Relation of application time to bioactivity of a potent topical glucocorticoid formulation.

The vasoconstrictor assay in human beings was used to assess bioavailability during different time periods of exposure when 0.05% clobetasol propionate cream (Temovate) was applied and left on for periods of 0.5, 1.0, 1.5, and 16.0 hours and subsequently washed. Maximal responses were achieved by 1.5 hours of exposure, but there was no significant difference in intensity of vasoconstriction between 1.0, 1.5, and 16.0 hours of exposure before washing the sites. Exposures to 0.05% clobetasol propionate cream for 0.5 hour were not significantly different from 16-hour exposures to 0.05% fluocinonide cream, but exposures to 0.05% clobetasol propionate cream for 1.0, 1.5, and 16.0 hours all resulted in significant increases in vasoconstriction responses compared with fluocinonide cream applied and left on for 16 hours. Topical exposures to a superpotent topical steroid for a short time give vasoconstrictor responses equivalent to long time exposures.