprise the therapeutic region 200 with a therapeutic agent and the control region 300. The control region 300 can have first and second control regions 300a-b, such as those shown and described above with reference to FIGS. 4-13, and the control region 300 comprises a bioresorbable polymer and a releasing agent mixed with the bioresorbable polymer. The releasing agent is configured to dissolve when the depot 100 is placed in vivo to form diffusion openings in the control region 300. The depot is further configured such that, following submersion of the depot in buffer solution until approximately 75% of the therapeutic agent by weight has been released, the flexural strength of the depot decreases by no more than 75%, or by no more than 70%, or by no more than 65%, or by no more than 60%, or by no more than 55%, or by no more than 50%, or by no more than 45%.

A. Therapeutic Region

The total payload and release kinetics of the depots 100 of the present technology may be tuned for a particular application by varying the composition of the therapeutic region 200. In many embodiments, the therapeutic region 200 may include a high therapeutic payload of a therapeutic agent, especially as compared to other known polymer devices of equal thickness or polymer weight percentage. For example, the depots 100 of the present technology may comprise at least 15% by weight of the therapeutic agent, at least 20% by weight of the therapeutic agent, at least at least 25% by weight of the therapeutic agent, at least 30% by weight of the therapeutic agent, at least 35% by weight of the therapeutic agent, at least 40% by weight of the therapeutic agent, at least 45% by weight of the therapeutic agent, at least 50% by weight of the therapeutic agent, at least 55% by weight of the therapeutic agent, at least 60% by weight of the therapeutic agent, at least 65% by weight of the therapeutic agent, at least 70% by weight of the therapeutic agent, at least 75% by weight of the therapeutic agent, at least 80% by weight of the therapeutic agent, at least 85% by weight of the therapeutic agent, at least 90% by weight of the therapeutic agent, at least 95% by weight of the therapeutic agent, or 100% by weight of the therapeutic agent.

The therapeutic agent may be any of the therapeutic agents disclosed herein, for example in Section C (“Therapeutic Agents”) below.

In various embodiments of the depots 100 disclosed herein, the therapeutic region 200 may take several different forms. In some embodiments (for example, FIG. 4), the therapeutic region 200 may comprise a single layer comprised of a therapeutic agent, a therapeutic agent mixed with a bioresorbable polymer, or a therapeutic agent mixed with a bioresorbable polymer and a releasing agent. In some embodiments, the therapeutic region 200 itself may comprise a structure having multiple layers or sub-regions of therapeutic agent (and/or bioresorbable polymer and/or releasing agent). Some or all layers or sub-regions of such a multiple layer therapeutic region 200 may be directly adjacent (i.e., in contact with) one another (laterally or axially), and/or some or all layers or sub-regions may be spaced apart with one or more other regions therebetween (such as control region(s) 300 and/or barrier region(s))). In some embodiments, 2, 3, 4, 5, 6, 7, 8, 9, 10 or more therapeutic sub-regions or layers may be grouped together and spaced apart from another therapeutic region or group of therapeutic sub-regions or layers (having the same or different numbers of layers as the other group) with one or more other regions therebetween (such as control region(s) 300 and/or barrier region(s))) (see, for example, FIG. 5, FIG. 6, etc.).

In any of the depot embodiments disclosed herein, the ratio of the mass of the therapeutic agent in the depot to the mass of polymer in the depot is at least 3:1, 3.5:1, 4:1, 4.5:1, 5:1, 5.5:1, 6:1, 6.5:1, 7:1, 8:1, 9:1, 10:1, 11:1, 12:1, 13:1, 14:1, 15:1, or 16:1.

In any of the depot embodiments disclosed herein, the ratio of the mass of the polymer in the therapeutic region 200 to the mass of therapeutic agent in the therapeutic region 200 is at least 1:1, 1:1.5, 1:2, 1:2.5, 1:3, 1:3.5, 1:4, 1:4.5, 1:5, 1:5.5, 1:6, 1:6.5, 1:7, 1:7.5, 1:8, 1:8.5, 1:9, 1:9.5, or 1.10.

In any of the embodiments disclosed herein, the weight ratio of releasing agent to polymer in the therapeutic region 200 may be 1:1, 1:1.5, 1:2, 1:3, 1:4, 1:5, 1:6, 1:7, 1:8, 1:9, 1:10, 1:11, 1:12, 1:13, 1:14, 1:15, or 1:16.

In some embodiments, the ratio of releasing agent to polymer to therapeutic agent in the therapeutic region 200 is of from about 0.1:10:20 to about 2:10:20, about 0.1:10:20 to about 1:10:20, about 0.1:10:20 to about 0.5:10:20, about 0.5:10:20 to about 0.1:10:20, or about 0.5:10:20 to about 1:10:20.

In any of the embodiments disclosed herein having a single therapeutic region 200, the therapeutic region 200 may have a thickness of from about 5 μm to 100 μm, 5 μm to 50 μm, 5 μm to 25 μm, 5 μm to 10 μm, 5 μm to 7 μm, 7 μm to 9 μm, 10 μm to 80 μm, 10 μm to 70 μm, 10 μm to 60 nm, 20 μm to 60 μm, 15 μm to 50 μm, about 15 μm, about 20 μm, about 25 μm, about 30 μm, about 35 μm, about 40 μm, about 45 μm, about 50 μm, about 55 μm, about 60 μm, about 65 μm, about 70 μm, about 75 μm, about 80 μm, about 85 μm, about 90 μm, about 95 μm, about 100 μm, 100 μm to 2 mm, 100 μm to 1.5 mm, 100 μm to 1 mm, 100 μm to 200 μm, 200 μm to 300 μm, 300 μm to 400 μm, 400 μm to 500 μm, 500 μm to 600 μm, 600 μm to 700 μm, 700 μm to 800 μm, 800 μm to 900 μm, 900 μm to 1 mm, 1 mm to 1.5 mm, 200 μm to 600 μm, 400 μm to 1 mm, 500 μm to 1.1 mm, 800 μm to 1.1 mm, about 200 μm, about 300 μm, about 400 μm, about 500 μm, about 600 μm, about 700 μm, about 800 μm, about 900 μm, about 1 mm, about 1.1 mm, about 1.2 mm, about 1.3 mm, about 1.4 mm, about 1.5 mm, about 1.6 mm, about 1.7 mm, about 1.8 mm, about 1.9 mm, or about 2 mm.

In those embodiments having multiple therapeutic regions and/or sub-regions, the individual sub-regions or combinations of some or all sub-regions may have a thickness of from about 5 μm to 100 μm, 5 μm to 50 μm, 5 μm to 25 μm, 5 μm to 10 μm, 5 μm to 7 μm, 7 μm to 9 μm, 10 μm to 80 μm, 10 μm to 70 μm, 10 μm to 60 μm, 20 μm to 60 μm, 15 μm to 50 μm, about 15 μm, about 20 μm, about 25 μm, about 30 μm, about 35 μm, about 40 μm, about 45 μm, about 50 μm, about 55 μm, about 60 μm, about 65 μm, about 70 μm, about 75 μm, about 80 μm, about 85 μm, about 90 μm, about 95 μm, about 100 μm, 100 μm to 2 mm, 100 μm to 1.5 mm, 100 μm to 1 mm, 100 μm to 200 μm, 200 μm to 300 μm, 300 μm to 400 μm, 400 μm to 500 μm, 500 μm to 600 μm, 600 μm to 700 μm, 700 μm to 800 μm, 800 μm to 900 μm, 900 μm to 1 mm, 1 mm to 1.5 mm, 200 μm to 600 μm, 400 μm to 1 mm, 500 μm to 1.1 mm, 800 μm to 1.1 mm, about 200 μm, about 300 μm, about 400 μm, about 500 μm, about 600 μm, about 700 μm, about 800 μm, about 900 μm, about 1 mm, about 1.1 mm, about 1.2 mm, about 1.3 mm, about 1.4 mm, about 1.5 mm, about 1.6 mm, about 1.7 mm, about 1.8 mm, about 1.9 mm, or about 2 mm.

The therapeutic regions 200 of the present technology may comprise at least 15% by weight of the therapeutic agent, at least 20% by weight of the therapeutic agent, at least at least 25% by weight of the therapeutic agent, at least 30% by weight of the therapeutic agent, at least 35% by weight of the therapeutic agent, at least 40% by weight of the therapeutic agent, at least 45% by weight of the therapeutic agent, at least 50% by weight of the therapeutic agent, at least 55% by weight of the therapeutic agent, at least 60% by weight of the therapeutic agent, at least 65% by weight of the therapeutic agent, at least 70% by weight of the therapeutic agent, at least 75% by weight of the therapeutic agent, at least 80% by weight of the therapeutic agent, at least 85% by weight of the therapeutic agent, at least 90% by weight of the therapeutic agent, at least 95% by weight of the therapeutic agent, or 100% by weight of the therapeutic agent.

In any of the embodiments disclosed herein, the therapeutic region 200 may include of from about 0.1%-10% by weight of the releasing agent, about 0.1%-6% by weight of the releasing agent, 0.2%-10% by weight of the releasing agent, about 0.3%-6% by weight of the releasing agent, about 0.1%-1% by weight of the releasing agent, about 0.1%-0.5% by weight of the releasing agent, 1%-2% by weight of the releasing agent, about 1%-3% by weight of the releasing agent, or about 2%-6% by weight of the releasing agent. In those embodiments having multiple therapeutic regions or sub-regions, one or more of the therapeutic regions or sub-therapeutic regions may individually include of from about 0.1%-10% by weight of the releasing agent, about 0.1%-6% by weight of the releasing agent, 0.2%-10% by weight of the releasing agent, about 0.3%-6% by weight of the releasing agent, about 0.1%-1% by weight of the releasing agent, about 0.1%-0.5% by weight of the releasing agent, 1%-2% by weight of the releasing agent, about 1%-3% by weight of the releasing agent, or about 2%-6% by weight of the releasing agent. The therapeutic region 200 may not include any releasing agent. In those embodiments having multiple therapeutic regions and/or sub-regions, one, some, or all of the individual therapeutic regions and/or sub-regions may not include any releasing agent.

In any of the embodiments disclosed herein, the therapeutic region 200 may include no more than 5% by weight of the polymer, no more than 10% by weight of the polymer, no more than 15% by weight of the polymer, no more than 20% by weight of the polymer, no more than 25% by weight of the polymer, no more than 30% by weight of the polymer, no more than 35% by weight of the polymer, no more than 40% by weight of the polymer, no more than 45% by weight of the polymer, or no more than 50% by weight of the polymer. In those embodiments having multiple therapeutic regions or sub-regions, one or more of the therapeutic regions or sub-therapeutic regions may individually include no more than 5% by weight of the polymer, no more than 10% by weight of the polymer, no more than 15% by weight of the polymer, no more than 20% by weight of the polymer, no more than 25% by weight of the polymer, no more than 30% by weight of the polymer, no more than 35% by weight of the polymer, no more than 40% by weight of the polymer, no more than 45% by weight of the polymer, or no more than 50% by weight of the polymer. In some embodiments, the therapeutic region 200 may not include any polymer.

In those embodiments disclosed herein where the therapeutic region 200 includes multiple therapeutic regions or sub-regions, some or all of the therapeutic regions or sub-therapeutic regions may have the same or different amounts of releasing agent, the same or different concentrations of releasing agent, the same or different releasing agents, the same or different amounts of polymer, the same or different polymers, the same or different polymer to releasing agent ratios, the same or different amounts of therapeutic agents, the same or different types of therapeutic agents, and/or the same or different thicknesses. Moreover, a single therapeutic region or sub-region may comprise a single type of polymer or multiple types of polymers, a single type of releasing agent or multiple types of releasing agents, and/or a single type of therapeutic agent or multiple types of therapeutic agents. In those embodiments having multiple therapeutic regions and/or sub-regions, one, some, or all of the individual therapeutic regions and/or sub-regions may not include any polymer.

In some embodiments the therapeutic region 200 (or one or more therapeutic sub-regions) comprises the therapeutic agent as an essentially pure compound or formulated with a pharmaceutically acceptable carrier such as diluents, adjuvants, excipients or vehicles known to one skilled in the art

B. Control Region

The composition of the control region 300 may also be varied. For example, in many embodiments, the control region 300 does not include any therapeutic agent at least prior to implantation of the depot at the treatment site. In some embodiments, the control region 300 may include a therapeutic agent which may be the same as or different than the therapeutic agent in the therapeutic region 200.

Within the control region 300, the amount of releasing agent may be varied to achieve a faster or slower release of the therapeutic agent. In those embodiments where both the therapeutic region 200 and control region 300 include a releasing agent, the type of releasing agent within the therapeutic region 200 may be the same or different as the releasing agent in the control region 300. In some embodiments, a concentration of a first releasing agent within the control region is the greater than a concentration of a second releasing agent (the same or different as the first releasing agent) within the therapeutic region. In some embodiments, a concentration of the releasing agent within the control region is less than a concentration of the releasing agent within the therapeutic region. In some embodiments, a concentration of the releasing agent within the control region 300 is the same as a concentration of the releasing agent within the therapeutic region 200.

In various embodiments of the depots disclosed herein, the control region 300 may take several different forms. In some embodiments (for example, FIG. 4), the control region 300 may comprise a single layer on either side of the therapeutic region 200 comprised of a bioresorbable polymer mixed with a releasing agent. In some embodiments, the control region 300 itself may comprise a structure having multiple layers or sub-regions of bioresorbable polymer and releasing agent. Some or all layers or sub-regions of such a multiple layer control region 300 may be directly adjacent (i.e., in contact with) one another (laterally or axially), and/or some or all layers or sub-regions may be spaced apart with one or more other regions therebetween (such as therapeutic region(s) 200 and/or barrier region(s))). In some embodiments, 2, 3, 4, 5, 6, 7, 8, 9, 10 or more control sub-regions or layers may be grouped together and spaced apart from another control region or group of control sub-regions or layers (having the same or different numbers of layers as the other group) with one or more other regions therebetween (such as therapeutic region(s) 200 and/or barrier region(s))) (see, for example, FIG. 5, FIG. 6, etc.).

Without being bound by theory, it is believed that such a multilayer configuration improves the control region's ability to control the release of the therapeutic agent as compared to a single layer control region, even if the multilayer configuration has the same or lower thickness as the single layer control region. The channels left by dissolution of the releasing agent in both microlayers and/or sub-regions of the control region create a path for a released therapeutic agent to travel that is longer and, potentially, more cumbersome to traverse as compared to the more direct path created by the channels in the single layer control region. The control region(s) and/or sub-regions thereby regulate the therapeutic agent release rate by allowing a releasing agent to form independent non-contiguous channels through one or more control regions and/or sub-regions. In those embodiments having multiple control layers or sub-regions, some or all of the control layers or sub-regions may be heat compressed together. The one or more control regions, heat-compressed first or not, may be heat compressed together with the therapeutic region 200. Having a control region 300 with multiple layers may provide a more linear, controlled release of the therapeutic agent over time (beyond the first day of implantation). In addition, layering of the control region 300 may also contribute to a more flexible, structurally competent depot (as compared to a depot having a therapeutic region comprised of pure therapeutic agent). Such durability is beneficial for the clinician when handling/manipulating the depot 100 before and while positioning the depot 100 at a treatment site.

In any of the embodiments disclosed herein having a single control region 300, the thickness of the control region 300 may be of from about 5 μm to 100 μm, 5 μm to 50 μm, 5 μm to 25 μm, 5 μm to 10 μm, 5 μm to 7 μm, 7 μm to 9 μm, 10 μm to 80 μm, 10 μm to 70 μm, 10 μm to 60 μm, 20 μm to 60 μm, 15 μm to 50 μm, about 15 μm, about 20 μm, about 25 μm, about 30 μm, about 35 μm, about 40 μm, about 45 μm, about 50 μm, about 55 μm, about 60 μm, about 65 μm, about 70 μm, about 75 μm, about 80 μm, about 85 μm, about 90 μm, about 95 μm, or about 100 μm. In those embodiments having multiple control regions and/or sub-regions, the individual sub-regions or combinations of some or all sub-regions may have a thickness of from about 5 μm to 100 μm, 5 μm to 50 μm, 5 μm to 25 μm, 5 μm to 10 μm, 5 μm to 7 μm, 7 μm to 9 μm, 10 μm to 80 μm, 10 μm to 70 μm, 10 μm to 60 μm, 20 μm to 60 μm, 15 μm to 50 μm, about 15 μm, about 20 μm, about 25 μm, about 30 μm, about 35 μm, about 40 μm, about 45 μm, about 50 μm, about 55 μm, about 60 μm, about 65 μm, about 70 μm, about 75 μm, about 80 μm, about 85 μm, about 90 μm, about 95 μm, or about 100 μm.

In any of the embodiments disclosed herein, the weight ratio of releasing agent to polymer in the control region 300 may be 2:1, 1.5:1, 1:1, 1:1.5, 1:2, 1:3, 1:4, 1:5, 1:6, 1:7, 1:8, 1:9, 1:10, 1:11, 1:12, 1:13, 1:14, 1:15, 1:16, 1:17, 1:18, 1:19, 1:20, 1:21, 1:22, 1:23, 1:24, or 1:25.

In any of the embodiments disclosed herein, the control region 300 may include at least 5% by weight of the releasing agent, at least 10% by weight of the releasing agent, at least 15% by weight of the releasing agent, at least 20% by weight of the releasing agent, at least 25% by weight of the releasing agent, at least 30% by weight of the releasing agent, at least 35% by weight of the releasing agent, at least 40% by weight of the releasing agent, at least 45% by weight of the releasing agent, or at least 50% by weight of the releasing agent. In those embodiments having multiple control regions or sub-regions, one or more of the control regions or sub-control regions may individually include at least 5% by weight of the releasing agent, at least 10% by weight of the releasing agent, at least 15% by weight of the releasing agent, at least 20% by weight of the releasing agent, at least 25% by weight of the releasing agent, at least 30% by weight of the releasing agent, at least 35% by weight of the releasing agent, at least 40% by weight of the releasing agent, at least 45% by weight of the releasing agent, or at least 50% by weight of the releasing agent.

In any of the embodiments disclosed herein, the control region 300 may include at least 5% by weight of the polymer, at least 10% by weight of the polymer, at least 15% by weight of the polymer, at least 20% by weight of the polymer, at least 25% by weight of the polymer, at least 30% by weight of the polymer, at least 35% by weight of the polymer, at least 40% by weight of the polymer, at least 45% by weight of the polymer, at least 50% by weight of the polymer, at least 55% by weight of the polymer, at least 60% by weight of the polymer, at least 65% by weight of the polymer, at least 70% by weight of the polymer, at least 75% by weight of the polymer, at least 80% by weight of the polymer, at least 85% by weight of the polymer, at least 90% by weight of the polymer, at least 95% by weight of the polymer, or 100% by weight of the polymer. In those embodiments having multiple control regions or sub-regions, one or more of the control regions or sub-control regions may individually include at least 5% by weight of the polymer, at least 10% by weight of the polymer, at least 15% by weight of the polymer, at least 20% by weight of the polymer, at least 25% by weight of the polymer, at least 30% by weight of the polymer, at least 35% by weight of the polymer, at least 40% by weight of the polymer, at least 45% by weight of the polymer, at least 50% by weight of the polymer, at least 55% by weight of the polymer, at least 60% by weight of the polymer, at least 65% by weight of the polymer, at least 70% by weight of the polymer, at least 75% by weight of the polymer, at least 80% by weight of the polymer, at least 85% by weight of the polymer, at least 90% by weight of the polymer, at least 95% by weight of the polymer, or 100% by weight of the polymer.

In those embodiments disclosed herein where the control region 300 includes multiple control regions or sub-regions, some or all of the control regions or sub-control regions may have the same or different amounts of releasing agent, the same or different concentrations of releasing agent, the same or different releasing agents, the same or different amounts of polymer, the same or different polymers, the same or different polymer to releasing agent ratios, and/or the same or different thicknesses. A single control region or sub-region may comprise a single type of polymer or multiple types of polymers and/or a single type of releasing agent or multiple types of releasing agents.

C. Therapeutic Agents

The therapeutic agent carried by the depots 100 of the present technology may be any biologically active substance (or combination of substances) that provides a therapeutic effect in a patient in need thereof. As used herein, “therapeutic agent” or “drug” may refer to a single therapeutic agent, or may refer to a combination of therapeutic agents. In some embodiments, the therapeutic agent may include only a single therapeutic agent, and in some embodiments, the therapeutic agent may include two or more therapeutic agents for simultaneous or sequential release.

In several embodiments, the therapeutic agent includes an analgesic agent. The term “analgesic agent” or “analgesic” includes one or more local or systemic anesthetic agents that are administered to reduce, prevent, alleviate or remove pain entirely. The analgesic agent may comprise a systemic and/or local anesthetic, narcotics, and/or anti-inflammatory agents. The analgesic agent may comprise the pharmacologically active drug or a pharmaceutically acceptable salt thereof. Suitable local anesthetics include, but are not limited to, bupivacaine, ropivacaine, mepivacaine, etidocaine, levobupivacaine, trimecaine, carticaine, articaine, lidocaine, prilocaine, benzocaine, procaine, tetracaine, chloroprocaine, and combinations thereof. Preferred local anesthetics include bupivacaine, lidocaine, and ropivacaine. Typically, local anesthetics produce anesthesia by inhibiting excitation of nerve endings or by blocking conduction in peripheral nerves. Such inhibition is achieved by anesthetics reversibly binding to and inactivating sodium channels. Sodium influx through these channels is necessary for the depolarization of nerve cell membranes and subsequent propagation of impulses along the course of the nerve. When a nerve loses depolarization and capacity to propagate an impulse, the individual loses sensation in the area supplied by the nerve. Any chemical compound possessing such anesthetic properties is suitable for use in the present technology.

In some embodiments, the therapeutic agent includes narcotics, for example, cocaine, and anti-inflammatory agents. Examples of appropriate anti-inflammatory agents include steroids, such as prednisone, betamethasone, cortisone, dexamethasone, hydrocortisone, and methylprednisolone. Other appropriate anti-inflammatory agents include non-steroidal anti-inflammatory drugs (NSAIDs), such as aspirin, Ibuprofen, naproxen sodium, diclofenac, diclofenac-misoprostol, celecoxib, piroxicam, indomethacin, meloxicam, ketoprofen, sulindac, diflunisal, nabumetone, oxaprozin, tolmetin, salsalate, etodolac, fenoprofen, flurbiprofen, ketorolac, meclofenamate, mefenamic acid, and other COX-2 inhibitors, and combinations thereof.

In some embodiments, the therapeutic agent comprises an antibiotic, an antimicrobial or antifungal agent or combinations thereof. For example, suitable antibiotics and antimicrobials include, but are not limited to, amoxicillin, amoxicillin/clavulanate, cephalexin, ciprofloxacin, clindamycin, metronidazole, azithromycin, levofloxacin, sulfamethoxazole/trimethoprim, tetracycline(s), minocycline, tigecycline, doxycycline, rifampin, triclosan, chlorhexidine, penicillin(s), aminoglycides, quinolones, fluoroquinolones, vancomycin, gentamycin, cephalosporin(s), carbapenems, imipenem, ertapenem, antimicrobial peptides, cecropin-mellitin, magainin, dermaseptin, cathelicidin, α-defensins, and α-protegrins. Antifungal agents include, but are not limited to, ketoconazole, clortrimazole, miconazole, econazole, intraconazole, fluconazole, bifoconazole, terconazole, butaconazole, tioconazole, oxiconazole, sulconazole, saperconazole, voriconazole, terbinafine, amorolfine, naftifine, griseofulvin, haloprogin, butenafine, tolnaftate, nystatin, cyclohexamide, ciclopirox, flucytosine, terbinafine, and amphotericin B.

In several embodiments, the therapeutic agent may be an adrenocorticostatic, a β-adrenolytic, an androgen or antiandrogen, an antianemic, a antiparasitic, an anabolic, an anesthetic or analgesic, an analeptic, an antiallergic, an antiarrhythmic, an anti-arteriosclerotic, an antibiotic, an antidiabetic, an antifibrinolytic, an anticonvulsive, an angiogenesis inhibitor, an anticholinergic, an enzyme, a coenzyme or a corresponding inhibitor, an antihistaminic, an antihypertensive, an antihypotensive, an anticoagulant, an antimycotic, an antiseptic, an anti-infective, an antihemorrhagic, a β-receptor antagonist, a calcium channel antagonist, an antimyasthenic, an antiphlogistic, an antipyretic, an antirheumatic, a cardiotonic, a chemotherapeutic, a coronary dilator, a cytostatic, a glucocorticoid, a hemostatic, an immunoglobulin or its fragment, a chemokine, a cytokine, a mitogen, a cell differentiation factor, a cytotoxic agent, a hormone, an immunosuppressant, an immunostimulant, a morphine antagonist, an muscle relaxant, a narcotic, a vector, a peptide, a (para)sympathicomimetic, a (para)sympatholytic, a protein, a cell, a selective estrogen receptor modulator (SERM), a sedating agent, an antispasmodic, a substance that inhibits the resorption of bone, a vasoconstrictor or vasodilator, a virustatic or a wound-healing agent.

In various embodiments, the therapeutic agent comprises a drug used in the treatment of cancer or a pharmaceutically acceptable salt thereof. Such chemotherapeutic agents include antibodies, alkylating agents, angiogenesis inhibitors, antimetabolites, DNA cleavers, DNA crosslinkers, DNA intercalators, DNA minor groove binders, enediynes, heat shock protein 90 inhibitors, histone deacetylase inhibitors, immunomodulators, microtubule stabilizers, nucleoside (purine or pyrimidine) analogs, nuclear export inhibitors, proteasome inhibitors, topoisomerase (I or II) inhibitors, tyrosine kinase inhibitors, and serine/threonine kinase inhibitors. Specific therapeutic agents include, but are not limited to, adalimumab, ansamitocin P3, auristatin, bendamustine, bevacizumab, bicalutamide, bleomycin, bortezomib, busulfan, callistatin A, camptothecin, capecitabine, carboplatin, carmustine, cetuximab, cisplatin, cladribin, cytarabin, cryptophycins, dacarbazine, dasatinib, daunorubicin, docetaxel, doxorubicin, duocarmycin, dynemycin A, epothilones, etoposide, floxuridine, fludarabine, 5-fluorouracil, gefitinib, gemcitabine, ipilimumab, hydroxyurea, imatinib, infliximab, interferons, interleukins, beta-lapachone, lenalidomide, irinotecan, maytansine, mechlorethamine, melphalan, 6-mercaptopurine, methotrexate, mitomycin C, nilotinib, oxaliplatin, paclitaxel, procarbazine, suberoylanilide hydroxamic acid (SAHA), 6-thioguanidine, thiotepa, teniposide, topotecan, trastuzumab, trichostatin A, vinblastine, vincristine, vindesine, and tamoxifen.

In some embodiments, the therapeutic agent comprises a botulinum toxin (or neurotoxin) drug used in the treatment of various neuromuscular and/or neuroglandular disorders and neuropathies associated with pain. The botulinum toxin (or neurotoxin) may comprise the pharmacologically active drug or a pharmaceutically acceptable salt thereof. The botulinum toxin (or neurotoxin) as described and used herein may be selected from a variety of strains of Clostridium botulinum and may comprise the pharmacologically active drug or a pharmaceutically acceptable salt thereof. In one embodiment, the botulinum toxin is selected from the group consisting of botulinum toxin types A, B, C, D, E, F and G. In a preferred embodiment, the botulinum toxin is botulinum toxin type A. Commercially available botulinum toxin, BOTOX® (Allergan, Inc., Irvine, Calif.), consists of a freeze-dried, purified botulinum toxin type A complex, albumin and sodium chloride packaged in sterile, vacuum-dried form.

The paralytic effect of botulinum toxin is the most common benefit of commercial therapeutics, where muscles are relaxed in order to treat muscle dystonias, wrinkles and the like. However, it has been shown that in addition to its anti-cholinergic effects on muscle and smooth muscle, the neurotoxin can have therapeutic effects on other non-muscular cell types, and on inflammation itself. For example, it has been shown that cholinergic goblet cells, which produce mucus throughout the airway system, react to and can be shut down by introduction of botulinum toxin. Research also shows that botulinum toxin has direct ant-inflammatory capabilities. All of these therapeutic effects, muscle, smooth muscle, goblet cell and anti-inflammatory affects, may be derived from delivery of the toxin from the inventive devices.

A pharmaceutically acceptable salt refers to those salts that retain the biological effectiveness and properties of neutral therapeutic agents and that are not otherwise unacceptable for pharmaceutical use. Pharmaceutically acceptable salts include salts of acidic or basic groups, which groups may be present in the therapeutic agents. The therapeutic agents used in the present technology that are basic in nature are capable of forming a wide variety of salts with various inorganic and organic acids. Pharmaceutically acceptable acid addition salts of basic therapeutic agents used in the present technology are those that form non-toxic acid addition salts, i.e., salts comprising pharmacologically acceptable anions, such as the hydrochloride, hydrobromide, hydroiodide, nitrate, sulfate, bisulfate, phosphate, acid phosphate, isonicotinate, acetate, lactate, salicylate, citrate, tartrate, pantothenate, bitartrate, ascorbate, succinate, maleate, gentisinate, fumarate, gluconate, glucaronate, saccharate, formate, benzoate, glutamate, methanesulfonate, ethanesulfonate, benzenesulfonate, p-toluenesulfonate and pamoate [i.e., 1,1′-methylene-bis-(2-hydroxy-3-naphthoate)] salts. The therapeutic agents of the present technology that include an amino moiety may form pharmaceutically acceptable salts with various amino acids, in addition to the acids mentioned above. Suitable base salts are formed from bases which form non-toxic salts and examples are the aluminum, calcium, lithium, magnesium, potassium, sodium, zinc and diethanolamine salts.

