Metribolone (Methyltrenbolone, R1881)

Detailed overview

Metribolone (methyltrenbolone, R1881) is the 17-alpha-methylated version of trenbolone. It leads a double life, and the two must not be conflated. In science it exists as R1881 and is one of the most important research tools available: for decades it has served as the reference ligand in androgen receptor binding assays. It was chosen for that role for the same reason users find it attractive: it binds the androgen receptor extremely strongly and stably, and does not degrade quickly under assay conditions. Brinkmann's 1986 photoaffinity-labelling work and Luderschmidt's 1987 binding-affinity study illustrate this role well: both use it as a laboratory tool rather than studying it as a therapy. Its other life is that of a black-market oral steroid. Here it is important to state plainly what is usually blurred: no human therapeutic clinical trial has ever been conducted with metribolone. There is no regulatory dossier, dosing recommendation or safety database relating to human use. What we know about it in humans comes from two sources: doping-control analytics (Thevis 2009) and the general literature on anabolic-steroid-induced hypogonadism (Rahnema 2014). The pharmacological profile, however, is entirely predictable. The 17-alpha-methyl group is what makes the compound orally effective, and the same group is what loads the liver: this structural element is also responsible for the hepatotoxicity of superdrol and halotestin. Paired with the trenbolone skeleton it yields an extremely potent androgen with minimal therapeutic precedent and maximal hepatic risk.