Evaluation of Two Olibanum Resins as Rate Controlling Matrix Forming Excipients in Oral Sustained Release Tablets

Abstract

Olibanum is an oleo-gum resin which is economically and culturally valuable product obtained from several species of the genus Boswellia. In this study, the resins extracted from local olibanum: Boswellia papyrifera (Tigray type) and Boswellia rivae (Ogaden type) were evaluated as matrix forming agents in sustained release tablet formulations employing diclofenac sodium as a model drug. Some physico-chemical characterization of the resins revealed low solubility, moisture content and swelling ratio. Sustained release matrix tablets containing 100 mg of diclofenac sodium were then prepared using different proportions of the olibanum resins by wet granulation and direct compression methods, and evaluated for their pharmacotechnical properties and in vitro drug release kinetics. Both resins produced matrix tablets with acceptable weight variation, hardness and friability. Dissolution studies showed that the olibanum resins sustain the drug release beyond 12 h. Drug release from the olibanum resins matrix tablets were best fitted to the Korsmeyer-Peppas model with the mechanism of drug release generally following non-Fickian diffusion process. Diclofenac release profiles from some of the formulated tablets were comparable to that of the commercial sustained release tablet Diclo-Denk® Retard.

Keywords: Olibanum resin, matrix tablet, diclofenac sodium, sustained release, release kinetics