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Toxicological study on RU 486

Deraedt, R
Vannier, B
Fournex, R
Toxicological study on RU 486 / R. Deraedt, B. Vannier, R. Fournex.
Reproductive biology
Found In:
Antiprogestin steroid RU 486 and human fertility control, edited by Etienne-Emile Baulieu and Sheldon J. Segal
Country of Publication:
United States
New York, New York, Plenum Press, 1985.
p. 123-126.
At Roussel-Uclaf, in France, researchers conducted animal studies and in vitro studies to examine the toxicity of RU-486. An acute toxicity study showed that 10 male and 10 female mice tolerated RU-486 at a dose of 1 g/kg over 21 days, but 1 of 20 rats died at the same dose over 14 days. Thus, the LD50 of RU-486 should be higher in mice than in rats. Chronic toxicity of oral RU-486 was tested in rats and cynomolgus monkeys. Rats experienced hormonal effects (females, estrus and mammary secretion; males, antiandrogenic effects), even at doses as low as 40 mg/kg. RU-486 apparently affected the antiglucocorticoid properties of 50% of the monkeys, who experienced vomiting, diarrhea, anorexia, weight loss, and increased blood urea. At 6 months, oral daily doses of 5, 25, or 125 mg/kg in 20 male and 20 female rats and oral daily doses of 5, 15, or 45 mg/kg in 5 male and 5 female monkeys caused no deaths. (5 mg/kg corresponds to the mean total dose per day women receive when they use RU-486 for contraception or termination of early pregnancy.) The high doses of oral RU-486 did cause changes in biochemistry, organic weights, and histopathology, however. In monkeys, strong antiprogesterone, antiglucocorticoid, and antiandrogenic properties were likely responsible for these effects. Specific effects were frequent estrus and mammary-gland development in rats; suppression of menstruation, reduction in serum progesterone, increase in serum cortisol and ACTH in monkeys; increase in kidney and adrenal gland weights; and a decrease in prostate and seminal vesicle weights in male rats. Embryotoxicity studies consisted of administration to rats and rabbits of 0.25, 0.5, and 1 mg/kg RU-486 every day during days 6 to 18 of pregnancy. At the highest dose, 6 of 22 rats aborted. RU-486 did not affect mean fetal weight or induce congenital abnormalities in rats (even among surviving fetuses at 1 mg/kg) or rabbits. Neither the Ames test nor the micronucleus test revealed mutagenic or genetic effects of RU-486.
Animals, Laboratory*
Endocrine Glands*
Proceedings of a Conference on the Antiprogestational Compound RU 486, Bellagio, Italy, October 23-25, 1984.
Includes bibliographical references.
2 ref.
Report Number:
Other ID:
101065547 [Book Chapter]

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