Methylhydroxynandrolone (MOHN, MHN), also known as 4-hydroxy-17ñ-methyl-19-nortestosterone (HMNT), as well as 4,17ò-dihydroxy-17ñ-methylestr-4-en-3-one, is a synthetic, orally active anabolicâÂÂandrogenic steroid (AAS) and a 17ñ-alkylated derivative of nandrolone (19-nortestosterone) which was never marketed. It was first described in 1964 and was studied in the treatment of breast cancer, but was not introduced for clinical use. The drug re-emerged in 2004 when it started being sold on the Internet as a "dietary supplement". MOHN joined other AAS as a controlled substance in the United States on 20 January 2005.
MOHN is non-aromatizable due to the presence of a hydroxy group at the C4 position, and for this reason, poses no risk of estrogenic side effects like gynecomastia at any dosage, unlike many other AAS. 5ñ-Reduction is also inhibited by the C4 hydroxy group of MOHN and, because of this, MOHN may have a relatively higher ratio of androgenic to anabolic activity than other nandrolone derivatives (as 5ñ-reduction, opposite to the case of most other AAS, decreases AAS potency for most nandrolone derivatives). Early assays found that MOHN had approximately 13 times the anabolic activity and 3 times the androgenic activity of methyltestosterone.
MOHN is the 4-hydroxylated derivative of normethandrone (17ñ-methyl-19-nortestosterone), the 17ñ-methylated derivative of oxabolone (4-hydroxy-19-nortestosterone), the 4-hydroxylated and 17ñ-methylated derivative of nandrolone (19-nortestosterone), and the 19-demethylated analogue of oxymesterone (4-hydroxy-17ñ-methyltestosterone).