Formulation for Controlled Release of Drugs by Combining Hydrophilic And
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(19) & (11) EP 2 298 353 A1 (12) EUROPEAN PATENT APPLICATION (43) Date of publication: (51) Int Cl.: 23.03.2011 Bulletin 2011/12 A61K 47/34 (2006.01) A61K 9/10 (2006.01) (21) Application number: 10012665.5 (22) Date of filing: 31.05.1996 (84) Designated Contracting States: • Kochinke, frank AT BE CH DE DK ES FI FR GB GR IE IT LI LU MC San Jose, CA 95148 (US) NL PT SE (74) Representative: Chung, Hsu Min (30) Priority: 02.06.1995 US 459134 Boult Wade Tennant Verulam Gardens (62) Document number(s) of the earlier application(s) in 70 Gray’s Inn Road accordance with Art. 76 EPC: London WC1X 8BT (GB) 04019466.4 / 1 477 187 96916903.6 / 0 831 912 Remarks: This application was filed on 01-10-2010 as a (71) Applicant: Allergan, Inc. divisional application to the application mentioned Irvine, CA 92612 (US) under INID code 62. (72) Inventors: • Wong, Vernon G. Menlo Park, CA 94025 (US) (54) Formulation for c ontrolled release of drugs by c ombining hydrophilic and hydr ophobic agents (57) An implant for sustained drug release compris- the implant; a release modulator at a concentration from ing: a pharmacologically acceptable biodegradable pol- 10 to 50 weight percent of the implant; wherein said ther- ymer which is degraded at the site of implantation, where- apeutically active agent is released within a therapeutic in said biodegradable polymer comprises at least about dosage which does not vary by more than about 100% 20 weight percent of the implant; a therapeutically active for a period of at least about 3 days. agent at a concentration from 10 to 50 weight percent of EP 2 298 353 A1 Printed by Jouve, 75001 PARIS (FR) EP 2 298 353 A1 Description INTRODUCTION 5 Technical Field [0001] Biodegradable implants formulated for controlled, sustained drug release. Background of the Invention 10 [0002] Solid pharmaceutically active implants that provide sustained release of an active ingredient are able to provide a relatively uniform concentration of active ingredients in the body. Implants are particularly useful for providing a high local concentration at a particular target site for extended periods of time. These sustained release forms reduce the number of doses of the drug to be administered, and avoid the peaks and troughs of drug concentration found with 15 traditional drug therapies. Use of a biodegradable drug delivery system has the further benefit that the spent implant need not be removed from the target site. [0003] Many of the anticipated benefits of delayed release implants are dependent upon sustained release at a relatively constant level. However, formulations of hydrophobic drugs with biodegradable matrices may have a release profile which shows little or no release until erosion of the matrix occurs, at which point there is a dumping of drug. 20 [0004] The eye is of particular interest when formulating implantable drugs, because one can reduce the amount of surgical manipulation required, and provide effective levels of the drug specifically to the eye. When a solution is injected directly into the eye, the drug quickly washes out or is depleted from within the eye into the general circulation. From the therapeutic standpoint, this may be as useless as giving no drug at all. Because of this inherent difficulty of delivering drugs into the eye, successful medical treatment of ocular diseases is inadequate. 25 [0005] Improved sustained release formulations which allow for a constant drug release rate are of considerable interest for medical and veterinary uses. Relevant Literature 30 [0006] U.S. Patents 4,997,652 and 5,164,188 disclose biocompatible implants for introducing into an anterior chamber or posterior segment of an eye for the treatment of an ocular condition. [0007] Heller, Biodegradable Polymers in Controlled Drug Delivery, in: CRC Critical Reviews in Therapeutic Drug Carrier Systems, Vol. 1, CRC Press, Boca Raton, FL, 1987, pp 39-90, describes encapsulation for controlled drug delivery. Heller in: Hydrogels in Medicine and Pharmacy, N.A. Peppes ed., Vol. III, CRC Press, Boca Raton, FL, 1987, 35 pp 137-149, further describes bioerodible polymers. [0008] Anderson et al., Contraception (1976) 13: 375 and Miller et al., J. Biomed. Materials Res. (1977) 11:711, describe various properties ofpoly(dL-lactic acid). U.S. Patent 5,075,115 discloses sustained release formulations with lactic acid polymers and copolymers. [0009] Di Colo (1992) Biomaterials 13:850-856 describes controlled drug release from hydrophobic polymers. 