Controlled Release Of Glipizide From Ethylene Vinyl Acetate Microcapsules
An industrially feasible technique of microencapsulation by ethylene vinyl acetate copolymerand the resulting microcapsules were investigated. Ethylene vinyl acetate microcapsules of glipizide were prepared by an emulsion solvent evaporation method employing various proportions of coaland core materials and chloroform as solvent for the polymer ethylene vinyl acetate.The microcapsules are spherical, discrete, free flowing and monolithic, multinucleate type. Microencapsulation efficiency was i n the range of 89-97%. 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 was diffusion controlled and 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% release) values. Release from some of themicrocapsules was very close to that from a commercial SR tablet formulation of glipizide.