Preparation and Evaluation of Ethylene Vinyl Acetate Copolymer Coated Microcapsules of Glipizide for Controlled Release

Abstract

Ethylene vinyl acetate copolymer (EVA) was evaluated as microencapsulating agent and to prepare EVA coated microcapsules. Ethylene vinyl acetate copolymer coated microcapsules of glipizide were prepared by an industrially feasible emulsification-solvent evaporation method and the microcapsules were investigated. The EVA coated microcapsules are spherical, discrete, free-flowing and multinucleate monolithic type. Microencapsulation efficiency was found to be in the range 89-95 %. Glipizide release from the EVA coated microcapsules was slow and extended over longer periods of time and depended on core:coat ratio, wall thickness and size of the microcapsules. Drug release from the microcapsules was by non-Fickian diffusion mechanism. Good linear relationship was observed between wall thickness of microcapsules and release rate (k₀). Ethylene vinyl acetate copolymer was found suitable as microencapsulating agent and the EVA coated microcapsules of glipizide exhibited good controlled release characteristics and were found suitable for oral controlled release products.