40 SUMMARY OF THE INVENTION [0010] Compositions and methods are provided for biodegradable implants formulated to provide a controlled, sus- tained drug release. The release rate is modulated by combining in the implant hydrophobic and hydrophilic agents. The 45 release modulator may act to accelerate or retard the rate of release. Optionally, the modulator will be a therapeutically active agent. The invention provides a sustained release implant having a combination of active agents with a defined release profile. BRIEF DESCRIPTION OF THE DRAWINGS 50 [0011] Figure 1A shows the release profile of a hydrophobic drug from an extended release drug delivery system. Figure 1B shows the release profile of the same drug when formulated in a drug delivery system with a release modulator. 55 Figure 2A shows the release profile of dexamethasone in the absence or presence of the release modifier, cipro- flaxacin HCl. Figure 2B shows the release of ciprofloxa cin in the presence of dexamethasone. Figure 2C shows the release of ciprofloxacin in the absence of a release modifier. Figure 2D shows the releae profile from a drug delivery system having combined hydrophilic and hydrophobic drugs, and further having a pharmaceutically inactive 2 EP 2 298 353 A1 release modifier. Figure 3 shows a cross-sectional view of an eye. DESCRIPTION OF THE SPECIFIC EMBODIMENTS 5 [0012] A controlled drug release is achieved by an improved formulation of slow release biodegradable implants. The release rate of a drug from an implant is modulated by addition of a release modulator to the implant. Release of a hydrophobic agent is increased by inclusion of an accelerator in the implant, while retardants are included to decrease the release rate of hydrophilic agents. The release modulator may be physiologically inert, or a therapeutically active 10 agent. Formulations of interest includes antiinflammatory drugs, e.g. glucocorticoids, NSAIDS, etc., combined with an ophthalmically active agent. [0013] The rate of release of the therapeutically active agent is controlled by the rate of transport through the polymeric matrix of the implant, and the action of the modulator. By modulating the release rate, the agent is released at a sub- stantially constant rate within a therapeutic dosage range, over the desired period of time. The rate of release will usually 15 not vary by more than about 100% over the desired period of time, more usually by not more than about 50%. The agent is made available at the specific site(s) where the agent is needed, and it is maintained at an effective dosage. [0014] The transport of drug through the polymer barrier is also affected by drug solubility, polymer hydrophilicity, extent of polymer cross-linking, expansion of the polymer upon water absorption so as to make the polymer barrier more permeable to the drug, geometry of the implant, and the like. At high drug loadings, i.e. at a loading concentration above 20 the theoretical percolation threshold, percolation theory predicts the potential for drug leaching from the drug delivery system matrix. In such cases release modulators are useful to slow down the leaching process. [0015] The release modulator is an agent that alters the release of a drug from a biodegradable implant in a defined manner. It may be an accelerator or a retardant. Accelerators will be hydrophilic compounds, which are used in combi- nation with hydrophobic agents to increase the rate of release. Hydrophilic agents are those compounds which have at 25 least about 100 Pg/ml solubility in water at ambient temperature. Hydrophobic agents are those compounds which have less than about 100 Pg/ml solubility in water at ambient temperature. [0016] Therapeutically active agents that benefit from formulation with a release modulator may come from, but are not limited to, the following therapeutic classes: Ace-inhibitor, endogenous cytokines that influence basement membrane; agents that influence growth of endothelial cells; adrenergic agonist or blocker; aldose reductose inhibitor, analgesic; 30 anesthetic; antiallergic; antibacterial; antifibrotic; antifungal, e.g. amphoteracin B; antiglaucoma; antihyper- or hypoten- sive; anti-inflammatory; antineoplastic; antiprotozoal; antitumor; antiviral; carbonic anhydrase inhibitor, chelating agents; cholinergic; cholinesterase inhibitor; GNS stimulant; contraceptive; dopamine receptor agonist or antagonist; estrogen; glucocorticoid; glucosidase inhibitor; releasing factor; growth hormone inhibitor; growth stimulant; hemolydc; heparin antagonist; immunomodulator; immunosuppressant; LH-RH agonist; antimitotics; NSAm; progesterone; thrombolytic; 35 vasodilator; vasopressor; and vitamin. Among hydrophobic drugs, which typicallyhave a slow release profile and therefore benefit from formulation with a release accelerator, are cyclosporines,e.g . cyclosporin A, cyclosporin G, etc.; vinca alkaloids, e.g. vincristine and vinblastine; methotrexate; retinoic acid; certain antibiotics,e.g . ansamycins such as ri- fampin; nitrofurans such as nifuroxazide;