Penetration of various corticosteroids through epidermis in vitro.

The penetration through the epidermis in vitro of various topically used corticosteroids was compared. The amount penetrating through the epidermis from an ethanolic solution showed good correlation with the polarity of the corticosteroids under study. Hydrocortisone, the most polar corticosteroid, penetrates the epidermis the most rapidly; clobetasone butyrate, the least polar, the slowest. Other corticosteroids, i.e., hydrocortisone-17-butyrate, triamcinolone acetonide, and clobetasol-17-propionate, form an intermediate group whose penetration rates and polarities decrease in the indicated sequence. The corticosteroid generally accepted as having greater clinical efficacy in creams or ointments did not permeate better from an ethanolic solution in vitro.