Formulation, Development and Optimization of Controlled Release Osmotic Tablets of Venlafaxine Hydrochloride

Abstract

Osmotic drug delivery system is a dosage form which follows a zero order release and provides controlled release for longer time in sustained manner. Venlafaxine Hydrochloride an anti depressant BCS class I drug and having bioavailability 45% it undergoes the first pass metabolism. Half life of Venlafaxine HCl is 5 hours so it necessitates for a twice daily dosage regimen which is inconvenient for maintenance therapy in patients. Therefore once a day osmotic tablets formulated and evaluated by using two different coating methods as EOP and Asymmetric membrane coating and done comparative study between EOP and Asymmetric membrane coating. In this study core tablets were formulated with two different osmogens PEG-400 and Mannitol at three level of concentration. Tablets were formulated at different process parameters like concentration of binder solution, different granulation parameters and amount of granulating agent. EOP coating was done with Cellulose Acetate and PEG 400 and while in Asymmetric membrane coating Glycerol was used as a pore forming agent with Cellulose Acetate. Drug release profile of the batches was evaluated for the optimization of osmotic pressure, concentration of coating, permeability of membrane, and concentration of plasticizer. Optimized formulations were studied for the effect of agitation intensity and osmotic pressure. The drug release profiles of all the batches were compared with marketed product Venlafaxine Hydrochloride ER tablets. In comparative study between EOP and Asymmetric membrane coating found that EOP coating was better as compared to asymmetric membrane coating. A Box-Behnken design using statistical software version 7.0 was applied on the batches to get the optimized result. Model fitting of optimized batch confirmed zero order drug release.