Pharmacology and toxicology of diflunisal.

1 Diflunisal, a new salicylate, possesses anti-inflammatory, analgesic and antipyretic activity. It was found to be about 7.5-13 times more active than aspirin as an analgesic (Randall-Selitto assay in rats) and as an anti-inflammatory agent (carrageenin foot oedema and adjuvant arthritis in rats). 2 Diflunisal was 1.4 times as active as aspirin as an antipyretic in the rat and about three times as potent in reducing lameness induced by injecting urate crystals into the knee joint of dogs. 3 Diflunisal inhibited adenosine diphosphate, adrenaline and thrombin-induced aggregation of human platelets in vitro. The concentrations required were 18-35 times higher than those needed with aspirin.