PLASMA-CONCENTRATIONS OF BETAMETHASONE AFTER TOPICAL APPLICATION OF BETAMETHASONE 17-VALERATE - COMPARISON WITH ORAL-ADMINISTRATION

Plasma concentrations of betamethasone were measured by r.i.a. after o ral administration of 0.6 mg betamethasone and topical application of betamethasone 17-valerate in the same five healthy subjects. Betametha sone 17-valerate was prepared as a suspension in medical grade pressur e sensitive adhesive and applied to a 100 cm2 area on the back for 28 h. Mean maximum plasma concentrations were 5.0 and 0.24 ng ml-1 and me an AUC values were 75.4 and 7.74 ng ml-1 h after oral and topical admi nistrations, respectively. The mean plasma elimination half-life of be tamethasone after the removal of topical betamethasone 17-valerate was 16.6 h which was twice that after oral administration, 8.1 h. Betamet hasone 17-valerate may require application to the skin more than twice daily.