A pharmaceutically acceptable salt may involve the inclusion of another molecule such as water or another biologically compatible solvent (a solvate), an acetate ion, a succinate ion or other counterion. The counterion may be any organic or inorganic moiety that stabilizes the charge on the parent compound. Furthermore, a pharmaceutically acceptable salt may have more than one charged atom in its structure. Instances where multiple charged atoms are part of the pharmaceutically acceptable salt can have multiple counter ions. Hence, a pharmaceutically acceptable salt can have one or more charged atoms and/or one or more counterion.

The therapeutic agent or pharmaceutically acceptable salt thereof may be an essentially pure compound or be formulated with a pharmaceutically acceptable carrier such as diluents, adjuvants, excipients or vehicles known to one skilled in the art. The carrier(s) must be “acceptable” in the sense of being compatible with the other ingredients of the formulations and not deleterious to the recipient thereof. For example, diluents include lactose, dextrose, sucrose, mannitol, sorbitol, cellulose, glycine and the like. For examples of other pharmaceutically acceptable carriers, see Remington: THE SCIENCE AND PRACTICE OF PHARMACY (21st Edition, University of the Sciences in Philadelphia, 2005).

The therapeutic agent or pharmaceutically acceptable salt form may be jet milled or otherwise passed through a sieve to form consistent particle sizes further enabling the regulated and controlled release of the therapeutic agent. This process may be particularly helpful for highly insoluble therapeutic agents.

An important criterion for determining the amount of therapeutic agent needed for the treatment of a particular medical condition is the release rate of the drug from the depot of the present technology. The release rate is controlled by a variety of factors, including, but not limited to, the rate that the releasing agent dissolves in vivo into the surrounding fluid, the in vivo degradation rate of the bioresorbable polymer or copolymer utilized. For example, the rate of release may be controlled by the use of multiple control regions between the therapeutic region and the physiological fluid. See, for example, FIGS. 6-8.

Suitable dosage ranges utilizing the depot of the present technology are dependent on the potency of the particular therapeutic agent, but are generally about 0.001 mg to about 500 mg of drug per kilogram body weight, for example, from about 0.1 mg to about 200 mg of drug per kilogram body weight, and about 1 to about 100 mg/kg-body wt. per day. Dosage ranges may be readily determined by methods known to one skilled in the art. Dosage unit forms will generally contain between about 1 mg to about 500 mg of active ingredient. For example, commercially available bupivacaine hydrochloride, marketed under the brand name Marcaine™ (Pfizer; New York, N.Y.), is generally administered as a peripheral nerve block using a dosage range of 37.5-75 mg in a 0.25% concentration and 25 mg up to the daily maximum level (up to 400 mg) in a 0.5% concentration (Marcaine®™ package insert; FDA Reference ID: 3079122). In addition, commercially available ropivacaine hydrochloride, marketed under the brand name Naropin® (Fresenius Kabi USA, LLC; Lake Zurich, Ill.), is administered in doses of 5-300 mg for minor and major nerve blocks (Naropin® package insert; Reference ID: 451112G). Suitable dosage ranges for the depot of the present technology are equivalent to the commercially available agents customarily administered by injection.

In some aspects of the technology, the therapeutic region 200 may include multiple layers. In such embodiments, the multiple layers may improve efficient loading of therapeutic agents. For example, multilayering may be a direct and effective way of loading substantial amounts of therapeutic agent. It can often be challenging to load a large amount of therapeutic agent in a single film layer, even by increasing the drug to polymer ratio or increasing the thickness of the layer. Even when the thickness of the therapeutic region can be theoretically increased to load more drug, consistent fabrication of a thick therapeutic region via casting could prove to be a challenge. In contrast, the stacking and bonding of thin films or sheets, each with a predetermined load of therapeutic agent, may present as a more reliable casting alternative. Data from an example of loading an analgesic (i.e., ropivacaine) is provided in Table 2.

TABLE 2

Drug load (ug)
Thickness (mm)

Single layer
212.66
0.019

Five layers
1120.83
0.046

Multiple
5.27
2.42

As but one example, a single layer loaded with ropivacaine and having a thickness of 0.019 mm was produced. A 5-layer film sample, where each layer was loaded with ropivacaine, having a thickness of 0.046 mm was also produced. Even though the thickness of the 5-layer film sample was only 2.42 times the thickness of the single layer, the load of therapeutic agent in the S-layer sample was 5.27 times that of the single layer sample. Accordingly, the multilayering approach enabled a substantially higher density of therapeutic agent.

As described above, heat compression bonding of multiple layers enables an effective reduction in film thickness and an increased density of therapeutic agent loading. In the example illustrated in Table 2, the multilayer structure enabled a 124% increase in the density of the therapeutic agent. In other embodiments, the increase in density of the therapeutic agent enabled by a multilayer structure of the therapeutic region may be approximately 50%, 75%, 100%, 125%, 150% or 200%.

D. Polymers

The depots 100 of the present technology are comprised of bioresorbable polymers. In some embodiments, both the therapeutic region 200 and the control region 300 comprise a polymer (or mix of polymers), which can be the same or different polymer (or mix of polymers) in the same or different amount, concentration, and/or weight percentage. In some embodiments, the control region 300 comprises a polymer and the therapeutic region 200 does not include a polymer. In some embodiments, the therapeutic region 200 comprises a polymer and the control region 300 does not include a polymer. At least as used in this section, “the polymer” applies to a polymer that may be used in the therapeutic region 200 and/or in the control region 300.

The bioresorbable polymers used in the present technology preferably have a predetermined degradation rate. The terms “bioresorbable,” or “bioabsorbable,” mean that a polymer will be absorbed within the patient's body, for example, by a cell or tissue. These polymers are “biodegradable” in that all or parts the polymeric film will degrade over time by the action of enzymes, by hydrolytic action and/or by other similar mechanisms in the patient's body. In various embodiments, the bioresorbable polymer film can break down or degrade within the body to non-toxic components while a therapeutic agent is being released. Polymers used as base components of the depots of the present technology may break down or degrade after the therapeutic agent is fully released. The bioresorbable polymers are also “bioerodible,” in that they will erode or degrade over time due, at least in part, to contact with substances found in the surrounding tissue, fluids or by cellular action.

Criteria for the selection of the bioresorbable polymer suitable for use in the present technology include: 1) in vivo safety and biocompatibility; 2) therapeutic agent loading capacity; 3) therapeutic agent releasing capability; 4) degradation profile; 5) potential for inflammatory response; and 6) mechanical properties, which may relate to form factor and manufacturability. As such, selection of the bioresorbable polymer may depend on the clinical objectives of a particular therapy and may involve trading off between competing objectives. For example, PGA (polyglycolide) is known to have a relatively fast degradation rate, but it is also fairly brittle. Conversely, polycaprolactone (PCL) has a relatively slow degradation rate and is quite elastic. Copolymerization provides some versatility if it is clinically desirable to have a mix of properties from multiple polymers. For biomedical applications, particularly as a bioresorbable depot for drug release, a polymer or copolymer using at least one of poly(L-lactic acid) (PLA), PCL, and PGA are generally preferred. The physical properties for some of these polymers are provided in Table 3 below.

TABLE 3

Elastic
Tensile
Tensile
Degradation

Tg
Tm
Modulus
Strength
Elongation
Time

Materials
(° C.)
(° C.)
(GPa)
(MPa)
(%)
(months)

PLA
45-60
150-162
0.35-3.5
21-60
2.5-6
12-16

PLLA
55-65
170-200
2.7-4.14
15.5-150
3-10
>24

PDLA
50-60
—
1.0-3.45
27.6-50
2-10
6-12

PLA/PGA
40-50
—
1.0-4.34
41.4-55.2
2-10
3

(50:50)

PGA
35-45
220-233
6.0-7.0

60-99.7
1.5-20
6-12

PCL
−60-−65
58-65
0.21-0.44
20.7-42
300-1000
>24

In many embodiments, the polymer may include polyglycolide (PGA). PGA is one of the simplest linear aliphatic polyesters. It is prepared by ring opening polymerization of a cyclic lactone, glycolide. It is highly crystalline, with a crystallinity of 45-55%, and thus is not soluble in most organic solvents. It has a high melting point (220-225° C.), and a glass transition temperature of 35-40° C. (Vroman, L., et al., Materials, 2009, 2:307-44). Rapid in vivo degradation of PGA leads to loss of mechanical strength and a substantial local production of glycolic acid, which in substantial amounts may provoke an inflammatory response.

In many embodiments, the polymer may include polylactide (PLA). PLA is a hydrophobic polymer because of the presence of methyl (—CH3) side groups off the polymer backbone. It is more resistant to hydrolysis than PGA because of the steric shielding effect of the methyl side groups. The typical glass transition temperature for representative commercial PLA is 63.8° C., the elongation at break is 30.7%, and the tensile strength is 32.22 MPa (Vroman, 2009). Regulation of the physical properties and biodegradability of PLA can be achieved by employing a hydroxy acids co-monomer component or by racemization of D- and L-isomers (Vroman, 2009). PLA exists in four forms: poly(L-lactic acid) (PLLA), poly(D-lactic acid) (PDLA), meso-poly(lactic acid) and poly(D,L-lactic acid) (PDLLA), which is a racemic mixture of PLLA and PDLA. PLLA and PDLLA have been the most studied for biomedical applications.

Copolymerization of PLA (both L- and D,L-lactide forms) and PGA yields poly(lactide-co-glycolide) (PLGA), which is one of the most commonly used degradable polymers for biomedical applications. In many embodiments, the polymer may include PLGA. Since PLA and PGA have significantly different properties, careful choice of PLGA composition can enable optimization of performance in intended clinical applications. Physical property modulation is even more significant for PLGA copolymers. When a composition is comprised of 25-75% lactide, PLGA forms amorphous polymers which are very hydrolytically unstable compared to the more stable homopolymers. This is demonstrated in the degradation times of 50:50 PLGA, 75:25 PLGA, and 85:15 PLGA, which are 1-2 months, 4-5 months and 5-6 months, respectively. In some embodiments, the polymer may be an ester-terminated poly (DL-lactide-co-glycolide) in a molar ratio of 50:50 (DURECT Corporation).

In some embodiments, the polymer may include polycaprolactone (PCL). PCL is a semi-crystalline polyester with high organic solvent solubility, a melting temperature of 55-60° C., and glass transition temperature of −54° C. (Vroman, 2009). PCL has a low in vivo degradation rate and high drug permeability, thereby making it more suitable as a depot for longer term drug delivery. For example, Capronor® is a commercial contraceptive PCL product that is able to deliver levonorgestrel in vivo for over a year. PCL is often blended or copolymerized with other polymers like PLLA, PDLLA, or PLGA. Blending or copolymerization with polyethers expedites overall polymer erosion. Additionally, PCL has a relatively low tensile strength (˜23 MPa), but very high elongation at breakage (4700%), making it a very good elastic biomaterial. PCL also is highly processable, which enables many potential form factors and production efficiencies.

Suitable bioresorbable polymers and copolymers for use in the present technology include, but are not limited to, poly(alpha-hydroxy acids), poly(lactide-co-glycolide)(PLGA or DLG), poly(DL-lactide-co-caprolactone) (DL-PLCL), polycaprolactone (PCL), poly(L-lactic acid) (PLA), poly(trimethylene carbonate) (PTMC), polydioxanone (PDO), poly(4-hydroxy butyrate) (PHB), polyhydroxyalkanoates (PHA), poly(phosphazene), polyphosphate ester), poly(amino acid), polydepsipeptides, poly(butylene succinate) (PBS), polyethylene oxide, polypropylene fumarate, polyiminocarbonates, poly(lactide-co-caprolactone) (PLCL), poly(glycolide-co-caprolactone) (PGCL) copolymer, poly(D,L-lactic acid), polyglycolic acid, poly(L-lactide-co-D,L-lactide), poly(L-lactide-co-glycolide), poly(D,L-lactide-co-glycolide), poly(gycolide-trimethylene carbonate), poly(glycolide-co-carolactone) (PGCL), poly(ethyl glutamate-co-glutamic acid), poly(tert-butyloxy-carbonylmethyl glutamate), poly(glycerol sebacate), tyrosine-derived polycarbonate, poly 1,3-bis-(p-carboxyphenoxy) hexane-co-sebacic acid, polyphosphazene, ethyl glycinate polyphosphazene, polycaprolactone co-butylacrylate, a copolymer of polyhydroxybutyrate, a copolymer of maleic anhydride, a copolymer of poly(trimethylene carbonate), polyethylene glycol (PEG), hydroxypropylmethylcellulose and cellulose derivatives, polysaccharides (such as hyaluronic acid, chitosan and starch), proteins (such as gelatin and collagen) or PEG derivatives and copolymers thereof. Other suitable polymers or copolymers include polyaspirins, polyphosphagenes, collagen, starch, pre-gelatinized starch, hyaluronic acid, chitosans, gelatin, alginates, albumin, fibrin, vitamin E analogs, such as alpha tocopheryl acetate, d-alpha tocopheryl succinate, D-lactide, D,L-lactide, L-lactide, D,L-lactide-caprolactone (DL-CL), D,L-lactide-glycolide-caprolactone (DL-G-CL), dextrans, vinylpyrrolidone, polyvinyl alcohol (PVA), PVA-g-PLGA, PEGT-PBT copolymer (polyactive), methacrylates, poly(N-isopropylacrylamide), PEO-PPO-PEO (pluronics), PEO-PPO-PAA copolymers, PLGA-PEO-PLGA, PEG-PLG, PLA-PLGA, poloxamer 407, PEG-PLGA-PEG triblock copolymers, SAIB (sucrose acetate isobutyrate)hydroxypropyl cellulose, hydroxypropyl methylcellulose, hydroxyethyl methylcellulose, carboxymethylcellulose or salts thereof, Carbopol®, poly(hydroxyethylmethacrylate), poly(methoxyethylmethacrylate), poly(methoxyethoxy-ethylmethacrylate), polymethylmethacrylate (PMMA), methylmethacrylate (MMA), gelatin, polyvinyl alcohols, propylene glycol, or combinations thereof.

In various embodiments, the molecular weight of the polymer can be a wide range of values. The average molecular weight of the polymer can be from about 1000 to about 10,000,000; or about 1,000 to about 1,000,000; or about 5,000 to about 500,000; or about 10,000 to about 100,000; or about 20,000 to 50,000.

As described above, it may be desirable in certain clinical applications using depots for controlled delivery of therapeutic agents to use copolymers comprising at least two of PGA, PLA, PCL, PDO, and PVA. These include, for example, poly(lactide-co-caprolactone) (PLCL) (e.g. having a PLA to PCL ratio of from 90:10 to 60:40) or its derivatives and copolymers thereof, poly(DL-lactide-co-caprolactone) (DL-PLCL) (e.g. having a DL-PLA to PCL ratio of from 90:10 to 50:50) or its derivatives and copolymers thereof, poly(glycolide-co-caprolactone) (PGCL) (e.g. having a PGA to PCL ratio of from 90:10 to 10:90) or its derivatives and copolymers thereof, or a blend of PCL and PLA (e.g. a ratio blend of PCL and PLA having a wt:wt ratio of 1:9 to 9:1). In one preferred embodiment, the bioresorbable polymer comprises a copolymer of polycaprolactone (PCL), poly(L-lactic acid) (PLA) and polyglycolide (PGA). In such a preferred embodiment, the ratio of PGA to PLA to PCL of the copolymer may be 5-60% PGA, 5-40% PLA and 10-90% PCL. In additional embodiments, the PGA:PLA:PCL ratio may be 40:40:20, 30:30:50, 20:20:60, 15:15:70, 10:10:80, 50:20:30, 50:25:25, 60:20:20, or 60:10:30. In some embodiments, the polymer is an ester-terminated poly (DL-lactide-co-glycolide-co-caprolactone) in a molar ratio of 60:30:10 (DURECT Corporation).

In some embodiments, a terpolymer may be beneficial for increasing the degradation rate and ease of manufacturing, etc.

To minimize the size of a bioresorbable depot, it is generally preferred to maximize the loading of therapeutic agent in the polymer to achieve the highest possible density of therapeutic agent. However, polymer carriers having high densities of therapeutic agent are more susceptible to burst release kinetics and, consequently, poor control over time release. As described above, one significant benefit of the depot structure described herein, and particularly the control region feature of the depot, is the ability to control and attenuate the therapeutic agent release kinetics even with therapeutic agent densities that would cause instability in other carriers. In certain embodiments, the therapeutic agent loading capacity includes ratios (wt:wt) of the therapeutic agent to bioresorbable polymer of approximately 1:3, 1:2, 1:1, 3:2, 2:1, 3:1, 4:1, 5:1, 6:1, 7:1, 8:1, 9:1, 10:1, 12:1, 14:1, or 16:1. In some embodiments, it may be desirable to increase the therapeutic effect or potency of the therapeutic agent released from the depot described herein while still maintaining the same or similar polymer to therapeutic agent ratio. This can be accomplished by using an essentially pure form of the therapeutic agent as opposed to a salt derivative. Additionally or alternatively, the therapeutic agent can be mixed with clonidine or epinephrine, which are known to increase the therapeutic effect of certain drugs.

In some embodiments, the bioresorbable polymer used in various layers of the depot may manifest as a layer of electrospun microfibers or nanofibers. Biocompatible electrospun microfibers/nanofibers are known in the art and may be used, for example, to manufacture implantable supports for the formation of replacement organs in vivo (U.S. Patent Publication No. 2014/0272225; Johnson; Nanofiber Solutions, LLC), for musculoskeletal and skin tissue engineering (R. Vasita and D. S. Katti, Int. J. Nanomedicine, 2006, 1:1, 15-30), for dermal or oral applications (PCT Publication No. 2015/189212; Hansen; Dermtreat APS) or for management of postoperative pain (U.S. Patent Publication No. 2013/0071463; Palasis et al.). As a manufacturing technique, electrospinning offers the opportunity for control over the thickness and the composition of the nano- or micro-fibers along with control of the porosity of the fiber meshes (Vasita and Katti, 2006). These electrospun scaffolds are three-dimensional and thus provide ideal supports for the culture of cells in vivo for tissue formation. Typically, these scaffolds have a porosity of 70-90% (U.S. Pat. No. 9,737,632; Johnson; Nanofiber Solutions, LLC). Suitable bioresorbable polymers and copolymers for the manufacture of electrospun microfibers include, but are not limited to, natural materials such as collagen, gelatin, elastin, chitosan, silk fibrion, and hyaluronic acid, as well as synthetic materials such as poly(c-caprolactone) (PCL), poly(glycolic acid) (PGA), poly(lactic-co-glycolic acid) (PLGA), poly(l-lactide-co-ε-caprolactone), and poly(lactic acid) (PLA).

Electrospun microfibers that are made from a bioresorbable polymer or copolymer and have been used in conjunction with a therapeutic agent are known in the art. For example, Johnson et al. have disclosed the treatment of joint inflammation and other conditions with an injection of biocompatible polymeric electrospun fiber fragments along with a carrier medium containing chitosan (U.S. Published Application No. 2016/0325015; Nanofiber Solutions, LLC). Weldon et al. reported the use of electrospun bupivacaine-eluting sutures manufactured from poly(lactic-co-glycolic acid) in a rat skin wound model, wherein the sutures provided local anesthesia at an incision site (J. Control Release, 2012, 161:3, 903-909). Similarly, Palasis et al. disclosed the treatment of postoperative pain by implanting electrospun fibers loaded with an opioid, anesthetic or a non-opioid analgesic within a surgical site (U.S. Patent Publication No. 2013/0071463; Palasis et al.). Electrospun microfibers suitable for use in the present technology may be obtained by the methods disclosed in the above cited references, which are herein incorporated in their entirety.

When implanted in a patient's joint (for example, a knee joint), the bioresorbable depot described above may be positioned in the joint such that it will be articulating throughout the duration of release. So as to avoid premature release of the analgesic, it is desirable for the depot to have a threshold level of mechanical integrity and stability until most of the analgesic has been released. While it may be desirable to maximize the loading of therapeutic agent in the bioresorbable depot, as described above, such maximization can typically be at the expense of mechanical integrity and stability of the depot. Given the high dosage of anesthetic necessary to provide analgesia through both the acute and subacute postoperative pain periods and limited space in the knee, it is desirable for the depot described herein to have a high density loading of anesthetic while still maintaining sufficient mechanical integrity and stability in the knee. The layered structure and, particularly, the presence of the control region provide some safeguard against the premature release of anesthetic. Moreover, the use of heat compression in the manufacturing process enables substantial loading of anesthetic into the therapeutic region while creating a thermal bond between the therapeutic region and control region, thereby preventing delamination, and a consequent uncontrolled release of drug, when the depot is subjected to mechanical stress in the knee.

It is generally desirable that the implanted polymer fully degrade following complete delivery of the therapeutic agent. Full degradation is preferred because, unless the implanted polymer provides some structural function or support, the clinical practitioner would have to reconcile leaving in a foreign body with no functional purpose, which could be a source of inflammation or infection, or perform another surgery simply to remove the remaining polymer. As an alternative to full degradation, it would be desirable for any remaining polymer to be fully encapsulated by the body.

The degradation of an implanted polymer consists essentially of two sequential processes: diffusion of an aqueous solution (e.g., physiological fluids) followed by hydrolytic degradation. Degradation usually takes one of two forms: (1) surface erosion; and (2) bulk degradation. Surface erosion of a polymer occurs when the polymer erodes from the surface inward, where hydrolytic erosion at the surface is faster than the ingress of water into the polymer. Conversely, bulk degradation occurs throughout the entire polymer, where water penetrates and degrades the interior of the material faster than the surface can erode. Polymers such as PLA, PGA, PLGA and PCL all resorb into the body via bulk degradation.

The time necessary for complete degradation can vary greatly based on the material selected and the clinical performance requirements of the depot. For example, in the case of treating and managing postoperative pain, it may be desirable for the polymer depot to release therapeutic agent (i.e., an analgesic) for anywhere from 5 to 30 days. In the case of treating or preventing infection of a prosthetic joint (e.g., knee or hip implant), it may be desirable for the polymer depot to release an anti-infective agent for anywhere from 2 to 4 months. Alternatively, even if the entire amount of therapeutic agent loaded into the polymer has been released, it may be desirable for the polymer to degrade over a longer period than the duration of drug release. For example, rapid degradation can often make the polymer brittle and fragile, thereby compromising mechanical performance, or provoking an inflammatory response from the body. In particular, it may be desirable, in certain clinical applications, to have an embodiment wherein degradation of the polymer commenced only after release of substantially all of the therapeutic agent.

In certain embodiments of the present technology, it may be desirable for the polymer to fully resorb into the body after substantially all therapeutic agent loaded therein is released. In certain embodiments, this degradation can be as short as 1 month. Alternatively, in other embodiments, full degradation could take as long as 2 months, 3 months, 4 months, 6 months, 9 months or 12 months. In some embodiments, the bioresorbable polymer substantially degrades in vivo within about one month, about two months, about three months, about four months, about five months or about six months. In some embodiments, it may be desirable for full degradation to be 6 months such that the mechanical properties of the implanted polymer are preserved for the first 2 months following implantation.

Core Acidification

Traditional bioresorbable implants often lead to tissue inflammation due to a phenomenon known as “core acidification.” For example, as shown schematically in FIG. 17, polymer implants having a thickness greater than 1 mm degrade by bulk erosion (i.e., degradation occurs throughout the whole material equally; both the surface and the inside of the material degrade at substantially the same time). As the polymer degrades, lactate accumulates at an internal region of the implant. Eventually, because of the high pH in the internal region of the implant, the lactate becomes lactic acid. The accumulated lactic acid will invariably release into the body, thereby provoking an inflammatory response. FIG. 18, for example, is a scanning electron microscope (“SEM”) image of a polymer tablet of the prior art after 20 days of degradation. Inflammation in and around a prosthetic joint may be particularly concerning because of the risk of inflammation-induced osteolysis, which may cause a loosening of the newly implanted joint. Moreover, core acidification causes extracellular pH to drop, which then causes the amount of free base bupivacaine to drop. Only free base bupivacaine can cross the lipid bilayer forming the cell membrane into the neuron. Once bupivacaine crosses into the neuron the percent of bupivacaine HCl increases. It is the bupivacaine HCl form that is active by blocking sodium from entering the neuron thus inducing analgesia. Thus, any reduction in extracellular pH (for example, via core acidification) slows transfer of the analgesic into the neuron, thereby reducing or altogether eliminating the therapeutic effects of the analgesic.

The degree of core acidification is determined in large part by the geometry and dimensions of the polymer implant. (See, e.g., Grizzi et al., Hydrolytic degradation of devices based on poly(dl-lactic acid) size-dependence, BIOMATERIALS, 1995, Vol. 16 No. 4, pp. 305-11; Fukuzaki et al., in vivo characteristics of high molecular weight copoly(l-lactide/glycolide) with S-type degradation pattern for application in drug delivery systems, Biomaterials 1991, Vol. 12 May, pp. 433-37; Li et al., Structure-property relationships in the case of degradation of massive alipathic poly-(α-hydroxy acids) in aqueous media, JOURNAL OF MATERIALS SCIENCE: MATERIALS IN MEDICINE I (1990), pp. 123-130.) For example, degradation in more massive monolithic devices (mm-size scales and greater) proceeds much more rapidly in their interior than on their surface, leading to an outer layer of slowly degrading polymer entrapping more advanced internal degradation products from interior zone autocatalysis (so-called “S-type” non-linear kinetic degradation profile.). In contrast to a thicker film, a thin film of less than 1 mm thickness will typically degrade via surface erosion, wherein the lactate resulting from degradation will not accumulate in the interior of the film. Thin films, because of their high surface area to volume ratios, are known to degrade uniformly and do not lead to core acidification. (See Grizzi et al.)

As shown schematically in FIG. 19A, the depots of the present technology may shed up to 50%, 60%, 70% or 80% of their individual mass (anesthetic and releasing agent) over the course of releasing the anesthetic (e.g., 5 days, 7 days, 10 days, 14 days, 20 days, 30 days, etc.), resulting in a highly porous, mesh-like system that—at least for the purpose of degradation—behaves like a thin-film because of its high surface area to volume ratio. Body fluids will invade the highly porous polymer carrier to degrade the remaining polymer via surface erosion, thereby avoiding core acidification and the resulting inflammatory response. Without being bound by theory, it is believed that the drug core matrix of the therapeutic region becomes highly porous as degradation continues. For example, FIGS. 19B and 19C are scanning electron microscope (“SEM”) images showing the therapeutic region before and after elution, respectively. However, even after the release of therapeutic agent, there is still a clear porous structure left through which water and acid can diffuse effectively. Thus, depots 100 of the present technology having a thickness greater than about 1 mm degrade like a thin film, and surprisingly do not exhibit core acidification.

E. Releasing Agent

In many implantable drug eluting technologies, the depot provides an initial, uncontrolled burst release of drug followed by a residual release. These drug release kinetics may be desirable in certain clinical applications, but may be unavoidable even when undesirable. Hydrophilic drugs loaded in a polymer carrier will typically provide a burst release when exposed to physiologic fluids. This dynamic may present challenges, particularly when it is desirable to load a large volume of drug for controlled, sustained in vivo administration. For example, although it may be desirable to implant several days or weeks' worth of dosage to achieve a sustained, durable, in vivo pharmacological treatment, it is imperative that the therapeutic agent is released as prescribed, otherwise release of the entire payload could result in severe complications to the patient.

To achieve finer control over the release of the therapeutic agent when exposed to fluids, the depots 100 of the present technology may include a releasing agent. In some embodiments, both the therapeutic region 200 and the control region 300 include a releasing agent (or mix of releasing agents), which can be the same or different releasing agent (or mix of releasing agents) in the same or different amount, concentration, and/or weight percentage. In some embodiments, the control region 300 includes a releasing agent and the therapeutic region 200 does not include a releasing agent. In some embodiments, the therapeutic region 200 includes a releasing agent and the control region 300 does not include a releasing agent. At least as used in this section, “the releasing agent” applies to a releasing agent that may be used in the therapeutic region 200 and/or in the control region 300.

The type and/or amount of releasing agent within the therapeutic region 200 and/or control region 300 may be varied according to the desired release rate of the therapeutic agent into the surrounding biological fluids. For example, choosing releasing agents with different dissolution times will affect the rate of release. Also, the weight percentage of releasing agent in a region of polymer will influence the number and the size of the diffusion openings subsequently formed in the polymer, thereby affecting the rate of therapeutic agent release from the depot 100 (e.g., the greater the weight percentage of releasing agent, the faster the release). The presence of releasing agent in select regions also influences the release rate of therapeutic agent. For example, a depot with releasing agent in the control region 300 and/or therapeutic region 200 will generally release therapeutic agent at a higher rate compared to a depot with no releasing agent. Similarly, releasing agent in both the control region 300 and the therapeutic region 200 will generally release therapeutic agent at a higher rate than when releasing agent is in the control region alone.

In certain embodiments of the present technology, the layer-by-layer ratio of releasing agent to bioresorbable polymer can be adjusted to control the rate of therapeutic agent released from the depot 100. For example, in many embodiments of the present technology, the depot 100 includes a therapeutic region 200 having a weight percentage of releasing agent that is different than the weight percentage of the releasing agent in the control region 200. For example, the therapeutic region 200 may have a greater or lesser weight percentage of releasing agent than the control region 300. In some embodiments, the control region 300 may have a weight percentage of releasing agent that is at least 2 times greater than the weight percentage of the releasing agent in the therapeutic region 200. In some embodiments, the control region 300 may have a weight percentage of releasing agent that is at least 3-20 times greater, at least 4 times greater, at least 5 times greater, at least 6 times greater, at least 7 times greater, at least 8 times greater, at least 9 times greater, at least 10 times greater, at least 11 times greater, at least 12 times greater, at least 13 times greater, at least 14 times greater, at least 16 times greater, at least 17 times greater, at least 18 times greater, at least 19 times greater, at least 20 times greater, at least 25 times greater, at least 30 times greater, about 5 to 10 times greater, about 10 to 15 times greater, about 5 to 15 times greater, or about 15 to 25 times greater than the weight percentage of the releasing agent in the therapeutic region 200.

