Mifepristone, (
RU 486, Roussel Uclaf, Romainville, France), a
progesterone (P) receptor blocking agent, and
Epostane, (WIN 32,729, Sterling-Winthrop, Guildford, United Kingdom), a P synthesis inhibitor, were compared for their ability to terminate early human pregnancy. Seventy-eight healthy women, with a gestational length of less than 49 days from the last menstrual period and who requested termination of pregnancy, were recruited to the study. The patients were randomly allocated to three treatment regimens: (1)
Mifepristone 25 mg bid for 7 days; (2)
Mifepristone 50 mg bid for 7 days; and (3)
Epostane 200 mg qid for 7 days. The results of the study confirmed that both compounds are potent
abortifacients in early human pregnancy. No difference in efficacy was seen between the two dose regimens of
Mifepristone, which both resulted in 61% complete abortions. Seventy-three percent aborted completely in the
Epostane group. Subjective side effects, especially
nausea, were more common in the women treated with
Epostane, but no serious side effects were seen.