New Technique of Microencapsulation by EVA Copolymer

Abstract

An industrially feasible new technique of microencapsulation by ethylene vinyl acetate copolymer (EVA) and the resulting microcapsules was investigated. EVA microcapsules of glipizide were prepared by an emulsion solvent evaporation method employing various proportions of coat and core materials and chloroform as solvent for the polymer EVA. The microcapsules are spherical, discrete, free flowing and monolithic, multinucleate type. Microencapsulation efficiency was between 89-97 per cent. Glipizide release from the microcapsules was slow and extended over more than 12 h and depended on coat:core ratio, wall thickness and size of the microcapsules. Drug release followed zero order kinetics after a lag period of 1 h. Good linear relationships were observed between wall thickness and release rate and T₅₀(time for 50 per cent release) values. The microcapsules were found suitable for both oral and parenteral controlled release. Release from some of the

microcapsules was very close to that from a commercial SR tablet formulation of glipizide.