Claims
- 1. An improvement in a method for delivering a beneficial agent to an animal, wherein the method comprises:
- (a) admitting into the animal a dispenser comprising:
- (1) a wall that surrounds an internal lumen, which wall comprises a pair of ends with one end inside the other end, said wall comprising a section that limits the passage of fluid through the wall and a section that permits the passage of fluid through the wall;
- (2) 5 ng to 20 g a beneficial agent in the lumen, said beneficial agent comprising a member selected from the group consisting of drug, protein, peptide and hormone;
- (3) an expandable hydrogel in the lumen comprising the section that permits the passage of fluid through the wall;
- (4) a fluid impermeable partition between the beneficial agent and the hydrogel;
- (5) at least one exit passageway in the wall for delivering the beneficial agent from the dispenser; and,
- (b) delivering the beneficial agent from the dispenser by the hydrogel increasing the volume and occupying space in the lumen, thereby pushing the beneficial agent through the passageway to the animal, and wherein the improvement comprises:
- (c) maximizing the delivery of the beneficial agent by protecting the beneficial agent from the fluid of the animal and by maintaining the beneficial agent in the section of the wall that limits the passage of fluid through the wall for delivering the beneficial agent in an effective dose to the animal over a prolonged period of time.
CROSS-REFERENCE TO RELATED APPLICATIONS
This application is a division of U.S. Ser. No. 07/283,359 filed on Dec. 13, 1988, now U.S. Pat. No. 5,034,229 issued Jul. 23, 1991, which application is incorporated herein by reference, and benefit is claimed of its filing date. These applications are assigned to the ALZA Corporation of Palo Alto, Calif.
This invention pertains to both a novel and to an unobvious delivery system. More particularly, the invention relates to a delivery system comprising (1) housing means, (2) a compartment, and (3) exit means. The housing means comprises (a) a section that substantially restricts the ingress of fluid into the delivery system, and (b) a section that permits the ingress of fluid into the delivery system. The compartment comprises (c) a bioavailable and biocompatible beneficial agent formulation and (d) means for delivering the agent formulation from the delivery system. The exit means comprises (e) at least one passageway in the housing means for connecting the exterior with the interior of the delivery system for delivering the agent formulation from the delivery system.
Delivery systems for administering a beneficial agent to a biological, fluid environment of use are known to the prior art. For example, U.S. Pat. No. 3,845,770 issued to Theeuwes and Higuchi, and in U.S. Pat. No. 3,916,899 issued to the same patentees, a device is disclosed comprising a wall that surrounds a compartment containing a beneficial agent. The wall is permeable to the passage of fluid and comprises a passageway that is preformed or formed during use through the wall for delivering the beneficial agent from the device. The devices of these patents release the beneficial agent by fluid being imbibed through the wall into the compartment at a rate determined by the permeability of the wall and the osmotic pressure gradient across the wall. The fluid imbibed into the device mixes with the beneficial agent to form an aqueous solution comprising the beneficial agent that is dispensed through the passageway from the device. The devices of these patents are extraordinarily effective for delivering a beneficial agent that is stable and soluble in aqueous and biological fluids and exhibits an osmotic pressure gradient across the wall against the fluid. The devices are effective also for delivering a beneficial agent that is mixed with an osmotically effective solute soluble in fluid that exhibits an osmotic pressure gradient across the wall against an aqueous fluid.
A further advancement in the delivery art for dispensing a stable formulation is disclosed in U.S. Pat. No. 3,995,632 issued to Nakano, Higuchi and Hussain. The dispenser disclosed in this patent dispenses a stable composition that absorbs heat and forms a dispensable melt. The melt is dispensed by a solution of magnesium sulfate increasing in volume and occupying the space originally occupied by the melt.
A quantum improvement in osmotic devices was presented to the pharmaceutical dispensing art by inventor Theeuwes in U.S. Pat. Nos. 4,111,202; 4,111,203; and 4,203,439. In these patents the delivery kinetics of the devices were enhanced for delivering a beneficial agent with different degrees of solubility in an aqueous-type fluid. The kinetics were improved by manufacturing the devices with a beneficial agent compartment separated by a film from an osmotic compartment. The devices deliver the beneficial agent by fluid being imbibed through the wall into the osmotic compartment to fill the compartment with fluid that acts as a driving force and causes the film to move. The film moves against the beneficial agent compartment and the driving force pushes the beneficial agent through a passageway from the device.
A pioneer advancement in osmotic delivery devices was made by Cortese and Theeuwes in U.S. Pat. No. 4,327,725 and by Wong, Barclay, Deters and Theeuwes in U.S. Pat. No. 4,612,008. The devices disclosed in these patents comprise a semipermeable wall that surrounds a compartment. The compartment contains a beneficial agent formulation and a hydrogel. These devices operate by imbibing fluid into the compartment, wherein it contacts the biological agent formulation and forms a dispensable aqueous formulation, and wherein it contacts the hydrogel causing it to expand and push the dispensable aqueous formulation from the device.
The delivery devices described in the above patents operate successfully for their intended use and they can deliver many beneficial agents for their intended effects. Now, it has been observed their use can be limited because they lack the necessary elements to deliver beneficial agents that are sensitive to fluids, and to fluids containing biological gases. Their use may be limited because beneficial agents that are sensitive to such aqueous-biological fluids or to other fluids external to the delivery device may be adversely affected by fluids that enter the device and contact the beneficial agents during operation of the device. Examples of such fluid sensitive agents include proteins and peptides, and hormones. Moreover, the prior art devices lack the necessary means for their use fluid-rich environment of use.
