Norethandrolone, sold under the brand names Nilevar and Pronabol among others, is an androgen and anabolic steroid (AAS) medication which has been used to promote muscle growth and to treat severe burns, physical trauma, and aplastic anemia but has mostly been discontinued. It is still available for use in France however. It is taken by mouth. Norethandrolone, sold under the brand names Nilevar and Pronabol among others, is an androgen and anabolic steroid (AAS) medication which has been used to promote muscle growth and to treat severe burns, physical trauma, and aplastic anemia but has mostly been discontinued. It is still available for use in France however. It is taken by mouth. Side effects of norethandrolone include symptoms of masculinization like acne, increased hair growth, voice changes, and increased sexual desire. It can also cause estrogenic effects like fluid retention, breast tenderness, and breast enlargement in men and 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. Norethandrolone was discovered in 1953 and was introduced for medical use in 1956. It was the first AAS with a favorable separation of anabolic and androgenic effect to be marketed. The drug was mostly withdrawn in the 1980s due to concerns of liver damage. In addition to its medical use, norethandrolone has been used to improve physique and performance. The drug is a controlled substance in many countries and so non-medical use is generally illicit. Norethandrolone has been used in the treatment of muscle wasting, patients with severe burns, after severe trauma, and for certain forms of aplastic anemia among other indications. Side effects of norethandrolone include virilization among others. It has estrogenic effects and can cause gynecomastia and fluid retention. As with all 17α-alkylated AAS, long-term use of norethandrolone in high doses may result in hepatotoxicity including elevated liver enzymes and cirrhosis. Norethandrolone is an androgen and anabolic steroid and hence is an agonist of the androgen receptor, the biological target of androgens like testosterone and dihydrotestosterone. It has a high ratio of anabolic to androgenic activity. Analogously to the case of nandrolone and 5α-dihydronandrolone, 5α-dihydronorethandrolone, the 5α-reduced metabolite of norethandrolone, shows diminished affinity for the androgen receptor relative to norethandrolone. This is likely related to the high ratio of anabolic to androgenic activity observed with norethandrolone. Norethandrolone has relatively high estrogenic activity via transformation by aromatase into the potent estrogen ethylestradiol. It also has strong progestogenic activity. In addition, norethandrolone is hepatotoxic. The pharmacokinetics of norethandrolone have been reviewed. Norethandrolone, also known as 17α-ethyl-19-nortestosterone or as 17α-ethylestr-4-en-17β-ol-3-one, is a synthetic estrane steroid and a 17α-alkylated derivative of testosterone and 19-nortestosterone (nandrolone). It is closely related to normethandrone (17α-methyl-19-nortestosterone) and to ethylestrenol (3-deketo-17α-ethyl-19-nortestosterone). Chemical syntheses of norethandrolone have been published.