Patent Application
20140114241
The present invention is in the field of medicinal products. Particularly, the present invention relates to the coating of surfaces of microscopic and macroscopic substrates with drugs for sustained drug release.
Drug delivery technologies are formulation technologies that modify drug release profile, absorption, distribution and elimination for the benefit of improving product efficacy and safety, as well as patient convenience and compliance. For many medical applications and pharmaceutically active agents, a controlled drug delivery and release is desired. While some applications require a rapid release of a drug at the desired target, other applications require a delayed or sustained drug release. This does not only apply for the administration of drug s for therapeutic, preventive or diagnostic purposes but also to certain implantable or insertable medical devices such as catheters or stents.
Numerous approaches exist for targeted delivery and/or sustained drug formulations. For example, sustained release formulations include liposomes, drug loaded biodegradable microspheres and drug polymer conjugates.
The present invention provides a method for coating surfaces of microscopic or macroscopic substrates with a drug for sustained release of the drug.
The present invention is in part based on the inventors' finding that layer-by-layer coatings of surfaces of microscopic or macroscopic substrates have particularly advantageous properties when layers of the pharmaceutically active ingredient (the “drug”) and polyelectrolyte layers are applied in an alternating manner, wherein under the conditions of coating the polyelectrolyte layers and the drug layers have opposite net charges and under release conditions, e.g. physiological conditions, the two layers have substantially the same net charge. Hence either the polyelectrolyte or the drug is an amphoteric substance that substantially changes its net charges under the conditions were the release of the drug is desired, e.g. at physiological conditions.
The invention relates in particular to a method for coating a surface of a substrate with a drug for sustained release:
The present invention also relates to a substrate comprising
In a first aspect the present relates to a method for coating a surface of a substrate with a drug for sustained release:
It is particularly preferred that the two layers of the bilayer have the same net charge under physiological conditions. Preferably, herein, the depositing of the at least one bilayer on the surface takes place at a pH<6 or a pH>8, preferably at a pH<5.4 or at a pH>9.
In one embodiment of the invention the pharmaceutically active ingredient is an amphoteric substance that has an isoelectric point IEP>9.4 or IEP<5.4. In another embodiment of the invention the polyelectrolyte is an amphoteric substance that has an isoelectric point IEP>9.4 or IEP<5.4.
The present invention can be applied to surfaces of microscopic substrates as well as to surfaces of macroscopic substrates. Microscopic substrates in the context of the present invention include solid particles, porous particles, particularly magnetic beads, nanoparticles and microparticles.
The particles of the present invention may be porous or non-porous. They may be of organic or inorganic material. Organic particles and beads may for instance be particles or beads of gelatin, chitosan, albumin, alginate, poly(lactic-co-glycolic acid) (PLGA), polyglycolic acid (PGA), or polylactic acid (PLA). Inorganic particles or beads may for example be particles of calcium carbonate (CaCO3), silica (SiO2), gold, silver, magnetite, maghemite.
Macroscopic substrates include for example implantable or insertable medical devices. Implantable or insertable medical devices benefiting from the present invention include any medical device for which controlled release of a therapeutic agent is desired. Examples of such medical devices include for instance, catheters (e.g., renal or vascular catheters such as balloon catheters), guide wires, balloons, filters (e.g., vena cava filters), stents (including coronary vascular stents, cerebral, urethral, ureteral, biliary, tracheal, gastrointestinal and esophageal stents), stent grafts, cerebral aneurysm filler coils (including Guglilmi detachable coils and metal coils), vascular grafts, myocardial plugs, patches, pacemakers and pacemaker leads, heart valves, orthopedic implants, temporary implants in the mouth (e.g., temporarily crown jackets which release a pain killer), artificial implanted lenses and biopsy devices. Hence, the drug-eluting implantable or insertable medical device of the invention may for example be an expandable device and/or comprises an inflatable portion. The device may also a be removable device. Preferred examples of implantable or insertable medical device according to the invention include stents, catheters, particularly balloon catheters, pacemakers, or artificial vessels (permanent or transient) or parts of such devices such as balloons in the case of balloon catheters. The medical devices of the present invention include medical devices that are used for either systemic treatment or for the localized treatment of any mammalian tissue or organ. Examples include tumors; organs including the heart, coronary and peripheral vascular system (referred to overall as “the vasculature”), lungs, trachea, esophagus, brain, liver, kidney, bladder, urethra and ureters, eye, intestines, stomach, pancreas, ovary, and prostate; skeletal muscle; smooth muscle; breast; dermal tissue; cartilage; and bone.
