Formulation, In Vitro Optimization and In Vivo Evaluation of Sustained Release Transdermal Patches of Venlafaxine Hydrochloride

Recently, transdermal drug delivery systems (TDDS) attracted a great interest in pharmaceutical research owing to their marked patient compliance and low side effect. Venlafaxine hydrochloride (VFH), a novel antidepressant drug, showed extensive metabolism following oral administration. Venlafaxine hydrochloride TDDS were developed utilizing various polymers including ethyl cellulose (EC), hydroxypropylmethyl cellulose (HPMC) and cellulose acetate phthalate (CAP) with and without a penetration enhancer. Visual inspection, physicomechanical evaluation, in vitro drug release, skin permeation and in vivo drug evaluation though forced swimming and tail suspension tests were performed. Smooth patches with acceptable physicomechanical characters were obtained. Based on in vitro drug release profile, F6 (EC/HPMC, 3:1) and F8 (EC/CAP, 2:1) with and without 10% geraniol as penetration enhancer were selected for skin permeation studies. Geraniol successfully enhanced VFH skin permeation by 1.5 and 1.7 folds for F6 and F8, respectively. The in vivo antidepressant activity was evidenced by the significant reduction in the animal's duration of immobility.