Ethinyl estradiol is a synthetic derivative of the natural estrogen estradiol. It is one of two estrogens currently used in oral contraceptive pills. The other, mestranol, is converted to ethinyl estradiol before it is biologically active. Ethinyl estradiol and norethindrone are used together as an oral contraceptive agent. Estrogens diffuse into their target cells and interact with a protein receptor. Target cells include the female reproductive tract, the mammary gland, the hypothalamus, and the pituitary. Estrogens increase the hepatic synthesis of sex hormone binding globulin (SHBG), thyroid-binding globulin (TBG), and other serum proteins and suppress follicle-stimulating hormone (FSH) from the anterior pituitary. This cascade is initiated by initially binding to the estrogen receptors. The combination of an estrogen with a progestin suppresses the hypothalamic-pituitary system, decreasing the secretion of gonadotropin-releasing hormone (GnRH). Used for treatment of moderate to severe vasomotor symptoms associated with the menopause, female hypogonadism, prostatic carcinoma-palliative therapy of advanced disease, breast cancer, as an oral contraceptive, and as emergency contraceptive.

Estradiol benzoate is the synthetic benzoate ester of estradiol, a steroid sex hormone vital to the maintenance of fertility and secondary sexual characteristics in females. As the primary, most potent estrogen hormone produced by the ovaries, estradiol binds to and activates specific nuclear receptors. This agent exhibits mild anabolic and metabolic properties, and increases blood coagulability. Although estradiol benzoate is not approved by the FDA for use in humans in the United States, it is approved for veterinary use as a subdermal implant both alone (CELERIN®) and in combination with the anabolic steroid trenbolone acetate (SYNOVEX® Plus).

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 ALK-001 is a chemically-modified vitamin A, in which 3 hydrogen atoms have been replaced by 3 deuterium atoms at carbon number 20.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.