Surfaces of the implantable or insertable medical devices may for example be plastic, metal glass or ceramic surfaces. The surface can e.g. be polyamide-based. In the case of balloons, the surface for example is based on nylon-12, nylon-11 or nylon-6 or nylon-co-polymers, such as Pebax. Surfaces of balloons may also be made out of polyurethane or PET.
However, also surfaces of other macroscopic substrates may be temporarily or permanently coated with a drug according to the present invention. Such substrates may for example be surfaces of gold, silver, metal and glass.
Preferably herein, the substrate is a microsphere, porous particle, magnetic bead, a nanoparticle, a microparticle, or an implantable or insertable medical device.
The terms “therapeutic agent”, “drug”, “pharmaceutically active agent” and “pharmaceutically active ingredient” and other related terms may be used interchangeably herein.
As used herein, “treatment” refers to the prevention of a disease or condition, the reduction or elimination of symptoms associated with a disease or condition, or the substantial or complete elimination a disease or condition. Preferred subjects are mammalian subjects and more preferably human subjects.
Multilayers can be assembled using various known layer-by-layer techniques. Layer-by-layer techniques involve coating various substrates using charged materials, e.g. polyelectrolytes, via electrostatic, self-assembly. In the layer-by-layer technique, a first layer having a first net charge is typically deposited on an underlying substrate, followed by a second layer having a second net charge that is opposite in sign to the net charge of the first layer, and so forth. The two consecutive oppositely charged layers are together designated as bilayer. The charge on the outer layer is reversed upon deposition of each sequential layer or at least the net charge is substantially reduced. To the extent that the surface to be coated does not have an inherent net surface charge, a surface charge may be provided. For example, where the surface to be coated is conductive, the surface charge can be provided by applying an electrical potential to the same. Once a first layer is established in this fashion, a polyelectrolyte layer having a second net charge that is opposite in sign to the net charge of the first layer can readily be applied, and so forth. As another example, a surface charge can be provided by exposing the surface to be coated to a charged amphiphilic substance. Amphiphilic substances include any substance having hydrophilic and hydrophobic groups. Where used, the amphiphilic substance should have at least one electrically charged group to provide the substrate surface with a net electrical charge. Therefore, the amphiphilic substance that is used herein can also be referred to as an ionic amphiphilic substance. Amphiphilic polyelectrolytes can be used as ionic amphiphilic substances. For example, a polyelectrolyte comprising charged groups (which are hydrophilic) as well as hydrophobic groups, such as polyethylenimine (PEI) or poly(styrene sulfonate) (PSS), can be employed. Cationic and anionic surfactants can also be used as amphiphilic substances. Cationic surfactants include quaternary ammonium salts (R4N+X″), for example, didodecyldimethylammonium bromide (DDDAB), alkyltrimethylammonium bromides such as hexadecyltrimethylammonium bromide (HDTAB), dodecyltrimethylammonium bromide (DTMAB), myristyltrimethylammonium bromide (MTMAB), or palmityl trimethylammonium bromide, or N-alkylpyridinium salts, or tertiary amines (R3NH+X″), for example, cholesterol-3,3-N-(dimethyl-aminoethyl)-carbamate or mixtures thereof, wherein X″ is a counter-anion, e.g. a halogenide. Anionic surfactants include alkyl or olefin sulfate (R—OSO3M), for example, a dodecyl sulfate such as sodium dodecyl sulfate (SDS), a lauryl sulfate such as sodium lauryl sulfate (SLS), or an alkyl or olefin sulfonate (R—SO3M), for example, sodium-n-dodecyl-benzene sulfonate, or fatty acids (R—COOM), for example, dodecanoic acid sodium salt, or phosphoric acids or cholic acids or fluoro-organics, for example, lithium-3-[2-(perfluoroalkyl)ethylthio]propionate or mixtures thereof, where R is an organic radical and M is a counter-cation. Hence, the method may in particular embodiments comprise the step of depositing a layer of an amphiphilic substance to said portion of the surface before depositing the multilayer structure. Such a layer is herein designated “basic layer” (21).