In many embodiments of the present technology, the releasing agent is a surfactant. Unlike the use as a releasing agent as described herein, surfactants are usually used to control the dispersions, flocculation and wetting properties of a drug or polymer. Fundamentally, surfactants operate on the interface between the polymer and drug or the interface between the drug and biological membrane. Depending on the type of formulation, surfactants typically play a role in several aspects of drug delivery: (1) solubilization or stabilization of hydrophobic drugs by lowering the entropic cost of solvating hydrophobic drug through complexation with drug molecules in solution (C. Bell and K. A. Woodrow, ANTIMICROB. AGENTS CHEMOTHER., 2014, 58:8, 4855-65); (2) improvement of the wetting of tablet or polymer for fast disintegration (M. Irfan, et al., SAUDI PHARM. J., 2016, 24, 537-46); (3) formation of colloidal drug delivery systems, such as reverse micelles, vesicles, liquid crystal dispersions, nanoemulsions and nanoparticles (M. Fanun, Colloids in Drug Delivery, 2010, p. 357); and (4) improvement the bioperformance of drugs by altering the permeability of biological membrane and consequently drug penetration/permeation profile (S. Jain, et al., Lipid Based Vesicular Drug Delivery Systems, 2014, Vol. 2014, Article ID 574673).

In order to illustrate the unique aspects of using a releasing agent in the polymeric control region to form diffusion openings and/or microchannels in the present technology, it is helpful to explain the more common approach of using hydrophilic molecules to enhance drug release. Conventionally, drug release is enhanced by creating a larger surface area in order to increase contact between the drug and the bodily fluid, thereby accelerating drug release. The most common mechanism for forming pores prior to implantation is to use non-surfactant hydrophilic molecules as pore-forming agents in polymer layers, either as a coating layer or a free-standing film (Kanagale, P., et al., AAPS PHARM. SCI. TECH., 2007; 8(3), E1-7). Usually, pores are pre-formed by blending hydrophilic molecules with polymer, then removing the hydrophilic molecules by contact with water. However, when hydrophilic molecules are blended with hydrophobic polymer, the molecules tend to form hydrophilic domains and hydrophobic domains, which are energetically favorable due to the increase in entropy. When the film contacts water, hydrophilic domains are removed and replaced with large pores. The rate of drug release in this case is solely controlled by the porosity of the film and the resulting increased total surface area. The typical drug release curve in this case has a high, uncontrolled initial burst followed with a very slow release of residual drug afterwards.

Previously, when non-surfactant hydrophilic molecules are mixed into the polymer and then removed, a film with a porous structure is created. This porous layer reduces mechanical strength and elasticity, making it less suitable for certain applications. Additionally, this structure does not withstand heat compression bonding of the film because the pores would collapse. The loss of porous structure during heat compression negates the original intent of using the hydrophilic molecule, thus resulting in a densely packed film without any enhanced therapeutic agent release capability.

Further, if the hydrophilic molecule remains in the polymer layer during heat compression, the dissolution of the hydrophilic molecule in vivo causes the formation of very large pores, approximately 3-10 μm in diameter. Such large pores provide a large surface area, thereby causing a burst release of drug. In contrast to the use of hydrophilic molecules, the use of a surfactant as a releasing agent in the present technology enables the formation of microchannels approximately 5-20 nanometers in diameter, which is two orders of magnitude smaller than the pores resulting from the use of hydrophilic molecules. This allows tight control of the drug release by diffusion and, if desirable, without an uncontrolled burst release upon implantation. Additionally, use of a surfactant as a releasing agent allows the agent to remain present in the polymer prior to use and no pre-formed pores are created. This approach is particularly advantageous because the polymer's mechanical properties are preserved, thereby allowing the polymer to be easily processed and worked into different configurations.

In the present technology, the releasing agent is pre-mixed into the bioresorbable polymer such that each layer of polymer is contiguous and dense. The depot 100 is then formed when these layers are bonded together via heat compression without any adverse impact to the functional capabilities of the film. When the densely packed film is ultimately implanted, the releasing agent dissolves to enable efficient, controlled release of the therapeutic agent.

In some embodiments, the releasing agent comprises a polysorbate. Polysorbate is commonly used in the pharmaceutical industry as an excipient and solubilizing agent. Polysorbate is a non-ionic surfactant formed by the ethoxylation of sorbitan followed by esterification by lauric acid. Polysorbate 20 [IUPAC name: polyoxyethylene(20)sorbitan monolaurate] contains a mixture of ethoxylated sorbitan with 20 repeat units of polyethylene glycol distributed among four different sites in the sorbitan molecule. Common commercial names include Tween™ and Tween20™ (Croda International Plc, Goole, East Yorkshire, UK) and Alkest® TW 20 (Oxiteno, Houston, Tex.).

Polysorbate is often utilized to improve oral bioavailability of a poorly water-soluble/hydrophobic drug. For example, polysorbate was used to improve bioavailability of active molecules that possess low solubility and/or intestinal epithelial permeability and it was observed that the bioavailability of this poorly water-soluble drug was greatly enhanced in a formulation with polysorbate or similar surfactants. (WO2008/030425; Breslin; Merck.) Akbari, et al., observed that using the hydrophilic carrier polyethylene glycol (PEG) along with polysorbate leads to faster an oral enhanced drug release rate because the polysorbate brings the drug in close contact with the PEG. (Akbari, J., et al., ADV. PHARM. BULL., 2015, 5(3): 435-41.)

Polysorbate also functions as a water-soluble emulsifier that promotes the formation of oil/water emulsions. For example, the drug famotidine is known to have high solubility in water but low in vivo permeability. Polysorbate was used in an oral microemulsion formulation for enhancing the bioavailability of famotidine. (Sajal Kumar Jha, et al., IJDDR, 2011, 3(4): 336-43.) Polysorbate is also used as a wetting agent to achieve rapid drug delivery. For example, Ball et al., achieved rapid delivery of maraviroc via a combination of a polyvinylpyrrolidone (PVP) electrospun nanofiber and 2.5 wt % Tween 20, which allowed for the complete release of 28 wt % maraviroc in just six minutes. It was believed that use of Tween 20 as a wetting agent allowed water to penetrate the PVP nanofiber matrix more quickly, thereby increasing the rate of drug release. (Ball, C., et al., ANTIMICROB. AGENTS CHEMOTHERAPY, 2014, 58:8, 4855-65.)

As described above, in order to improve drug release in certain polymer carriers, hydrophilic polymers, such as polysorbate, have been added to these carriers to accelerate or to enhance drug release from biocompatible polymers such as polyethylene glycol (PEG) in oral formulations (Akbari, J., et al., ADV. PHARM. BULL., 2015, 5(3): 435-441). However, these formulations are intended to provide an immediate release of a hydrophobic drug into a hydrophilic environment (the in vivo physiologic fluid), not a variable or sustained controlled release as part of a control region.

In some embodiments, the releasing agent is polysorbate 20, commercially known as Tween20™. Other releasing agents suitable for use in the present technology include polysorbates, such as Polysorbate 80, Polysorbate 60, Polysorbate 40, and Polysorbate 20; sorbitan fatty acid esters, such as sorbitan monostearate (Span 60), sorbitan tristearate (Span 65), sorbitane trioleate (Span 85), sorbitan monooleate (Span 80), sorbitan monopalmitate, sorbitan monostearate, sorbitan monolaurate, sorbitan monopalmitate, sorbitan trioleate, and sorbitan tribehenate; sucrose esters, such as sucrose monodecanoate, sucrose monolaurate, sucrose distearate, and sucrose stearate; castor oils such as polyethoxylated castor oil, polyoxyl hydrogenated castor oil, polyoxyl 35 castor oil, Polyoxyl 40 Hydrogenated castor oil, Polyoxyl 40 castor oil, Cremophor® RH60, and Cremophor® RH40; polyethylene glycol ester glycerides, such as Labrasol®, Labrifil® 1944; poloxamer; polyoxyethylene polyoxypropylene 1800; polyoxyethylene fatty acid esters, such as Polyoxyl 20 Stearyl Ether, diethylene glycol octadecyl ether, glyceryl monostearate, triglycerol monostearate, Polyoxyl 20 stearate, Polyoxyl 40 stearate, polyoxyethylene sorbitan monoisostearate, polyethylene glycol 40 sorbitan diisostearate; oleic acid; sodium desoxycholate; sodium lauryl sulfate; myristic acid; stearic acid; vitamin E-TPGS (vitamin E d-alpha-tocopherol polyethylene glycol succinate); saturated polyglycolized glycerides, such as Gelucire® 44/14 and and Gelucire® 50/13; and polypropoxylated stearyl alcohols such as Acconon® MC-8 and Acconon® CC-6.

Diffusion Openings

The channels or voids formed within the therapeutic region 200 and/or control region 300 by dissolution of the releasing agent may be in the form of a plurality of interconnected openings or pores and/or a plurality of interconnected pathways, referred to herein as “diffusion openings.” In some embodiments, one or more of the channels may be in the form of discrete pathways, channels, or openings within the respective therapeutic and/or control region. Depending on the chemical and material composition of the therapeutic and control regions, one or more of the formed channels may extend: (a) from a first end within the therapeutic region to a second end also within the therapeutic region; (b) from a first end within the therapeutic region to a second end at the interface of the therapeutic region and the control region; (c) from a first end within the therapeutic region to a second end within the control region; (d) from a first end within the therapeutic region through the control region to a second end at an outer surface of the control region; (e) from a first end at the interface between the therapeutic region and the control region through the control region to a second end within the control region; (f) from a first end at the interface between the therapeutic region and the control region to a second end at an outer surface of the control region; (g) from a first end within the control region to a second end also within the control region; and (h) from a first end within the control region to a second end at an outer surface of the control region. Moreover, one or more of the channels may extend between two or more microlayers of the therapeutic region and/or control region.

F. Constituent Ratios

In some embodiments, the ratio of the polymer in the control region 300 to the releasing agent in the control region 300 is at least 1:1. In some embodiments, the ratio may be at least 1.5:1, at least 2:1, at least 2.5:1, or at least 3:1.

In some embodiments, a ratio of the mass of the therapeutic agent in the depot 100 to the polymer mass of the depot is at least 1:1, at least 2:1, at least 3:1, at least 4:1, at least 5:1, at least 6:1, at least 7:1, at least 8:1, at least 9:1, at least 10:1, at least 11:1, at least 12:1, at least 13:1, at least 14:1, at least 15:1, or at least 16:1.

In some embodiments, the ratio of releasing agent to polymer to therapeutic agent in the therapeutic region 200 is of from about 0.1:10:20 to about 2:10:20, and in some embodiments of from about 0.1:10:20 to about 1:10:20, and in some embodiments of from about 0.1:10:20 to about 0.5:10:20.

In some embodiments, the ratio of releasing agent to polymer in the control region 300 is of from about 1:2 to about 1:10. In some embodiments, one or more of the control regions may have a ratio of releasing agent to polymer of 1:2, and one or more of the other control regions may have a ratio of releasing agent to polymer of 1:10

G. Selected Depot Embodiments Including a Barrier Region

In some embodiments, the depot 100 may be configured to release the therapeutic agent in an omnidirectional manner. In other embodiments, the depot may include one or more barrier regions 400 covering one or more portions of the therapeutic region 200 and/or control region 300, such that release of the therapeutic agent is limited to certain directions. The barrier region 400 may provide structural support for the depot. The barrier region 400 may comprise a low porosity, high density of bioresorbable polymer configured to provide a directional release capability to the depot. In this configuration, the substantial impermeability of this low porosity, high density polymer structure in the barrier region 400 blocks or impedes the passage of agents released from the therapeutic region 200. Accordingly, the agents released from the therapeutic region 200 take a path of less resistance through the control region 300 opposite from the barrier region 400, particularly following the creation of diffusion openings in the control region 300.

An example a depot 100 of the present technology having a barrier region 400 is shown in FIG. 16A. The barrier region 400 may comprise a low porosity, high density of bioresorbable polymer configured to provide a directional release capability to the multi-region depot. In this configuration, the low porosity, high density polymer structure in the barrier region 400 blocks or impedes passage of agents release from the therapeutic region 200. Accordingly, the agents released from the therapeutic region 200 take a path of lesser resistance through the control region opposite from the barrier region 400, particularly following the creation of channels in the control region. In an additional embodiment, the porosity of other regions of the multi-region depot can be varied to facilitate the release of therapeutic agent. For example, in this embodiment, the barrier region 400, the therapeutic region 200, and the control region 300 of the multi-region depot depicted in FIG. 16A may have different porosities ranging from low porosity in the barrier region 400 to higher porosities in the therapeutic agent and control regions to facilitate the release of therapeutic agent from the multi-region depot. In additional embodiments, the porosities of the edges of the multi-region depot, or within portions of any of the individual regions, can be varied to properly regulate or manipulate the release of therapeutic agent.

In the embodiment depicted in FIG. 16B, the multi-region depot provides for a bilateral or bidirectional release of therapeutic agent. This bidirectional release capability is accomplished through symmetric regioning about a high-density barrier region 400, wherein, as described above, the therapeutic agent releases along a path of less resistance, thereby releasing away from the high density barrier region 400. More specifically, disposed on one side of the barrier region 400 is a control region 300a and a therapeutic region 200a and, disposed on the other side of the barrier region 400, is a control region 300b and a therapeutic region 200b that are substantially similar to the pair on the other side. These pairs on either side of the barrier region 400 are configured to produce substantially equivalent, bidirectional release of therapeutic agent. In an alternate embodiment, a bidirectional release that is not equivalent (i.e., the therapeutic agent and/or rate of release in each direction is not the same) may be accomplished by asymmetric regioning, whereby the control region and therapeutic region pairs on either side of the barrier region 400 are substantially different.

In additional embodiments, it may be desirable for the multi-region depot to release multiple therapeutic agents. This capability can be particularly useful when multimodal pharmacological therapy is indicated. In the embodiment shown in FIG. 16C, the multi-region depot comprises a topmost or outermost control region 300a, a first therapeutic region 200a adjacent to the control region, a second therapeutic region 200b adjacent to the first therapeutic region 200a, and a barrier region 400 adjacent to the second therapeutic region 200b. In this embodiment, the first therapeutic region 200a and the second therapeutic region 200b comprise a first therapeutic agent and a second therapeutic agent, respectively. In certain embodiments, the first and second therapeutic agents are different. In one embodiment, the multi-region depot is configured to release the first and second therapeutic agents in sequence, simultaneously, or in an overlapping fashion to yield a complementary or synergistic benefit. In this configuration, the presence and function of the control region 300a may also ensure consistent and, if desired, substantially even release of multiple therapeutic agents residing beneath. Since many conventional drug delivery devices can fail to provide an even release of multiple drugs with different molecular weights, solubility, etc., the role of the control region in achieving a substantially even release of different therapeutic agents can be a significant advantage.

In some embodiments, the first therapeutic agent and second therapeutic agent are the same therapeutic agent but are present in the first and second therapeutic regions, respectively, in different relative concentrations to represent different dosages to be administered. In some embodiments, the first and second therapeutic agents of the first and second therapeutic regions, respectively, may have no clinical association or relationship whatsoever. For example, in an embodiment for use as part of a total joint replacement (e.g., total knee arthroplasty, total hip arthroplasty) or other surgical procedure, it may be clinically desirable to administer in the vicinity of the surgical site both an analgesic (e.g., local anesthetic) to treat and better manage postoperative pain for several days or weeks following the surgery and an antibiotic to treat or prevent surgical site infection associated with the surgery or implanted prosthesis (if any) for several weeks or months following the surgery. In this embodiment, the first therapeutic region 200a may comprise a therapeutically effective dose of local anesthetic to substantially provide pain relief for no less than 3 days and up to 15 days following the surgery and the second therapeutic region 200b may comprise a therapeutically effective dose of antibiotics to substantially provide a minimally effective concentration of antibiotic in the vicinity of the surgical site for up to three months following the surgery.

In some embodiments, as shown in FIG. 16D, the depot 100 comprises a first dosage region and a second dosage region, wherein the first and second dosage regions correspond to first and second dosage regimens. More specifically, each dosage region comprises a control region and therapeutic region pair, wherein each pair is configured for controlled release of a therapeutic agent from the therapeutic region 200a, 200b in accordance with a predetermined dosage regimen. For example, in treating and/or managing postoperative pain, it may be desirable for the multi-region depot to consistently release 50-400 mg/day of local anesthetic (e.g., bupivacaine, ropivacaine and the like) for at least 2-3 days following surgery (i.e., first dosage regimen) and then release a local anesthetic at a slower rate (e.g., 25-200 mg/day) for the next 5 to 10 days (i.e., second dosage regimen). In this exemplary embodiment, the first dosage region, and the control region and therapeutic region pair therein, would be sized, dimensioned, and configured such that the multi-region depot releases the first therapeutic agent in a manner that is consistent with the prescribed first dosage regimen. Similarly, the second dosage region, and the control region and therapeutic region pair therein, would be sized, dimensioned and configured such that the multi-region depot releases the second therapeutic agent in a manner that is consistent with the prescribed second dosage regimen. In another embodiment, the first and second dosage regions may correspond to dosage regimens utilizing different therapeutic agents. In one embodiment, the multi-region depot 100 is configured to administer the first and second dosage regimens in sequence, simultaneously, or in an overlapping fashion to yield a complementary or synergistic benefit. In an alternate embodiment of this scenario, the first and second dosage regimens, respectively, may have no clinical association or relationship whatsoever. For example, as described above with respect to the embodiment depicted in FIG. 16C, the first dosage regimen administered via the first dosage region may be treating or managing postoperative pain management and the second dosage regimen administered via the second dosage region may be treating or preventing infection of the surgical site or implanted prosthesis (if any).

Certain embodiments of the present invention utilize delayed release agents. As illustrated in FIG. 16E, the depot 100 may include a barrier region 400 as the outermost (i.e., topmost) region to the multi-region depot and adjacent to a control region 300 comprising a releasing agent. The barrier region 400 presents a barrier to physiologic fluids from reaching and dissolving the releasing agent within the control region. In one embodiment, the barrier region 400 may comprise a delayed release agent mixed with a bioresorbable polymer, but without a releasing agent. Delayed release agents are different from the releasing agents used in the multi-region depot of the invention. Delayed release agents dissolve in physiological fluids more slowly than do releasing agents and thus provide the possibility for release of a therapeutic agent a defined amount of time following implantation of the multi-region depot. In embodiments where a delayed release agent is not present in the barrier region 400, it may take more time for the physiological fluids to traverse the barrier region 400 and contact the releasing agent. Only when the physiological fluids make contact with the control region will the releasing agent begin to dissolve, thus allowing the controlled release of the therapeutic agent. Delayed release agents may be advantageously used in the therapeutic methods of the invention wherein the therapeutic agent is not immediately required. For example, a nerve blocking agent may be injected prior to a surgical procedure, numbing the entire area around a surgical site. The controlled release of a local anesthetic is not required in such a surgery until the nerve block wears off

Suitable delayed release agents for use in the present invention are pharmaceutically acceptable hydrophobic molecules such as fatty acid esters. Such esters include, but are not limited to, esters of myristoleic acid, sapienic acid, vaccenic acid, stearic acid, arachidic acid, palmitic acid, erucic acid, oleic acid, arachidonic acid, linoleic acid, linoelaidic acid, eicosapentaenoic acid, docosahexaenoic acid. Preferred esters include stearic acid methyl ester, oleic acid ethyl ester, and oleic acid methyl ester. Other suitable delayed release agents include tocopherol and esters of tocopherol, such as tocopheryl nicotinate and tocopheryl linolate.

H. Additional Depot Configurations

FIGS. 20-36 illustrate various examples of depots 100 having an elongated form. As depicted in FIG. 20, an “elongated depot” or an “elongated form” as used herein refers to a depot configuration in which the depot 100 has a length L between its ends along a first axis A1 (e.g., a longitudinal axis) that is at least 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2, 3, 4, 5, 6, 7, 8, 9, 10, 20, or 30 times greater than a maximum dimension D of a cross-sectional slice of the depot 100 within a plane orthogonal to the first axis A1. The elongated depots 100 described herein may include a therapeutic region 200 containing a therapeutic agent (such as any of the therapeutic agents described herein) and a control region 300 at least partially surrounding the therapeutic region 200 to control release of the therapeutic agent from the depot 100. The therapeutic region 200 may optionally include a bioresorbable polymer (such as any of the polymers described herein) and/or a releasing agent (such as any of the releasing agents described herein). The control region 300 may include a bioresorbable polymer (such as any of the polymers described herein) mixed with a releasing agent (such as any of the releasing agents described herein), but does not include any therapeutic agent at least prior to implantation. In some embodiments, the control region 300 may include some therapeutic agent prior to implantation, for example having a lower concentration of therapeutic agent than the therapeutic region 200. As discussed in greater detail below, the thickness of the control region 300, the concentration of releasing agent in the control region 300, the amount of exposed (uncovered) surface area of the therapeutic region 200, the shape and size of the depot 100, and other suitable parameters may be varied to achieve a desired release profile for the sustained, controlled release of the therapeutic agent from the depot 100.

In the embodiments shown in FIGS. 20-36, the elongated depot 100 has a cylindrical, columnar, and/or rod-like shape such that the cross-sectional shape is a circle and the cross-sectional dimension D is the diameter of the circle. In some embodiments, however, the elongated depot 100 may have another elongated configuration and/or cross-sectional shape along all or a portion of its length L. For example, the depot 100 may be in the form of a ribbon-like strip and thus have a square or rectangular cross-sectional shape. In other embodiments, the elongated depot 100 may have a circular, triangular, rhomboid, or other polygonal or non-polygonal cross-sectional shape based on the desired application. The elongated depot 100 may be a solid or semi-solid formulation with sufficient column strength to be pushed or pulled from a delivery device and sufficient durability and/or structural integrity to maintain its shape while the therapeutic agent is released into the surrounding anatomy for the desired duration of release.

A length L of the elongated depot 100 can be about 2 mm to about 300 mm, about 10 mm to about 200 mm, or about 10 mm to about 100 mm. In some embodiments, the maximum cross-sectional dimension D of the depot 100 can be between about 0.01 mm to about 5 mm, between about 0.1 mm to about 3 mm, or between about 0.5 mm to about 2 mm. The elongated form may be particularly well suited for injection or insertion to a subcutaneous, intramuscular, or other location through a needle or other suitable delivery device. Additionally or alternatively, the elongated depots 100 may be implanted using other techniques, for example surgical implantation through an open incision, a minimally invasive procedure (e.g. laparoscopic surgery), or any other suitable technique based on the application.

FIG. 20 illustrates an example of an elongated, generally cylindrical depot 100 comprising tubular, concentric therapeutic and control regions 200 and 300. The therapeutic region 200 comprises a tubular sidewall having an outer surface covered by the control region 300 and an exposed inner surface defining a lumen 350 that extends through the length L of the depot 100. The lumen 350 can be devoid of any material such that when the depot 100 is exposed to physiological fluid in vivo, the inner surface of the therapeutic region 200 is in direct contact with the fluid, thereby enhancing release of the therapeutic agent (relative to an elongated depot without a lumen through the therapeutic region). As shown in FIG. 20, the end surfaces of the therapeutic region 200 at the longitudinal ends 101, 103 of the depot 100 may also remain exposed/uncovered by the control region 300 (only one end surface is visible in FIG. 20). In some embodiments, the elongated depot 100 may include multiple, layered control regions 300 having the same composition or different compositions and/or the same thickness or different thicknesses. In these and other embodiments, the control region 300 may extend over one or both end surfaces of the therapeutic region 200. In particular embodiments, the lumen 350 extends through only a portion of the length L of the depot 100 and/or the tubular therapeutic region 200 is not concentric with the control region 300.

In some embodiments, the elongated depot 100 may include multiple lumens (e.g., two, three, four, five, six, etc.) extending through all or a portion of the length of the depot 100 and/or the length of the therapeutic region 200. For example, FIG. 21 is an end view of an elongated depot 100 having an inner therapeutic region 200 and an outer core region 300 covering an outer surface of the therapeutic region 200 along its length. In this particular example, the depot 100 includes three lumens 350 extending through the length of the therapeutic region 200. In the illustrated embodiment, each of the lumens 350 has a substantially circular cross-section and similar dimensions. In other embodiments, the lumens 350 may have other cross-sectional shapes, and/or the dimensions of each lumen 350 may vary from one another. In some embodiments, the elongated depot 100 may include multiple, layered control regions 300 having the same composition or different compositions and/or the same thickness or different thicknesses. In these and other embodiments, the control region 300 may extend over one or both end surfaces of the therapeutic region 200.

As shown in the end view of FIG. 22, the depot 100 can include a plurality of separate therapeutic regions 200 (labeled 200a-200e) extending longitudinally along the length of the depot 100. Although the depot 100 is shown having five therapeutic regions 200, in other embodiments the depot 100 may have more or fewer therapeutic regions 200 (e.g., two, three, four, six, seven, eight, etc.). The therapeutic regions 200 may be separated from one another by the control region 300. In the illustrated example, a central lumen 350 extends through the length of the control region 300, and the therapeutic regions 200 are distributed around the central lumen 350. In other embodiments, the elongated depot 100 may not include a lumen extending through any of its regions and may be solid across its cross-sectional dimension.

The therapeutic regions 200a-200e may have the same or different compositions, shapes, and/or dimensions. For example, the therapeutic regions 200a-200e may contain the same or different therapeutic agents, the same or different amount of therapeutic agent, the same or different polymers, and/or the same or different concentrations of releasing agents, depending on the desired release profile of each of the therapeutic regions 200a-200e. In the illustrated embodiment, each of the elongated therapeutic regions 200 has a substantially circular cross-section and similar dimensions. In other embodiments, the elongated therapeutic regions 200 may have other cross-sectional shapes and/or dimensions. In some embodiments, the elongated depot 100 may include one or more additional control regions 300 layered on top of the inner control region 300 surrounding the therapeutic regions 200a-200e. having the same composition or different compositions and/or the same thickness or different thicknesses. In these and other embodiments, the control region 300 may extend over one or both end surfaces of the therapeutic region 200.

FIG. 23 illustrates another embodiment of an elongated depot 100 in which the cross-sectional area is composed of three elongated therapeutic regions 200a-200c separated radially from one another by three elongated control regions 300. In the illustrated embodiment, each of the separate regions intersects at a center in a pie-shaped configuration, however the constituent control regions 300a-300c and therapeutic regions 200a-200c can take any shape and form in different embodiments. Optionally, the depot 100 may include an additional control region 300d covering an outer surface of the more inner therapeutic regions 300a-300c and control regions 300a-300c to provide another layer of controlled release. In some embodiments, the elongated depot 100 may include multiple, layered control regions 300 having the same composition or different compositions and/or the same thickness or different thicknesses. In these and other embodiments, the control region 300 may extend over one or both end surfaces of the therapeutic region 200.

In certain instances, it may be beneficial to provide an elongated depot 100 having an inner therapeutic region 200 and an outer control region 300 of variable thickness and/or non-uniform coverage. Several examples of such depots 100 are shown FIGS. 24A-28. As depicted in FIGS. 24A-24C, the depot 100 can include an elongated therapeutic region 200 having a substantially uniform cross-sectional profile. The outer control region 300 radially surrounds the therapeutic region 200 along the length of the depot 100 and has a thickness that varies along the length of the depot 100. As shown in FIG. 24A, the control region 300 may have alternating first and second portions 305, 307 along its length. The first portions 302 can have a first thickness and the second portions 304 can have a second thickness greater than the first thickness. As such, the first portions 302 form annular grooves within the control region 300 at the outer surface of the depot 100. When implanted, the thinner first portions 302 may release the therapeutic agent more quickly than the thicker second portions 304, as the therapeutic agent has less control region to travel through before leaving the depot 100. By separately providing for faster-releasing portions and slower-releasing portions of the depot 100, the overall release rate of therapeutic agent from the therapeutic region 200 to a treatment site can be precisely tailored to a desired application. In addition to controlling the overall release rate, the release of therapeutic agent(s) can be spatially controlled, for example by directing a first therapeutic agent towards a first portion of the treatment site and a second therapeutic agent towards a second portion of the treatment site.

As shown in FIG. 24D, in some embodiments the elongated therapeutic region 200 may have different therapeutic agents disposed at different sections 200a, 200b along the length of the therapeutic region 200, where each section having a different therapeutic agent is axially aligned with a corresponding section of the control region 300 that has a thickness that is specific to the desired release profile of the underlying therapeutic agent. For example, in some applications it may be beneficial to release a first therapeutic agent at a faster rate and shorter duration and a second therapeutic agent at a slower rate for a longer duration. In such instances, the elongated therapeutic region 200 may have a first section 200a containing the first therapeutic agent (and optionally a polymer and/or releasing agent) and a second section 200b adjacent the first section 200a along the length of the therapeutic region 200 that has a second therapeutic agent (and optionally a polymer and/or releasing agent). The first section 302 of the control region 300 surrounding the first section 200a may have a thickness that is less than a thickness of the second section 304 of the control region 300 surrounding the second section 200b. As such, the first therapeutic agent contained in the first section 200a may release at a faster rate than the second therapeutic agent contained in the second section 200b. In some embodiments, a depot 100 can be configured to deliver two, three, four, five, or more different therapeutic agents, any or all of which can have different rates and times of release from the depot 100.

