Preparation of slow release coprecipitates of soluble drugs using polyvinyl acetate crotonic acid copolymer

Coprecipitates of soluble drugs; namely, diphenhydramine HCI and tripelennamine HCI with polyvinyl acetate crotonic acid copolymer were prepared with different drug to polymer ratios. Comparative dissolution rate studies of the coprecipitates and physical mixture showed that the coprecipitates slowed the release rate of the drug. The decrease in release rate was more pronounced for compressed disks prepared from coprecipitates. As the polymer concentration increased, the retardation effect increased