Patent ID: 7604820

Claim:
A sustained release preparation comprising a medicament-containing solid material and a water-insoluble coating film, wherein said medicament-containing solid material consists of a medicament and a pharmaceutical excipient, and said water-insoluble coating film consists essentially of a water-insoluble polymer and a chitosan powder dispersed in said polymer, wherein said polymer is selected from the group consisting of ethyl cellulose, ethyl acrylate-methyl methacrylate-trimethylammoniumethyl methacrylate chloride copolymer, and methyl methacrylate-ethyl acrylate copolymer, said chitosan powder having a mean particle size diameter in the range of about 0.5 μm to about 400 μm, and the weight ratio of said polymer and said chitosan powder is from 4:1 to 1:4.