Inhibition of ovarian, placental, and adrenal steroidogenesis in the rhesus monkey by trilostane.

Trilostane inhibits adrenal, ovarian, and placental steroidogenesis when administered orally to rhesus monkeys. By inhibiting 3 beta-hydroxysteroid dehydrogenase activity, it causes an increase in circulating levels of pregnenolone. Trilostane reverses the stimulation of luteal progesterone production and the delay in onset on menstruation induced by human chorionic gonadotropin. In pregnant monkeys it reduces circulating progesterone levels and is an effective interceptive agent if given for 5 days beginning on day 16, 25, or 50 of gestation. Concurrent administration of progesterone prevents this interceptive effect. Trilostane reduces plasma cortisol levels at doses lower than those necessary to terminate pregnancy.