FIG. 25 illustrates another embodiment of an elongated depot 100 comprising an inner therapeutic region 200 radially surrounded by an outer control region 300. In the illustrated embodiment, the control region 300 includes three discrete sections 302, 304, 306 having increasing thickness. Although these increases in thickness are shown as step-changes between discrete sections, in other embodiments there may be a gradual taper or change in thickness of the control region 300 over the length of the depot 100. In some embodiments, the number of discrete sections may be varied as desired (e.g., two, four, five, six, seven, eight, nine, ten, or more discrete sections), and each discrete section may have an increased or decreased thickness and/or length relative to adjacent discrete sections. Each discrete section may be positioned around a corresponding section of the therapeutic region 200, and each section of the therapeutic region may include the same therapeutic agent, or may include different therapeutic agents as described with respect to FIG. 24D.

FIGS. 26-28 depict examples of elongated depots 100 comprising an inner therapeutic region 200 radially surrounded by an outer control region 300, where the outer control region 300 has one or more windows or openings extending through the entire thickness of the control region 300 to expose the underlying therapeutic region 200 through the opening(s). The openings can be notched into or laser cut from the control region 300, or the therapeutic region 200 can be masked while the control region 300 is applied (e.g., via spray- or dip-coating) to achieve the desired openings. The opening(s) provide a more rapid release route for the therapeutic agent to operate in concert with the more gradual release of therapeutic agent through the covered portions of the therapeutic region. The geometry of the opening(s) may be varied as desired, and can include squares, rectangles, circles, ellipses, slits, polygonal shapes, linear shapes, non-linear shapes, or combinations thereof.

As shown in FIG. 26, in some embodiments the openings may comprise a plurality of windows 308, some or all of which may extend around all or a portion of the circumference of the depot 100 and may be spaced apart along the length of the depot 100. FIG. 27 illustrates another embodiment of an elongated depot 100 in which the control region 300 is provided with a single elongated slit or opening 310. The opening 310 extends along the entire length of the control region 300 and/or depot 100 such that the control region 300 has a C-shape in cross-section. In the illustrated embodiment, the opening 310 extends substantially straight along a path parallel to the long axis of the depot 100, however in other embodiments the opening 310 may be curved, wind helically around the depot 100, or take any other suitable shape. The depot 100 shown in FIG. 28 is similar to that of FIGS. 26 and 27 except that the openings 350 are a plurality of circular holes or apertures extending through the thickness of the control region 300.

FIGS. 29A and 29B are side and end cross-sectional views, respectively, of an elongated depot 100 comprising first and second elongated therapeutic regions 200a and 200b extending longitudinally within a surrounding control region 300. In the depicted embodiment, the central longitudinal axes of first and second therapeutic regions 200a and 200b are offset from each other and from the central longitudinal axis of the control region 300. In some embodiments, the first therapeutic region 200a can be configured to release the therapeutic agent more quickly than the second therapeutic region 200b, for example by varying the releasing agent concentration (if present), the therapeutic agent concentration, the polymer composition (if present), or other properties of the respective therapeutic regions 200a and 200b. The first and second therapeutic regions 200a and 200b can contain the same or different therapeutic agents.

The depot 100 shown in FIG. 30 is similar to that of FIG. 29A except that each therapeutic region 200a is interspersed along its length by barrier regions 400. As noted previously, certain embodiments of the depots 100 described herein employ barrier regions that present a barrier to physiologic fluids. In one embodiment, one or more of the barrier regions 400 may comprise a bioresorable polymer without any releasing agent. In another embodiment, one or more of the barrier regions 400 can include a delayed release agent mixed with a bioresorbable polymer, but without a releasing agent.

As depicted in FIG. 30, the first therapeutic region 400a is interspersed with three barrier regions 400 of a first length, while the second therapeutic region 200b is interspersed with four delayed release regions 400 having a shorter length. The relative lengths, number, composition, and spacing of the barrier regions 400 can be selected to achieve the desired release profiles. In operation, an exposed portion of the first or second therapeutic regions 200a or 200b may release therapeutic agent relatively quickly. However, once the therapeutic region 200a or 200b has been eroded and the exposed face of the depot 100 is a barrier region 400, the release of therapeutic agent from that particular therapeutic region may drop significantly. Accordingly, the use of such barrier regions 400 can allow for highly controlled release, with multiple periods of relatively steady release of therapeutic agent punctuated by periods in which little or no therapeutic agent is released due to the presence of the barrier regions 400.

FIG. 31 illustrates a depot 100 in which the inner therapeutic region 200 is continuous along the length of the depot 100, while the control region 300 is punctuated by barrier regions 400. The incorporation of these barrier regions 400 reduces the exposed surface area of the control region 300 and thereby decreases the rate of release of therapeutic agent from the depot 100.

In the embodiments shown in FIG. 32-35, the elongated, columnar depot 100 includes first and second end caps formed of barrier regions 400. This configuration can eliminate the exposed surface at the ends of the columnar structure, thereby reducing the rate of release of therapeutic agent from the therapeutic region 200. As seen in FIGS. 32 and 33, the end caps formed of barrier regions 400 can have a diameter or cross-sectional transverse dimension substantially similar to that of the control region 300, such that the outer surface of the control region 300 is coplanar with a radially outermost surface of the barrier regions 400 forming the end caps.

In the embodiment shown in FIG. 33, the depot 100 includes first and second therapeutic regions 200a and 200b that are coaxially aligned and directly adjacent to one another (e.g., arranged in an end-to-end fashion along their longitudinal axes), while in FIGS. 34 and 35 the adjacent therapeutic regions 200a-200c are separated from one another by intervening barrier regions 400. FIG. 34 additionally shows optional end caps 400 that extend further radially, for example as shown in Section I, the end caps formed by barrier regions 400 can have the same diameter or transverse dimension as the control region 300, or alternatively as shown in Section II, the barrier regions 400 forming the end caps can project radially beyond the control region 300. In some embodiments, as best seen in FIG. 35, the thickness of the barrier regions 400 can vary across the depot 100 in order to achieve the desired release profile.

FIGS. 36A-39B illustrate various configurations of a depot 100 containing one or more therapeutic regions 200 that are at least partially surrounded by one or more control regions 300 and/or one or more barrier regions 400, with a form factor configured to provide the desired release profile. As noted previously, different therapeutic regions 200 can vary from one another in the composition of therapeutic agent(s) contained therein, the concentration of therapeutic agent(s) contained therein, polymer composition, or any other parameter that can vary the release profile. Similarly, in some embodiments the depot 100 may include multiple, layered control regions 300 and/or barrier regions 400 having the same composition or different compositions and/or the same thickness or different thicknesses. These depots 100 that include a plurality of different therapeutic regions 200, a plurality of different control regions 300, and/or a plurality of different barrier regions 400 can allow for controlled release of a single therapeutic agent or multiple different therapeutic agents according to a desired release profile. For example, in some applications it may be beneficial to release a first therapeutic agent at a faster rate and shorter duration and a second therapeutic agent at a slower rate for a longer duration. As described in more detail below, by varying the configuration and composition of the depots 100, the release profile of therapeutic agent(s) can be sequential (in the case of multiple therapeutic agents), delayed, zero-order, or otherwise.

In some embodiments, a plurality of depots can be provided together (for example as a kit, an assembly, pre-loaded into a delivery device such as a syringe, etc.). In some embodiments, the depots can have a variety of different release profiles. For example, a system can include a plurality of depots selected from at least two of the following groups: (1) depots configured to provide for a substantially immediate burst release of therapeutic agent, (2) depots configured to provide for a substantially first-order release of therapeutic agent, (3) depots configured to provide for a substantially zero-order release of therapeutic agent, and (4) depots configured to exhibit delayed release of therapeutic agents (as discussed below with respect to FIGS. 39A-39B).

FIG. 36A shows a side view of a depot 100, and FIG. 36B shows a cross-sectional view taken along line B-B in FIG. 36A. As seen in FIGS. 36A-36B, in some embodiments the first therapeutic region 200a can envelop or at least partially or completely surround the second therapeutic region 200b. As a result, the first therapeutic region 200a will release its therapeutic agent(s) first, and release of therapeutic agent(s) from the second therapeutic region 200b will be relatively delayed. In some embodiments, the first therapeutic region 200a completely encapsulates the second therapeutic region 200b, such that no surfaces of the second therapeutic region 200b are directly exposed to physiologic fluids upon implantation in a patient's body. In other embodiments, the second therapeutic region 200b can be exposed along at least one face, thereby allowing more immediate release of therapeutic agent from the second therapeutic region 200b. In the illustrated embodiment, the first and second therapeutic regions 200a and 200b are arranged concentrically around the long axis of the depot 100, however in other embodiments the second therapeutic region 200b may be off-center, such that the first therapeutic region 200a is thicker along one side of the second therapeutic region 200b than along another side.

In the embodiment shown in FIG. 36C, first and second therapeutic regions 200a and 200b are arranged in an end-to-end fashion (e.g., in direct contact with one another), while a parallel third therapeutic region 200c extends along the length of the depot 100 and contacts both the first and second therapeutic regions 200a and 200b. FIG. 36D illustrates another embodiment in which first and second therapeutic regions 200a and 200b are arranged end-to-end and aligned along the length of the depot 100. These embodiments may be used to achieve directional release of therapeutic agents, e.g., the therapeutic agent of the first therapeutic region 200a is primarily released from a first end of the depot 100, and the therapeutic agent of the second therapeutic region 200b is primarily released from a second, opposite end of the depot 100, while the therapeutic agent of the third therapeutic region 200c releases from both ends of the depot 100.

FIG. 37A illustrates a depot 100 configured to release therapeutic agent(s) from first and second therapeutic regions 200a and 200b in a sequential manner. As seen in FIG. 37A, the first therapeutic region 200a is partially covered by an overlying control region 300. The first therapeutic region 200a in turn overlies a first barrier region 400a. In the illustrated embodiment, the first therapeutic region 200a, the control region 300, and the first barrier region 400a each extend the entire length of the depot 100 and are each exposed along the side surfaces of the depot 100, however in other embodiments side surfaces may be covered completely or partially by a control region 300 and/or a barrier region 400. Beneath the first barrier region 400a is the second therapeutic region 200b, which may contain the same or different polymer composition and/or therapeutic agent as the first therapeutic region 200a. The second therapeutic region 200b is surrounded laterally by a second barrier region 400b, which also extends beneath the second therapeutic region 200b. As a result, the second therapeutic region 200b has at least one surface in contact with the first barrier region 400a and one or more remaining surfaces in contact with the second barrier region 400b, such that the second therapeutic region 200b is completely encapsulated by the first and second barrier regions 400a, 400b. In some embodiments, one or both of the barrier regions 400a and 400b can be substituted for control regions having a lower concentration of release agent than the control region 300.

As noted previously, barrier regions may present a barrier to physiologic fluids, for example by comprising a bioresorbable polymer without any releasing agent, or a delayed release agent mixed with a bioresorbable polymer, but without a releasing agent. The first barrier region 400a and the second barrier region 400b may differ from one another in composition, thickness, or any other parameters affecting dissolution of the barrier regions 400a and 400b. In some embodiments, the second barrier region 400b can be configured to dissolve more slowly than the first barrier region 400a, such that, after the first barrier region 400a has partially or completely dissolved, the second barrier region 400b remains intact and continues to block or delay passage of physiologic fluids therethrough.

In operation, the first barrier region 400a dissolves more slowly than either the control region 300 or the first and second therapeutic regions 200a and 200b, and therefore presents a barrier to physiological fluids passing through the first barrier region 400a. As a result, when the depot 100 is first placed into contact with physiologic fluids, the release agent of the control region 300 may begin to dissolve, thereby creating diffusion openings for the therapeutic agent(s) in the first therapeutic region 200a to escape therethrough. The therapeutic agent(s) in the first therapeutic region 200a may also escape directly through the exposed surfaces of the first therapeutic region 200a. However, at least in the initial period following implantation, the first barrier region 400a may stop or slow the passage of physiologic fluids through the barrier region 400a and to the underlying second therapeutic region 200b, such that the therapeutic agent(s) within the second therapeutic region 200b exhibits minimal or no release in the initial period. After a first period of time, the control region 300, first therapeutic region 200a and/or the first barrier region 400a may be partially or completely dissolved, thereby allowing at least some physiologic fluid to pass therethrough and come into contact with the second therapeutic region 200b. At this point, therapeutic agent(s) contained within the second therapeutic region 200b may begin to be released from the depot 100, for example by passing through openings formed in the first or second barrier regions 400a and 400b. Accordingly, the depot 100 can be configured such that all or substantially all (e.g., more than 80%, more than 90%) of the therapeutic agent(s) from the first therapeutic region 200a are released from the depot 100 before the therapeutic agent(s) from the second therapeutic region 200b are released in any substantial quantity (e.g., more than 1%, more than 5%, more than 10% of the therapeutic agent(s) contained within the second therapeutic region 200b). In some embodiments, the therapeutic agent(s) from the second therapeutic region 200b are not released in any substantial quantity until at least 12 hours, at least 18 hours, at least 24 hours, at least 36 hours, at least 48 hours, at least 3 days, at least 4 days, at least 5 days, at least 6 days, at least 7 days, at least 8 days, at least 9 days, at least 10 days, at least 11 days, at least 12 days, at least 13 days, at least 2 weeks, at least 3 weeks, at least 4 weeks, at least 5 weeks, at least 6 weeks, at least 7 weeks, at least 8 weeks, at least 9 weeks, at least 10 weeks, at least 11 weeks, or at least 12 weeks after implantation of the depot 100 and/or after release of substantially all of the therapeutic agent(s) from the first therapeutic region 200a.

In one example, the control region 300 is a PLGA film with a releasing agent, the first therapeutic region 200a is a PLGA film loaded with a first therapeutic agent (e.g., bupivacaine), the first barrier region 400a is a PLGA film with no releasing agent, the second therapeutic region 200b is a PLCL film loaded with a second therapeutic agent (e.g., 5-fluorouracil), and the second barrier region 400b is a PLCL film with no releasing agent. As will be understood, the particular polymers, therapeutic agents, releasing agents, concentrations thereof, and dimensions can be selected to achieve the desired release profiles of the first and second therapeutic agents and to achieve the desired total erosion of the depot 100 after a predetermined period of time.

Examples of the release profile from the depot 100 of FIG. 37A are illustrated in FIG. 37B. In this example, Samples 1 and 2 were each prepared with a configuration as shown in FIG. 37A with a thickness of approximately 1.8 mm and a length and width of approximately 20 mm. The control region 300 includes PLGA with polysorbate 20, commercially known as Tween20™ as a releasing agent, with the ratio of Tween to polymer of 5:10. The first therapeutic region 200a includes a PLGA polymer with Tween 20 and bupivacaine HCl, with the ratio of tween to polymer to bupivacaine of 1:10:20. The first barrier region 400a includes a PLGA film with no releasing agent or therapeutic agent, and the second barrier region 400b includes a PLCL film with no releasing agent or therapeutic agent. The second therapeutic region 200b includes a PLCL polymer with 5-FU and no releasing agent, with a polymer to 5-FU ratio of 1:1.

Referring to FIG. 37B, the “Drug 1” lines illustrate release of a first therapeutic agent from the first therapeutic region 200a. The “Drug 2” lines illustrate release of a second therapeutic agent from the second therapeutic region 200b, which is not released in any substantial amount until a first period has passed (approximately 19 days in the embodiment of FIG. 37B), after which the second therapeutic agent begins to release from the depot 100. The result is a sequential release in which the first therapeutic agent is substantially completely released (e.g., more than 80%, more than 90%, more than 95%, more than 99% of the first therapeutic agent is released from the depot 100) before the second therapeutic agent begins to be released in any significant amount (e.g., more than 1%, more than 5%, or more than 10% of the second therapeutic agent is released from the depot 100).

FIG. 38A illustrates a depot 100 configured to release a therapeutic agent from a therapeutic region 200 in accordance with a substantially zero-order release profile. In the illustrated embodiment, the depot 100 includes a therapeutic region 200 that is laterally surrounded by one or more barrier regions 400. In some embodiments, the therapeutic region 200 and the barrier region 400 can have a substantially similar thickness such that upper and lower surfaces of the therapeutic region and the barrier region 400 are substantially coplanar. First and second control regions 300 can be disposed over upper and lower surfaces of both the therapeutic region 200 and the barrier region 400, such that the therapeutic region 200 is completely encapsulated by the first and second control regions 300 and the barrier region 400.

When the depot 100 is placed in contact with physiological fluids (e.g., when implanted at a treatment site in vivo), the release agent in the control regions 300 will begin to dissolve to form diffusion openings therein, after which therapeutic agent(s) contained within the therapeutic region 200 may begin to pass through to be released from the depot 100. By virtue of the laterally disposed barrier regions 400, little or no therapeutic agent may pass from the therapeutic region 200 through the barrier regions 400 for at least a period of time (e.g., at least 1 day, at least 2 days, at least 3 days, at least 4 days, at least 5 days, at least 6 days, at least 7 days, at least 8 days, at least 9 days, at least 10 days, at least 11 days, at least 12 days, at least 13 days, at least 2 weeks, at least 3 weeks, at least 4 weeks, at least 5 weeks, at least 6 weeks, at least 7 weeks, at least 8 weeks, at least 9 weeks, at least 10 weeks, at least 11 weeks, or at least 12 weeks). As a result, substantially linear release of therapeutic agent can be achieved by controlling the dimensions and composition of the control regions 300 and the therapeutic region 200. As used herein, “substantially linear” includes a release profile in which the rate of release over the specified time period does not vary by more than 5%, or more than 10% from the average release rate over the time period. The substantially linear release profile can be maintained over a desired period of time, e.g., over at least 1 day, at least 2 days, at least 3 days, at least 4 days, at least 5 days, at least 6 days, at least 7 days, at least 8 days, at least 9 days, at least 10 days, at least 11 days, at least 12 days, at least 13 days, at least 2 weeks, at least 3 weeks, at least 4 weeks, at least 5 weeks, at least 6 weeks, at least 7 weeks, at least 8 weeks, at least 9 weeks, at least 10 weeks, at least 11 weeks, or at least 12 weeks.

In one example, the control region 300 can be a PLCL or PLGA film containing a releasing agent, the therapeutic region can be a PLCL film loaded with a therapeutic agent (e.g., bupivacaine; 5-fluorouracil, etc.), and the barrier region 400 can be a PLCL film with no releasing agent. As will be understood, the particular polymers, therapeutic agents, releasing agents, concentrations thereof, and dimensions can be selected to achieve the desired release profiles of the therapeutic agent(s) and to achieve the desired total erosion of the depot 100 after a predetermined period of time (e.g., approximately 40 days).

Examples of the release profile from the depot 100 of FIG. 38A are illustrated in FIG. 38B, with four samples with varying polymer configurations illustrated. In this example, Samples 1-4 were each prepared with a configuration as shown in FIG. 38A with a thickness of approximately 0.8 mm and a length and width of approximately 20 mm. Samples 1 and 2 were prepared using the same configuration, in which the control region 300 includes a PLCL polymer and Tween as a releasing agent with a Tween to polymer ratio of 1:2. The therapeutic region 200 includes a PLCL polymer with 5-FU and no releasing agent, with a polymer to 5-FU ratio of 1:1, and the barrier region 400 includes a PLCL polymer with no releasing agent. Samples 3 and 4 were prepared using the same configuration, in which the control region 300 includes a PLGA polymer and Tween as a releasing agent with a Tween to polymer ratio of 1:2. The therapeutic region 200 includes a PLCL polymer with 5-FU and no releasing agent, with a polymer to 5-FU ratio of 1:1, and the barrier region 400 includes a PLGA polymer with no releasing agent.

As seen in FIG. 38B, by varying the polymer configurations (e.g., composition, release agent, thickness, etc.), the zero-order release profile can be tuned to release at different rates. In some embodiments, there is an initially higher rate of release for a first short period (e.g., approximately 1 day in the illustrated examples), followed by a substantially linear release for the remaining period of time.

FIG. 39A illustrates a depot 100 configured to release a therapeutic agent from a therapeutic region 200 in accordance with a delayed release profile, in which little or none of the therapeutic agent(s) are released in a first period (e.g., less than 10%, less than 20% of the therapeutic agent(s) are released), followed by a rapid increase in release rate during a second period in which the therapeutic agent is released from the depot 100. In the illustrated embodiment, the depot 100 includes a therapeutic region 200 that is at least partially surrounded on opposing sides (e.g., over top and bottom surfaces) by barrier regions 400. In some embodiments, the therapeutic region 200 and the barrier region 400 can have a substantially similar length and width such that the therapeutic region 200 is exposed at one or more side surfaces of the depot 100.

When the depot 100 is placed in contact with physiological fluids (e.g., when implanted at a treatment site in vivo), the therapeutic agent(s) contained within the therapeutic region 200 will pass from the therapeutic region 200 into the surrounding environment through the exposed side surface(s) of the therapeutic region 200. In some embodiments, little or none of the therapeutic agent passes through the barrier regions 400 during an initial period. During this period, a relatively small portion of the therapeutic agent may be released through the exposed side surfaces (e.g., less than 20%, less than 15%, less than 10%, or less than 5% of the therapeutic agent may be released). After the first time period, the barrier regions 400 may begin to degrade, after which the therapeutic agent begins to be released through openings formed in the barrier regions 400. As a result, the depot 100 achieves a delayed release in which little or none of the therapeutic agent is released over a first time period (e.g., more than 1 week, more than 2 weeks, more than 3 weeks, more than 4 weeks, more than 5 weeks, more than 6 weeks, more than 7 weeks, more than 8 weeks, more than 9 weeks, more than 10 weeks), after which the therapeutic agent is released from the depot 100 at an increased rate. In some embodiments, the exposed side surfaces of the therapeutic region 200 can be partially or completely covered by one or more control regions 300 and/or by one or more barrier regions 400, which can further delay release of the therapeutic agent from the therapeutic region 200.

In one example, the therapeutic region 200 can be a PLCL film loaded with a therapeutic agent (e.g., bupivacaine; 5-fluorouracil, etc.), and the barrier regions 400 can be PLGA film with no release agent or PLCL film with no release agent. As will be understood, the particular polymers, therapeutic agents, concentrations thereof, and dimensions can be selected to achieve the desired release profiles of the therapeutic agent and to achieve the desired total erosion of the depot 100 after a predetermined period of time.

Examples of the release profile from the depot 100 of FIG. 39A are illustrated in FIG. 39B. Samples 1 and 2 illustrate a release profile for a bare therapeutic region with no surrounding barrier regions. In samples 1 and 2, release of the therapeutic agent commences immediately after exposure to fluid. Samples 3-6 were each prepared with a configuration as shown in FIG. 39A. Samples 3 and 4 were prepared using the same configuration, in which the control region 300 includes a PLCL polymer and Tween as a releasing agent with a Tween to polymer ratio of 1:2. The therapeutic region 200 includes a PLCL polymer with 5-FU and no releasing agent, with a polymer to 5-FU ratio of 1:1, and the barrier region 400 includes a PLCL polymer with no releasing agent.

Samples 3-6 illustrate different examples of release profiles for the depot 100 of FIG. 39A with varying polymer configurations illustrated. In samples 3 and 4, the barrier regions 400 are made of a PLGA polymer, while in samples 5 and 6, the barrier regions 400 are made of a PLCL polymer. In samples 3 and 4, release of the therapeutic agent is delayed for approximately 2 weeks (e.g., less than 20%, less than 15%, less than 10%, or less than 5% of the therapeutic agent is released from the depot 100), after which the therapeutic agent is released from the depot 100 at an increased rate (e.g., at least 2 times, at least 3 times, at least 4 times, at least 5 times, or at least 10 times of the initial release rate). In samples 5 and 6, release of the therapeutic agent delayed for approximately 15 weeks (e.g., less than 20%, less than 15%, less than 10%, or less than 5% of the therapeutic agent is released from the depot 100), after which the therapeutic agent is released at an increased rate (e.g., at least 2 times, at least 3 times, at least 4 times, at least 5 times, or at least 10 times of the initial release rate). The barrier regions 400 in samples 3 and 4 are configured to degrade more quickly than the barrier regions 400 in samples 5 and 6, because PLGA degrades more quickly than PLCL. As a result, the delay period in samples 3 and 4 is shorter than the delay period in samples 5 and 6. In various embodiments, the degradation rate of the barrier regions 400 can be tuned by varying dimensions, selecting different polymers, or making any other suitable modifications to the barrier regions 400. By varying the polymer configurations (e.g., composition, thickness, etc.), the delayed release profile can be tuned to have different delay periods (e.g., an initial period during which little or none of the therapeutic agent is released) and to release the therapeutic agent at different rates following the delay period.

In some embodiments, it can be beneficial to provide a plurality of pre-formed openings or apertures extending through the depot 100, either in a regular or irregular pattern. Such openings can provide additional pathways for a therapeutic agent to pass from the therapeutic region to the treatment site, and as such can be controlled to vary the desired release profile. For example, in some embodiments the openings or apertures permit at least some of the therapeutic agent to be released directly from the therapeutic region 200 to the surrounding area, without passing through any overlying control region 300. These pre-formed openings or apertures may differ from diffusion openings formed by dissolution of releasing agent in that the openings or apertures are formed in the depot 100 prior to implantation in the patient's body. The openings or apertures may be used in combination with diffusion openings formed by dissolution of releasing agent to modulate the release profile of therapeutic agent. For example, a depot 100 having openings or apertures may release therapeutic agent at a higher rate than a depot 100 without openings or apertures.

FIG. 40A illustrates a depot 100 with a sponge-like configuration in which a plurality of irregular openings 350 are formed through the depot 100. In some embodiments, such a depot 100 may be formed by introducing air or otherwise agitating the polymer composition during formation of the depot 100 and while encouraging the solvent to evaporate, resulting in a porous depot 100 with a plurality of openings therein. Such a depot 100 can be substantially uniform in its composition or can include an outer control region and an inner therapeutic region, one or both of which are permeated by some or all of the openings formed in the depot 100.

FIG. 40B illustrates a depot 100 in which a plurality of openings 350 extend through a thickness of the depot 100. In the illustrated embodiment, the openings 350 are substantially cylindrical and pass through upper and lower control regions 300 as well as an inner therapeutic region 200 along substantially parallel trajectories. In other embodiments, the openings 350 can assume other cross-sectional shapes, extend along other axes, and/or vary among one another in orientation, size, shape, etc.

In some instances, it can be useful to provide a depot that has a curved, bent, or rounded configuration. For example, such curved depots can beneficially provide adequate contact with a curved surface area of a treatment site, such as the interior of a bladder, an abdominal wall, a surface of a tumor, or any other suitable treatment site. In some embodiments, the depot can have a substantially straight configuration prior to being deployed in vivo and the curved configuration can be achieved after the depot 100 is deployed in vivo in the presence of physiological fluids, while in other embodiments the depot 100 can have maintain the curved configuration both prior to and after being deployed in vivo. FIGS. 41A-44 illustrate various examples of depots 100 having curved configurations. With reference to FIGS. 41A-B, the depot 100 can have an actuating region 320 that is less elastic than a therapeutic region 200. For example, the actuating region 320 can have a different composition, different dimensions, and/or can be manufactured according to different processes than the therapeutic region 200. By stretching the depot 100 beyond the elastic hysteresis point of the less elastic actuating region 320, the depot 100 can transition from the substantially straightened configuration (shown in FIG. 41A) to the curved configuration (shown in FIG. 41B), in which the less elastic actuating region 320 pulls the depot 100 into the curved shape. In some embodiments, this stretching can occur after implantation, while in other instances the stretching is performed during manufacturing or by a surgeon before implantation. In some embodiments, this transition involves plastic deformation of the depot 100, such that the depot 100 maintains the curved shape even after the stretching force has been removed.

A similar result can be achieved by varying the polymer compositions of different layers or regions as in FIGS. 42A-42B. For example a first region 322 may have a polymer composition that is more hydrophilic than a second region 324, and accordingly the first region 322 may absorb more water or other fluids when implanted in vivo than the second region 324. In various embodiments, either or both of the first and second regions 322, 324 can carry a therapeutic agent. In the embodiment illustrated in FIGS. 42A-42B, the second region 324 is made of poly(L-lactic acid) (PLLA) and the first region 322 is made of polycaprolactone (PCL). In the presence of water, the PCL will experience a higher water uptake than the PLLA when placed in the presence of fluids. As a result, the PCL expands to a greater degree than the PLLA, resulting in a transition from the straightened state (shown in FIG. 42A) to the curved state (shown in FIG. 42B). In this embodiment, the depot 100 may advantageously retain the straightened state until it is deployed in vivo at the treatment site, at which point the depot 100 will begin to absorb water, resulting in a transition to the curved state.

FIGS. 43A-43C illustrate another mechanism for achieving a curved depot. As shown in FIGS. 43A and 43B, the depot 100 may include an outer region B and an axially offset inner region A. The inner region A can have a different composition (e.g., different polymer, the presence of therapeutic agent, etc.) compared to the outer region B. Because the inner region A if offset from the axial centerline of the depot 100, a difference in elasticity or expansion between the inner region A and the outer region B can result in curvature of the depot 100. In one example, the inner region A may include PLLA and the outer region B may include PCL, such that when exposed to water, outer region B expands more than the inner region A, resulting in a curved state.

As noted previously, a curved depot 100 may advantageously be deployed against a curved treatment site, for example in apposition with a concavely curved tissue surface (e.g., the interior of the bladder) as shown in FIG. 44, or in apposition with a convexly curved tissue surface (e.g., over a surface of a protruding tumor) as shown in FIG. 45. In other embodiments, the depot 100 may be configured to have a more complex curvature, for example at least one concave region and at least one convex region, or having different regions with different degrees of curvature. Such complex curvature can be tailored to achieve tissue apposition at a desired treatment site, and can improve delivery of therapeutic agent to the treatment site.

