Membrane-coated sustained-release tablets and method

Abstract

A sustained-release coated pharmaceutical tablet comprising a drug-containing tablet and a coating or membrane surrounding the same, wherein the coating or membrane is water-insoluble and insoluble in gastrointestinal fluids and consists essentially of a terpolymer of polyvinylchloride, polyvinylacetate, and polyvinylalcohol and a water-soluble pore-creating substance, the said pore-creating substance being randomly distributed in said terpolymer coating, said pore-creating substance being present in amount of one part to 35 parts for each one to ten parts of terpolymer, said coated tablet exhibiting a substantially constant dissolution rate during a major portion of its dissolution time when exposed to gastrointestinal fluids, especially wherein the terpolymer contains 80 to 95% weight per weight of polyvinylchloride, 0.5 to 19% weight per weight of polyvinylacetate, and 0.5 to 10% weight of polyvinylalcohol, and a method for the preparation thereof, are disclosed.

Dependencies are inferred from the claim text.