Olibanum Resin Coated Microcapsules of Glipizide: Preparation and Evaluation for Controlled Release

Abstract

The objective of the study is to evaluate olibanum resin, a natural lipophilic polymer for its application as microencapsulating agent and to prepare and evaluate olibanum resin-coated microcapsules of glipizide for controlled release. Controlled release formulations are needed for glipizide because of its short biological half-life of 3.4 ± 0.7 h and for better control of blood glucose levels to prevent hypoglycemia, enhance clinical efficacy and patient compliance. Olibanum resin coated microcapsules of glipizide were prepared by an industrially feasible emulsification-solvent evaporation method and the microcapsules were evaluated for controlled release. The resin coated microcapsules prepared were spherical, discrete, free flowing and multinucleate monolithic type. Microencapsulation efficiency was in the range 101-107 %. Glipizide release from the microcapsules was slow over 24 h and depended on core:coat ratio, wall thickness and size of the microcapsules. Drug release from the microcapsules was by fickian diffusion mechanism. Good linear relationship was observed between wall thickness of the microcapsules and release rate (K₁). Olibanum resin was found suitable as a new microencapsulating agent and the resin coated microcapsules exhibited good controlled release characteristics. Glipizide release from the olibanum resin coated microcapsules, MC 3 (size 20/30) was similar to that from glynase XL-10 tablets, a commercial controlled release formulation of glipizide.