Antipyretic activity of prazosin.

Thermal responses to prazosin (0.75 mg/kg, i.v. as a bolus injection or 3 h infusion) were investigated in febrile rabbits (treated with E. coli lipopolysaccharide, PLPS) at 3 ambient temperatures (Ta) of 5, 19, 28 degrees C. The drug produced antipyresis which increased with the simultaneous drop of Ta. This antipyretic activity was accompanied by an inhibition of heat production or enhanced elimination of heat, depending on Ta. It is suggested that antipyresis produced by prazosin is mainly due to the effector part of the thermoregulatory system.