As shown in FIGS. 46 and 47, in some embodiments a treatment device can include an anchoring member 500 and a depot 100 carried on a surface of the anchoring member 500. The anchoring member 500 may be a generally hemispherical (as in FIG. 46), spherical (as in FIG. 47), or other suitable structure configured to expand from a low-profile state to a deployed state in apposition with a treatment site. The anchoring member 500 is configured to provide structural support to the treatment device, engage the adjacent anatomy (e.g., a bladder, etc.) to secure the treatment device to a selected treatment site.

In some embodiments, the depot 100 is bonded or otherwise adhered to the surface of the anchoring member 500. In other embodiments, the treatment device may include a depot 100 without an anchoring member 500. The depot 100 may comprise a biocompatible carrier loaded with one or more therapeutic agents and configured for a controlled, sustained release of the therapeutic agent(s) following in vivo placement of the depot. In some embodiments, the depot may be a thin, multilayer film loaded with a therapeutic agent, wherein, as described herein, the depot 100 is configured to release the therapeutic agent(s) at the treatment site.

In some embodiments the structure forming the anchoring member 500 may be a mesh structure. As used herein, “mesh” or “mesh structure” refers to any material (or combination of materials) having one or more openings extending therethrough. For example, in some embodiments, the anchoring member 500 comprises a plurality of filaments (e.g., wires, threads, sutures, fibers, etc.) that have been braided or woven into a tubular shape and heat set. In some embodiments, the mesh structure may be a stent formed of a laser-cut tube or laser-cut sheet, or the mesh structure may be a stent formed via thin film deposition. The anchoring member 500 may be in the form of a flat wire coil attached to a single longitudinal strut, a slotted tube, a helical band that extends circumferentially and longitudinally along the length of the anchoring member, a modular ring, a coil, a basket, a plurality of rings attached by one or more longitudinal struts, a braided tube surrounding a stent, a stent surrounding a braided tube, and/or any suitable configuration or embodiment disclosed herein.

In some embodiments, the anchoring member 500 may be formed of a superelastic material (e.g., nickel-titanium alloys, etc.) or other resilient materials such as stainless steel, cobalt-chromium alloys, etc. configured to self-expand when released from a delivery catheter. For example, the anchoring member may self-expand when pushed through the distal opening of the catheter, or by the delivery catheter being pulled proximally of the anchoring member. In some embodiments the anchoring member 500 may self-expand upon release from other constraining mechanisms (e.g., removable filaments, etc.). In some embodiments, the anchoring member 500 may be expanded manually (e.g., via balloon expansion, a push wire, a pull wire, etc.).

In some embodiments, the anchoring member 500 includes gold, magnesium, iridium, chromium, stainless steel, zinc, titanium, tantalum, and/or alloys of any of the foregoing metals or including any combination of the foregoing metals. In some embodiments, the anchoring member 500 may include collagen or other suitable bioresorbable or biodegradeable materials such as PLA, PLG, PLGA etc. In certain embodiments, the metal comprising the mesh structure may be highly polished and/or surface treated to further improve its hemocompatibility. The anchoring member 500 may be constructed solely from metallic materials without the inclusion of any polymer materials, or may include a combination of polymer and metallic materials. For example, in some embodiments the anchoring member 500 may include silicone, polyurethane, polyethylene, polyesters, polyorthoesters, polyanhyrides, and other suitable polymers. This polymer may form a complete sphere or hemisphere to block passage of tumor or drug though the anchoring member 500, or it may have microscopic pores to allow passage of drug but not tumor cells, or it may have small or large openings. In addition, all or a portion of the anchoring member may include a radiopaque coating to improve visualization of the device during delivery, and/or the anchoring member 500 may include one or more radiopaque markers.

In some embodiments, the anchoring member 500 may have other suitable shapes, sizes, and configurations. To improve fixation, in some embodiments the anchoring member 500 may have one or more protrusions extending radially outwardly from the mesh structure along all or a portion of its length, the one or more protrusions being configured to engage with tissue at the treatment site. For example, the anchoring member 500 may include one or more barbs, hooks, ribs, tines, and/or other suitable traumatic or atraumatic fixation members.

As previously mentioned, the depot 100 may be bonded or otherwise adhered to an outer surface of the anchoring member 500. For example, the depot 100 may be bonded to the anchoring member 500 by adhesive bonding, such as cyanoacrylate or UV curing medical grade adhesive, chemical or solvent bonding, and/or thermal bonding, and other suitable means. The depot 100 may also be sewn or riveted to the anchoring member 500. In some embodiments, the depot 100 may be woven into the anchoring member 500 at one or more sections of the anchoring member 500. In some embodiments, the anchoring member 500 may be dip coated in a solution comprising the material elements of the depot 100, and/or the anchoring member 500 may be spray coated with the depot 100. Sections of the anchoring member 500 may be selectively masked such that only certain portions of the anchoring member 500 may be coated with the depot 100. In some embodiments, the anchoring member 500 may be originally in the form of a sheet, and the sheet may be embedded into the depot 100 (for example, with the depot 100 as a multilayer film construction.) The resulting sheet structure (i.e., the anchoring member 500 embedded within the depot 100) may be rolled into a tubular structure (with or without the adjacent ends attached) for delivery into the body. In some embodiments, the depot may be coated with a bioresorbable adhesive derived from polyethylene glycol (PEG or PEO), for example, or from other hydrogels. The PEG or hydrogel may also be integral to the depot 100 via mixing in solution with the depot materials and not a separate coating.

The depot 100 may be disposed along all or a portion of the surface of the anchoring member 500, all or a portion of the circumference of the mesh structure, and/or cover or span all or some of the openings in the mesh structure depending on the local anatomy of the treatment site. For example, the volume, shape, and coverage of the tumor may vary patient-to-patient. In some cases, it may be desirable to use a treatment device having a depot 100 extending around the entire outer surface and/or inner surface of the anchoring member 500. In other cases, it may be desirable to use a treatment device having a depot 100 extending around less than the entire outer surface and/or inner surface of the anchoring member 500 to reduce exposure of potentially healthy tissue to the chemotherapeutic agents.

In some cases, the depot 100 may be elastically expandable, such that the depot 100 expands with the anchoring member 500 as it is deployed. The depot 100 may also be less elastic but can be folded for delivery in a compact form. Alternatively, the depot 100 could be configured to change shape as it is expanded. For example, a tubular depot could have a pattern of overlapping longitudinal slots, so that it expands into a diamond-shaped pattern as it is expanded. The expanded pattern of the depot 100 may align with the pattern of the anchoring member 500, or it may be totally independent of the anchoring member 500. This approach may enable the highest volume of therapeutic agent to be delivered in the most compact delivery format, while still enabling expansion on delivery and flexion, compression and expansion while positioned at the treatment site.

In certain cases, it can be useful to provide a depot 100 with a larger opening or lumen 350 therethrough. For example, a depot 100 deployed in a bladder may benefit from a relatively large opening that allows urine to pass therethrough. Such an opening can reduce the risk of the depot 100 interfering with normal physiological function. FIGS. 48A and 48B illustrate two different embodiments of such depots 100. As seen in FIG. 48A, the depot 100 can be substantially annular or ring-like structure with a central opening 350. For example, the central opening 350 can have a greatest transverse dimension that is more than 10%, more than 20%, more than 30%, more than 40%, or more than 50% of the length of a maximum transverse dimension and the annular depot 100. In the embodiment shown in FIG. 48B, the depot 100 can be a curved (e.g., semi-spherical or semi-ellipsoid) structure with a central opening 350 configured to allow fluid to pass therethrough. Although single openings 350 are illustrated in these embodiments, in other embodiments there may be two or more openings 350 configured to facilitate normal physiological function when the depot 100 is implanted at a treatment site.

FIGS. 49A-C illustrate perspective, top, and cross-sectional views, respectively, of a depot 100 having an annular semi-annular shape. As illustrated, the depot 100 is an elongated strip, ribbon, or band that curls about an axis A. The depot 100 in the form of an elongated strip has an inwardly facing lateral surface 144a and an outwardly facing lateral surface 144b each having a width W. First and side second surfaces 144c and 144d can extend between the lateral surfaces 144a and 144b, defining a thickness T, such that the depot has a substantially rectangular cross-section as seen in FIG. 49C. In some embodiments, the band can have a thickness T of between about 0.1 mm and about 10 mm, or between about 0.5 mm and about 5 mm, or about 2 mm. In some embodiments, the depot 100 can have a height H of between about 0.1 mm and about 10 mm, or between about 0.5 mm and about 5 mm, or about 1 mm. The depot 100 can be curled about the axis A such that first and seconds ends are adjacent to one another, while leaving a gap 145 therebetween. In this curled configuration, the depot 100 is characterized by an inner diameter D. In some embodiments, for example for use in a bladder, the diameter D can be between about 2 cm and about 20 cm, for example between about 2 cm and about 10 cm, or between about 4 cm and about 8 cm, or approximately 6 cm. In some embodiments, the depot 100 can have a length of between about 20 cm and about 100 cm, for example between about 30 cm and about 50 cm, or approximately 38 cm.

In some embodiments, the ends can be joined together, creating a closed annular shape. As seen in FIG. 49C, in some embodiments the depot 100 includes a control region 300 disposed on the inwardly facing lateral surface 144a and another control region 300b disposed on the outwardly facing lateral surface 144b. In some embodiments, a therapeutic region 200 disposed between the two control regions 200 can be partially or completely exposed along the side surface 144c. Optionally, the therapeutic region 200 can also be partially or completely exposed along an opposing side surface 144d disposed opposite the first side surface 144c.

In some embodiments, the depot 100 of FIGS. 49A-49C can be delivered to the treatment site in a compressed configuration, either straightened longitudinally, or curled tightly about a central axis, or other compressed state. When delivered, the depot 100 can expand into the annular or semi-annular configuration as shown in FIG. 49A. In some embodiments, the depot 100 can be positioned such that the outwardly facing lateral surface 144b is in apposition with tissue along at least a portion of its length.

FIG. 50A shows an end view of a depot 100 in a spirally curled state and FIG. 50B shows a side view of the depot 100 in an uncurled state. The depot 100 includes a plurality of segments I-IV having different structural and mechanical properties that cause the depot 100 to assume the spirally curled configuration shown in FIG. 50A when placed in the presence of physiological fluids in vivo at a treatment site. For example, the different segments I-IV can vary in polymer composition, therapeutic agent, concentration of therapeutic agent, concentration of release agent, or any other parameter that affects the mechanical and structural properties of the depot 100, resulting in a spirally wound depot 100 as seen in FIG. 50A. In some embodiments, the spiral winding can facilitate placement of the depot 100 at a treatment site, and/or improve attachment to anatomical tissue at the treatment site.

FIG. 51 illustrates a plurality of depots 100 in the form of microbeads, microspheres or particles. In various embodiments, each microbead can include a therapeutic region at its core and one or more control regions partially, substantially, or completely surrounding the therapeutic region. In some embodiments, the microbead may include multiple, layered control regions and/or therapeutic regions having the same composition or different compositions and/or the same thickness or different thicknesses. The release profile of any particular microbead is determined by its size, composition, and the thickness of the control region and therapeutic region. In some embodiments, a plurality of microbeads are provided having varying dimensions, varying shapes (e.g. spherical, ellipsoid, etc.), varying polymer compositions, varying concentration of therapeutic agent in the therapeutic region, varying concentration of releasing agent in the control region, or variation of any other parameters that affect the release profile. As a result, the composite release profile of the plurality of microbeads can be finely tuned to achieve the desired cumulative release of therapeutic agent to the treatment site. In various embodiments, some or all of the microbeads can have a diameter or largest cross-sectional dimension of between about 0.01 to about 5 mm, or between about 0.1 mm to about 1.0 mm. In some embodiments, some or all of the microbeads can have a diameter or largest cross-sectional dimension that is less than about 5 mm, less than about 2 mm, less than about 1.0 mm, less than about 0.9 mm, less than about 0.8 mm, less than about 0.7 mm, less than about 0.6 mm, less than about 0.5 mm, less than about 0.4 mm, less than about 0.3 mm, less than about 0.2 mm, or less than about 0.1 mm.

FIGS. 52A and 52B illustrate end and side views, respectively, of a plurality of depots 100 in the form of pellets. In the illustrated embodiment, the pellets are substantially cylindrical, however the particular shape and dimensions of the pellets may vary to achieve the desired release kinetics and form factor. For example, the pellets can have rounded ends (e.g., ellipsoid), and/or can have a cross-sectional shape that is circular, elliptical, square, rectangular, regular polygonal, irregular polygonal, or any other suitable shape. In some embodiments, each pellet can include an inner therapeutic region at least partially surrounded by an outer control region. In some embodiments, the pellet may include multiple, layered control regions and/or therapeutic regions having the same composition or different compositions and/or the same thickness or different thicknesses. As with the microbeads shown in FIG. 51, individual pellets of the plurality can vary from one another in one or more of shape, polymer composition, concentration of therapeutic agent in the therapeutic region, concentration of the releasing agent in the control region, thickness of the control region, thickness of the therapeutic region, and any other parameter that affect the release profile. As a result, the composite release profile of the plurality of pellets can be finely tuned to achieve the desired cumulative release of therapeutic agent to the treatment site.

In some embodiments, a thickness of the control region (a single sub-control region or all sub-control regions combined) is less than or equal to 1/10, 1/15, 1/20, 1/25, 1/30, 1/35, 1/40, 1/45, 1/50, 1/75, or 1/100 of a thickness of the therapeutic region. In some embodiments, the depot 100 has a width and a thickness, and a ratio of the width to the thickness is 21 or greater. In some embodiments, the ratio is 22 or greater, 23 or greater, 24 or greater, 25 or greater, 26 or greater, 27 or greater, 28 or greater, 29 or greater, 30 or greater, 35 or greater, 40 or greater, 45 or greater, or 50 or greater. In some embodiments, the depot 100 has a surface area and a volume, and a ratio of the surface area to volume is at least 1, at least 1.5, at least 2, at least 2.5, or at least 3.

I. EXAMPLE METHODS OF MANUFACTURE

The depots of the present technology may be constructed using various combinations of bioresorbable polymer layers, wherein these layers may include therapeutic agents, releasing agents, delayed release agents, etc., in varying combinations and concentrations in order to meet the requirements of the intended clinical application(s). In some embodiments, the polymer regions or layers may be constructed using any number of known techniques to form a multilayer film of a particular construction. For example, a bioresorbable polymer and a therapeutic agent can be solubilized and then applied to the film via spray coating, dip coating, solvent casting, and the like. In an alternative embodiment, a polymer layer for use as a control region and/or a therapeutic region can be constructed from electrospun nanofibers.

The depots 100 described herein may be constructed by placing therapeutic regions (and/or sub-regions) and/or control regions (and/or sub-regions) on top of one another in a desired order and heat compressing the resulting multilayer configuration to bond the layers together. Heat compression may be accomplished using any suitable apparatus known in the art. In one embodiment, the heat compression process consists of utilizing a heat compressor (Kun Shan Rebig Hydraulic Equipment Co. Ltd., China), and heat compressing the stacked assembly of therapeutic 200 and/or control regions 300 at a temperature that is above room temperature (e.g., at least 30° C., 35° C., 40° C., 45° C., 50° C., 55° C., 60° C., 65° C., 70° C., 75° C., 80° C., 85° C., 90° C., 95° C., 100° C., 105° C., 110° C., 115° C., or 120° C., etc.) and a pressure of from about 0.01 MPa to about 1.0 MPa, or about 0.10 MPa to about 0.8 MPa, or about 0.2 MPa to about 0.6 MPa. The inventors have discovered that heating the therapeutic and control regions during compression (separately or after stacking) increases the therapeutic agent density in the depot 100. The inventors have also discovered that heat compression at lower pressures enable higher drug densities.

Depending on the therapeutic dosage needs, anatomical targets, etc., the depot 100 can be processed, shaped and otherwise engineered to produce form factors that can be administered to the patient by implantation in the body by a clinical practitioner. For example, various configurations of the film may be achieved by using a jig with a pre-shaped cutout, hand cutting the desired shape or both. Some of the form factors producible from the multilayer film for implantation into the body include: strips, ribbons, hooks, rods, tubes, patches, corkscrew-formed ribbons, partial or full rings, nails, screws, tacks, rivets, threads, tapes, woven forms, t-shaped anchors, staples, discs, pillows, balloons, braids, tapered forms, wedge forms, chisel forms, castellated forms, stent structures, suture buttresses, coil springs, and sponges. As described below with respect to FIG. 52C, in some embodiments a pellet-like or mini-cylindrical depot 100 can be punched or otherwise cut out of a sheet of a multilayer film. A depot 100 may also be processed into a component of the form factors mentioned above. For example, the depot 100 could be rolled and incorporated into tubes, screws tacks or the like. In the case of woven embodiments, the depot 100 may be incorporated into a multi-layer woven film wherein some of the filaments used are not the inventive device. In one example, the depot 100 is interwoven with Dacron, polyethylene or the like.

In some embodiments, one or more depots 100 can be cut into a desired shape or form factor using precision laser cutting. Various laser modalities may be used, for example infrared lasers, near-infrared lasers, deep ultraviolet lasers, or other suitable lasers for cutting depots 100 to the desired configurations. Such laser cutting can use continuous or pulsed, and the operating parameters (e.g., intensity, frequency, polarization, etc.) may be selected to achieve the desired cut. Using computer-controller laser-cutting can provide for a precise, repeatable manufacturing process that achieves consistent dimensions and release profiles. In some embodiments, the cut surfaces resulting from the laser-cut can be significantly smoother than those achieved using a mechanical stamp, jig, or punch to cut depots from a sheet of a multi-layer film. In some instances, the smoother cut surfaces can provide for improved release profiles, for example with more consistency among depots 100 manufactured according to this process.

In some embodiments, the therapeutic region 200 can be extruded into an elongated form (e.g., a cylindrical rod), after which the control region 300 may be spray- or dip-coated over the extruded therapeutic region 200. Portions of the extruded therapeutic region 200 may be masked to leave gaps in the control region 300, or alternatively portions of the control region 300 may be removed via etching, scraping, or other techniques to achieve any desired openings or thinning of the control region 300 in any desired portions. In some embodiments, an extruded cylinder having a lumen extending therethrough can be selectively filled with a therapeutic region 200 and/or a control region 300 along its length to form an elongated depot 100.

In some embodiments, a therapeutic region 200 in the shape of a cylindrical rod is formed by dissolving the therapeutic region composition (e.g., a mixture of polymer(s) and therapeutic agent) into acetone, and then loading the dissolved therapeutic region composition into a syringe (e.g., a 1 mL syringe) and attaching a needle thereto (e.g., a 19G needle). The therapeutic region solution is then injected into ethanol for polymer solidification. After waiting for the solution to harden (e.g., approximately 90 seconds), the resulting rod can be removed from the ethanol and air-dried. In another embodiment, the therapeutic region composition can be injected into a cross-linking solution to solidify the polymer.

The therapeutic region 200 may be spray- or dip-coated with a surrounding control region 300. Alternatively, in some embodiments, the therapeutic region 200 in elongated cylindrical form can be inserted into an inner lumen of a coaxial needle. The coaxial needle can include an inner needle disposed coaxially within the lumen of an outer needle. In one example, the inner needle can have an inner diameter of approximately 0.84 mm and an outer diameter of approximately 1.24 mm, and the outer needle can have an inner diameter of approximately 1.6 mm and an outer diameter of approximately 2.11 mm, though these dimensions can vary and be tailored to the desired dimensions of the therapeutic region 200 and control region 300. A control region composite (e.g., a mixture of polymer and releasing agent) can be dissolved in acetone, and then loaded into a syringe (e.g., a 1 mL syringe). The control region solution is then injected through the outer needle, surrounding the cylindrical therapeutic region disposed within the inner needle. The resulting depot 100 is a cylindrical form with a control region 300 substantially uniformly surrounding the inner cylindrical therapeutic region 200. In some embodiments, the resulting cylindrical form can be suitable for injecting using a needle, thereby providing for a convenient mechanism to deliver the depot to any number of different treatment sites. In other embodiments, a coaxial needle having three or more coaxial lumens can be used for the formation of multiple therapeutic and/or control regions, for example having a plurality of different therapeutic agents that can be configured to be released sequentially from the depot 100.

In some embodiments, an extruded depot 100 in the form an elongated columnar structure (e.g., a cylindrical rod, strip, etc.) can be pinched down at one or more positions along its length to be subdivided into discrete portions. For example, an elongated depot 100 may be pinched such that the depot is completely severed into discrete sections, or to provide a narrowed, weakened portion that can be susceptible to flexing and/or breaking.

FIG. 52C illustrates one method of manufacturing depots in the form of pellets as shown in FIGS. 52A and 52B. A sheet including a plurality of layered regions such as outer control regions 300 at least partially surrounding an inner therapeutic region 200 is provided. A punch 600 with a hollow blade can be used to cut out individual pellets from the sheet, for example by pressing the punch 600 through the sheet along an axis orthogonal to the surface of the sheet. In some embodiments, the resulting pellets each retain the layered regions of the sheet (e.g., a therapeutic region 200 sandwiched between first and second control regions 300). In such embodiments, the resulting pellet can have at least a portion of the therapeutic region 200 exposed through the control region(s) 300, for example with lateral sides of the pellet having exposed portions of the therapeutic region 200. Such exposed portions of the therapeutic region 200 can contribute to a higher initial release rate of the therapeutic agent.

In some embodiments, the punch 600 is heated before cutting the pellets from the sheet, for example by being heated in an oven to approximately 80° C., or to a suitable temperature to at least partially melt or deform the control region 300. The heated punch 600 can at least partially deform the top layer (e.g., partially melting the upper control region 300) causing it to wrap around the lateral edges of the therapeutic region 200. The resulting depot 100 may then take the form of a pellet 100 in which the inner therapeutic region 200 is completely or substantially completely surrounded by the control region(s) 300. In some embodiments, the motion of pressing the punch 600 can be varied to achieve the desired coverage of the control region(s) 300 over the therapeutic region 200. For example, in some embodiments, the punch 600 can be rotated while being pressed through the sheet, and in some embodiments the punch 600 can be moved more slowly or move quickly to allow varying degrees of deformation and flow of the control region(s) 300. In other embodiments, the punch 600 is not heated before being pressed through the sheet.

The dimensions of the depots 100 in the form of pellets or mini-cylinders can be controlled by varying the thickness of the sheet and by selecting the diameter or lumen cross-sectional dimensions of the punch 600. In some embodiments, the sheet can have a thickness of between about 0.5 and 2 mm (e.g., approximately 0.85 mm), and the punch 600 can have a circular lumen with a diameter of between about 0.5 mm and about 3 mm (e.g., approximately 1 mm). In other embodiments, the punch 600 can cut out depots 100 in other shapes, for example, square, rectangular, elliptical, star-shaped, wavy, irregular polygonal, or any other suitable cross-sectional shape. In some embodiments, a wavy or jagged shape can provide a larger surface area for the resulting pellets, thereby increasing a rate of release of therapeutic agent from the pellets. In some embodiments, the resulting depots 100 in the form of pellets or mini-cylinders are insertable through a needle or other suitable delivery shaft. For example, a plurality of approximately pellets having 1 mm diameters may be loaded coaxially into a 17-gauge needle and inserted subcutaneously to a treatment site in a patient. Smaller pellet-like depots 100 could be inserted through even smaller needles, for example 18- to 22-gauge needles. Such pellets or mini-cylinders can achieve a considerably high drug loading, as described elsewhere herein, for example at least 50% by weight of the therapeutic agent or more.

In some embodiments, microbead and/or pellet-like depots (e.g., as in FIGS. 51-52) can be formed by providing an elongated structure (e.g., a cylindrical, columnar, or rod-shaped structure) having a therapeutic region 200 at least partially surrounded by a control region 300, and then cutting or otherwise dividing the structure into a plurality of pellets, particles, or microbeads along its length.

II. EXAMPLES

The following examples are offered by way of illustration and not by way of limitation.

Example 1

Preparation of bioresorbable polymer/drug films. Two depots of the present technology containing a high payload the local anesthetic bupivacaine were prepared according to the following procedures.

Each of the sample depots consisted of a heat compressed, multi-layer film having the configuration shown in FIG. 5. The therapeutic region consisted of a single layer and was sandwiched between two inner control layers (closest to the therapeutic layer, such as 302b and 302c in FIG. 5, and referred to as “Control Layer A” in Table 4 below) and two outer control layers (farthest from therapeutic region, such as 302a and 302d in FIG. 5, and referred to as “Control Layer B” in Table 4). The constituents of the therapeutic region and the control region are detailed in Table 4.

TABLE 4

Therapeutic Region
Single layer

Polymer
Poly(L-lactide-co-glycolic-co-s-caprolactone)

(1760 mg) (Durect Corp, Birmingham)

PLA to PGA to PCL ratio of from 90:5:5 to

60:30:10

Releasing Agent
Tween 20 (860 mg) (Sigma-Aldrich Pte Ltd;

Singapore)

Anesthetic
bupivacaine hydrochloride (3520 mg) (Xi'an

Victory Biochemical Technology Co., Ltd.;

Shaanxi, People's Republic of China)

Anesthetic:Polymer
2:1

Releasing
5:10:20

Agent:Polymer:Anesthetic

Control Region

Control Layer A
innermost layer on top and bottom

Polymer
PLGACL (1056 mg)

Releasing Agent
Tween 20 (517 mg)

Control Layer B
outermost layer on top and bottom

Polymer
PLGACL (1056 mg)

Releasing Agent
Tween 20 (103 mg)

Therapeutic region components. The therapeutic region was prepared by combining the polymer, releasing agent, anesthetic, and 3.15 mg of acetone (Merck; Kenilworth, N.J.) in a glass vial and mixing thoroughly. The resulting blend was poured onto a flat plate and compressed multiple times to form a thick film (about 1 mm thick) upon drying.

Control region components. The control region was prepared by combining the polymer, releasing agent, and 4.7 mg of acetone (Merck; Kenilworth, N.J.) in a glass vial and mixing thoroughly. The resulting blend was poured onto a flat plate and drawn by a film applicator to form a thin film (<200 μm thickness) upon drying.

For the sample depot, the single layer therapeutic region and the four layers comprising the control region were aligned and compressed by a heat compressor. The thin film was cut to form a 25 mm×15 mm sample with overall film thickness <1.2 mm.

in vitro drug release testing of bupivacaine depot. The purpose of this procedure was to measure the release of bupivacaine from a bioresorbable polymer depot into a receiving fluid of 1×PBS. Each release experiment was conducted in duplicate. The in vitro release procedure consisted of placing a known size of film into an apparatus containing the receiving fluid. The in vitro release apparatus consisted of a 200 mL glass bottle. A receiving fluid in the amount of 100 mL was added to each sample bottle. During the release study, the apparatus was placed in a water bath maintained at 37±2° C. At predetermined intervals, samples of the receiving fluid were removed and analyzed for bupivacaine concentration by UV-Visible Spectrophotometer.

FIG. 53 shows the drug release profile for the depots with effectively reduced initial burst effect and demonstrated a desirable consistent controlled release of drug.

Example 2A

Preparation of bioresorbable polymer/drug films. Two depots of the present technology comprising the local anesthetic bupivacaine were prepared as described in Example 1, except the depots of the present example comprised two of the depots of Example 1 stacked on top of one another and heat compressed to form a new, thicker sample having an overall film thickness of about 2 mm (for example, see the configuration shown in FIG. 6).

in vitro drug release testing of bupivacaine depot. in vitro drug release testing of the depots was performed as described in Example 1.

Release profiles. FIG. 54 shows the average cumulative dose profiles of the bupivacaine films. The graph shows controlled release of over 500 hours with the initial 24-hour release of about 20%.

Example 2B

Preparation of bioresorbable polymer/drug films. Two depots of the present technology comprising the local anesthetic bupivacaine were prepared as described in Example 1, except the depots of the present example comprised three of the depots of Example 1 stacked on top of one another and heat compressed to form a new, thicker sample having an overall film thickness of about 3 mm (for example, see the configuration shown in FIG. 7).

In vitro drug release testing of bupivacaine depot. in vitro drug release testing of the depots was performed as described in Example 1.

Release profiles. FIG. 55 shows the average cumulative dose profiles of the bupivacaine films. The graph shows controlled release of over 500 hours with the initial 24-hour release of about 20%.

Example 3

Preparation of bioresorbable polymer/drug films. Four depots of the present technology comprising the local anesthetic bupivacaine were prepared as described below.

Each of the sample depots consisted of a heat compressed, multi-layer film formed of an inner depot similar to that shown in FIG. 5 encapsulated by a different control region (described below). The inner depot of each sample depot consisted of a therapeutic region (formed of 10 heat-compressed therapeutic layers) sandwiched between two inner control layers (closest to the therapeutic region, such as 302b and 302c in FIG. 5, and referred to as Control Layer A in Table 5 below) and two outer control layers (farthest from therapeutic region, such as 302a and 302d in FIG. 5), and referred to as Control Layer B in Table 5). The constituents of the therapeutic region and the control region are detailed in Table 5.

TABLE 5

Therapeutic Region
10 heat-compressed microlayers

Polymer
Poly(L-lactide-co-s-caprolactone)(PLCL) (Corbion;

Lenexa, KS) having a PLA to PCL ratio of from

90:10 to 60:40 (880 mg)

Releasing Agent
Tween 20 (440 mg) (Sigma-Aldrich Pte Ltd;

Singapore)

Anesthetic
bupivacaine hydrochloride (1760 mg) (Xi'an

Victory Biochemical Technology Co., Ltd.;

Shaanxi, People's Republic of China)

DCM 13.33 g

Anesthetic:Polymer
2:1

Control Region

Control Layer A

Polymer
PLCL (352 mg)

Releasing Agent
Tween 20 (172 mg)

DCM
5.3 g

Control Layer B

Polymer
PLCL (352 mg)

Releasing Agent
Tween 20 (35 mg)

DCM
5.3 g

Therapeutic region. The therapeutic region constituents (see Table 5 above) were added to a glass vial and mixed thoroughly. The resulting blend was poured onto a flat plate and drawn by a film applicator to form a thin film upon drying (<200 μm thickness).

