EP0406315B1 — Controlled release composition

USPTO Abstract

A composition for controlled delivery of an active substance into an aqueous phase by erosion at a substantially constant rate of a surface or surfaces of the composition, the composition comprising a matrix of at least one substantially water soluble crystalline polymer, one or more surface active agents dispersed in the crystalline polymer phase, at least one active substance substantially homogeneously dispersed in the crystalline polymer phase and/or located in geometrically well-defined zones within the crystalline polymer phase and/or dispersed in the surface active agent and, optionally, a filler. The surface active agent and/or the active substance substantially eliminates water diffusion in the interface between the polymer crystals. In an alternative embodiment, the composition comprises a matrix of room-temperature vulcanizing rubber (RTV rubber) in which particles of a superabsorbent polymer are substantially homogeneously distributed and at least one active substance substantially homogeneously dispersed in the matrix and/or located in geometrically well-defined zones within the matrix.