In Vitro Evaluation of Controlled Release Matrix Tablets of Glipizide and Effect of Different Parameters

Controlled release drug delivery systems reduce dosage frequency and ultimately results in improved patient compliance with once a day dosing. Glipizide directly compressed controlled release matrix tablets were designed at different drug-to-polymer ratios (D: P) 10: 1. 10: 2, and 10: 3 using polymeric blend of Eudragit RS 100 and Carbopol P 974 NF and in some selected formulations 10% of filler was replaced by co-excipients, acacia and guar gums. Various parameters like flow properties, in vitro dissolution, effect of above mention co-excipients, effect of drug-to-polymer ratio, effect of wet granulation and release kinetic and dissolution profile comparison was evaluated. In vitro dissolution was conducted in phosphate buffer (pH 7.4). Drug release kinetic and dissolution patterns comparison was also determined. It was found that this polymeric blend extended the glipizide release rates up to 24 h and an increase in D: P ratios resulted in more extended the release rates. The drug was released by anomalous non-fickian diffusion and co-excipients enhanced the drug release rates. Wet granulation method more extended the release rates than direct compression method. It is concluded from this study that controlled release matrix tablets is an economical approach for extending drug release rates and with patient compliance.