Levonorgestrel is a synthetic progestogen used as an active ingredient in some hormonal contraceptives. Target: Progesterone Receptor A synthetic progestational hormone with actions similar to those of progesterone and about twice as potent as its racemic or (+-)-isomer (norgestrel). It is used for contraception, control of menstrual disorders, and treatment of endometriosis. It is usually supplied in a racemic mixture (Norgestrel, 6533-00-2). Only the levonorgestrel isomer is active. Levonorgestrel is marketed mostly as a combination oral contraceptive under several brand names such as Alesse, Triphasil, and Min-Ovral .