Endocrine properties of RMI 12,936, an antiprogestational steroid

RMI 12,936 (17 beta-hydroxy-7 alpha-methyl-5-androstene-3-one) exhibited postcoital contragestative activity at 10 mg/kg in hamsters. The endocrinological profile was determined for this steroid. This antifertility agent had significant antiprogestational, antiuterotrophic and gonadotropin-inhibiting activity. RMI 12,936 also exhibited weak uterotrophic and androgenic properties when given to immature gonadectomized rats. Hormonal antagonism and weak estrogen agonist properties would appear to contribute to the contragestative activity of RMI 12,936 in hamsters.