Triclosan: release from transdermal adhesive formulations and in vitro permeation across human epidermal membranes

Malarial resistance is an escalating global problem and consequently new and more efficacious treatments to combat malaria are urgently needed. The transdermal delivery of anti-malarials may provide an effective alternative or adjunct to conventional regimens. Triclosan is widely used as an anti-bacterial agent and it has recently been demonstrated that this compound has anti-malarial properties. Its high lipophilicity makes it a potential candidate for delivery across the skin and this paper examines in vitro the potential for the transdermal delivery of triclosan from 'drug-in-glue' formulations. Model patches were prepared using DuroTak 2287, 2516 and 2051 acrylic polymer adhesives loaded with 0, 30 and 50 mg per 0.785 cm(-2) triclosan and dissolution was measured over a 12-h period. There was no apparent difference between the adhesives at the 30 mg patch loading, but at 50 mg, the trend for increased release was 2051>2516>2287. No significant burst effect was apparent. Patches of 50 mg per 0.785 cm2 were then used to determine the permeation of triclosan across heat-separated human epidermal membranes in Franz diffusion cells, over a period of 48 h. The above general trend was reflected in the steady state flux values obtained: 2051:16.91 microg x cm(-2) x h(-1) (S.E.M. 1.29), 2516:15.05 microg x cm(-2) x h(-1) (S.E.M. 1.00), 2287 12.83 microg x cm(-2) x h(-1) (S.E.M. 2.81). Although pharmacokinetic data are not currently available to permit calculation of an efficacious patch size, the transdermal delivery of triclosan is feasible.