Hyperpyrexia as a contributory factor in the toxicity of amphetamine to aggregated mice.

A rise of body temperature into a range lethal to mice preceded death in groups of mice injected with amphetamine sulphate. At dose levels from 8.8 to 66.7 mg/kg, mortality was associated with the extent of rise in body temperature of the mice, irrespective of the actual dose administered. Isolated mice given comparable doses of amphetamine also showed a marked increase in body temperature. However, except in a very few cases, it did not rise into the range found to be lethal. Amphetamine was more toxic to isolated mice subjected to foot-shock than to isolated mice housed under normal conditions. This has also been shown to be related to the extent of rise in body temperature of the mice. The effect of a number of substances on grouped amphetamine toxicity was investigated. Chlorpromazine and phenoxybenzamine partially antagonized the sharp rise in temperature following the administration of amphetamine, and also significantly reduced mortality. Calcium acetylsalicylate was without effect on the rise of body temperature or on mortality. Both the hypothermic compound 4-methyl-5-(beta-chlorethyl)-thiazole (S.C.T.Z.) and L-thyroxine sodium potentiated the rise in temperature and caused a significant increase in mortality.