Mechanism of in vitro percutaneous absorption enhancement of carvedilol by penetration enhancers.

The effect of penetration enhancers like tulsi (basil) oil, eucalyptus oil, clove oil, black cumin oil, oleic acid and Tween 80 on the percutaneous absorption of model lipophilic drug-carvedilol was investigated using excised rat abdominal skin. Transdermal flux, permeability coefficient and enhancement factor were calculated for each penetration enhancer. Black cumin oil (5% v/v) was selected on the basis of its highest enhancement in permeation and was evaluated further for its mode of action using DSC, FTIR and histological studies. The results indicated that the oil shows its action by extraction of lipids from stratum corneum as well as by loosening the hydrogen bonds between ceramides subsequently leading to fluidization of the lipid bilayer.