Control region. The control region constituents (see Table 5 above) were added to a glass vial and mixed thoroughly. The resulting blend was poured onto a flat plate and drawn by a film applicator to form a thin film upon drying (<200 μm thickness).

For each sample film, 10 drug layers (each initially <200 μm thickness) and 4 control layers were aligned (Control B-Control A-10 therapeutic layers-Control A-Control B) and compressed by a heat compressor (Kun Shan Rebig Hydraulic Equipment Co. Ltd.; People's Republic of China). The resulting thin film was cut to form a 20 mm×20 mm triangle sample with an overall film thickness of <0.2 mm. The triangle samples were further aligned, and fully encapsulated, with (a) a Control Layer A on both sides (i.e., two additional control layers), (b) a Control Layer B on both sides (i.e., two additional control layers), (c) two of Control Layer A on both sides (i.e., four additional control layers), (d) two of Control Layer B on both sides (i.e., four additional control layers). The resulting assembly was then compressed by a heat compressor (Kun Shan Rebig Hydraulic Equipment Co. Ltd.; People's Republic of China).

in vitro drug release testing of bupivacaine depot. The purpose of this procedure was to measure the release of bupivacaine, from a bioresorbable polymer depot into a receiving fluid of 1×PBS. Each release experiment was conducted in duplicate. The in vitro release procedure consisted of placing a known size of film into an apparatus containing the receiving fluid. The in vitro release apparatus consisted of either a 20 mL or a 100 mL glass bottle. A receiving fluid in the amount of 12 mL or 50 mL was added to each sample bottle. During the release study, the apparatus was placed in a water bath maintained at 37±2° C. At predetermined intervals, samples of the receiving fluid were removed and analyzed for bupivacaine concentration by a UV-Visible Spectrophotometer.

Release profiles. FIG. 56 shows the average cumulative dose profiles of the bupivacaine films. The graph shows controlled release of over 1500 hours for some of the configurations.

Example 4

Sample depots of the present technology were implanted subcutaneously in living rabbits (one depot per rabbit). The depots were placed in a subcutaneous pocket.

The present example tested two groups of depots, each utilizing a different polymer. The depots in Group A included Poly (DL-lactide-glycolide-ε-caprolactone) in a molar ratio of 60:30:10, and the depots in Group B included Poly (DL-lactide-co-glycolide) in a molar ratio of 50:50. Each group included a depot having a low, medium, or high dose of bupivacaine HCl.

For the depots of Group A, each inner control layer consisted of 3.9 mg, 4.0 mg, or 4.7 mg of the polymer (for Low, Med, and High dose groups, respectively) and 1.9 mg, 2.0 mg, or 2.3 mg of a releasing agent (polysorbate 20) (for Low, Med, and High dose groups, respectively). Each outer control layer consisted of 5.3 mg, 5.5 mg, or 6.3 mg of the polymer (for Low, Med, and High dose groups, respectively) and 1.9 mg, 2.0 mg, or 2.3 mg of a releasing agent (polysorbate 20) (for Low, Med, and High dose groups, respectively).

For the depots of Group A, the therapeutic region consisted of 71.5 mg, 152.6 mg, or 269 mg of the polymer (for Low, Med, and High dose groups, respectively), 34.9 mg, 74.6 mg, or 131.5 mg of a releasing agent (polysorbate 20) (for Low, Med, and High dose groups, respectively), and 142.9 mg, 305.2 mg, or 538.1 mg of a local anesthetic (bupivacaine HCl).

For the depots of Group B, each inner control layer consisted of 4.7 mg, 5.1 mg, or 5.3 mg of the polymer (for Low, Med, and High dose groups, respectively) and 2.3 mg, 2.5 mg, or 2.6 mg of a releasing agent (polysorbate 20) (for Low, Med, and High dose groups, respectively). Each outer control layer consisted of 6.4 mg, 6.9 mg, or 7.3 mg of the polymer (for Low, Med, and High dose groups, respectively), and 0.6 mg, 0.7 mg, or 0.7 mg of a releasing agent (polysorbate 20) (for Low, Med, and High dose groups, respectively).

For the depots of Group B, the therapeutic region consisted of 87.0 mg, 171.1 mg, or 317.7 mg of the polymer (for Low, Med, and High dose groups, respectively), 42.5 mg, 83.6 mg, or 155.2 mg of a releasing agent (polysorbate 20) (for Low, Med, and High dose groups, respectively), and 173.9 mg, 342.2 mg, or 635.4 mg of a local anesthetic (bupivacaine HCl).

Within each of Group A and Group B, the low dose depots were about 20 mm×20 mm x<1 mm (e.g., 0.89 mm and 0.9 mm), the medium dose depots were about 20 mm×20 mm x<2 mm (e.g., 1.8 mm and 1.6 mm), and the high dose depots were about 20 mm×20 mm x<3 mm (e.g., about 2.7 mm and about 2.8 mm).

Blood draws for bupivacaine concentration analysis were collected through Day 28.

Group A

The Group A depots were administered to 3 rabbits/dose group and PK samples were collected to day 28. The semi-log plot of the group mean data for each dose is shown in FIG. 57. The product, regardless of dose, exhibits peak exposure within the first 72 hours and then a plateau of exposure that is determined by the dose (the higher the dose the longer the plateau) followed by more rapid terminal clearance. The release of bupivacaine is rapid with a consistent similar profile for each rabbit with moderate variability over the first 72 hours.

The in vitro pharmacokinetic (“PK”) profile for Group A is shown in FIG. 57B. The half-life of the initial distribution phase through the first 72-96 hours was generally consistent through the three dose strengths (implant sizes) and T_maxoccurred within the first 24 hours for all rabbits, with a median T_maxbetween 4-8 hours. The peak exposure (C_max) for the high dose exhibited a low CV % of 17.6%. This data would indicate a controlled initial rapid release of bupivacaine during the period of greatest discomfort post TKA surgery. The exposure profile was stable from 72 hours through at least 436 hours. The terminal phase half-life started to exhibit the more innate half-life of bupivacaine, particularly in the high dose where the terminal phase t_1/2was 17.4 hours. This would suggest that the depot had almost completely released the drug by Day 21.

The high dose, Group A depot was consistent in average exposure from Day 3 to Day 18, while the mid and low dose depots were consistent from Day 3 to Day 14. There was not a significant difference in exposure between the Mid and High dose groups from Day 3-14, while the Low dose was approximately half the exposure level during this time period.

Group B

Formulation 50:50 copolymer was administered to 3 rabbits/dose group and PK samples were collected to hour 672 (Day 28). The semi-log plot of the group mean data for each dose is presented in FIG. 57C. The product, regardless of dose, exhibits peak exposure within the first 72 hours and then a gradual decline in exposure followed by a secondary faster release coupled with a secondary peak in exposure at approximately Day 19-21. After the secondary peak, bupivacaine exposure declined with different rates dependent on dose (lower the dose the faster the clearance). FIG. 57C highlights the group mean (SD) and individual rabbits for Low Dose (126 mg) in Panel A, Mid Dose (252 mg) in Panel B and High Dose (420 mg) in Panel C through the first 96 hours. The release of bupivacaine is rapid with a consistent and similar profile for each rabbit with moderate variability over the first 72 hours.

The in vitro pharmacokinetic profile is shown in FIG. 57D. The 50:50 copolymer did not exhibit an initial distribution half-life like the 631 terpolymer, however T_maxoccurred within the first 24 h for all rabbits, with a median T_maxthat was slightly further out in time, between 16-20 hours. The peak exposure (C_max) exhibited a very low CV % of 5.99%. This data would indicate a controlled initial rapid release of bupivacaine during the acute postoperative pain period (i.e., period of greatest discomfort post TKA surgery) followed by a more gradual decline in release rate through the subacute postoperative pain period, which is consistent with the presumed steady decline in pain during that same period. This release profile having the steady decline in release rate during the acute postoperative pain period is in contrast with the release rate of the 631 polymer formulation, where the release rate states substantially constant throughout the postoperative pain period.

All three dose levels slowly decreased exposure over the Day 3 to Day 18 time period.

Example 5

Two sample depots of the present technology were implanted in the intraarticular space of a knee joint of a living canine. The surgeon performed a medial and lateral parapatellar arthrotomy to insert one sample depot in the medial gutter and one sample depot in the lateral gutter. The depots were anchored in place by 4-0 PDS II suture. Two canines were the subject of the present study.

Each of the sample depots consisted of a heat compressed, multi-layer film having the configuration shown in FIG. 5. The therapeutic region consisted of a single layer and was sandwiched between two inner control layers (closest to the therapeutic layer, such as 302b and 302c in FIG. 5) and two outer control layers (farthest from therapeutic region, such as 302a and 302d in FIG. 5). Each inner control layer consisted of 5.7 mg of a bioresorbable polymer (60:30:10 terpolymer Poly (DL-lactide-glycolide-ε-caprolactone)) and 2.8 mg of a releasing agent (polysorbate 20). Each outer control layer consisted of 7.7 mg of a bioresorbable polymer (60:30:10 terpolymer Poly (DL-lactide-glycolide-ε-caprolactone)) and 0.8 mg of a releasing agent (polysorbate 20).

The therapeutic region comprised a single layer consisting of 118 mg of a bioresorbable polymer (60:30:10 terpolymer Poly (DL-lactide-glycolide-ε-caprolactone)), 57.6 mg of a releasing agent (polysorbate 20), and 235.9 mg of a local anesthetic (bupivacaine HCl).

Each of the depots was about 15 mm×about 25 mm×about 1 mm.

Following implantation, the canines were evaluated at predetermined intervals to determine the post-operative pharmacokinetic (PK) profile of bupivacaine in synovial fluid and blood plasma. For PK values of bupivacaine in the blood plasma (i.e., representing systemic bupivacaine levels), blood was drawn at scheduled intervals after implantation of the depots. The PK results for the plasma fluid samples are shown at FIG. 58.

As shown in FIG. 58, the depot 100 released an initial, controlled burst over about the first three days, followed by a tapering release for the remaining 11 days.

Example 6

Three sample depots of the present technology were implanted in the intraarticular space of a knee joint of a living sheep. The surgeon performed a medial and lateral parapatellar arthrotomy to insert one sample depot in the medial gutter and two sample depots in the lateral gutter. The lateral gutter depots were sutured side-by-side prior to implantation to keep the depots in place relative to each other in the gutter. The depots were then anchored in place to the capsular tissue by 4-0 PDS II suture.

Each of the sample depots consisted of a heat compressed, multi-layer film having the configuration shown in FIG. 5. The therapeutic region consisted of a single layer and was sandwiched between two inner control layers (closest to the therapeutic layer, such as 302b and 302c in FIG. 5) and two outer control layers (farthest from therapeutic region, such as 302a and 302d in FIG. 5). Each inner control layer consisted of 5.3 mg of a bioresorbable polymer (Poly (DL-lactide-co-glycolide) in a molar ratio of 50:50)) and 2.6 mg of a releasing agent (polysorbate 20). Each outer control layer consisted of 7.2 mg of a bioresorbable polymer (Poly (DL-lactide-co-glycolide) in a molar ratio of 50:50)) and 0.7 mg of a releasing agent (polysorbate 20).

The therapeutic region comprised a single layer consisting of 118.1 mg of a bioresorbable polymer (Poly (DL-lactide-co-glycolide) in a molar ratio of 50:50), 57.7 mg of a releasing agent (polysorbate 20), and 236.3 mg of a local anesthetic (bupivacaine HCl).

Each of the depots was about 15 mm×about 25 mm×about 1 mm.

Following implantation, the sheep was evaluated at 1, 4, 8, 15, and 30 days to determine the post-operative pharmacokinetic (PK) profile of bupivacaine in synovial fluid and blood plasma.

For PK values of bupivacaine in the blood plasma (i.e., representing systemic bupivacaine levels), 1 mL of blood was drawn 1, 2, 4, 8, 12, 16, 20, 24 and 48 hours after implantation of the depots, then every 48 hours (at the same time as was drawn on previous days, +/−1 hr) in all animals until day 28 prior to sacrifice. The PK results for the plasma fluid samples are shown in FIG. 59A. As shown, the systemic plasma bupivacaine concentration showed an initial, controlled burst over the first 2-4 days, followed by a tapering release for the remaining period.

For PK values of bupivacaine in the synovial fluid (i.e., representing local bupivacaine levels), a minimum of 0.5 mL of synovial fluid was aspirated from the joint at 0 hours (i.e., just prior to surgery), 24 hours, 96 hours, and 192 hours. The PK results for the synovial fluid samples are shown in FIG. 59B. As shown, the local synovial concentration showed an initial, controlled burst over the first 2-4 days, followed by a tapering release for the remaining period.

FIG. 59C is a plot depicting the blood plasma bupivacaine concentration versus the synovial bupivacaine concentration over time. As demonstrated in FIG. 59C, the PK values are illustrative of a release profile achieved in prior in vitro and in vivo studies, wherein the initial, controlled burst over the first 2-4 days provides a substantial dosage of bupivacaine during the acute postoperative pain period and the tapering release that follows provides a therapeutic dosage during the subacute postoperative pain period. As shown, local bupivacaine levels were an order of magnitude greater than systemic bupivacaine levels. Achieving a high local concentration of bupivacaine without correspondingly high systemic levels allows for optimized analgesia without the risk of systemic toxicity.

III. SELECTED SYSTEMS AND METHODS FOR TREATING POSTOPERATIVE PAIN ASSOCIATED WITH ORTHOPEDIC SURGERY

The depots 100 of the present technology may be used to treat a variety of orthopedic injuries or diseases depending upon the nature of the therapeutic agent delivered as described above. The therapeutic agent may be delivered to specific areas of the patient's body depending upon the medical condition being treated. The depots 100 of the present technology may be positioned in vivo proximate to the target tissue (i.e., bone, soft tissue, etc.) in the patient's body to provide a controlled, sustained release of a therapeutic agent for the treatment of a particular condition. This implantation may be associated with a surgery or intervention for acutely treating the particular condition, whereby the depot enables chronic, sustained pharmacological treatment following completion of the surgery or intervention. The depot may be a standalone element, or may be coupled to or integrated as part of an implantable device or prosthesis associated with the intervention or surgery.

The amount of the therapeutic agent that will be effective in a patient in need thereof will depend on the specific nature of the condition, and can be determined by standard clinical techniques known in the art. In addition, in vitro or in vivo assays may optionally be employed to help identify optimal dosage ranges. The specific dose level for any particular individual will depend upon a variety of factors including the activity of the drug, the age, body weight, general physical and mental health, genetic factors, environmental influences, sex, diet, time of administration, location of administration, rate of excretion, and the severity of the particular problem being treated.

Some aspects of the present technology include a system comprising a plurality of depots (each of which could be any of the depots described herein) provided for implantation by a clinical practitioner. In this system, each depot may be configured for controlled release of therapeutic agent to tissue proximate to the implantation site of the depot. The depots in the system may be identical or may vary in several respects (e.g., form factor, therapeutic agent, release profile, etc.). For example, the system may be comprised of a depot having a release profile that provides for an immediate release of therapeutic agent and other depots comprised of a depot having a release profile that provides for a delayed release of therapeutic agent.

Many depots of the present technology are configured to be implanted at a surgical site to treat postoperative pain at or near the site. As used herein, the term “pain” includes nociception and the sensation of pain, both of which can be assessed objectively and subjectively, using pain scores and other methods well-known in the art, such as opioid usage. In various embodiments, pain may include allodynia (e.g., increased response to a normally non-noxious stimulus) or hyperalgesia (e.g., increased response to a normally noxious or unpleasant stimulus), which can in turn be thermal or mechanical (tactile) in nature. In some embodiments, pain is characterized by thermal sensitivity, mechanical sensitivity and/or resting pain. In other embodiments, pain comprises mechanically-induced pain or resting pain. In still other embodiments, the pain comprises resting pain. The pain can be primary or secondary pain, as is well-known in the art. Exemplary types of pain reducible, preventable or treatable by the methods and compositions disclosed herein include, without limitation, include post-operative pain, for example, from the back in the lumbar regions (lower back pain) or cervical region (neck pain), leg pain, radicular pain (experienced in the lower back and leg from lumbar surgery in the neck and arm from cervical surgery), or abdominal pain from abdominal surgery, and neuropathic pain of the arm, neck, back, lower back, leg, and related pain distributions resulting from disk or spine surgery. Neuropathic pain may include pain arising from surgery to the nerve root, dorsal root ganglion, or peripheral nerve.

In various embodiments, the pain results from “post-surgical pain” or “post-operative pain” or “surgery-induced pain”, which are used herein interchangeably, and refer to pain arising in the recovery period of seconds, minutes, hours, days or weeks following a surgical procedure (e.g., hernia repair, orthopedic or spine surgery, etc.). Surgical procedures include any procedure that penetrates beneath the skin and causes pain and/or inflammation to the patient. Surgical procedure also includes arthroscopic surgery, an excision of a mass, spinal fusion, thoracic, cervical, or lumbar surgery, pelvic surgery or a combination thereof.

FIGS. 60A and 60B illustrate common locations within a patient that may be sites where surgery is conducted and locations where the depots of the present technology can be administered. It will be recognized that the locations illustrated in FIGS. 60A and 60B are merely exemplary of the many different locations within a patient where a surgery may take place. For example, surgery may be required at a patient's knees, hips, upper extremities, lower extremities, neck, spine, shoulders, abdomen and pelvic region. FIG. 61 is a table showing common surgical procedures for which the depots 100 of the present technology may be utilized for treating postoperative pain.

Many embodiments of the present technology include one or more depots, having the same or different configuration and/or dosing, that are configured to be positioned at or near a surgical site of a knee joint to treat pain associated with a total knee replacement surgery. As previously described, the depots of the present technology may be solid, self-supporting, flexible thin films that is structurally capable of being handled by a clinician during the normal course of a surgery without breaking into multiple pieces and/or losing its general shape. This way, the clinician may position one or more of the depots at various locations at or near the intracapsular and/or extracapsular space of the knee joint, as necessary to address a particular patient's needs and/or to target particular nerves innervating the knee.

FIGS. 62A-62C, for example, are front, lateral, and medial views of a human knee, showing the location of the nerves innervating the extra- and intracapsular portion of a knee joint. In some embodiments, the depots may be implanted adjacent to one or more nerves (such as the nerves shown in FIGS. 62A-62C) innervating the knee.

In some instances, it may be beneficial to position one or more of the depots within the joint capsule. For example, FIG. 63A is a splayed view of a human knee exposing the intracapsular space and identifying potential locations for positioning one or more depots, and FIG. 63B is a splayed view of a human knee exposing the intracapsular space and showing several depots 100 positioned within for treating postoperative pain. As shown in FIGS. 63A and 63B, in some instances, one or more depots may be positioned at or near the suprapatellar pouch SPP, specifically under the periosteum and attached to the quadriceps tendon or any other suitable tissue. Additional areas for placement of one or more depots 100 may include generally the medial and lateral gutters MG, LG (including optional fixation to tissue at the medial or lateral side of the respective gutter), on the femur F, on the tibia T (e.g., posterior attachment to the tibial plateau, at or near the anterior tibia to anesthetize infrapatellar branches of the saphenous nerve). In some embodiments, one or more depots may be positioned adjacent to at least one of a posterior capsule PC of the knee, a superior region of the patella P, and/or the arthrotomy incision into the knee capsule. In some embodiments, one or more depots 100 may be positioned at or near the saphenous nerve, the adductor canal, and/or the femoral nerve. In some embodiments, one or more of the depots may be configured to be positioned at or near an infrapatellar branch of the saphenous nerve, one or more genicular nerves of the knee, a superior region of the patella P. It may be desirable to position the depot within the knee capsule but away from any articulating portions of the knee joint itself.

Instead of or in addition to the placement of depots within the intracapsular space, one or more depots may be placed at an extracapsular position. FIGS. 64A and 64B, for example, show anterior and posterior views, respectively, of the nerves as positioned at an extracapsular location. In some embodiments, the depots may be implanted adjacent to one or more extracapsular nerves (such as the nerves shown in FIGS. 64A and 64B). As shown in FIG. 65, in some embodiments one or more depots 100 may be positioned along or adjacent the subcutaneous skin incision.

In some embodiments, the system includes a first depot (or plurality of depots) and a second depot (or plurality of depots), all of which are configured to be implanted at or near the knee joint. The first depot(s) may have the same or different release profile, rate of release, therapeutic agent (such as non-anesthetic analgesics, NSAIDs, antibiotics, etc.), duration of release, size, shape, configuration, total payload, etc. as the second depot(s).

So as not to interfere or overlap with a peripheral nerve block administered perioperatively to the patient, one or more of the depots may optionally include a delay release capability for 6 to 24 hours following implantation. In some embodiments, one or more depots placed in the adductor canal and knee capsule may be configured to have a delay in the release of therapeutic agent that may exceed 24 hours.

The depots 100 disclosed herein may be used to treat postoperative pain associated with other knee surgeries. For example, one or more depots may be used to treat postoperative pain associated with an ACL repair surgery, a medial collateral ligament (“MCL”) surgery, and/or a posterior cruciate ligament (“PCL”) surgery. For ACL repair, one or more depots may be positioned to delivery analgesic the femoral and/or sciatic nerves, while for PCL repair surgery, one or more depots may be positioned parasacral to deliver analgesic to the sciatic nerve. The one or more depots may be used to treat postoperative pain associated with a partial knee replacement surgery, total knee replacement surgery, and/or a revision surgery of a knee replacement surgery. In such procedures, one or more depots can be placed contiguous to the joint or repair site to provide a local block, or else may suitably positioned to provide a regional block by delivering an analgesic to one or more of the femoral nerve or the sciatic nerve, for example via placement in the adductor canal.

In addition to the knee-related surgeries described above, embodiments of the depots disclosed herein can be used to treat postoperative pain associated with other orthopedic surgeries as described in more detail below and as summarized in part in FIG. 61. Examples include surgical procedures involving the ankle, hip, shoulder, wrist, hand, spine, legs, or arms. For at least some of these surgical procedures, analgesic can be provided to deliver a local block or a regional block to treat postoperative pain. For a local block, one or more depots can be attached under direct vision in open surgery, for example during joint arthroplasty, open reduction and internal fixation (ORIF) surgery, ligament reconstruction, etc. In such procedures involving a joint, one or more depots can be positioned at the joint capsule (e.g., at or near the intracapsular and/or extracapsular space of the joint) or adjacent soft tissues spaced apart from articulating surfaces to avoid the depot interfering with joint movement or being damaged by contact with articulating surfaces. In cases involving fracture repair or ligament repair, one or more depots can be positioned at or adjacent to the repair site to provide a local block. For a regional block, one or more depots can be deposited at a treatment site adjacent to the target nerve via ultrasound guidance using a blunt trocar catheter or other suitable instrument. In at least some embodiments, it can be beneficial to combine delivery of analgesic or other therapeutic agents via the depot(s) with delivery of NSAIDs, a long-acting narcotic delivered pre-operatively, and/or acetaminophen. The sustained, controlled, release of an analgesic via the one or more depots may work in concert with these other therapeutic agents to provide a reduction in postoperative pain associated with orthopedic and other surgical procedures.

In one example, one or more depots as described herein can be used to treat postoperative pain associated with foot and ankle surgeries such as ankle arthroplasty (including ankle revision, ankle replacement, and total ankle replacement), ankle fusion, ligament reconstruction, corrective osteotomies (e.g., bunionectomy, pes planus surgery), or open reduction and internal fixation (ORIF) of ankle or foot fractures. In treating postoperative pain associated with such surgeries, one or more depots can be configured and positioned adjacent to the joint or repair site to provide a local block. Additionally or alternatively, one or more depots can be placed parasacral or at another suitable location to target one or more of the subgluteal sciatic nerve, popliteal sciatic nerve, deep peroneal nerve, or the superficial peroneal nerve. In some embodiments, depots positioned to treat postoperative pain associated with ankle or foot surgeries can have a release profile configured to deliver therapeutically beneficial levels of analgesic for a period of between 3-7 days.

In another example, one or more depots as described herein can be used to treat postoperative pain associated with hip surgeries such as hip arthroplasty (including hip revision, partial hip replacement, and total hip replacement) or open reduction and internal fixation (ORIF) of hip fractures. In treating postoperative pain associated with such surgeries, one or more depots can be configured and positioned adjacent to the joint or repair site to provide a local block. Additionally or alternatively, a regional block can be provided by placing depots in the psoas compartment, lumbar paravertebral space, fascia iliaca, or other suitable location to target one or more of the lumbar plexus, sacral plexus, femoral nerve, sciatic nerve, superior gluteal nerve, or obturator nerve. In some embodiments, it may be beneficial to secure the one or more depot(s) (e.g., using a fixation mechanism as described herein) to maintain an anterior position of the depot, thereby preventing or reducing exposure of analgesic to motor nerves (e.g., sciatic or femoral nerves). In some embodiments, depots positioned to treat postoperative pain associated with hip surgeries can have a release profile configured to deliver therapeutically beneficial levels of analgesic for a period of 5-7 or 7-10 days depending on the particular surgical procedure.

Post-operative pain associated with shoulder and upper-arm surgeries can likewise be treated using one or more depots as disclosed herein. Examples of such surgeries include shoulder arthroplasty (including shoulder revision, partial shoulder replacement, and total shoulder replacement), upper-arm fracture repair (scapular, humerus), ligament/tendon repair (e.g., rotator cuff, labrum, biceps, etc.), or open reduction and internal fixation (ORIF) of fractures of the shoulder or upper arm. In treating postoperative pain associated with such surgeries, one or more depots can be configured and positioned adjacent to the joint or repair site to provide a local block. Additionally or alternatively, one or more depots can be configured and positioned to target the brachial plexus by placing one or more depots in the cervical paravertebral space, interscalene, or supraclavicular space. In some embodiments, interscalene placement of the depots can avoid exposure of analgesic to native cartilage, thereby reducing the risk of chondrotoxicity. In some embodiments, depots positioned to treat postoperative pain associated with shoulder or upper-arm related surgeries can have a release profile configured to deliver therapeutically beneficial levels of analgesic for a period of 3-7 days.

In another example, one or more depots as described herein can be used to treat postoperative pain associated with elbow surgeries such as elbow arthroplasty (including elbow revision, partial elbow replacement, and total elbow replacement), ligament reconstruction, or open reduction and internal fixation (ORIF) of fractures of the elbow. In treating postoperative pain associated with such surgeries, one or more depots can be positioned adjacent to the joint or repair site to provide a local block. Additionally or alternatively, one or more depots can be configured and positioned to target the brachial plexus nerves, for example by being placed at or near the cervical paravertebral space, infraclavicular, or axillary position, or other suitable location. In some embodiments, depots positioned to treat postoperative pain associated with elbow surgeries can have a release profile configured to deliver therapeutically beneficial levels of analgesic for a period of 3-7 days.

Post-operative pain associated with wrist and hand surgeries can also be treated using one or more depots as described herein. Examples of wrist and hand surgeries include wrist arthroplasty (including wrist revision, partial wrist replacement, and total wrist replacement), wrist fusion, and open reduction and internal fixation (ORIF) of fractures of the wrist. In treating postoperative pain associated with such surgeries, one or more depots can be configured and positioned adjacent to the wrist joint or repair site to provide a local block. Additionally or alternatively, one or more depots can be configured and positioned to target the target the ulnar, median, radial, and cutaneous forearm nerves, for example via placement at the antecubital fossa, cervical paravertebral space, infraclavicular, or axillary position. In some embodiments, depots positioned to treat postoperative pain associated with wrist and hand surgeries can have a release profile configured to deliver therapeutically beneficial levels of analgesic for a period of 3-7 days.

The depots disclosed herein may likewise be used to treat postoperative pain from other orthopedic surgeries. For example, post-operative pain associated with spinal fusion can be treated via placement of one or more depots subcutaneously or in the paravertebral space. In treatment of post-operative pain associated with fibular fracture repair, one or more depots can be configured and placed to target the sciatic nerve and/or the popliteal sciatic nerve, for example being placed parasacral. Various other placements and configurations are possible to provide therapeutic relief from post-operative pain associated with orthopedic surgical procedures.

IV. SELECTED SYSTEMS AND METHODS FOR TREATING POSTOPERATIVE PAIN ASSOCIATED WITH NON-ORTHOPEDIC SURGERY

The depots 100 of the present technology may be used to treat a variety of medical conditions depending upon the nature of the therapeutic agent delivered as described above. The therapeutic agent may be delivered to specific areas of the patient's body depending upon the medical condition being treated. The depots 100 of the present technology may be positioned in vivo proximate to the target tissue in the patient's body to provide a controlled, sustained release of a therapeutic agent for the treatment of a particular condition. This implantation may be associated with a surgery or intervention for acutely treating the particular condition, whereby the depot enables chronic, sustained pharmacological treatment following completion of the surgery or intervention. The depot 100 may be a standalone element, or may be coupled to or integrated as part of an implantable device or prosthesis associated with the intervention or surgery.

Many depots of the present technology are configured to be implanted at a surgical site to treat postoperative pain at or near the site. As used herein, the term “pain” includes nociception and the sensation of pain, both of which can be assessed objectively and subjectively, using pain scores and other methods well-known in the art, such as opioid usage. In various embodiments, pain may include allodynia (e.g., increased response to a normally non-noxious stimulus) or hyperalgesia (e.g., increased response to a normally noxious or unpleasant stimulus), which can in turn be thermal or mechanical (tactile) in nature. In some embodiments, pain is characterized by thermal sensitivity, mechanical sensitivity and/or resting pain. In other embodiments, pain comprises mechanically-induced pain or resting pain. In still other embodiments, the pain comprises resting pain. The pain can be primary or secondary pain, as is well-known in the art. Exemplary types of pain reducible, preventable or treatable by the methods and compositions disclosed herein include, without limitation, include post-operative pain and neuropathic pain of the arm, neck, back, lower back, leg, and related pain distributions. Neuropathic pain may include pain arising from surgery to the nerve root, dorsal root ganglion, or peripheral nerve.

