Carrageenin-Induced Edema in Hind Paw of the Rat as an Assay for Antiinflammatory Drugs

A method is presented for measuring the edema induced by injection of 0.05 ml of 1% solution of carrageenin, an extract of Chondrus, into the plantar tissues of the hind paw of the rat. Peak edema develops within the first 3 to 4 hours, and is inhibited by pretreatment of the animals by single oral doses of antiinflammatory agents, steroid or non-steroid. Log dose responses to drugs are linear and parallel, and yield potency ratios with relatively narrow confidence limits. The potency ratios obtained for aspirin, phenylbutazone and hydrocortisone are fairly close to the ratios of their respective daily doses in the treatment of rheumatic disease. A potent antihistaminic-antiserotonin compound, cyproheptadine, is without effect on carrageenin-induced edema.