Design and evaluation of sustained-release matrix once daily formulation of stavudine

The aim of the present study was to formulate once daily sustained release matrix tablets of Stavudine to increase therapeutic efficacy, reduce frequency of administration and improve patient compliance. The sustained release tablets were prepared by direct compression and formulated using different drug: polymer ratios, formulations such as F1to F15. Hydrophilic polymers like Hydroxy propyl methyl cellulose (HPMC), Carboxymethyl cellulose (CMC) and Starch 1500 were used. Compatibility of the drug with various excipients was studied. The compressed tablets were evaluated and showed compliance with pharmacopoeial standards. Formulation containing Stavudine:HPMCK15: Na-CMC (1:2:0.5) with hardness 10-11kg/cm2 showed the desired release profile which matched the theoretical release profile. SEM studies of the formulations were carried out for the confirmation of mechanism of drug release. The in vitro drug release characteristics were studied in both simulated gastric and intestinal fluids for a period of 24 hr using USP Type 2 dissolution apparatus. Mathematical analysis of the release kinetics indicated a coupling of diffusion and erosion mechanisms. The study proves that the developed sustained release tablet is capable of releasing the drug in a sustained manner for 24 hr. Keywords: Sustained release; Matrix tablets; Hydroxy propyl methylcellulose; Stavudine