Effects of single intramuscular administration of various preparations of corticosteroids on bentonite-induced oedema of rat hind paw.

Effects of single prophylactic and/or therapeutic i.m. doses of various esters of anti-inflammatory steroids on the bentonite-induced oedema of the rat paw were followed. The short-lasting actions (1 d) of soluble sodium succinate esters of hydrocortisone, prednisolone and 6-methylprednisolone on the one hand, and the long-lasting actions (1 to 2 weeks) of insoluble hydrocortisone acetate, 6-methylprednisolone acetate or cyclopentylpropionate, and triamcinolone diacetate or acetonide on the other hand have been proved. Both the preparations of beta-methasone tested exerted short-lasting effects (1 d). It has been confirmed that triamcinolone acetonide is more effective (and also more toxic) than the diacetate ester of this steroid. The bentonite-induced oedema has proved to be a suitable model of inflammatory reaction for screening anti-inflammatory corticosteroids because it makes possible the determination and differentiation of the time of onset, intensity and duration of action of single doses of various pharmaceutical formulations of these agents.