nvestigation of Two Naturally Occurring Hydrophilic Matrix Materials for Oral Controlled Drug Delivery Systems

R T J Chigwanda; I Pfaira

R T J Chigwanda Department of Pharmacy, Faculty of Medicine, University of Zimbabwe, P.O. Box MP 167„ Mt. Pleasant, Harare, Zimbabwe
I Pfaira Department of Pharmacy, Faculty of Medicine, University of Zimbabwe, P.O. Box MP 167„ Mt. Pleasant, Harare, Zimbabwe

Keywords: Hydrophilic matrix, Controlled release,

Abstract

The purpose of the present study was to investigate two naturally occurring hydrophilic matrix materials, ginn tragacanth and agar, for controlled release characteristics. All the tablets prepared were 250 mg and contained 40% w/w drug. Dissolution studies were carried out using the USP rotating basket method. Gum tragacanth was found to possess appreciable release sustaining characteristics depicted by drug release over a 5 hour period. In contrast drug release from agar matrices was complete within 30 minutes. However, matrices made from a combination of gum tragacanth and agar possessed controlled release properties of 2-3 hours. Drug release from gum tragacanth matrices was best explained by the Higuchi mechanism. There was a gradual change in the release on combining the two matrix materials from Higuchi mechanism to first order mechanism. However, coating one face of the gum tragacanth:agar (1:1) matrices with ethylcellulose improved zero order kinetics of the matrices. This study showed that oral controlled release devices of the release sustaining type can be easily prepared from cheap naturally occurring hydrophilic materials.