| 摘要 |
Articles for the controlled delivery of an active substance into an aqueous phase by erosion of surfaces of the articles at a substantially constant and pH-independent rate, the articles comprising a matrix of crystalline polyethylene glycol polymer and a non-ionic emulsifier having an HLB value in the range of from about 4 to about 16 dispersed in the matrix in an amount of between about 2% and 50% by weight of the crystalline polyethylene glycol polymer and the emulsifier, the emulsifier having at least one domain which enables the emulsifier to become emulsified in the melted crystalline polyethylene glycol polymer and being selected from the group consisting of a fatty acid ester and a fatty alcohol ether, the active substance being dispersed in the matrix or located in geometrically well-defined zones within the crystalline PEG phase or dispersed in the emulsifier and, optionally, a filler. The non-ionic emulsifier or the active substance substantially eliminates water diffusion in the interface between the polymer crystals to thereby act as a repair medium and maintain substantially the geometric shape of the articles and, thus, maintain substantially constant the surface area exposed to solution. |
