Author(s): Shilpa Allabotharam, T. Rama Rao, Mohammed Asif Hussain
The objective of the present study was to formulate and evaluate once-daily sustained release matrix tablets of Stavudine to increase therapeutic efficacy, reduce frequency of administration and improve patient compliance. The sustained release matrix tablets were prepared by wet granulation method and formulated using different drug:polymer ratios and combination of polymers. Matrix tablets of Stavudine were prepared by using Hydroxy Propyl Methyl Cellulose (HPMC K4M), Sodium carboxy methyl cellulose, Ethyl cellulose and natural gums like Xanthum gum, Guar gum, Gum karaya. After fixing ratio of drug and polymer for controlling the release of drug to the desired time, the release rates were modulated by combination of two different rate controlling materials. 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 HCl for 2 hrs and in phosphate buffer pH 7.4 up to 24 hrs. Tablets having combination of HPMC K4M with ethyl cellulose / sodium CMC (F4, F5) gave more sustained release. The release data was fitted to various mathematical models such as Higuchi, korsmeyer-peppas, first order and zero order to evaluate the kinetics and the mechanism of drug release of all the formulations (F1-F8) was found to be diffusion dominated drug release.