In other embodiments, a surface charge is provided by adsorbing cations (e.g., protamine sulfate, polyallylamine, polydiallyldimethylammonium species, polyethyleneimine, chitosan, gelatin, spermidine, among others) or anions (e.g., polyacrylic acid, sodium alginate, polystyrene sulfonate, Eudragit S, gelatin (gelatin is an amphoteric polymer, hence it fits in both categories depending how it is being prepared), hyaluronic acid, carrageenan, chondroitin sulfate, carboxymethylcellulose, among others) to the surface to be coated as a first charged layer. Although full coverage may not be obtained for the first layer, once several layers have been deposited, a full coverage should ultimately be obtained, and the influence of the substrate is expected to be negligible. The species for establishing surface charge can be applied to region of the surface to be coated by a variety of techniques. These techniques include, for example, spraying techniques, dipping techniques, rinsing techniques, roll and brush coating techniques, techniques involving coating via mechanical suspension such as air suspension, ink jet techniques, spin coating techniques, web coating techniques and combinations of these processes. Alternatively or additionally, an activation of the surface can be performed, for instance by chemical etching with e.g. a H2O/HCl/H2O2 mixture and/or a H2O/NH3/H2O2 mixture. This results in temporary charges on the surface which in turn promote the adsorption of polyelectrolytes to the surface. An exemplary protocol for chemical etching is given in Example 2.
Once a sufficiently charged substrate is obtained, it can be coated with a layer of an oppositely charged substance, preferably a polyelectrolyte. Multilayers are formed by repeated treatment with alternating oppositely charged substances, i.e., by alternating treatment with cationic and anionic substances. The polymer layers self-assemble by means of electrostatic layer-by-layer deposition, thus forming a multilayered coating over the surface to be coated. In accordance with the invention one of the layers comprises a polyelectrolyte and the other layer comprises the pharmaceutically active ingredient.
Polyelectrolytes are polymers having charged (e.g., ionically dissociable) groups. Usually, the number of these groups in the polyelectrolytes is so large that the polymers in dissociated form (also called polyions) are water-soluble. Depending on the type of dissociable groups, polyelectrolytes are typically classified as polyacids and polybases. When dissociated, polyacids form polyanions, with protons being split off. Polyacids include inorganic, organic and bio-polymers. Examples of polyacids are polyvinylphosphoric acids, polyvinylsulfonic acids, polyvinylsulfonic acids, polyvinylphosphonic acids and polyacrylic acids. Examples of the corresponding salts, which are also called polysalts, are polyvinylphosphates, polyvinylsulfates, polyvinylsulfonates, polyvinylphosphonates and polyacrylates. Polybases contain groups which are capable of accepting protons, e.g., by reaction with acids, with a salt being formed. Examples of polybases having dissociable groups within their backbone and/or side groups are polyallylamine, polyethylimine, polyvinylamine and polyvinylpyridine. By accepting protons, polybases form polycations. Quaternary ammonium groups are also preferred cationic groups in the context of the present invention. For example polydiallyl dimethyl ammonium chloride (PDADMAC) is a very strong cationic charged polyelectrolyte.
