Investigation of Theophylline Release Kinetics from Carbopol 940P Sustained Release Matrix Tablets

Abstract

The hydrophilic matrix material, Carbopol 940P, has not been extensively investigated for drug release as the other polymers such as Carbopol 971P and 934P. The present study was aimed at investigating the release kinetics of a highly soluble drug, theophylline, from Carbopol 940P only without the addition of any other ingredient or excipient. Drug release from these matrices was analysed according to Higuchi, first order and zero order release kinetics. At low drug loading (20 %), release was mainly diffusion-controlled as the release pattern was best explained by square root of time kinetics (Higuchi mechanism). However, at higher drug loading (30 % and 40 %), constant release rates were obtained as shown by zero order kinetics explaining the release data best. Constant release rates are most desirable with controlled or sustained release devices. This ensures that constant drug levels in the blood/body are achieved. Carbopol 940P demonstrated that it is applicable in the fabrication of a controlled release matrix that is simple, easy to prepare and cost effective.