In various embodiments, the pain results from “post-surgical pain” or “post-operative pain” or “surgery-induced pain,” which are used herein interchangeably, and refer to pain arising in the recovery period of seconds, minutes, hours, days or weeks following a surgical procedure. Surgical procedures include any procedure that penetrates beneath the skin and causes pain and/or inflammation to the patient. Surgical procedure also includes arthroscopic surgery, an excision of a mass, spinal fusion, thoracic, cervical, or lumbar surgery, pelvic surgery, chest-related surgery, breast-related surgery, gynecological or obstetric surgery, general, abdominal, or urological surgery, ear, nose, and throat (ENT) surgery, oral and maxillofacial surgery, oncological surgery, cosmetic surgery, or a combination thereof. FIG. 61 is a table showing common surgical procedures for which the depots 100 of the present technology may be utilized for treating postoperative pain.

Many embodiments of the present technology include one or more depots, having the same or different configuration and/or dosing, that are configured to be positioned at or near a surgical site to treat pain associated with recovering from a surgical procedure. As previously described, the depots of the present technology may be solid, self-supporting, flexible thin films that is structurally capable of being handled by a clinician during the normal course of a surgery without breaking into multiple pieces and/or losing its general shape. This way, the clinician may position one or more of the depots at various locations at or near the treatment site, as necessary to address a particular patient's needs and/or to target particular nerves innervating the surgical site.

In some embodiments, the system includes a first depot (or plurality of depots) and a second depot (or plurality of depots), all of which are configured to be implanted at or near the treatment site. The first depot(s) may have the same or different release profile, rate of release, therapeutic agent contained (such as non-anesthetic analgesics, NSAIDs, antibiotics, etc.), duration of release, size, shape, configuration, total payload, etc. as the second depot(s).

So as not to interfere or overlap with a peripheral nerve block administered perioperatively to the patient, one or more of the depots may optionally include a delay release capability for 6 to 24 hours following implantation. In some embodiments, one or more depots placed at the treatment site may be configured to have a delay in the release of therapeutic agent that may exceed 24 hours.

The depots disclosed herein may be used to treat postoperative pain associated with a wide variety of surgeries. For example, as summarized in FIG. 61, the depots may be used to treat postoperative pain for chest-related surgery, breast-related surgery, gynecological or obstetric surgery, general, abdominal, or urological surgery, ear, nose, and throat (ENT) surgery, oral and maxillofacial surgery, oncological surgery, or cosmetic surgery). For particular surgeries or classes of surgeries, one or more depots can be positioned at a treatment site to treat postoperative pain. The treatment site may be at or near the surgical site, or in some embodiments may be separated from the surgical site and proximate to a target nerve or nerve bundle that innervates the surgical site.

In one example, one or more depots as described herein can be used to treat postoperative pain associated with chest-related surgeries such as a thoracotomy, esophageal surgery, cardiac surgery, lung resection, thoracic surgery, or other such procedure. In treating postoperative pain associated with such surgeries, one or more depots can be configured and positioned to target the intercostal nerves, for example by being placed at or near the thoracic paravertebral space or other suitable location. Analgesics delivered to the intercostal nerves can reduce pain in a patient's chest area, thereby relieving postoperative pain associated with the above-noted chest-related surgical procedures.

In another example, one or more depots disclosed herein can be used to treat postoperative pain associated with breast-related surgeries such as a mastectomy, breast augmentation, breast reduction, breast reconstruction procedure, or other such procedure. To treat postoperative pain from such procedures, one or more depots can be positioned and configured to deliver analgesics or other therapeutic agents to the intercostal nerves, for example via placement at or near the patient's infraclavicular space or other suitable location. Additionally or alternatively, one or more depots can be positioned and configured to deliver analgesics or other therapeutic agents to the lateral pectoral nerve and/or the medial pectoral nerve, for example via placement between the serratus anterior muscle and the latissimus dorsi muscle or other suitable location. As noted above, analgesics delivered to the intercostal nerves can reduce pain in a patient's chest area, while analgesics delivered to the lateral and/or medial pectoral nerves can reduce pain in the pectoralis major and pectoralis minor, thereby reducing postoperative pain associated with the above-noted chest-related surgical procedures.

As another example, one or more depots can be used to treat postoperative pain associated with general, abdominal, and/or urological procedures. Examples of such procedures include proctocolectomy, pancreatectomy, appendectomy, hemorrhoidectomy, cholecystectomy, kidney transplant, nephrectomy, radical prostatectomy, nephrectomy, gastrectomy, small bowel resection, splenectomy, incisional hernia repair, inguinal hernia repair, sigmoidectomy, liver resection, enterostomy, rectum resection, kidney stone removal, and cystectomy procedures. For such operations, postoperative pain can be treated by placing one or more depots to target nerves at the transverse abdominis plane (TAP). Analgesics delivered to the TAP can anesthetize the nerves that supply the anterior abdominal wall, thereby reducing postoperative pain in this region. In some embodiments, one or more depots are disposed between the internal oblique and transverse abdominis muscles. In some embodiments, one or more depots can be disposed at or adjacent to the abdominal wall, for example being secured in place via fixation mechanisms as described in more detail below.

In some embodiments, one or more depots are used to treat postoperative pain associated with gynecological and obstetric surgeries, for example a myomectomy, Caesarian section, hysterectomy, oophorectomy, pelvic floor reconstruction, or other such surgical procedure. For such procedures, the depot(s) can be configured and positioned to deliver analgesics or other therapeutic agents to one or more of the nerves innervating the pelvic and/or genital area, for example the pudendal nerve, intercostal nerve, or other suitable nerve.

In some embodiments, one or more depots can be used to treat postoperative pain associated with ear, nose, and threat (ENT) surgical procedures, for example tonsillectomy, submucosal resection, rhinoplasty, sinus surgery, inner ear surgery, parotidectomy, submandibular gland surgery, or other such operation. Similarly, one or more depots can be used to treat postoperative pain associated with oral and maxillofacial surgeries, for example dentoalveolar surgery, dental implant surgery, orthognathic surgery, temporomandibular joint (TMJ) surgery, dental reconstruction surgeries, or other such operations. For ENT surgical procedures and oral and maxillofacial surgical procedures, the depot(s) can be configured and positioned to deliver analgesics or other therapeutic agents to one or more of the nerves innervating regions affected by the surgical procedure, for example the mandibular nerve, the mylohyoid nerve, lingual nerve, inferior alveolar nerve, buccal nerve, auriculotemporal nerve, anterior ethmoidal nerve, or other suitable nerve.

One or more depots 100 can also be used to treat postoperative pain for other surgical procedures, for example oncological surgeries (e.g., tumor resection), cosmetic surgeries (e.g., liposuction), or other surgical procedure resulting in postoperative pain. For treatment of postoperative pain associated with any particular surgery, the number of depots and the characteristics of individual depots can be selected to deliver the desired therapeutic benefits. For example, the dimensions of the depot(s), the amount of therapeutic agent per depot, the release profile, and other characteristics can be tuned to provide the desired treatment of postoperative pain. For example, while a patient recovering from a knee-replacement surgery may benefit from delivery of analgesics for at least 14 days, a patient recovering from a tonsillectomy may not require the same level or duration of analgesic drug delivery. As such, depots delivered to a patient for treatment of postoperative pain following a tonsillectomy may require fewer depots, or depots having a smaller payload of therapeutic agent, or depot(s) having a steeper release profile, etc. Additionally, the number and characteristics of the depot(s) selected for implantation can be tailored to accommodate the target anatomical region for placement in the patient's body.

V. SELECTED SYSTEMS AND METHODS FOR FIXATION AND DELIVERY

In some embodiments, one or more depots may be simply placed at a treatment site within the body as noted above. However, in certain instances, after a depot has been implanted at the treatment site, the depot may migrate from the treatment site prior to surgical closure (e.g., due to blood flow or tissue repositioning as the surgical site is closed) or as physiological conditions change (e.g., repair and regeneration of cells, tissue ingrowth, movement at the implant site, etc.). Such migration may reduce efficacy of the therapeutic agent as the depot migrates away from the treatment site and lodges in a distant site. In some embodiments, the depot may need to be removed from the distant site and repositioned to the treatment site, resulting in additional physical trauma to the patient and increased recovery time. In certain instances, migration of the depot may result in impaired biomechanical functionality, for example if the depot migrates into a joint in such a manner as to inhibit movement. Migration into the joint might be of great concern, particularly when there is substantial drug present in the depot, because of the risk of damage to the depot and a resulting premature release of drug. In more severe cases, a dislodged depot may restrict blood flow causing an ischemic event (e.g., embolism, necrosis, infarction, etc.), which could be detrimental to the patient. Accordingly, it can be useful to provide a depot assembly having a fixation mechanism used to secure the depot(s) in place at a treatment site.

In various embodiments, a depot assembly can include a depot as described above in addition to a fixation portion configured to facilitate attachment or fixation of the depot to a treatment site. The depot can include, for example, one or more control regions and one or more therapeutic regions as described above. The fixation portion can include one or more structural features configured to facilitate attachment to, or engagement with, anatomical features at the treatment site. In some embodiments, the structural features are configured to directly engage anatomical features of the treatment site to secure the depot assembly to the treatment site. For example, the fixation portion can include tabs, ridges, hooks, barbs, protrusions, notches, or other features configured to engage soft tissue or other anatomical features at the treatment site to resist migration of the depot assembly.

In some embodiments, the fixation portion includes structural features configured to engage with a separate fixation device. For example, the fixation portion can include loops, eyelets, grommets, channels, or hooks configured to receive a suture, yarn, or other suitable fixation device therethrough. In another example, the fixation portion can include tabs, protrusions, ridges, or other structural features configured to receive a staple or other suitable fixation device therethrough.

In some embodiments, the fixation portion is made of a biodegradable and/or bioerodible material, for example one or more of the biodegradable, bioresorbable polymers listed above. The fixation portion may include a reinforcement or margin of material extending from the depot that does not contain any therapeutic agent. In some embodiments, the fixation portion includes a polymer or copolymer using at least one of PLA, PCL, or PGA. In some embodiments, the fixation portion can be made of the same or similar material to one or more of the components of the depot, for example using the same polymer as the control region(s) or therapeutic region(s) of the depot. In other embodiments, the fixation portion can be made of a biodegradable material different from those of the depot itself. In still other embodiments, some or all of the fixation portion can be made of non-biodegradable and/or non-bioresorbable materials.

It can be advantageous to provide for visibility of the depot assemblies under fluoroscopy or other imaging modality. Accordingly, in some embodiments, the fixation portion can be loaded with radiopaque material to enhance visibility under fluoroscopy. In some embodiments, a photosensitive chemical can be included in the fixation portion or the depot portion such that when activated with a suitable light source or chemical, the depot assembly can be seen or detected, e.g., by a clinician.

The relative orientation and configuration of the depot and the fixation portion can take a variety of forms. In some embodiments, the fixation portion and the depot can be structurally separate but contiguous or adjacent to one another, for example with the fixation portion being disposed around a periphery of the depot or extending from one region of the depot. In other embodiments, the fixation portion can be structurally integrated or overlapping with the depot, for example with a region of the depot being configured to receive a suture or other fixation device therethrough, and thereby constituting a fixation portion. In some embodiments, a fixation portion can be structurally separate from the device, for example with the depot being coupled to the fixation portion via an intervening member such as a tether, suture, wire, etc. In some embodiments, the fixation portion can be deposited (e.g., using 3-D printing or other suitable technique) onto or around the depot to form the depot assembly. For example, a PLA-based material can be 3-D printed over a depot to form desired structural features (e.g., hooks, barbs, etc.), thereby forming a fixation portion of a depot assembly.

In certain embodiments, such as those described in more detail below with references to FIGS. 95A-97C, the depot 100 can be inserted using a delivery tube in such a manner that separate fixation portions are not required. For example, a delivery tube in the form of a tunneling device may form an opening between a bone and the adjacent periosteum. Delivery of a depot through the tunneling device to the newly formed opening can provide a secure positioning of the depot at the desired treatment site without separate fixation portions.

In some embodiments, one or more depots may be positioned at a treatment site (e.g., within or adjacent to the knee) without fixation. The depots can be configured to have a softer material composition than bone and prosthetic materials used in total knee fixation procedures, and accordingly the depots may present little risk of damage to the knee or any implanted components. In some embodiments, the depot can retain its structural integrity even if it migrates into the joint following implantation, thereby beneficially avoiding a burst release of drug even when subjected to forces from articulating surfaces of the knee or other joint.

Several examples of depot assemblies having fixation portions are described below with respect to FIGS. 66A-85B. It will be recognized that the particular fixation mechanisms illustrated in FIGS. 66A-85B are merely exemplary of the many different fixation mechanisms that can be employed in accordance with the present technology. Although the depot is shown as having a generally rectangular shape in many of these examples, it will be understood by one of ordinary skill in the art that the depot can be any shape (e.g., pellet, oval, strip, rod, sheet, mesh, or the like). It will also be understood by one of ordinary skill in the art that the fixation portion of the depot assembly can include one or more tabs, ridges, hooks, protrusions, notches, channels, ports, grooves, slits, loops, hooks, barbs, posts, or other structural features instead of or in addition to the particular fixation portions illustrated in FIGS. 66A-85B.

FIG. 66A illustrates a depot assembly 700 including a depot 100 and two fixation portions 702a and 702b on opposing lateral sides of the depot 100. FIG. 66B illustrates a detailed view of a portion of one of the fixation portions 702b. With reference to FIGS. 66A-66B together, the fixation portions 702a-b each include an elongated tubular member 703 with protrusions or barbs 704 extending therefrom. The elongated tubular member 703 can define a lumen extending through the fixation portions 702a-b, or in other embodiments the elongated member can be substantially solid along its length. The elongated tubular member 703 may alternatively be a hollow member (e.g., balloon, pontoon, etc.) that is inflated with a gas or liquid or a viscoelastic material (e.g., similar in viscosity to synovial fluid) or a combination of materials such that the inflated member fills the anatomical space to engage the irregular outer surface features with the tissue to prevent migration. The balloon-like structure can be made of a bioresorbable material such that, as the material degrades, the viscoelastic material moves into and lubricates the joint. In some embodiments, the fluid filling the hollow member contains radiopaque contrast such that the depot assembly 700 may be visualized under fluoroscopy. In operation, the depot assembly 700 can be placed at a treatment site such that the barbs 704 engage soft tissue or other anatomical features proximate the treatment site to help anchor the depot assembly 700 in place at the treatment site. The elongated tubular member 703 may also have a hydrogel coating that swells in the presence of synovial fluid or other bodily fluid. In some embodiments, the hollow member can be made of a hydrogel material in whole or in part. When placed in the body, the hydrogel may cause the elongated tubular member 703 to swell such that the protrusions or other members further engage surrounding tissue to prevent migration of the depot 100.

Although the illustrated embodiment shows two elongated tubular members 703 disposed adjacent opposite lateral edges of the depot 100, in other embodiments there may be one, three, or four elongated tubular members 703 disposed around different lateral edges of the depot 100. The barbs 704 can extend from any combination of upper, side, and lower surfaces of the fixation portions 702a-b. In some embodiments, the elongated tubular members 703 can be made of a biodegradable and/or bioerodible polymer material, and the barbs 704 can be formed by notching or cutting the polymer material of the elongated tubular members 703. In some embodiments, the protrusions 704 of the elongated tubular members 703 can be hook-and-loop structures or other suitable features rather than the barbs 704.

In some embodiments, the fixation portions 702a-b can be formed integrally with the depot 100. In other embodiments, the fixation portions 702a-b can be formed separately and attached to the depot 100 as described in more detail with respect to FIGS. 67A-67B. In such embodiments, the fixation portions 702a-b can be formed by extruding a biodegradable polymer material over a rod to form the elongated tubular members, following by notching or cutting to make the barbs 704 or other structural features of the fixation portions 702a-b.

FIGS. 67A and 67B illustrate one method of manufacturing the depot assembly 700 illustrated in FIGS. 66A and 66B. In FIG. 67A, a depot 100 includes two tabs 705a-b that each extend laterally from one edge of the depot 100. The tabs 705a-b can be made of a biodegradable and/or bioerodible material, for example the same material used for the control region(s) of the depot 100. In some embodiments, the tabs 705a-b are substantially devoid or completely devoid of any drug or other therapeutic agent.

FIG. 67B illustrates an enlarged view of the second tab 705b shown in FIG. 67A. In this embodiment, the fixation portion 702b is structurally separate from the depot 100. As illustrated, the fixation portion 702b is disposed adjacent to the tab 705b and includes an elongate tubular member 703 (as described in FIGS. 66A and 66B) in addition to a pair of extensions 706 that receive a portion of the second tab 705b therebetween. Once the tab 705b is disposed between the extensions 706, the extensions 706 can be compressed together or otherwise manipulated to secure the tab 705b therein. In other embodiments, different attachment techniques can be used, for example, heat compression, suturing, adhering, bonding or otherwise attaching the tab 705b to the fixation portion 702b.

FIG. 68 illustrates another embodiment of a depot assembly 700 including a depot 100 and a plurality of fixation portions 702a-d. In this embodiment, the fixation portions 702a-d include elongated ridges or protrusions extending over a surface of the depot 100. In the illustrated embodiment, the ridges are disposed over an upper surface of the depot 100, however in other embodiments, the elongated ridges or other such features can be disposed on any one of the surfaces of the depot 100, and/or on any combination of the surfaces of the depot 100. In use, the ridges are configured to engage soft tissue or other anatomical features to help anchor the depot assembly 700 in place at the treatment site.

FIGS. 69 and 70 illustrate additional embodiments of a depot assembly 700 having a depot 100 and a fixation portion 702, in which the fixation portion 702 includes a region of the depot 100 having an increased thickness. In each of these embodiments, the increased width of the fixation portion 702 is configured to receive a fixation device 707 (e.g., a suture, yarn, etc.) through the thickness of the fixation portion 702. In some embodiments, the increased thickness can help secure the suture with respect to the depot 100 and/or reduce the risk of the depot 100 degrading or breaking apart prematurely. In operation, the fixation device 707 could pierce the fixation portion 702 (e.g., by insertion via a needle), or the fixation device 707 could be inserted through a pre-formed lumen or aperture configured to receive the fixation device 707 therethrough.

In the embodiment shown in FIG. 69, the fixation portion 702 includes additional structures or layers deposited or formed onto upper and lower surfaces of the depot 100. These can be, for example, additional thicknesses of a film, such as the polymer material used in the control regions(s) of the depot 100 or other suitable material. In the embodiment shown in FIG. 70, the control regions 300a and 300b of the depot assembly 700 can have a profile that increases in thickness towards the fixation portion 702, such that the fixation portion 702 has a greater thickness of the control region than the remainder of the depot 100. The thicker areas may also include a pre-formed opening 701 configured to receive a suture 707. The thicker areas may also include a grommet or other reinforcing structure to prevent tearing of the depot material. In the illustrated embodiment, the profile is a gradual taper, though in other embodiments the profile can assume a step profile, a non-uniform slope, or other shape that provides an increased width of the control regions 300a-b at the fixation portion 702.

As one example, to implant the depot assembly 700 shown in FIGS. 69 and 70, a clinician accesses the target tissue site and threads a suture using a needle into the depot assembly 700 through the fixation portion 702. The clinician then passes the suture and needle through tissue at the treatment site, followed by anchoring the depot assembly 700 at or near the treatment site, e.g., by tying a knot, so as to limit the movement of the depot assembly 700. The needle is then removed, and the suture is cut and knotted leaving the suture and the depot assembly 700 in the desired position. In various embodiments, the depot assembly 700 may be attached to the suture or other fixation device before or after the depot assembly 700 is affixed to the treatment site. By pre-attaching the needle and/or suture to the depot assembly 700, surgical steps are eliminated as the suture does not need to be threaded through the fixation portion 702. As a result, embodiments of the present technology may enable the surgery to be performed more quickly and easily compared to conventional device that do not contain the fixation portion 702 and or other features of the depot assembly 700.

FIGS. 71 and 72 illustrate a depot assembly 700 in which the fixation portion 702 takes the form of an adhesive material. The adhesive can be a hook-and-loop fastener type adhesive 710, or in other embodiments can be a liquid or gelatinous adhesive such as a biocompatible and/or bioerodible epoxy, silicone, a cyanoacrylate, methacrylate, a mussel byssus adhesive, a fibrin-based “muco-adhesive,” or other suitable adhesive material. In some embodiments, the adhesive can include a polymer mesh over which a bioabsorbable fastener material such as Covidien's ProGrip™ is disposed. The adhesive material can be attached to the depot assembly 700 via heat compression or other bonding technique. In some embodiments, the adhesive and/or any backing layer of the fixation portion 702 is porous to permit passage of drug from the depot 100 to the treatment site. In some embodiments, the adhesive is covered with an airtight material such as a layer of plastic which is removed prior to placement on the tissue.

In various embodiments, the adhesive can take other forms—for example the depot 100 may be ion-charged to provide adhesion. In one example, the depot 100 can be provided with a positive charge which can facilitate adhesion to the inner wall of the bladder, which is negatively charged. In another example, the adhesive may be a pressure-sensitive material (e.g., a cross-linked PVP (polyvinylpyrrolidone)) which obtains adhesive properties once pressure is applied to press the depot 100 onto a surface at the treatment site. In some embodiments, the depot 100 can be chemically functionalized to adhere the depot 100 to an implant. For example, by providing a thiol group, which has a strong adhesion to gold, at least a portion of the depot 100 can be secured to a gold-containing implant. In another example, rather than functionalizing a polymer of the depot, a chemical with a thiol group can be applied over the depot 100, for example via spray- or dip-coating.

As shown in FIG. 71, the fixation portion 702 in the form of an adhesive can be disposed over an upper surface of the depot 100. The fixation portion 702 can extend over some or all of the upper surface of the depot 100 in various embodiments. In other embodiments, the fixation portion 702 in the form of an adhesive can be disposed on any one of the surfaces of the depot 100, and on any combination of the surfaces of the depot 100. In use, the depot assembly 700 can be implanted at the treatment site such that the fixation portion 702 engages with and adheres to tissue or other anatomical features at the treatment site.

FIG. 72 illustrates another embodiment of a depot assembly 700 in which the fixation portion 702 in the form of an adhesive is disposed over a tab 705 that extends from one edge of the depot 100. The tab 705 can be made of a biodegradable and/or bioerodible material, for example the same material used for the control region(s) of the depot 100. In some embodiments, the tab 705 is substantially devoid or completely devoid of any drug or other therapeutic agent. Although the illustrated embodiment has a single tab 705 extending from one lateral edge of the depot 100, in other embodiments the tab 705 may extend from different surfaces and in different orientations with respect to the depot 100, and/or may be one of two or more tabs 705 that extend from any surface of the depot 100. In use, the depot assembly 700 can be implanted at the treatment site such that the tab fixation portion 702 over the tab 705 engages with and adheres to tissue or other anatomical features at the treatment site.

FIGS. 73A and 73B are top and side views, respectively, of a depot assembly 700 positioned at a treatment site 708. The depot assembly 700 includes a depot 100 and a fixation portion 702. In these and other embodiments, the fixation portion 702 takes the form of an adhesive extending around the lateral periphery of the depot 100 or treatment site 708. The adhesive can be similar to that described above with respect to FIGS. 71 and 72, for example a hook-and-loop fastener type adhesive, epoxy, silicone, fibrin-based “muco-adhesive,” or other suitable adhesive material. As shown in FIG. 73B, a thin cover 709 can extend over the adhesive fixation portion 702 and over the depot 100 along at least one surface of the depot assembly 700. In some embodiments, the cover 709 is porous to permit drug to be released from the depot assembly 700 to a treatment site 708 through the cover 709.

Although the embodiment illustrated in FIGS. 73A and 73B includes a fixation portion 702 that extends around an entire perimeter of the depot 100, in other embodiments the fixation portion 702 may extend around only a portion of the perimeter, for example being disposed only on opposing sides of the depot 100, or along only one side of the depot 100.

FIG. 74A shows a depot delivery system 710, and FIG. 74B is an enlarged, cross sectional view of a portion of the delivery system 710 with a multi-depot assembly 700 disposed therein. The delivery system 710 includes an elongate delivery shaft 714 and a pusher shaft 715 slidably received within a lumen of the delivery shaft 714. As shown in FIG. 74B, the pusher shaft 715 can receive a multi-depot assembly 700 therein. The assembly 700 includes a fixation portion 702 in the form of an anchor element having ridges, barbs, or teeth and configured to be implanted into tissue at a treatment site. The assembly 700 also includes a plurality of depots 100a-c coupled to the fixation element 702 via a series of lines 716a-c. In the illustrated embodiment, there are three depots 100a-c. However, in other embodiments, the number of depots 100 can vary, for example one, two, four, five, or more depots 100 can be coupled to the fixation portion 702. The lines 716a-c can be made of suture, yarn, a length of polymer, or any other suitable connective material. The first line 716a is coupled to an aperture at a proximal region of the fixation portion 702 at one end, with the other end coupled to the first depot 100a. A second line 716b connects the first depot 100a and the second depot 100b, and a third line 716c connects the second depot 100b and the third depot 100c. The lines 716a-c can have relative lengths configured to position the depots 100a-c along the treatment site with a desired spacing and configuration.

The assembly 700 is positioned partially within the pusher shaft 715 such that a distal end of the pusher shaft 715 abuts the fixation portion 702. For example, the fixation portion 702 can be an anchor element with a substantially planar proximally facing surface with an outer cross-sectional profile that is greater than the lumen of the pusher shaft 715. As a result, advancement of the pusher shaft 715 causes the fixation portion 702, and therefore the entire assembly 700, to be advanced distally.

As shown in FIG. 74A, an actuator 712 of the delivery system 710 can be used to distally advance the pusher shaft 715 relative to the delivery shaft 714, thereby moving the fixation portion 702 out of the delivery shaft 714. In some embodiments, the actuator 712 can include a handle with a trigger mechanism, and the pusher shaft 715 can be spring-loaded such that actuating the actuator 712 (e.g., by pulling the trigger mechanism) causes the pusher shaft 715 to be forcefully advanced with respect to the delivery shaft 714. In use, the distal end of the delivery shaft 714 can be positioned adjacent to tissue at the treatment site. The actuator 712 can then be actuated, causing the pusher shaft 715 to be forcefully advanced, thereby urging the fixation portion 702 out of the distal end of the delivery shaft 714 and into the tissue at the treatment site. The size, shape, and configuration of the fixation portion 702 can be such that it pierces tissue at the treatment site and remains lodged therein. Once the fixation portion 702 is securely positioned at the treatment site, the delivery device 710 can be removed, leaving the multi-depot assembly 700 in place at the treatment site.

FIGS. 75-77B illustrate examples of multi-depot assemblies 700 positioned at a treatment site in accordance with some embodiments of the present technology. As shown in FIG. 75, the multi-depot assembly 700 includes a fixation portion 702 in the form of an anchor element having ridges, barbs, or teeth and configured to be implanted into tissue at the treatment site 708. The assembly 700 includes a plurality of depots 100a-c, for example three in the illustrated embodiment. As described above with respect to FIG. 74B, a series of lines 716a-c connect the depots 100a-c to one another and to the fixation portion 702 in series. The lines 716a-c can have relative lengths configured to position the depots 100a-c along the treatment site 708 with a desired spacing and configuration when the fixation portion 702 is anchored into the tissue at the treatment site 708.

The multi-depot assembly 700 shown in FIG. 76 is similar to that described above with respect to FIG. 75, except that the three lines 716a-c each extend between the fixation portion 702 and a respective one of the depots 100a-c. In this instance, each depot 100a-c is separately coupled to the fixation portion 702 via one of the lines 716a-c, allowing for more relative movement of the depots 100a-c with respect to one another and with respect to the treatment site 708.

The multi-depot assembly 700 shown in FIG. 77A is similar to that described above with respect to FIG. 75, except that the assembly 700 includes three separate fixation portions 702a-c in the form of anchor elements, and each fixation portion 702a is coupled to a respective depot 100a-c via one of the lines 716a-c. In FIG. 77B, the assembly 700 includes three separation fixation portions 702a-c, but with each of the depots 100a-c coupled together via a series of tethers 716a-716c in sequence. Any of the assemblies 700 illustrated in FIGS. 75-77B can be delivered to the treatment site 708 using the delivery system of FIGS. 74A and 74B.

FIG. 78 illustrates another embodiment of a depot assembly 700 including a depot 100 and fixation portion 702. In this and other embodiments, the fixation portion 702 includes a plurality of protrusions 704 that extend away from a tab 705 disposed around a periphery of the depot 100. The tab 705 can extend laterally away from the edge of the depot 100 around its perimeter, and can be made of a biodegradable and/or bioerodible material, for example the same material used for the control region(s) of the depot 100. In some embodiments, the tab 705 is substantially devoid or completely devoid of any drug or other therapeutic agent. In some embodiments, the tab 705 may not extend around the entire periphery, but rather along only a portion of the depot 100.

The protrusions 704 can take the form of spikes, posts, columns, barbs, hooks, or other such features that project away from a surface of the tab 705. In the illustrated embodiment, the protrusions 704 project away from an upper surface of the depot assembly 700, however in other embodiments, the protrusions 704 can be disposed on any one of the surfaces of the depot assembly 700, and/or on any combination of the surfaces of the depot assembly 700. In use, the protrusions 704 are configured to engage soft tissue or other anatomical features to help anchor the depot assembly 700 in place at the treatment site.