Suitable polyelectrolytes according to the invention include those based on biopolymers, for example, alginic acid, gummi arabicum, nucleic acids, pectins and proteins, chemically modified biopolymers such as carboxymethyl cellulose and lignin sulfonates, and synthetic polymers such as polymethacrylic acid, polyvinylsulfonic acid, polyvinylphosphonic acid and polyethylenimine. Linear or branched polyelectrolytes can be used. Using branched polyelectrolytes can lead to less compact polyelectrolyte multilayers having a higher degree of wall porosity. Polyelectrolyte molecules can be crosslinked within or/and between the individual layers, e.g. by crosslinking amino groups with aldehydes, for example, to increase stability. However, it is preferred in the context of the present invention that the polyelectrolytes are not cross-linked. Furthermore, amphophilic polyelectrolytes, e.g. amphiphilic block or random copolymers having partial polyelectrolyte character, can be used to affect permeability towards polar small molecules. Such amphiphilic copolymers consist of units having different functionality, e.g. acidic or basic units, on the one hand, and hydrophobic units, on the other hand (e.g., polystyrenes, polydienes or polysiloxanes), which can be present in the polymer as blocks or distributed statistically. Suitable polyelectrolytes include low-molecular weight polyelectrolytes (e.g., polyelectrolytes having molecular weights of a few hundred Daltons) up to macromolecular polyelectrolytes (e.g., polyelectrolytes of biological origin, which commonly have molecular weights of several million Daltons). Preferably herein, at least one of the used polyelectrolytes has a molecular weight of below 100 kDa, preferably below 10 kDa. Specific examples of polycations include protamine sulfate polycations, poly(allylamine) polycations (e.g., poly(allylamine hydrochloride) (PAH)), polydiallyldimethylammonium (PDADMAC) polycations, polyethyleneimine (PEI) polycations, chitosan polycations, spermidine polycations and albumin polycations. Specific examples of polyanions include poly(styrenesulfonate) polyanions (e.g., poly(sodium styrene sulfonate) (PSS)), polyacrylic acid polyanions, sodium alginate polyanions, hyaluronic acid polyanions, carrageenan polyanions, chondroitin sulfate polyanions, carboxymethylcellulose polyanions and albumin polyanions.
By using polyelectrolytes that are biodisintegrable, the release of the therapeutic agent can be further controlled based on the rate of disintegration of the polyelectrolyte layers. Moreover, as indicated above, implantable or insertable medical articles containing a biodisintegrable multilayer polyelectrolyte coating leave behind only the underlying ceramic or metallic structure once the therapeutic agent is released from the medical article. As used herein, a “biodisintegrable” material is a material which undergoes dissolution, degradation, resorption and/or other disintegration processes upon administration to a patient. Preferred examples of biodisintegrable polyelectrolytes include protamine sulfate, gelatin, spermidine, albumin, carrageenan, chondroitin sulfate, heparin, other polypeptides and proteins, and DNA, among others. As with species for establishing surface charge (described above), the polyelectrolyte layers can be applied to the surface to be coated by a variety of techniques including, for example, spraying techniques, dipping techniques, rinsing techniques, roll and brush coating techniques, techniques involving coating via mechanical suspension such as air suspension, inkjet techniques, spin coating techniques, web coating techniques and combinations of these processes. Preferably, herein, the polyelectrolyte layers are applied by spraying, brushing or by immersion of the surface to be coated into a solution comprising the respective polyelectrolyte.
Tables 1 to 3 list preferred cationic, anionic and amphoteric polyelectrolytes, respectively.
Also the layers comprising the pharmaceutically active ingredient can be applied to the surface to be coated by a variety of techniques including, for example, spraying techniques, dipping techniques, rinsing techniques, roll and brush coating techniques, techniques involving coating via mechanical suspension such as air suspension, inkjet techniques, spin coating techniques, web coating techniques and combinations of these processes. Preferably, herein, the layers comprising the pharmaceutically active ingredient are applied by spraying, brushing or by immersion of the surface to be coated into a solution comprising the comprising the pharmaceutically active ingredient.
Preferably, herein, a plurality of bilayers is deposited on at least the portion of the surface to form a multilayer of layers with alternating charges. According to the method of the invention, preferably between 2 and 1000, more preferably between 2 and 250 layers are applied to the surfaces and a multilayer of alternating charge is formed. Hence, the coating of the microscopic or macroscopic surfaces according to the invention preferably comprises a multilayer having between 1 and 500, preferably between 1 and 125 bilayers.
In some preferred embodiments the coating has an overall thickness of from 2 nm to 500 nm, preferably 100 nm to 50 nm, more preferably 0.4 nm to 10 nm.
As described herein above, the polyelectrolytes can, inter alia, be synthetic polymers, biopolymers such as polypeptides, proteins, polysaccharides, oligosaccharides, nucleic acids and derivates of biopolymers such as chemically modified biological polymers.
