Oral and Rectal Thymolytic Activities of Some Anti-Inflammatory Steroids in Weanling Rats

Abstract

Various anti-inflammatory steroids and some of their phosphates, acetates and hemisuccinates have been assayed on intact weanling rats for thymolytic activity by the oral and rectal routes. The percentages of rectal over oral activity were: cortisol and its esters, 19-35; prednisone alcohol, 47; prednisolone and its esters, 29-53; betamethasone and its esters, 73-105; dexamethasone and its esters, 71-82. The 21-acetates of cortisol, prednisolone, betamethasone and dexamethasone had higher ratios of rectal to oral activity than did the parent alcohols and other esters. Prednisolone had a lower ratio to its esters than did cortisol, betamethasone and dexamethasone.The results are compared with published information on the rectal absorption of anti-inflammatory steroids in man.