Azastene (INN, USAN) (developmental code name WIN-17625) is a steroidogenesis inhibitor described as a contraceptive, luteolytic, and abortifacient which was never marketed. It acts as a competitive inhibitor of 3β-hydroxysteroid dehydrogenase (IC50 = 1 μM), and thereby inhibiting the formation of progesterone, corticosteroids, androgens, and estrogens.