FORMULATION AND EVALUATION OF GASTRORETENTIVE FLOATING TABLETS OF VENLAFAXINE HCl

Abstract

The purpose of the present investigation is to formulate gastroretentive floating tablets of Venlafaxine hydrochloride thus increasing its gastric residence time as well as bioavailability and therapeutic efficacy. Venlafaxine HCl having a short biological half-life of 4h is eliminated quickly from the body leading to low therapeutic efficacy. Therefore a sustained release medication was advantageous so as to achieve the prolonged therapeutic effect and to reduce peak and valley effect in plasma concentration. This can be circumvented by formulating modified gastro retentive sustained release dosage forms which resides in the stomach for sufficient time to release the drug in vicinity of the absorption zone. Nine formulations of Venlafaxine HCl tablets were formulated by hot melt extrusion technique (HME) using three polymers like HPMC K15M, Xanthan gum and Guar gum in a various concentrations. Bees wax was used as a melting aid and sodium bicarbonate was used as a gas generating agent. The prepared tablets were evaluated for pre and post compression parameters, buoyancy time, floating lag time and in vitro dissolution study. In vitro dissolution study was carried out in pH 1.2 buffer. It had been found that increase in polymer concentration diminishes drug release profile. The in vitro cumulative % drug release of nine formulations ranged from 88.58 – 99.19 with more than 12h buoyancy. The in vitro drug release of optimised formulation followed Higuchi kinetics and the drug release mechanism was found to be non- fickian type.