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.

Flumethasone 21-acetate is an anti-inflammatory corticosteroid. It has 300 times greater anti-inflammatory activity and 677 times greater capacity to promote liver glycogen deposition than hydrocortisone. It has anti-rheumatic potency 31 times higher than cortisol.

Alkeus Pharma's lead compound, ALK-001, is an oral compound with a well-understood mechanism of action. ALK-001 was specifically designed to prevent the formation of these toxic vitamin A dimers in the eye. ALK-001 is a chemically-modified vitamin A, in which 3 hydrogen atoms have been replaced by 3 deuterium atoms at carbon number 20. Replacing the retina's vitamin A with ALK-001 slows the formation of toxic vitamin A dimers. ALK-001 is in phase II clinical trials for the treatment of Stargardt's disease. The compound was co-developed by Alkeus Pharmaceuticals and Columbia University.