Progestagen

Progestagens (also spelled progestogens or gestagens) are hormones which produce effects similar to progesterone, the only natural progestagen. All other progestogens are synthetic and are often referred to as progestins.

All progestagens have antiestrogenic (counteracting the effects of estrogens on the body) and antigonadotropic (inhibiting the production of sex steroids by gonads) properties.

Progestogens differ in their potency (affinity for progesterone receptors) and side effects. Such side effects may be androgenic (medroxyprogesterone and most C19 progestagens), antiandrogenic (cyproterone acetate), estrogenic, glucocorticoid (some C21 progestogens) or antimineralocorticoid (progesterone).

Birth control

 * Progestogens are used alone in progestogen only pills, or with an estrogen in combined oral contraceptive pills, a contraceptive patch, and a contraceptive vaginal ring.
 * Medroxyprogesterone acetate (Depo-Provera) and norethindrone enantate (Noristerat) are used by depot injection.
 * Etonogestrol is released by subcutaneous implants (Implanon). Norplant and Jadelle implants release levonorgestrel.
 * Levonorgestrel is released by the intrauterine system IUS (Mirena).

Antiandrogen
Cyproterone is an antiandrogen.

Progestogen withdrawal bleeding
In a normal menstrual cycle, a sudden drop in progesterone levels triggers menstruation. Norethindrone acetate (brand name Aygestin) and medroxyprogesterone acetate (brand name Provera) may be used to artificially induce progestogen withdrawal bleeding.