Formulation and In-vitro Evaluation of Once-Daily Sustained- Release Matrix Tablets of Glipizide

The objective of the present study was to formul ate and evaluate once - daily susta ined release matrix tablets of S tavudine to increase therapeutic efficacy, reduce frequency of administration and improve patient compliance. The susta ined release matrix tablets were prepared by wet granulation method and formulated using different drug:polymer ratios and combination of polymers. M atrix tablets of S tavudine were prepared by using Hydroxy Propyl Methyl Cellulose (HPMC K4M ), Sodium carbox y methyl cellulose, E thyl c ellulose and natural gums like Xanthum gum, Guar gum, G um karaya. After fixing ratio of drug and p olymer for control ling the release of drug to the desired time, the release rates were modulated by combination of two different ra te controlling material s . The granules were evaluated for angle of repose, bulk density, Carr’s index and Hausner ’ s ratio . The tablets were also subjected to thickness, weight variation, drug content, hardness , friability and in vitro drug release studies. The granules showed satisfactory flow properties, compressibility and drug content. After evaluation of physical properties of tablets the in vitro drug release study was performed in 0.1 N HC l for 2 hrs and in phosphate buffer pH 7.4 up to 24 hrs. Tablet s having combination of H PMC K4M with ethyl cellulose / sodium CMC (F4, F5) gave more sustained release. The release data was fitted to various math ematical models such as Higuchi, kor smeyer - peppas, first order and zero order to evaluate the kin etics and t he mechanism of drug release of all the formulations (F1 - F8 ) was found to be diffusion dominated drug release.