# US 8,771,734 B2 · Sustained-release hydrogel preparation > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 8,771,734 B2 - Document ID: US8771734B2 - Status: Granted - Kind: B2 - Application number: 10/549,695 - Filed: 2004-03-15 - Published: 2006-11-09 - Granted: 2014-07-08 - Earliest claimed: 2003-03-17 - Assignees: Medgel Corporation - Applicants: Yasuhiko Tabata - Inventors: Yasuhiko Tabata - Web page: https://patentgrep.com/patent/US8771734B2 ## CPC - A61K 9/06: Ointments; Bases therefor; {Other semi-solid forms, e.g. creams, sticks, gels (composition of ointments, creams or gels A61K47/00)} - A61K: PREPARATIONS FOR MEDICAL, DENTAL OR TOILETRY PURPOSES (devices or methods specially adapted for bringing pharmaceutical products into particular physical or administering forms A61J3/00; chemical aspects of, or use of materials for deodorisation of air, for disinfection or sterilisation, or for bandages, dressings, absorbent pads or surgical articles A61L; soap compositions C11D) ## Abstract A sustained-release preparation is provided which comprises a drug and a bioabsorbable polymer hydrogel, wherein a concentration gradient of the drug is formed in the hydrogel. Also disclosed is a method of sustained release of a drug in vivo using the sustained-release preparation of the invention. The directionality of the drug release may be controlled by employing the sustained-release preparation of the invention. The sustained-release preparation of the invention is particularly useful as an anti-cancer agent. ## Claims ### Claim 1 A sustained-release preparation which comprises: a drug having a molecular weight of about 10,000 or less; and a gelatin hydrogel, wherein the drug is impregnated into said gelatin hydrogel through a surface thereof and is immobilized in said hydrogel by physiochemical interaction, and said hydrogel having a concentration gradient of the drug such that said concentration gradient being higher at said surface than in other parts of said hydrogel in said sustained-release preparation, and the drug is immobilized within said hydrogel by said physiochemical interaction, thereby controlling the directionality of the sustained release of the drug upon administration of the sustained-release preparation, and said sustained-release preparation is sterile. ### Claim 2 A method of sustained release of a drug in vivo comprising: administering a sustained-release preparation to a patient in need thereof, said preparation comprising a drug having a molecular weight of about 10,000 or less and a gelatin hydrogel, wherein said hydrogel has a concentration gradient of the drug in said sustained-release preparation, wherein degradation of the gelatin hydrogel in vivo causes more drug to be released from a region with higher drug concentration, thereby giving said sustained release of the drug, wherein the drug is impregnated into said gelatin hydrogel through a surface thereof and is immobilized in said hydrogel by physiochemical interaction, said concentration gradient being higher at said surface than in other parts of said hydrogel, and said sustained-release preparation is sterile. ### Claim 3 (depends on 2) The method of claim 2, where said administration is topical. ### Claim 4 (depends on 1) The sustained-release preparation of claim 1, wherein the drug is impregnated into said gelatin hydrogel by ionic bonding. ### Claim 5 (depends on 1) The sustained-release preparation of claim 1, wherein the preparation is in solid or semi-solid form. ### Claim 6 A sustained-release preparation which comprises: a drug having a molecular weight of about 10,000 or less; and a crosslinked gelatin hydrogel, said sustained-release preparation being made by adding an aqueous solution of said drug dropwise to said crosslinked gelatin hydrogel, thereby impregnating said drug into said crosslinked gelatin hydrogel through a surface thereof, immobilizing said drug in said crosslinked gelatin hydrogel by physiochemical interaction between said drug and crosslinked gelatin hydrogel, and forming a concentration gradient of the drug in the crosslinked gelatin hydrogel such that said concentration gradient is higher at said surface than in other parts of said hydrogel in said sustained-release preparation, wherein the amount of aqueous solution being added dropwise causes swelling of the crosslinked gelatin hydrogel and wherein said sustained-release preparation is sterile. ### Claim 7 (depends on 1) The sustained-release preparation of claim 1, in a form suitable for topical application. ### Claim 8 (depends on 6) The sustained-release preparation of claim 6, in a form suitable for topical application. ### Claim 9 (depends on 1) The sustained-release preparation of claim 1, which is in a solid or semisolid single dose form containing 0.01 to 10,000 μg of said drug. ### Claim 10 (depends on 2) The method of claim 2, wherein said sustained release preparation is in a solid or semisolid single dose form containing 0.01 to 10,000 μg of said drug. ### Claim 11 (depends on 6) The sustained-release preparation of claim 6, in a solid or semisolid single dose form containing 0.01 to 10,000 μg of said drug. ### Claim 12 (depends on 1) The sustained-release preparation of claim 1, which is in a solid single dose form containing 0.1 to 1,000 μg of said drug. ### Claim 13 (depends on 2) The method of claim 2, wherein said sustained release preparation is in a solid single dose form containing 0.1 to 1,000 μg of said drug. ### Claim 14 (depends on 6) The sustained-release preparation of claim 6, in a solid single dose form containing 0.1 to 1,000 μs of said drug.