Polymyxin B-induced oedema in hind paw of the rat as an assay for antiinflammatory drugs.

A method is presented for measuring the volume of the oedema induced by intraplantar infection of polymyxin B, a polyenic antibiotic, in the hind paw of the rat. Peak values of the oedema reached the maximum within 30 min to 1 h after injecting the drug and decreased with time until the 24th h, when it had almost disappeared. The phlogogenic effect of polymyxin B seems to be related to that induced by serotonin and histamine, rather than to the reaction provoked by carrageenin or prostaglandins. The oedema was inhibited by pretreating the animals p.o. with both steroidal and non-steroidal antiinflammatory agents. The inhibitory effect of antiinflammatory drugs was found to be dose-dependent.