The net charge of a polyelectrolyte or the pharmaceutically active ingredient may depend on the pH of the surrounding solution. For example some polyelectrolytes or pharmaceutically active ingredients may be amphoteric. An amphoteric substance is a substance that can react as either an acid or base. Amphoteric substances have an isoelectric point (pI or IEP), i.e. a pH at which they have no net charge and are thus neutral. Above the IEP the amphoteric substance is deprotonated and thus has a negative net charge. Below the IEP the amphoteric substance is protonated and thus has a positive net charge. Hence, whether a given amphoteric substance is a polyanion or a polycation depends on the surrounding pH. The present inventors have in a specific embodiment exploited this fact by using an amphoteric layer that has a different net charge during coating, i.e. oppositely charged than the neighbouring layers, than under in situ conditions or release conditions, e.g. under physiological conditions. When a substrate with a coating comprising such an amphoteric substance is brought to physiological pH, i.e. by administering, implanting or inserting the coated microscopic or macroscopic substrate to a subject, the net charge of the amphoteric substance changes, is resulting in a disintegration of the multilayer. This, in turn, leads to the release of the pharmaceutically active ingredient to the surrounding (target) tissue. Properties of the sustained release such as release rate, lack time, overall time of release etc. can for example be controlled by the selection of the polyelectrolyte and/or the numbers of layers applied to the surface.
“Physiological conditions”, particularly “physiological pH”, herein refers to the conditions, particularly the pH, at the place to which the coated substrate is administered, delivered, targeted, implanted or inserted, i.e. the conditions, particularly the pH, in situ or in vivo. In the case of blood vessels, for example, the pH is typically between 7.35 and 7.45, preferably around 7.4. The osmolarity in whole blood plasma is typically between 250 and 330 mosmol/kg, mostly between 275 and 299 mosmol/kg.
The pharmaceutically active ingredient in the context of the present invention is preferably water-soluble. It is preferably a water soluble drug according to groups I or III of the Biopharmaceutics Classification System (BCS) (FDA). In some embodiments the pharmaceutically active ingredient is an amphoteric substance that has a substantially different net charge at deposition conditions than at the conditions were the release of the pharmaceutically active ingredient is desired.
The pharmaceutically active ingredient in the context of the present invention is for instance substance for inhibiting cell proliferation or inflammatory processes, an anti-cancer drug, an antibiotic, a growth factor, a hormone, an antibody or functional fragment thereof, a cytostatic, an immunosuppressant or an antioxidant. Preferred pharmaceutically active ingredients in the context of the present invention are anti-TNF alpha antibodies and hormones and inhibitors of growth factors.
Table 4 lists some very particular proteins that are pharmaceutically active ingredients together with their isoelectric point and molecular weight.
According to the invention, the coating may additionally also comprise a layer comprising one or more substances that facilitate dissolution of the multilayer upon insertion or implantation of the device. Such substances include for example enzymes that cleave polyelectrolytes, e.g. polysaccharides. Such enzymes are for example chitinase, esterase, peptidase, and lysozyme.
The layer comprising the pharmaceutically active ingredient may in a particular embodiment further comprises a polyelectrolyte, an organic or inorganic salt, or organic or inorganic particles with low water solubility.
The present invention also relates to a substrate obtained or obtainable by a method according to the methods of the invention.
The invention, hence, in one aspect pertains to a substrate comprising
One particular embodiment of the coated substrate according to the invention is illustrated in
The coated microscopic and macroscopic substrates according to the invention, e.g. the particles, porous particles or implantable or insertable medical devices, may be used in a wide spectrum of medical, veterinary, pharmaceutical and diagnostic applications. For example, the coated microscopic and macroscopic substrates according to the invention may be used in the treatment of tumours, for creating open passages in the body, for the treatment of vascular diseases or circulatory disturbances, for facilitating wound healing or the healing of bone fractures, for the treatment of ophthalmic diseases, in surgery, for the treatment of gynecological diseases and conditions, for the treatment of articular and bone diseases, for the treatment of stenosis or in the prophylaxis of restenosis.
