Abstract

These experiments were designed to examine the antipyretic effects of acetaminophen and sodium salicylate given i.v. on fevers caused by bacterial endotoxin, administered either intracerebroventricularly or i.v., in light of recent reports which suggest that various antiinflammatory antipyretics may act peripherally to limit availability of leukocytic pyrogen rather than centrally. Cats were prepared chronically for recording of body core temperature and for i.v. and intracerebroventrimilar injections. Acetaminophen effectively inhibited fever produced by endotoxin, given by either route, in doses as low as 10 mg/kg. The magnitude of the antipyretic effect was dose related. These results are consistent with a central antipyretic action of acetaminophen. Sodium salicylate was much less effective than acetaminophen, producing a significant effect against i.v. endotoxin only with 50 mg/kg and requiring 100 mg/kg to reduce fever significantly after intraventricular endotoxin. Possible explanations for these antipyretic effects of salicylates are briefly discussed.