YK-11

YK-11 is a synthetic steroid, not a nonsteroidal SARM, despite being sold alongside them. Its full chemical name is methyl (17alpha,20E)-17,20-[(1-methoxyethylidene)bis(oxy)]-3-oxo-19-norpregna-4,20-diene-21-carboxylate, and it was described by an academic group at Toho University in Japan rather than by a pharmaceutical company. It has never entered clinical development. There is no company behind it, no investigational new drug program, and no human trial of any kind.

The original 2011 report showed that YK-11 activates the androgen receptor as a partial agonist in a reporter assay, moves the receptor into the nucleus, and does so without inducing the amino-terminal to carboxy-terminal interaction that full androgens produce. In androgen receptor positive human breast cancer cells it acted as a gene-selective agonist, so its effect relative to dihydrotestosterone depended on which gene was measured (PMID: 21372378). Later work from the same group traced that selectivity to different DNA binding and different co-regulator recruitment compared with dihydrotestosterone (PMID: 36030969).

The claim that YK-11 is a myostatin inhibitor comes from one cell study. In mouse C2C12 myoblasts, YK-11 induced expression of follistatin, a protein that binds and neutralizes myostatin, and the resulting myogenic differentiation was reversed by an anti-follistatin antibody (PMID: 23995658). That is an indirect, cell-culture result in mouse cells. There is no published evidence that YK-11 binds or inhibits myostatin directly, and no human data on myostatin or follistatin after taking it. Other preclinical results include increased proliferation and mineralization in mouse MC3T3-E1 osteoblast cells (PMID: 29491216), improved osteogenic differentiation of rat bone marrow stromal cells and repair of rat cranial bone defects (PMID: 39660819), and reduced inflammatory markers and mortality in mice with bacterial sepsis (PMID: 33588136).

The safety data that do exist are unfavorable and come from rats. In male Wistar rats, five weeks of YK-11 increased oxidative stress and impaired every measured marker of mitochondrial function in the hippocampus, and exercise did not reverse those changes (PMID: 37468001). A follow-up study in rats reported impaired memory consolidation, downregulation of BDNF signaling, higher pro-inflammatory interleukin 1 beta and interleukin 6, lower interleukin 10, and activation of an apoptotic cascade in the hippocampus (PMID: 38521455). There is no human safety data at all.

In sport, YK-11 is prohibited. It is named in the World Anti-Doping Agency anabolic agents class alongside the nonsteroidal SARMs (PMID: 28137616), its mass spectrometric behavior and human urinary metabolites have been characterized for testing (PMID: 28440570, PMID: 30379415), and it has been reported in an actual doping control sample (PMID: 37946705). FDA has named YK-11 in warning letters to firms selling SARM products as unapproved new drugs (FDA warning letter to Titan SARMs LLC, 12 December 2025). What is sold as YK-11 in liquid or capsule form is a research chemical of unverified content; across SARM-marketed products tested in one analysis, only 52 percent contained any SARM (PMID: 29183075).

YK-11 is available in capsule, liquid forms.

Compare prices, payment methods, shipping, and COA scores across 1 vendor.

1 of the vendors BodyHackGuide tracks list YK-11 (2 listings). Among BodyHackGuide's YK-11 listings recorded as in stock with a milligram count, the lowest price per milligram is $0.170/mg at Disguised Alpha and the median is $0.170/mg. The YK-11 prices on BodyHackGuide are vendors' listed prices as BodyHackGuide last recorded them, not transactions; the most recent recorded change to a YK-11 listing is dated 7 September 2026.

BodyHackGuide holds 1 third-party certificate record for YK-11, from . No editor has read any of BodyHackGuide's 1 certificate record for YK-11. The laboratory named on BodyHackGuide's YK-11 certificate record is Freedom Diagnostics Testing, and the test date on it is 29 July 2026. Each vendor page on BodyHackGuide shows how many certificate records BodyHackGuide holds for that vendor and links to each record that has its own page.