Decreases in spontaneous tumors in rats and mice after treatment with amphetamine

Toxicology and carcinogenesis studies of dl-amphetamine sulfate, a drug used in the treatment of weight control, narcolepsy, and behavioral syndromes in children, were performed in F344/N rats and B6C3F1 mice. In these studies, amphetamine was administered for 2 years at doses of 0, 20, or 100 ppm in the feed to groups of 50 animals/dose/sex/species. The average amount of amphetamine consumed per day was estimated to be 1 or 5 mg/kg for low or high dose rats, 4 or 30 mg/kg for low or high dose male mice, and 3 or 19 mg/kg for low or high dose female mice. Survival was similar in dosed and control groups. The most notable effect of long-term treatment with this drug was the reduction of body weight in comparison to controls, and reduction in spontaneous tumors including pheochromocytomas of the adrenal gland in male rats, fibroadenomas of the mammary gland in female rats, adenomas of the anterior pituitary gland in male and female rats and female mice, endometrial stromal polyps of the uterus of female rats, adenomas or carcinomas of the liver in male and female mice, adenomas of the Harderian gland in male and female mice, and adenomas or carcinomas of the lung in male and female mice. Decreases in spontaneous tumors have previously been seen in 2-year rodent studies in groups of animals that have a reduced body weight in comparison to controls, but the spectrum of reduction in spontaneous neoplasms after treatment with amphetamine is broader than has previously been observed.