Vasoconstrictor activities and bio-availabilities of seven proprietary corticosteroid creams assessed using a non-occluded multiple dosage regimen; clinical implications.

The bio-availabilities and activities of commercial creams (Metosyn, Synalar, Betnovate, Locoid, Alphaderm, Dioderm and Efcortelan 1%) were assessed using a multiple dosage regimen vasoconstrictor assay in ten volunteers. The blanching response first increased but then diminished with continued application over a 5-day period: following a 2-day 'resting period', when no steroid was applied, the application sites recovered considerably but tachyphylaxis again resulted from subsequent repeated applications. Acute tolerance occurred with the hydrocortisone formulations (Alphaderm, Dioderm and Efcortelan 1%) in a manner similar to that observed with the potent preparations. Metosyn was significantly more active (P less than 0.05), and Efcortelan 1% was significantly less active (P less than 0.05), than the other formulations. Apart from the reversal of Dioderm and Alphaderm the rank order of preparations was similar to that previously noted in the 6 h occluded single-application vasoconstrictor test. The results may have significance in dosage from design and application for topical corticosteroid formulations.