A Bio-ass ay for the Concomitant Assessment of the Antiphlogistic and Thymolytic Activities of Topically Applied Corticoids

Abstract

A reliable laboratory assay for rapidly quantitating the topical anti-inflammatory efficacy of steroids has been established. Croton oil, applied topically to the rat ear, elicited an acute phlogistic response which could be quantitated by removal and weighing of the ear 6 hr later. Co-application of increasing concentrations of corticoids resulted in grossly related decreases of the phlogistic responses; removal of thymi 48 hr subsequent to application permitted assessment of systemic action. The topical antiphlogistic effects of hydrocortisone, cortisone, corticosterone, prednisolone, 6[alpha]-methylprednisolone and triamcinolone grossly paralleled their thy-molytic activities. Utilizing the topical assay methodology, 9[alpha], 11[beta]-dichloro-21-hydroxy-16[alpha], Vi[alpha]-(isopropylidenedioxy)-1,4-pregnadiene-3,20 dione exhibited an antiphlogistic potency of 23.2 relative to hydro-cortisone, while the relative thymolytic potency was less than 1.0.