RELEASE OF DILTIAZEM FROM EUDRAGIT MICROPARTICLES PREPARED BY SPRAY-DRYING

Microparticles containing diltiazem hydrochloride were prepared by the spray-drying technique using acrylate-methacrylate copolymers, Eudrag it RS and Eudragit RL, as coating materials. The choice of solvent use d during spray-drying determined the structure of the resultant microp articles. Spray-drying using dichloromethane as the solvent resulted i n microspheres where the drug was distributed in the coating polymer m atrix, whereas using toluene gave microcapsules with the drug coated b y the polymer. The particle size distribution for both microspheres an d microcapsules was narrow, with mean particle size below 10 mu m. DTA -analysis showed that the drug was amorphous in the microspheres but c rystalline in the microcapsules. The release pattern of diltiazem hydr ochloride was affected by microparticle structure, whether the structu re was matrix (microspheres) or reservoir (microcapsules). The results indicate that spray-drying is a method that can be used to prepare mi croparticles from the Eudragit acrylic resins RL and RS with a narrow particle size distribution. It is concluded that drug release rate can be controlled by choice of polymer type and production conditions dur ing spray-drying.