A method for the assay of topical corticosteroids.

The dorsal skin of the hairless mouse when 'stripped' with sticky tape proved to be a suitable model for a study of the antimitotic effect of betamethasone-17-valerate and hydrocortisone. The application of 1%, betamethasone-17-valerate and 1% hydrocortisone creams under occlusive dressings for 24 h produced a three- to four-fold drop in the colcemid-induced mitotic index as compared to a control application. The antimitotic effect of the betamethasone-17-valerate preparation started at or before 5 h and continued for at least 4 days after removal of the active material. It was shown in addition, that 1%, betamethasone-17-valerate also reduced the number of cells entering DNA synthesis. The antimitotic effect of hydrocortisone was detected at a concentration of 10^-2 and that of betamethasone-17-valerate was detected at a concentration of 10^-4. It is suggested that the animal model used is a useful one for assaying the potency of topical corticosteroid compounds. [ABSTRACT FROM AUTHOR]