Intrinsic potencies of novel thiol ester corticosteroids RS-85095 and RS-21314 as compared with clobetasol 17-propionate and fluocinonide.

The intrinsic potencies of two novel topical thiol ester corticosteroids, RS-85095 and RS-21314, were compared with the high potency corticosteroids clobetasol 17-propionate and fluocinonide, using human vasoconstriction assays. In these assays, four or five concentrations (0.03 to 3 mg/L) of the corticosteroids in 95% ethanol (alcohol, USP) were applied to predetermined sites on the forearm of volunteers and were occluded following evaporation of the alcohol. The responses were scored in terms of the presence or absence of vasoconstriction and the degree of vasoconstrictive intensity. No statistically significant difference was found in the intrinsic potencies of RS-85095, RS-21314, and clobetasol 17-propionate, and all three corticosteroids were significantly more potent than fluocinonide.