| abstract |
ABSTRACT The invention relates to sustained-release pharmaceutical preparations comprising a drug-containing tablet and a coating surrounding the same, wherein the coating is insoluble in water and gastrointestinal fluids and consists essentially of a ter-polymer of polyvinylchloride, polyvinylacetate, and polyvinyl-alcohol and a water-soluble pore-creating substance, the said pore-creating substance being randomly distributed in the ter-polymer coating, the ratio of pore-creating substance to terpolymer being from 1:10 to 20:1 by weight and said pore-creating substance being essentially pharma-cologically inactive in the amount used. The invention also includes a method for the manufacture of the pre-paration. |