AGE, CONFINEMENT AND AGGREGATION AS FACTORS IN AMPHETAMINE GROUP TOXICITY IN MICE

¹ Research Department, CIBA Pharmaceutical Company, Summit, New Jersey

To demonstrate the importance of age as a factor in amphetamine group toxicity, LD50 values were obtained for male CF1 mice, weighing 9 to 13 and 25 to 30 g, in isolated and grouped situations. When the older animals were placed in groups of five, the LD50 value was much lower than that for animals of the same age in the isolated situation. Dose-response curves were not parallel, which might indicate different causes of death. However, LD50 values were approximately the same (and dose-response curves parallel) for the younger mice whether isolated or in groups of five. Reducing the area of the cage by one-half did not affect the grouped toxicity in the 9- to 13-g mice. On the other hand, doubling the number of animals per cage did markedly increase the toxicity of amphetamine for the younger mice.