Effects of the Antiprogesterone Steroid RU 486 during Midluteal Phase in Normal Women

Abstract

1) RU 486, given to normally cycling women at midluteal phase, provokes uterine bleeding. 2) This effect occurs whether or not luteal regression is induced by the compound, indicating that RU 486 acts directly upon the endometrial tissue, very likely at the progesterone receptor level. 3) The drug may impair simultaneously or separately luteal function and gonadotropin secretion in a dose-dependent manner. 4) The lack of antiglucocorticosteroid activity, at the dosage of 100 mg/day, suggests that RU 486 may be useful for fertility control.