ATC Group: G03A Hormonal contraceptives for systemic use

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.

Estetrol demonstrates anti-gonadotropic activity characterised by a dose-dependent decrease in both serum follicle-stimulating hormone (FSH) and luteinizing hormone (LH) levels. The progestogen drospirenone possesses progestagenic, antigonadotropic, antiandrogenic and mild antimineralocorticoid properties and has no oestrogenic, glucocorticoid or antiglucocorticoid activity. These properties are pharmacologically similar to the natural hormone progesterone. The contraceptive effect of drospirenone/estetrol is based on the interaction of various factors, the most important of which is inhibition of ovulation.

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.

Ulipristal is an orally-active synthetic selective progesterone receptor modulator which acts via high-affinity binding to the human progesterone receptor. When used for emergency contraception the mechanism of action is inhibition or delay of ovulation via suppression of the luteinising hormone (LH) surge. Pharmacodynamic data show that even when taken immediately before ovulation is scheduled to occur (when LH has already started to rise), ulipristal acetate is able to postpone follicular rupture for at least 5 days.