Bioavailability of clobetasol propionate in different vehicles

Topical clobetasol propionate is widely used for the treatment of psoriasis. One formulation of clobetasol propionate, Skin Cap, was thought by some practitioners and patients to be more effective than other formulations. Differences in corticosteroid bioavailability could account for differences in efficacy. The purpose of this study is to compare the relative bioavailability of clobetasol propionate from Skin Cap to two FDA-approved formulations of clobetasol propionate (Olux foam and Temovate scalp application). The bioavailability was assessed by measuring the percutaneous absorption of clobetasol propionate in vitro on scalp skin, using the human cadaver skin model. There was no significant difference in the percutaneous absorption of clobetasol propionate between Olux foam and Skin Cap (2.09 and 1.93% at 48 h, respectively) or between Olux foam and Temovate scalp application (3.70 and 3.46%, respectively) when applied under unoccluded conditions. Under occluded conditions, there was greater absorption of clobetasol propionate from the Olux foam as compared with Skin Cap (4.94 and 1.57%, respectively; p < 0.05). The Skin Cap vehicle does not provide more bioavailable clobetasol propionate than currently available, FDA-approved products. Other differences, including those in patient compliance, could account for the perceived efficacy of the product.