Structure-activity relationships of a series of novel topical corticosteroids

The effect of various heteroaroyl groups in the 17-position of topical corticosteroids has been studied. The corticosteroids esterified at C17 were of 9 alpha,11 beta-dichloro, 9 alpha-chloro 11 beta-hydroxy and 9 alpha-fluoro 11 beta-hydroxy series. Among the 17-acyl groups 2'-furoates were most extensively investigated, although 2'-thenoates, 3'-thenoates and 3'-furoates were also examined. Many of these esters exhibited enhanced topical anti-inflammatory potencies. The most potent compounds investigated were the 21-chloro 17(2'-furoates) either in the 9 alpha,11 beta-dichloro, or in the 9 alpha-chloro 11 beta-hydroxy series. These compounds were at least 6 times as potent as betamethasone 17-valerate. Among 16-substituents studied 16 alpha-methyl compounds had the highest potency. Topical anti-inflammatory potencies were determined by using a 5-day modification of the croton oil ear assay in mice. The more potent compounds were also evaluated in the P. ovale induced chronic psoriaform lesion in the guinea-pig.