A synthetic progestogen; binds to the progesterone, mineralocorticoid, and androgen receptors with binding affinities of 20, 230, and 65% relative to R5020, aldosterone, and R1881, respectively; inhibits spontaneous ovulation in rats (ID50s = 0.3-1.0 mg/day); maintains pregnancy in ovariectomized pregnant rats; reduces serum testosterone and luteinizing hormone in cynomolgus monkeys; inhibits testosterone-induced growth of the seminal vesicles and prostate in castrated rats