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Preparation and Evaluation of Olibanum Resin Coated Microcapsules for Controlled Release of Diclofenac

K. P. R. Chowdary and S. B. Dana

The objective of the study is to evaluate olibanum resin, a natural resin as a coat for controlled release microcapsules of diclofenac. Olibanum resin coated microcapsules were prepared by an emulsionsolvent evaporation method employing different proportions of core and coat and the microcapsules were evaluated for size, drug content and microencapsulation efficiency, wall thickness, surface character by SEM and drug release kinetics. The olibanum resin coated microcapsules prepared were found to be discrete, spherical and free flowing. Drug content was uniform (c.v. ≤ 0.193%) in each batch of microcapsules and the microencapsulation efficiency was in the range 33.92- 81.34%. Diclofenac release from the olibanum resin coated microcapsules was slow and spread over a period of 24 h and depended on core : coat ratio, wall thickness and size of the microcapsules. Drug release from these microcapsules was majorly by non-Fickian diffusion. Good linear relationships were observed between wall thickness of the microcapsules and release rate (K0) and (K1). Microcapsules prepared employing chloroform as solvent for olibanum exhibited higher release rates, when compared to those prepared employing dichloromethane as solvent. Olibanum resin was found to be a new and efficient microencapsulating agent for controlled release microcapsules and the olibanum resin coated microcapsules exhibited good controlled release characteristics and were found suitable for oral controlled release of diclofenac over 24 h.