Study on multilayer ethylcellulose matrices for controlled release of benzoic acid

Abstract

Matrix devices based on ethyl cellulose (EC) for controlled release (CR) applications were investigated for zero order release. These matrices were prepared by solvent casting and contained three or five layers arranged in symmetrical fashion with benzoic acid (BA) loaded only in inner layers; while the outermost layers were kept free from BA. It was found that

three layer matrices maintain high release rates inspite of outer barrier layer and heavy initial release (burst effect) was significantly induced: but linear release profile was not obtained. In five layer matrices four type of drug distribution profiles were tested and it was found that descending staircase type concentration gradient gave linear release profile. with enhanced

release duration and reduced burst effect.