Controlled Nifedipine Release from Microcapsules of its Dispersions in PVP-MCC and HPC-MCC

Abstract Nifedipine and its solid dispersions in polyvinyl-pyrrolidone-microcrystalline cellulose (PVP-MCC) and hydroxypropyl cellulose - microcrystalline cellulose (HPC-MCC) were microencapsulated with cellulose acetate by an emulsion solvent evaporation method. The microcapsules are spherical, discrete and free flowing. Nifedipine as such and its microcapsules gave very slow release because of its highly crystalline nature and poor solubility. Solid dispersion in PVP-MCC and HPC-MCC gave fast and rapid dissolution of nifedipine. When these solid dispersions were microencapsulated, a slow, controlled and complete release over a period of 12 hours was observed from the resulting microcapsules. Drug release depended on the proportion of PVP-MCC and HPC-MCC in the solid dispersions used as core, coat: core ratio and size of the microcapsules and the release was pH independent. Drug release was governed by diffusion rate and followed first-order kinetics.