Drug release on certain acrylate methacrylate-salicylic acid coacervated systems

Abstract

Coacervates containing certain acrylate methacrylate copolymers and salicylic acid (drug) in various proportions have been prepared by addition of excess non-solvent (water) to an ethanolic solution of the drug and polymer in the presence of a flocculating agent, sodium chloride (0.1 M strength). A series of polymers differing only in their content of quaternary ammonium (cationic) groups was used. Dried coacervates were compressed to tablets or filled into gelatin capsules. Drug release rates decreased exponentially with increase in polymer concentration in the coacervates, but increased exponentially with increase in the polymer cation content at a constant polymer concentration of 20% w/w. The increase in release rate was associated with a corresponding increase in polymer swellability. Drug release rates from tablets were retarded compared with those from the capsules, an effect associated with poor disintegration of the tablets.