Controlled release of Microencapsulated Indomethacin by colophony resin

Abstract

Colophony resin was evaluated as a microencapsulating agent and to prepare resin-coated microcapsules. Resin-coated microcapsules of indomethacin were prepared by an industrially feasible emulsification-solvent evaporation method and the microcapsules were investigated. The resin-coated microcapsules are spherical, discrete, free-flowing and multinucleate monolithic type. Microencapsulation efficiency was in the range 96-107%. Indomethacin release from the resin-coated microcapsules was slow over 24 h and depended on core: coat ratio, wall thickness and size of the microcapsules. Drug release was by Fickian diffusion mechanism. Good linear relationships were observed between wall thickness of the microcapsules and release rate and T50 values. Resin-coated microcapsules of indomethacin exhibited good controlled release characteristics and were found suitable for once a day oral controlled release products.

Key words: Colophony, indomethacin, microcapsules, controlled release