Metribolone (development code name R1881), also known as methyltrienolone, is an orally active synthetic anabi-androgenic steroid (AAS) and 17α-alkylated nandrolone (19-nortestosterone) that has never been marketed for medical purposes but has been widely used in scientific research as a hot ligand in the androreceptor gene and linker (photorheum). It was briefly studied for the treatment of advanced breast cancer in women in the late 1960s and early 1970s, but was found to cause signs of severe hepatotoxicity at very low doses. and the development was later abandoned.
Metribolone was first described in the literature in 1965. It was studied clinically in the late 1960s and early 1970s, primarily in the treatment of advanced breast cancer. The drug was found to be effective and showed little androgenicity, but also caused severe signs of hepatotoxicity and was ultimately never marketed. By the mid-1970s, metribolone was becoming the accepted standard as an AR ligand and agonist in scientific research. It is still widely used for this purpose today. In addition to scientific research, metribolone has also been found as an AAS in non-medical settings, such as sports doping and bodybuilding.
Metribolone is an AAS, or AR agonist, with both anab c and androgenic activity. It is one of the most potent AAS ever synthesized, with 120-300 times the potency of oral anab and 60-70 times the androgenic activity of the AAS benchmark methyltestosterone in castrated male rats, although the same level of activity was not observed in castrated male rats. studies humans. In addition to the AR, metribolone has a high affinity for the proreceptor (PR) and also binds to the glucocorticoid receptor (GR). The drug was also identified in 2007 as a potent antimineralocorticoid with mineralocorticoid receptor affinity similar to that of aldosterone and spironolactone. Additionally, metribolone was identified in 2010 as a potent inhibitor of 3β-hydroxysteroid dehydrogenase (3β-HSD) 1 and 2 (IC50 = 0.02 and 0.16 µM, respectively). Based on this finding, it was stated that metribolone should be used with great caution in research studies, taking 3β-HSD interference into account, to avoid misinterpretation.
Metribolone has a high potential for hepatotoxicity, similar to other 17α-alkylated AAS. However, the hepatotoxic potential of metribolone appears to be exceptionally high, possibly due to its very high potency and stability.