| abstract |
PURPOSE: To obtain a controlled release system composed of nucleus comprising a soluble active substance, infiltration-active auxiliary and swellable polymeric auxiliary and shell containing a film-forming element, capable of inducing release of the active substance according to zero-order rate process so as to easily control the delay period for the release. n CONSTITUTION: This controlled release system is composed of nucleus comprising a soluble active substance and infiltration-active auxiliary (e.g. lactose, fructose, sodium chloride) and a swellable polymeric auxiliary having hydration tendency not higher than those of the above active substance and infiltration-active auxiliary (e.g. polyvinyl alcohol 6-18wt.% in residual acetate content and 20,000-70,000 in average molar mass) and shell comprising a film-forming element such as cellulose acetate, polyvinyl acetate or polyacrylic acid copolymer and a soluble, hydrophilic or hydrophobic plasticizer (e.g. polyethylene glycol 400-20,000 in average molar mass). In this case, the shell has at least one release open pore for the active substance, or porous structure produced by the increase of intranuclear hydrostatic pressure. n COPYRIGHT: (C)1990,JPO |