DEVELOPMENT AND EVALUATION OF GASTRORETENTIVE DRUG DELIVERY SYSTEM FOR VENLAFAXINE HYDROCHLORIDE AS BILAYER TABLET

Present research work aims to develop venlafaxine hydrochloride gastro retentive tablets for prolonged release and increased gastric retention time. Venlafaxine is an antidepressant of the serotonin nor- epinephrine reuptake inhibitor (SNRI) class. Bioavailability is 45% following oral administration and half life is 5 hours. To study the effect of formulation variables on drug release and buoyancy properties of the sustained release venlafaxine hydrochloride gastro retentive floating drug delivery system, the floating matrix tablets of venlafaxine hydrochloride were prepared by bilayer tablet technology with sustained and floating layers. The different hydrophilic polymers for sustained release layer studied, were HPMC  K 4M, HPMC  K 15M, xanthan gum studied in order to obtain the desired sustained release up to 12 hrs and the effervescent component of floating layer was sodium bicarbonate along with HPMC K 100M. Drug compatibility with excipients was checked by FTIR studies. The formulation optimization batches were studied for physical parameters and floating behavior, dissolution studies and kinetics of drug release. Hardness of tablets was kept 6 kg/cm². The effect of concentration and type of polymer on drug release rate were studied. The optimized formulation was also tested for accelerated stability studies at 40 ⁰C /75% RH for one month and the formulation was checked for drug release study, uniformity of content and floating lag time after 30 days. In vitro buoyancy study results found to be 60 to 70 sec floating lag time and 12 hours total floating time respectively.