Diltiazem multi-dose gastrointestinal diffusion system: preparation and release rate studies.

The present paper is concerned with a multi-dose gastrointestinal diffusion system, releasing diltiazem through a controlled source of diffusional energy. The method calls for: a) encapsulation of the drug in a microball form, and b) coating of the resulting microballs by a porous membrane which controls the diffusion rate of the drug. The system would be expected to deliver the drug at a declining rate, due to the lower solubility of diltiazem hydrochloride in the intestinal than in the stomach fluid. To maintain a constant drug diffusion rate in the intestinal fluid, a membrane-modifying agent soluble in the intestinal tract (EudragitR L.) was introduced into the cellulose acetate microball coating. In this paper in vitro studies of drug release from the unit in relation to microball coating and coating mass are presented. The system provides a zero-order drug deliver in vitro, as the result of an appropriate selection of manufacturing parameters.