Medroxyprogesterone acetate (INN, USAN, BAN), also known as 17α-hydroxy-6α-methylprogesterone acetate, and commonly abbreviated as MPA, is a steroidal progestin, a synthetic variant of the human hormone progesterone. Medroxyprogesterone acetate (MPA) administered orally or parenterally in the recommended doses to women with adequate endogenous estrogen, transforms proliferative into secretory endometrium. Androgenic and anabolic effects have been noted, but the drug is apparently devoid of significant estrogenic activity. While parenterally administered MPA inhibits gonadotropin production, which in turn prevents follicular maturation and ovulation, available data indicate that this does not occur when the usually recommended oral dosage is given as single daily doses. MPA is a more potent derivative of its parent compound medroxyprogesterone (MP). While medroxyprogesterone is sometimes used as a synonym for medroxyprogesterone acetate, what is normally being administered is MPA and not MP. Used as a contraceptive and to treat secondary amenorrhea, abnormal uterine bleeding, pain associated with endometriosis, endometrial and renal cell carcinomas, paraphilia in males, GnRH-dependent forms of precocious puberty, as well as to prevent endometrial changes associated with estrogens. Progestins diffuse freely into target cells in the female reproductive tract, mammary gland, hypothalamus, and the pituitary and bind to the progesterone receptor. Once bound to the receptor, progestins slow the frequency of release of gonadotropin releasing hormone (GnRH) from the hypothalamus and blunt the pre-ovulatory LH surge.

17α-Hydroxyprogesterone (17α-OHP), or hydroxyprogesterone (OHP), also known as 17α-hydroxypregn-4-ene-3, 20-dione is used under the brand name Gestageno, and has been marketed for clinical use in Argentina. It was indicated for female infertility, hypertrichosis, menstrual disorders, premature labour, threatened or recurrent miscarriage. It is used to properly regulate the menstrual cycle and treat unusual stopping of the menstrual periods (amenorrhea). To help a pregnancy occur during egg donor or infertility procedures in women who do not produce enough progesterone. To prevent estrogen from thickening the lining of the uterus (endometrial hyperplasia) in women around menopause who are being treated with estrogen for ovarian hormone therapy (OHT). To treat a condition called endometriosis, to help prevent endometrial hyperplasia, or to treat unusual and heavy bleeding of the uterus (dysfunctional uterine bleeding) by starting or stopping the menstrual cycle. 17α-OHP is an agonist of the progesterone receptor (PR) similarly to progesterone. In addition, it is an antagonist of the mineralocorticoid receptor (MR) as well as a partial agonist of the glucocorticoid receptor (GR), albeit with very low potency (EC50 >100-fold less relative to cortisol) at the latter site, also similarly to progesterone.