Ethylestrenol, also known as ethyloestrenol or ethylnandrol and sold under the brand names Maxibolin and Orabolin among others, is an androgen and anabolic steroid (AAS) medication which has been used in the past for a variety of indications such as to promote weight gain and to treat anemia and osteoporosis but has been discontinued for use in humans. It is still available for veterinary use in Australia and New Zealand however. It is taken by mouth. Side effects of ethylestrenol include symptoms of masculinization like acne, increased hair growth, voice changes, and increased sexual desire. It can also cause liver damage. The drug is a synthetic androgen and anabolic steroid and hence is an agonist of the androgen receptor (AR), the biological target of androgens like testosterone and dihydrotestosterone (DHT). It has strong anabolic effects relative to its androgenic effects. The drug also has strong progestogenic effects. Ethylestrenol is a prodrug of norethandrolone. Ethylestrenol was first described in 1959 and was introduced for medical use in 1961. In addition to its medical use, ethylestrenol has been used to improve physique and performance. However, it is described as a very weak muscle-builder compared to other AAS and in relation to this has not been commonly used for such purposes. The drug is a controlled substance in many countries and so non-medical use is generally illicit. Medical uses Ethylestrenol has been used for a variety of indications including: To promote weight gain and muscle growth As an adjunct in the treatment of bone pain and decreased bone strength associated with osteoporosis As an adjunct for catabolic states such as corticosteroid therapy and convalescence as in chronic infections, extensive surgery, and severe trauma To treat treatment-refractory anemias (via stimulation of erythropoiesis) such as acquired and congenital aplastic anemia and anemia of chronic kidney disease As an adjunct to improve strength and well-being in arthritis To treat short stature in youth Contraindications Ethylestrenol should not be taken by pregnant women as it can masculinize female fetuses. It is contraindicated in men with prostate cancer as it may accelerate the progression of the disease. Side effects Side effects of ethylestrenol include virilization among others. Pharmacology Pharmacodynamics As an AAS, ethylestrenol is an agonist of the androgen receptor (AR), similarly to androgens like testosterone and dihydrotestosterone (DHT). It has low estrogenic activity (via aromatization into ethylestradiol following transformation into norethandrolone), strong progestogenic activity, and a high