FIG. 79A illustrates another example of depot assemblies 700 each including a depot 100 and a fixation portion 702, and FIG. 79B shows an enlarged side view of the fixation portion 702b of the depot assembly 700 shown in FIG. 79A. The depot assemblies 700 each include two fixation portions 702a-b extending along opposing sides of the depot 100. The fixation portions 702a-b can be made of a polymeric biodegradable and/or bioerodible material, for example the same material used for the control region(s) of the depot 100, and can in some embodiments be devoid of any therapeutic agent. The fixation portions 702a-b each include a plurality of barbs 704 projecting away from the surface of the depot assembly 700 in the fixation portions 702a-b. As best seen in FIG. 79B, the fixation portion 702b includes a plurality of barbs 704 projecting away from opposing surfaces of the fixation portion 702b. These barbs 704 can be formed by cutting or notching the material of the fixation portions 702a-b such that the material preferentially curves to form hook or barb-like protrusions 704.

FIG. 80 illustrates a variety of example depot assemblies 700 having depots 100 coupled to fixation portions 702. The fixation portions 702 can take the form of one or more wings projecting away from the depot 100. As illustrated, the depots 100 and fixation portions 702 assume a variety of shapes and configurations. For example, the depots 100 can be relatively planar, curved into semi-cylindrical shapes, bent, ridged, or having any other suitable shape. The fixation portions 702 can likewise assume a variety of forms as illustrated, for example curved or planar wings extending away from the depot 100, ridges or spines disposed along a surface of the depot 100, or other suitable structure configured to engage tissue at the treatment site.

FIGS. 81A-D illustrate top, side, end, and perspective views, respectively, of a depot assembly 700 in which a depot 100 has fixation portions 702a-d in the form of recesses or notches in the depot 100, e.g., to facilitate fixation at a treatment site. In the illustrated embodiment, the depot 100 is substantially planar with an upper surface, a lower surface, and a thinnest side surface extending therebetween. The recesses 702a-d are formed in the side surface. In the embodiment illustrated in FIGS. 81A-D, there are four recesses 702a-d, with recesses 702a and 702c disposed on opposing sides of the depot 100 and aligned along a first axis a1, and recesses 702b and 702d are disposed on opposing sides of the depot 100 and aligned along a second axis a2. The second axis a2 can be substantially perpendicular to the first axis a1, though in other embodiments the axes need not be perpendicular by may intersect at other angles. Additionally, in various embodiments the number of recesses can vary, for example one, two, three, five, six, seven, eight or more recesses. The recesses 702a-d provide a convenient path for a fixation device (e.g., suture, thread) to be passed through while reducing the risk of slipping. In some embodiments, the depot 100 can have rounded corners to prevent trauma to surrounding tissue during placement of the depot assembly 700 at the treatment site.

In one example method of securing the depot assembly 700 of FIGS. 81A-81D, a suture or other suitable fixation device can be anchored into tissue at or adjacent to the treatment site. The depot assembly 700 can then be positioned such that the suture passes through the second recess 702b, after which the suture can be wrapped around the depot 100 along axis a2 and extend through the fourth recess 702d. In this state, the depot assembly 700 can be advanced into position along the suture line, for example into contact or nearly into contact with tissue at the treatment site (e.g., within the suprapatellar pouch). This suture advancement technique can allow the depot 100 to be placed in more difficult to reach positions. The suture or other fixation device can then be secured to the tissue at the opposite side (e.g., near the fourth recess 702d). Using the same suture or another suture, the same process can be repeated in the orthogonal direction (e.g., with a suture extending along the first axis a1 and passing through the first recess 702a and the third recess 702c).

In another example method, a suture or other fixation device coupled to a needle can first be wrapped around the depot 100 (e.g., along axis a2, extending through notches 702b and 702d) one or more times before being positioned at the treatment site. This pre-loaded depot-and-suture assembly can then be positioned at the treatment site, and the needle inserted to throw the suture at a desired location. The needle can then be pulled back, thereby shuttling the pre-wrapped depot 100 toward contact or nearly into contact with tissue at the treatment site (e.g., within the suprapatellar pouch). The suture can then be tied off to secure the depot at the treatment site. This shuttling technique can advantageously facilitate placement of the depot into difficult to reach positions such as the lateral or medial gutters or proximal suprapatellar pouch.

Although the illustrated recesses are shown with a semi-circular cross-section, in various embodiments the cross-sectional shape of the recesses can vary, for example having angular grooves, elliptical recesses, a plurality of ridges, or any other shape that allows a suture or other fixation device to be received therein. In various embodiments, the suture or other fixation device may be slidably or non-slidably received within the recesses. In the illustrated embodiment, the recesses 702a-d are disposed centrally along each side, however in other embodiments the recesses can be disposed off-center along one or more sides of the depot assembly 700.

In one example, the depot assembly 700 can have a length of between about 20 mm and about 30 mm, (for example, approximately 26 mm), a height of between about 10 mm and about 20 mm (for example, approximately 16 mm), and a thickness of between about 0.5 mm and about 5 mm (for example, approximately 1 mm). The recesses can have a radius of between about 0.5 and about 3 mm (for example, approximately 1.5 mm) and the corners of the depot assembly 100 can have a radius of curvature of between about 1 mm and about 5 mm (for example, approximately 3 mm). In various embodiments, each particular dimension of the depot assembly 700 can be larger or smaller than these example dimensions as desired to facilitate delivery of the depot assembly 700 to the treatment site and secure attachment thereto.

FIGS. 82A and 82B illustrate top and side views, respectively, of a depot assembly 700 in which the fixation portion 702 comprises a receptacle configured to carry a plurality of depots 100a-c therein. In some embodiments, the receptacle 702 is a flexible, porous bag (e.g., mesh) that allows for the flow of fluids therethrough, while retaining the depots 100a-c therein. The receptacle 702 can be separated into discrete compartments, for example by suturing the receptacle 702 along division lines 717 to separate the receptacle 702 into three compartments, each compartment housing one of the depots 100a-c. This arrangement can eliminate the risk that the individual depots 100a-c may stack up or overlie one another, which may deleteriously affect the desired release profile of therapeutic agent to the treatment site. In some embodiments, the receptacle 702 can contain a number of individual depots 100 without being subdivided into separate compartments. In some embodiments, the receptacle 702 can be secured to tissue at a treatment site, for example by suturing through the receptacle at one or more positions around its periphery. This may advantageously allow a clinician to deliver a plurality of depots 100 to a treatment site while only requiring suturing or other attachment of a single component (i.e., the receptacle 702). Flexibility of the receptacle 702 can permit bending along its length, particularly in regions between the adjacent depots 100a-c, thereby allowing conformity with a wide range of anatomy. In some embodiments, a compartment of the receptacle 702 may bend relative to an adjacent compartment at an angle of or greater than 10°, 20°, 30°, 40°, 45°, 50°, 60°, 70°, 80° or 90°.

FIGS. 83-88 illustrate a variety of configurations in which a system 750 includes a plurality of depot assemblies 700 coupled together for delivery to a treatment site. Although the illustrated embodiments include substantially similar depot assemblies 700 coupled together, in other embodiments the system 750 can include a plurality of different configurations of depot assemblies 700. For example, a system 750 might include a plurality of different depots having different dimensions, shapes, number of recesses, fixation structures, and orientations. Additionally or alternatively, the composition of individual depot assemblies can vary. For example, a first depot assembly 700a can be provided with a first release profile and the second depot assembly 700b can be provided with a second, different release profile, such that the system 750 achieves a combined release profile that is different from either that of the first or second depot assemblies 700a and 700b. Additionally, the total number of depot assemblies 700 can be selected to achieve the desired release profile and total amount of therapeutic agent to be delivered. In various embodiments, the system 750 can include one, two, three, four, five, six, seven, eight, nine, ten, or more depot assemblies 700 coupled together for delivery to a treatment site. In some embodiments, one or more fixation devices (e.g., suture, yarn, thread, etc.) can be used to join one or more depot assemblies 700 together to form the system 750. Such fixation devices can also be used to secure the system 750 to anatomical structures at a treatment site, for example suturing the system 750 to soft tissue within the intracapsular space of the knee joint.

FIG. 83 illustrates a system 750 that includes three depot assemblies 700a-c. In some embodiments, each of the depot assemblies 700a-c can be substantially similar to the depot assembly described above with respect to FIGS. 81A-81D, in which each assembly 700 includes a depot 100 and a plurality of notches 702 are formed around the perimeter of each depot assembly 700. As shown in FIG. 83, a fixation device 707 (e.g., a suture, yarn, thread, tether, wire, etc.) can be used to couple the depot assemblies 700a-c together. In some embodiments, the fixation device 707 can be wrapped around each depot assembly 700 around a respective axis of the assembly 700. For example, the fixation device 707 can be wrapped around the short axis of the first depot assembly 700a by passing the fixation device 707 through the first and second recesses or notches 702a and 702b. After being wrapped around the first depot assembly 700a, the fixation device 707 can be wrapped around the second depot assembly 700b in a similar fashion (e.g., by passing through and being received in recesses or notches 702c and 702d), and similarly the fixation device 707 can be wrapped around the third depot assembly 700c in the same manner.

In the illustrated embodiment, the depot assemblies 700a-c are arranged side-by-side with the fixation device 707 spanning across them, such that the depot assemblies 700a-c can lie in substantially the same plane. In other configurations, one or more depot assemblies 700 can be stacked on top of each other, with the fixation device 707 wrapping around individual depot assemblies 700 and securing them together. In some instances, it can be useful to stack the depot assemblies so as to reduce the total footprint of the system 750 for delivery to the treatment site. In other instances, it can be useful to deliver the depot assemblies 700 in a side-by-side manner, either to reduce the total height, to increase the exposed surface area of the depot assemblies, or to allow for more articulation of each assembly 700 relative to the other assemblies 700. In some embodiments, these approaches can be combined, such that one or more depot assemblies 700 are stacked on top of one another and one or more additional assemblies 700 are arranged in a side-by-side manner. In some embodiments, the length of the fixation device 707 spanning between adjacent depot assemblies 700 can be selected to provide the desired freedom of movement of each depot assembly 700. For example, the fixation device 707 may leave little or no room between adjacent depot assemblies 700 or may leave a substantial length between adjacent depot assemblies 700, thereby permitting one depot assembly 700 to move (e.g., translate and/or rotate) relative to the other depot assemblies 700.

FIG. 84 illustrates a system 750 including three depot assemblies 700a-c coupled together via first and second fixation devices 707a-b. The fixation devices 707a-b can be an elongated flexible member such as a suture, yarn, thread, tether, wire, etc. In the illustrated embodiment, each fixation device 700 includes a depot 100 and two fixation portions 702 in the form of longitudinally extending lumens 702a and 702b configured to receive the fixation devices 707 therethrough. The lumens 702a-b can be formed across the length of each depot assembly 707a-c such that each fixation device 707a-b can extend through successive lumens 702 of each of the depot assemblies 700a-c. In this embodiment, the use of two fixation devices extending substantially in parallel may reduce the relative rotatability of each depot assembly 700 with respect to the others, while still allowing each depot assembly 700 to articulate, for example to fold over one another and assume a stacked configuration.

FIG. 85 illustrates another embodiment of a system 750 including three depot assemblies 700a-c coupled together via fixation devices 707a-d. Here, each depot assembly 700 includes a depot 100 and a plurality of fixation portions 702 in the form of grommets or apertures configured to receive a fixation device 707 therethrough. Adjacent depot assemblies 700 can be secured together by extending a fixation device 707 through the grommet or apertures of each depot assembly 700 in the form of a loop. For example, the fixation device 707b extends through the aperture 702b in the first depot assembly 700a and also extends through the aperture 702c in the second depot assembly 700b and forms a closed loop. With this configuration, any number of depot assemblies 700 can be strung together via a series of fixation devices 707 extending between adjacent assemblies 700. To position the system 750 in the body, one or more of the fixation devices 707 can be secured to anatomical structures at the treatment site, either directly or indirectly through another fixation device.

FIG. 86 illustrates a system 750 in which a plurality of depot assemblies 700a-c are coupled together via interlocking pieces. As illustrated, each depot assembly 700 includes a depot 100, a protrusion 704, and an opening 702 such that the protrusion 704 of one depot assembly 700 can be removably received within the opening 702 of another depot assembly 700. For example, the protrusion 704a of the first depot assembly 700a is interlocked with the opening 702b of the second depot assembly 700b. In various embodiments, some or all of the depot assemblies 700 can have one or more recesses and/or projections around the perimeter, such that at least one recess of one depot assembly can interlock or otherwise engage with one or more protrusion of another depot assembly. Such interlocking can facilitate delivery of multiple depot assemblies 700 to a surgical site together, for example allowing multiple depot assemblies 700 to be fitted together and sutured into place with a single fixation device 707 (e.g., a suture). Although the illustrated system 750 includes a series of depot assemblies 700 arranged in a side-by-side manner, the interlocking aspect can be applied to other arrangements, for example creating a grid of depot assemblies 700 that interlock with one another along two more sides. Such a system 750 can provide for multiple different shapes to be formed using the same component assemblies 700 by interlocking them together in different arrangements.

FIG. 87 illustrates a system 750 in which each of the depot assemblies 700a-c includes a depot 100 and a corresponding fixation portion 702a-c in the form of an elongated tubular member having a lumen extending therethrough. These fixation portions 702 can be similar to those of FIGS. 66A and 66B described above, except that each depot assembly 700 includes only a single tubular member disposed on one side of the depot assembly 700. As shown in FIG. 87, a fixation device 707 (e.g., a suture) extends through the tubular members 702 of each depot assembly 700. As a result, in some embodiments each depot assembly 700 can pivot or rotate around the longitudinal axis of the fixation device 707. In other embodiments, one or more of the depot assemblies 700 can also include additional fixation portions 702 in the form of elongated tubular members or any other suitable fixation portion.

FIG. 88 illustrates a system 750 in which a plurality of depot assemblies 700a-n take the form of depots 100 formed as cylindrical bodies having central apertures 702 formed therethrough, and the fixation device 707 (e.g., a suture, thread, wire, etc.) is threaded through each of the central apertures 702 such that the depot assemblies 700 are arranged similar to beads on a thread. Although the illustrated depot assemblies 700 are formed as cylinders, in various embodiments the depot assemblies 700 can take other shapes having apertures therethrough, for example having elliptical, square, rectangular, regular polygona, or irregular polygonal cross sections. In various embodiments, the depot assemblies 700 can be slidable or non-slidable and rotatable or non-rotatable with respect to the fixation device 707.

FIG. 89 illustrates a side view of a depot assembly 700 in which a depot 100 includes a fixation portion 702 in the form of a living hinge (e.g., a hinge formed of the same material as the depot 100). The hinge can be formed via grooves or narrowed regions along the depot. Although the illustrated embodiment illustrates a single hinge, in various embodiments there may be a number of hinges, which can be formed along parallel axes, perpendicular axes, or otherwise. In some embodiments, the hinge is configured to provide preferential bending of the depot 100 to better conform to the anatomy at the treatment site. In some embodiments, the depot 100 can be configured to enable additional bending of the depot 100, and/or to break apart one or more hinges or weakened portions, e.g., to facilitate subdividing the depot 100 as desired.

FIGS. 90A and 90B illustrate example depot assemblies 700 with protrusions 704 projecting away from a central region of the depot 100. In some embodiments, the protrusions 704 can be made of a biodegradable and/or bioerodible material, for example the same material used for the control region(s) of the depot 100. In some embodiments, the protrusions 704 are substantially devoid or completely devoid of any drug or other therapeutic agent. Although the illustrated embodiments have protrusions 704 in the form of frusta (as in FIG. 90A) or cones (as in FIG. 90B), in various embodiments the protrusions 704 can take the form of spikes, posts, columns, barbs, hooks, or other such features that project away from a surface of the depot 100. Although the illustrated embodiments have protrusions 704 projecting away from a central region of the depot 100, in various embodiments the protrusions 704 may project away from a non-central region (e.g., a peripheral region) of the depot 100. In the illustrated embodiment, the protrusions 704 project away from upper and lower surfaces of the depot assembly 700 in opposite directions, however in other embodiments, the protrusions 704 can be disposed on one of the surfaces of the depot assembly 700, and on any combination of the surfaces of the depot assembly 700. In use, the protrusions 704 are configured to engage soft tissue or other anatomical features to help anchor the depot assembly 700 in place at the treatment site.

FIG. 91A illustrates a depot assembly 700 including two fixation portions 702 in the form of elongated tubular members having lumens extending therethrough, similar to FIGS. 66A and 66B described above. Sutures 707 (or other suitable fixation devices) extend through lumens of the fixation portions 702 for a pre-loaded device that can be secured to tissue at a treatment site 708, e.g., as shown in FIG. 91B using a suture driver. In some embodiments, a single suture insertion device can carry both sutures 707 and be configured to pass both sutures 707 through the lumens of the respective tubular members 702 and insert the sutures 707 into soft tissue at or adjacent to the treatment site 708. Such a suture insertion device can be provided pre-loaded with the depot assembly 700 to provide for a no-touch solution in which the depot assembly 700 can be affixed to tissue at the treatment site via the suture insertion device without requiring that the clinician directly touch the depot assembly 700. In some embodiments, the fixation portions 702 can include barbs, hooks, or other suitable anchors thereon that can provide additional fixation of the assembly 700 to the tissue at the treatment site 708.

FIGS. 92A-92D illustrate various views of a coiled depot assembly 700. As seen in the top view in FIG. 92A, the depot assembly 700 can include a depot 100 coiled into a spiral configuration. In some embodiments, the spiral can be compressed (e.g., more tightly wound) for a delivery configuration and may at least partially expand (e.g., at least partially unwind) upon delivery. FIG. 92B illustrates a side view of the depot assembly 700 in a constrained delivery configuration in which the depot assembly 700 is spirally wound within a plane. As shown in FIG. 92C, once the depot assembly 700 is unconstrained, the spiral can at least partially unwind (e.g., expanding in the radial direction) and the depot assembly 700 can also extend along an axial direction substantially perpendicular to the radial direction. For example, the depot assembly 700 can be biased such that, in an unconstrained state, a central portion of the spiral extends upward and away from an outer portion of the spiral. This can facilitate anchoring the depot assembly 700 in place at a treatment site, as the spiral unwinds and expands radially and/or axially, thereby increasing the contact area against adjacent tissue. FIG. 92D illustrates an example delivery system 710 for the depot assembly 700, in which the constrained depot assembly 700 is slidably advanced out of a delivery tube 720 via a pusher shaft 715. In some embodiments, the lumen of the delivery tube 720 can be shaped and configured to maintain the depot assembly 700 in a constrained configuration while it is advanced through the tube 720 via the pusher shaft 715. Once the pusher shaft 715 urges the depot assembly 700 distally beyond the distal end of the delivery tube 720, the depot assembly 700 may assume the expanded configuration as shown in FIG. 92C.

FIG. 93A illustrates a side cross-sectional view of a depot assembly 700 comprising a depot 100 and a fixation portion 702 comprising a plurality of protrusions 704 (e.g., barbs, bumps, spikes, etc.) extending outwardly from the depot 100. In some embodiments, the protrusions 704 can be made of a biodegradable and/or bioerodible material, for example any of the polymers used for the control and/or therapeutic region(s) of the depots 100 disclosed herein. In some embodiments, the protrusions 704 are substantially or completely devoid of any drug or other therapeutic agent. In some embodiments, the protrusions 704 are substantially or completely devoid of any releasing agent. In some embodiments, the protrusions 704 are substantially or completely devoid of releasing agent and therapeutic agent.

In some embodiments, the depot 100 may have a generally cylindrical shape and the protrusions 704 can take the form of circumferential ridges extending around the depot 100. In the illustrated embodiment, the depot 100 has a substantially circular cross-section and the fixation portion 702 comprises a plurality of annular protrusions 704 spaced apart along a longitudinal axis of the depot 100. In some embodiments, the depot 100 and/or depot assembly 700 can have a rectangular or other polygonal cross-sectional shape. In any case, the protrusions 704 may be angled with respect to the long axis of the assembly 700. For example, as shown in FIG. 93A, the protrusions 704 can be angled proximally (e.g., away from the direction of insertion) to allow distal advancement of the depot assembly 700 through tissue without substantial resistance from the protrusions 704, while still engaging surrounding tissue and resisting proximal movement once the depot assembly 700 is in place.

The depot assembly 700 may include an interior void 724 that opens to a proximal side of the assembly 700. The void 724, for example, may be defined by the sidewalls of the fixation portion 702, the depot 100, or both. The void 724 may be configured to receive a distal portion of a delivery shaft 715, as shown in FIG. 93B. The interior void 724 can have a substantially columnar shape (e.g., substantially cylindrical, rectangular, conical, etc.) configured to correspond to the outer surface of the distal portion of the delivery shaft 715. To deliver the depot assembly 700, the depot assembly 700 is fitted over the delivery shaft 715 such that a distal portion of the delivery shaft 715 is received within the void 724. The delivery shaft 715 and the mounted depot assembly 700 can then be slidably inserted into a treatment site. Once the depot assembly 700 has been advanced to the desired location, the delivery shaft 715 can be proximally retracted. The barbs 704 can engage the surrounding tissue and resist proximal movement such that the depot assembly 700 remains in position and is separated from the pusher shaft 715. FIG. 93C illustrates one example placement, in which two depot assemblies 700a and 700b are placed within a suprapatellar pouch region of the intracapsular space of a knee joint. In various embodiments, the depot assemblies 700 can be inserted at other intra- or extra-capsular locations of the knee joint (e.g., lateral and/or medial gutters), at or adjacent another joint (e.g., the hip, ankle, shoulder, etc.) or at any other suitable location within the body.

The embodiment illustrated in FIGS. 94A and 94B can be similar to that shown in FIGS. 93A-93C, except that the interior void 724 is narrower than the proximal portion 715b of the pusher shaft 715. Accordingly, the pusher shaft 715 can be equipped with a narrower distal portion 715a configured to be slidably received within the central void 724. Because the proximal portion 715b is wider than the void 724, the proximal portion 715b of the pusher shaft 715 can push against the proximal end of the depot assembly 700. In some embodiments, this may reduce the force exerted on the depot 700 through the interior void 724, which may better maintain the structural integrity and improve pushability of the depot assembly 700. In operation, the depot assembly 700 shown in FIGS. 94A and 94B can be inserted at a treatment site in a manner similar to that described above with respect to FIG. 93C.

In some embodiments, the depot 100 can be delivered in a fashion that facilitates secure placement of the depot 100 without the use of additional fixation portions. For example, an elongated depot can be inserted into small spaces within tissue using a delivery tube such as a needle or delivery catheter. FIGS. 95A-97C illustrate different examples of such delivery techniques in which the depot 100 is less likely to become dislodged from the treatment site following implantation or insertion.

FIGS. 95A-95C illustrate a method for positioning a depot 100 at a treatment site 708 using a tunneling device 718 and a pusher shaft 719. The tunneling device 718 can have a tapered distal tip configured to pierce and/or penetrate tissue at the treatment site—including bone—to create a path through which the depot 100 can be delivered and/or a space into which the depot 100 may be deposited. In the illustrated example, the tunneling device 718 has been advanced between a bone and the adjacent periosteum, thereby creating and holding a space between the two. Once the tunneling device 718 is in position, the depot 100 can be advanced to a distal end of the lumen of the tunneling device 718, for example via a proximally positioned pusher shaft 719 (as shown in FIG. 95B). In some embodiments, the depot 100 may be pre-loaded in the distal region of the lumen of the tunneling device 718 before the tunneling device 718 is advanced to the treatment site 708. Referring to FIG. 95B, the tunneling device 718 may then be withdrawn proximally while the pusher shaft 719 remains in place such that withdrawal of the tunneling device 718 releases the depot 100 into the space created by the tunneling device 718. As shown in FIG. 95C, the tunneling device 718 and the pusher shaft 719 may be removed completely, leaving the depot 100 in place within the opening created by the tunneling device 718 at the treatment site 708.

While FIGS. 95A-95C show the tunneling device 718 creating a space between a bone and the periosteum, the tunneling device 718 can be advanced through or to other types of tissue and to any number of locations within the body in which it is advantageous to form a path through tissue and/or create an opening for placement of a depot 100 therein.

FIGS. 96A and 96B illustrate the steps of inserting a depot 100 through a delivery tube 720. In this and other embodiments, the depot 100 is an elongated, ribbon-like structure that can be helically wound around a pusher shaft 719 that is advanceable through the delivery tube 720. As shown in FIG. 96A, the pusher shaft 719 can include a proximal flange configured to abut a proximal end of the depot 100 and prohibit the depot 100 from moving proximally along the pusher shaft 719 during distal advancement through the delivery tube 720. Once the delivery tube 720, pusher shaft 719, and helically wound depot 100 are together advanced to the treatment site, then, as shown in FIG. 96B, the delivery tube 720 is retracted proximally while the pusher shaft 718 remains in place with the depot 100 mounted therein. If the depot 100 has been coiled around the pusher shaft 718 under tension, then the depot 100 may unravel and expand once the constraining influence of the delivery tube 720 has been removed. Following this unraveling or other decoupling of the depot 100 from the pusher shaft 719, the pusher shaft 719 may be retracted proximally, releasing the depot 100 at the treatment site.

FIGS. 97A-97C illustrate the steps of inserting a depot 100 through a delivery tube 720 using a pusher shaft 719. In some embodiments, the delivery tube 720 can be a needle or a cannula having a lumen therethrough. The depot 100 includes a shoulder region 722 that has a greater cross-sectional dimension than other portions of the depot 100. For example, the shoulder region 722 can define a radially extending flange. In the illustrated embodiment, the shoulder region 722 is disposed at a distalmost end of the depot 100, however in other embodiments the shoulder region 722 can be positioned at other locations along the depot 100. The pusher shaft 719 can have a lumen configured to receive a portion of the depot 100 therein such that the distal end of the pusher shaft 719 abuts against the proximal face of the shoulder region 722. With this engagement, the pusher shaft 719 can distally advance the depot 100 through the lumen of the delivery tube 720 without applying excessive compressive force along the length of the depot 100, as may be encountered with a pusher shaft that exerts a distal force on a proximalmost end of the depot 100. As shown in FIGS. 97B and 97C, as the delivery tube 720 is retracted proximally (and/or as the pusher shaft 719 is advanced distally), the depot 100 is moved distally out of the lumen of the delivery tube 720 and can be released at the treatment site.

VI. CONCLUSION

Although many of the embodiments are described above with respect to systems, devices, and methods for treating postoperative pain, the technology is applicable to other applications and/or other approaches. For example, the depots of the present technology may be used to treat postoperative pain associated with a veterinary procedure and/or surgery. Moreover, other embodiments in addition to those described herein are within the scope of the technology. Additionally, several other embodiments of the technology can have different configurations, components, or procedures than those described herein. A person of ordinary skill in the art, therefore, will accordingly understand that the technology can have other embodiments with additional elements, or the technology can have other embodiments without several of the features shown and described above with reference to FIGS. 2-88C.

The above detailed descriptions of embodiments of the technology are not intended to be exhaustive or to limit the technology to the precise form disclosed above. Where the context permits, singular or plural terms may also include the plural or singular term, respectively. Although specific embodiments of, and examples for, the technology are described above for illustrative purposes, various equivalent modifications are possible within the scope of the technology, as those skilled in the relevant art will recognize. For example, while steps are presented in a given order, alternative embodiments may perform steps in a different order. The various embodiments described herein may also be combined to provide further embodiments.

Moreover, unless the word “or” is expressly limited to mean only a single item exclusive from the other items in reference to a list of two or more items, then the use of “or” in such a list is to be interpreted as including (a) any single item in the list, (b) all of the items in the list, or (c) any combination of the items in the list. Additionally, the term “comprising” is used throughout to mean including at least the recited feature(s) such that any greater number of the same feature and/or additional types of other features are not precluded. It will also be appreciated that specific embodiments have been described herein for purposes of illustration, but that various modifications may be made without deviating from the technology. Further, while advantages associated with certain embodiments of the technology have been described in the context of those embodiments, other embodiments may also exhibit such advantages, and not all embodiments need necessarily exhibit such advantages to fall within the scope of the technology. Accordingly, the disclosure and associated technology can encompass other embodiments not expressly shown or described herein.

Unless otherwise indicated, all numbers expressing quantities of ingredients, percentages or proportions of materials, reaction conditions, and other numerical values used in the specification and claims, are to be understood as being modified in all instances by the term “about.” Accordingly, unless indicated to the contrary, the numerical parameters set forth in the following specification and attached claims are approximations that may vary depending upon the desired properties sought to be obtained by the present technology. At the very least, and not as an attempt to limit the application of the doctrine of equivalents to the scope of the claims, each numerical parameter should at least be construed in light of the number of reported significant digits and by applying ordinary rounding techniques. Additionally, all ranges disclosed herein are to be understood to encompass any and all subranges subsumed therein. For example, a range of “1 to 10” includes any and all subranges between (and including) the minimum value of 1 and the maximum value of 10, i.e., any and all subranges having a minimum value of equal to or greater than 1 and a maximum value of equal to or less than 10, e.g., 5.5 to 10.

It is noted that, as used in this specification and the appended claims, the singular forms “a,” “an,” and “the,” include plural referents unless expressly and unequivocally limited to one referent. For example, reference to “a therapeutic agent” includes one, two, three or more therapeutic agents.

The headings above are not meant to limit the disclosure in any way. Embodiments under any one heading may be used in conjunction with embodiments under any other heading.

Number	Date	Country
62723478	Aug 2018	US
62742357	Oct 2018	US
62832390	Apr 2019	US

DEVICES, SYSTEMS, AND METHODS FOR DELIVERING, POSITIONING, AND SECURING POLYMER DEPOTS IN SITU

Information

Publication Number

Date Filed

Date Published

Inventors

Original Assignees

CPC

International Classifications

Abstract

Description

Claims

CROSS-REFERENCE TO RELATED APPLICATIONS

PCT Information

Provisional Applications (3)