Particularly, implantable or insertable medical devices coated according to the invention may be used in the treatment of tumours, for creating open passages in the body, for the treatment of vascular diseases or circulatory disturbances, for facilitating wound healing or the healing of bone fractures, for the treatment of ophthalmic diseases, in surgery, for the treatment of gynecological diseases and conditions, for the treatment of articular and bone diseases, for the treatment of stenosis or in the prophylaxis of restenosis.
Hence, the invention in one aspect also relates to the use of an implantable or insertable medical device according to the invention to provide a means for the treatment of tumours, for creating open passages in the body, for the treatment of vascular diseases or circulatory disturbances, for facilitating wound healing or the healing of bone fractures, for the treatment of ophthalmic diseases, for the use in surgery, for the treatment of gynecological diseases and conditions, for the treatment of articular and bone diseases, for the treatment of stenosis or for the prophylaxis of restenosis.
Microscopic substrates, particularly the particles according to the invention, e.g. microspheres, porous particles, magnetic beads, nanoparticles or microparticles, coated with a drug in accordance with the invention may for example be used in the treatment of diseases, e.g. tumours, vascular diseases or circulatory disturbances, ophthalmic diseases, gynecological diseases and conditions, articular and bone diseases, for facilitating wound healing or the healing of bone fractures.
The invention therefore relates in a particular aspect to the use of microscopic substrates, particularly the particles according to the invention, e.g. microspheres, porous particles, magnetic beads, nanoparticles or microparticles, coated with a drug in accordance with the invention for the manufacture of a medicament for the treatment of diseases, e.g. tumours, vascular diseases or is circulatory disturbances, ophthalmic diseases, gynecological diseases and conditions, articular and bone diseases, for facilitating wound healing or the healing of bone fractures.
The particles according to the invention may for instance be used for topical (i.e. local) or systemic (i.e. enteral or parenteral) administration. They may for example be used in oral, nasal, rectal, intramuscular, intradermal, intravenous, subcutaneous or other administration routes.
The following examples illustrate particular embodiments and aspects of the present invention. However, they are not limiting the scope of the invention.
Polymer solution 1: containing 0.2 mg/ml BMP-2, pH 4 (cationic charged).
Polymer solution 2: containing 0.2 mg/ml Hyaluronic acid (Hya), pH 4 (anionic charged)
Washing: water pH 4 (adjusted with HCl/NaOH)
The surface of e.g. a medical device can be prepared for coating with multilayers by chemical etching. The following protocol is based on purification protocols of silicon wafers as established by the Radio Corporation of America (RCA) (W. Kern, Cleaning Solutions Based on Hydrogen Peroxide for Use in Silicon Semiconductor Technology RCA Review 31, 187-206, 1970).
The so-called RCA purification id based on a two-step oxidizing and complexing treatment of the surface with hydrogen peroxide solutions. In the first step, an alkaline mixture with high pH and in the second step an acidic mixture with low pH is used.
In the first step a mixture of concentrated ammonium hydroxide (29%), concentrated hydrogen peroxide (30%) and water is used, typically in a ratio of 1:1:5 (NH3:H2O2:H2O, % (v/v)).
In the second step a mixture of concentrated hydrochloric acid (37%), concentrated hydrogen peroxide (30%) and water is used, typically in a ratio of 1:1:6 (HCl:H2O2:H2O, % (v/v)).
Both steps are performed at elevated temperature, e.g. 60-80° C. for about 10 min.
For the coating, it is not required to apply both steps. Generally, the alkaline step is sufficient.
Example 3 illustrates an embodiment in which a surface (here: surface of crystals) are coated with polyelectrolyte multilayer layer (LbL: layer-by-layer). The layer is subsequently released at a physiological pH.
Quartz Crystal Micro Balance (QCM-D)
The crystals to be coated were treated with polymer solution 1 (basic layer)
PEI-[ChonS/GelB]12
Quartz Crystal Micro Balance (QCM-D)
PEI-[ChonS/HSA]12
The model protein (MP) is a model for a therapeutic protein, i.e. a drug
PEI-(ChonS-MP)5
| Number | Date | Country | Kind |
|---|---|---|---|
| 10164857.4 | Jun 2010 | EP | regional |
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/EP11/59063 | 6/1/2011 | WO | 00 | 10/4/2013 |
