ATC Group: G03AC Progestogens

Desogestrel is a progestogen. Like other progestogen-only pills, desogestrel is best suited for use during breast feeding and for women who may not or do not want to use oestrogens. In contrast to traditional progestogen-only pills, the contraceptive effect of desogestrel is achieved primarily by inhibition of ovulation. Other effects include increased viscosity of the cervical mucus.

Etonogestrel is the biologically active metabolite of desogestrel, a progestagen widely used in OCs. It is structurally derived from 19-nortestosterone and binds with high affinity to progesterone receptors in the target organs. The contraceptive effect of etonogestrel is primarily achieved by inhibition of ovulation.

The precise mode of action of levonorgestrel as an emergency contraceptive is not known. At the recommended regimen, levonorgestrel is thought to work mainly by preventing ovulation and fertilisation if intercourse has taken place in the preovulatory phase, when the likelihood of fertilisation is the highest.

Lynestrenol is an oral preparation of the synthetic progestagen, which shares various activities with the natural hormone progesterone. Lynestrenol has a strong progestational influence on the endometrium. In addition it suppresses the ovulation and menstruation for as long as the preparation is taken daily without interruption.

Medroxyprogesterone acetate exerts anti-oestrogenic, anti-androgenic and antigonadotrophic effects.

Megestrol possesses pharmacological properties similar to those of natural progesterone. Megestrol acetate is a potent progestogen that exerts significant anti-oestrogenic effects. It has no androgenic or oestrogenic properties.

Norethisterone has progestational actions similar to those of progesterone, but is a more potent inhibitor of ovulation and has weak oestrogenic and androgenic properties. It is used to treat a number of disorders of the menstrual cycle.