THE INDUCTION OF WITHDRAWAL BLEEDING WITH QUINESTRADOL (PENTOVIS) IN SPAYED MONKEYS, AND SOME OBSERVATIONS ON ITS EXCRETION AND THAT OF OESTRIOL IN THE URINE

Abstract

SUMMARY: 1. Daily oral administration of between 0·1 and 0·5 mg. quinestradol (3-cyclopentyl ether of oestriol) for 14 days to four spayed monkeys induced macroscopic uterine haemorrhage in three and microscopic bleeding in the fourth. This is in marked contrast to the finding that in women this compound seems to act only on the lower genital tract and does not cause uterine withdrawal bleeding. Oestriol, given in the same way at a daily dosage of 0·82 mg., also induced withdrawal bleeding in one monkey. 2. The urinary excretion of quinestradol and oestriol was studied in two of the monkeys and that of quinestradol alone in a post-menopausal woman. The findings indicate that some quinestradol is excreted as oestriol, which in monkeys, unlike women, appears to be unconjugated. 3. Possible reasons for the observed differences in the biological effects of quinestradol in the two species are briefly discussed.