FORMULATION DEVELOPMENT AND EVALUATION OF VALACYCLOVIR HYDROCHLORIDE SUSTAINED RELEASE MATRIX TABLETS

The present work is aimed at preparing and evaluating sustained release (SR) matrix tablets of valacyclovir hydrochloride (VH) using different polymers ethylcellulose (EC), hydroxypropyl methylcellulose (HPMCK100, HPMCE4PREMIUM), polyvinylpyrrolidone (PVPK 90), xanthum gum (XG) and Sodium carboxy methyl cellulose (NaCMC). In addition, the effect of different diluents (Micro Crystalline Cellusose MCC, Lactose, Di Calcium Phosphate DCP) on drug release was evaluated considering the method of preparation. A total of 18 different formulations were formulated (F1- F18). The blend of all formulations was evaluated for various precompression parameters like angle of repose, bulk density, tapped density, compressibility index, Hausner’s ratio and were found to be satisfactory. The tablets were evaluated for various parameters like weight variation, thickness, hardness, friability, wetting time, water absorption ratio, disintegration time, content uniformity and in vitro drug release. The data was subjected to kinetic analysis and the mechanism of the release was established. The results demonstrated that combination of both hydrophobic and hydrophilic polymers could be successfully employed for formulating sustained release matrix tablets of valacyclovir hydrochloride. The formulation containing drug, polymer (EC) and DCP as a diluent extended the drug release for 22 to 24 hours (R²=0.9989) which was established by subjecting the invitro release data to  peppas korsmeyer kinetic analysis. The drug release rate was good with the tablets containing hydrophobic ethylcellulose (EC) polymers compared to with that of hydrophilic polymers (HPMC K 100M and E 4 premium). Erosion was established to be the predominant mechanism of release.