It will be appreciated by those versed in the dispensing arts that if a delivery system is provided for administering at a controlled rate and for protecting a beneficial agent that is sensitive to aqueous and biological fluids, and which delivery system possesses the kinetic ability to deliver the protected beneficial agent in effective amounts over time, such a delivery system would have a positive value and represent an advancement in the dispensing arts. Likewise, it will be self-evident to those versed in the implant art that a pressing need exists for an implant that is essentially-free of the tribulation associated with the prior art, and, that if such an implantable delivery system is provided, it would have a practical application in the fields of human and veterinary medicine and in the breeding and management of farm animals.
Accordingly, it is an immediate object of this invention to provide a delivery system for delivering a beneficial agent that overcomes the limitations associated with the prior art.
Another object of the invention is to provide a delivery system for delivering in vivo a beneficial agent such as a drug that is difficult to deliver and now can be delivered by the delivery system in therapeutically effective amounts to both humans and livestock.
Another object of the invention is to provide a delivery system comprising means for protecting a beneficial agent from aqueous and biological fluids.
Another object of the invention is to provide a delivery device comprising means for protecting a fluid sensitive biological agent in the device from fluid, and means for administering the beneficial agent to an environment of use, wherein the environment of use may be a fluid, aqueous-biological environment.
Another object of the invention is to provide a delivery system comprising means for storing and for protecting a bioactive beneficial agent formulated in a biocompatible composition during its residency in the delivery system.
Another object of the invention is to provide an implant for livestock that can remain in the livestock until slaughter.
Another object of the invention is to provide a delivery system comprising means for high loading of a beneficial agent essentially-free from its inactivation while in the delivery system, and comprising means for delivering the beneficial agent at a controlled rate and continuously over time to a beneficial agent recipient.
Another object of the invention is to provide a delivery system manufactured as an osmotic therapeutic device comprising a beneficial agent, and which delivery system can administer a complete pharmaceutical dosage regimen at a controlled rate continuously for a particular time period, the use of which delivery system requires intervention only for initiation and the possible termination of the regimen.
Another object of the invention is to provide a delivery system for delivering a drug to an animal, including cattle and hogs, which term, "hogs," includes pigs and porcines, by using a delivery system manufactured as an osmotic device that possesses the ability to deliver the beneficial drug over a broad range of dosage delivery rates according to the predetermined time-release pattern to the biological recipient over time.
Another object of the invention is to provide an osmotic device comprising a compartment containing a drug shielded from a fluid environment of use, and an expandable driving member that operates to diminish the volume occupied by the drug, thereby displacing and thus delivering the drug from the device at a controlled rate over time.
Another object of the invention is to provide a delivery system for delivering a dosage unit amount of a drug to a warm-blooded animal, such as a ruminant or a swine, and which delivery system can be shaped, sized and adapted as an implant for implanting it in the muscle tissue of an animal, the subcutaneous space, the vaginal cavity, or in the peritoneal cavity.
Another object of the invention is to provide an implantable, pharmaceutical delivery system for delivering a beneficial agent to a human or to a veterinary host, with the implant releasing the beneficial agent at a rate controlled by the implant, and when the release of beneficial agent is terminated abruptly, the implantable system leaves a minimal agent residue in the implant and in the host.
Another object of the invention is to provide an implantable delivery system that is implantable by using simple injection techniques and does not require extensive surgery for its placement in a biological tissue.
Another object of the invention is to provide an implant that can be placed under the skin of an animal for releasing an effective amount of a beneficial agent for causing the animal to gain weight at a greater than normal rate, and which implant remains intact and is easily and completely removed for allowing a withdrawal period prior to slaughter.
Another object of the invention is to provide a drug delivery device that is implantable, is compact in size and shape to allow easy placement within the lumen of trocars and similar implanting or injecting instruments that are limited in dimensions and, consequently, are essentially-free of undue trauma and discomfort to a receiving animal.
Another object of the invention is to provide a delivery device shaped at its ends in a conical or spherical shape for reducing the force necessary to push the device into an implantation receiving site, thereby reducing the incidence of tissue damage and the incidence of damage to the delivery device, thereby enhancing the process of implantations.
Another object of the invention is to provide a delivery device comprising ends of a conical or spherical shape for producing a device better designed to withstand elevated interior pressures occurring within the device during hydrodynamic pumping, which shape is of value when the device is delivering high viscosity compositions that create higher pressures during pumping at given flow rates and exit sized passageways.
Another object of the invention is to provide a delivery system that can be placed under the skin of an animal for releasing an effective amount of a beneficial agent for causing increased productivity, which increases in productivity is a result of any combination of the following, higher feed conversion efficiency as exemplified by a greater ration of animal weight gain to amount of feed intake, improved carcass quality as exemplified by a higher ratio of muscle tissue to fat tissue, and a higher than normal rate of animal weight gain.
Another objective of the invention is to provide a delivery device that completely envelops the beneficial, fluid sensitive agent within the protective polymer housing shaped conically or otherwise tapered about a closed exit passageway that can be opened immediately prior to implantation either manually or automatically by snapping-off, or cutting-off the thin tapered closed end, thereby maximizing the period of protection offered by the sealed device and minimizing the opportunity for external environmental contamination of the beneficial agent housed within the device.
Other objects, features and advantages of the invention will be more apparent to those versed in the dispensing art from the following detailed specification taken in conjunction with the accompanying claims.
US Referenced Citations (31)
Divisions (1)
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Number |
Date |
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283359 |
Dec 1988 |
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Patent Grant
5110596
