Transdermal delivery of venlafaxine hydrochloride: the effects of enhancers on permeation across pig ear skin

Venlafaxine representing a new class of antidepressants is a potent serotonin/ norepinephrine reuptake inhibitor. Transdermal delivery of venlafaxine hydrochloride (VHCl) may result in proper patient compliance by reducing the incidence of the undesirable GI problems generally associated with its plural oral dosing. The present study is an attempt to investigate the improvement of the transdermal flux of the hydrophilic VHCl by certain permeation enhancers viz. glycerin, urea, propylene glycol and mixture of propylene glycol and ethanol across pig ear skin. The cumulative drug release was the highest from the formulation F5 consisting of the mixture of propylene glycol and ethanol in sodium alginate gel with a load of 25% w/w VHCl with 96% permeation enhancement. The steady state flux observed with F5 was 0.203 mg cm(-2) hr and an area of 15.27 cm(2) would suffice to arrive at a required therapeutic concentration of VHCl in the blood.