YK-11
PerformancePreclinicalAlso known as: YK11, YK 11, Myostine, Steroidal SARM 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.
Overview
At A Glance
YK-11 is a steroidal partial agonist of the androgen receptor. It binds the receptor and drives nuclear translocation, but does not induce the amino-terminal to carboxy-terminal interaction that full androgen agonists cause, which is thought to explain its partial and gene-select…
Overview
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).
Potential Research Fields
Chemical Information
IUPAC Name
Not yet available
CAS Number
1370003-76-1
Molecular Formula
C25H34O6
Molecular Mass
430.5 g/mol
Dosing & Protocols
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Interactions
Contraindications
No sourced clinical contraindications exist because there are no human studies. Mechanism-based: as an androgen receptor agonist it should be avoided in pregnancy because of the risk of virilizing a female fetus, and in anyone with known or suspected prostate cancer. The rat neurotoxicity findings are a mechanism-based reason for caution in general (PMID: 37468001, PMID: 38521455). Athletes in tested sport must avoid it, since it is prohibited at all times (PMID: 28137616).
Research Disclaimer
This interaction data is compiled from published research and community reports. It may not be exhaustive. Always consult a healthcare professional before combining compounds.
$79.99
up to $84.99
$0.1700
1
2
capsule, liquid
| Vendor | Product | Form | Qty | Price | $/mg | Coupon | |
|---|---|---|---|---|---|---|---|
 |
YK-11 capsules (60) | capsule | 60 capsules● In Stock | $79.99BEST | — | — | |
|
|
YK-11 50 mg/mL, 10 mL | liquid | 10 mL (50 mg/mL)● In Stock | $84.99VALUE | $0.170 | — |
Tracking since Sep 7, 2026 · 2 data points
Vendors Selling YK-11
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Every supplier above is graded 0–100 on COA verification, payment transparency, shipping, reviews, and active listings. Methodology published, no pay-to-rank.
Related Compounds
View AllITPP
PerformancePreclinicalITPP (myo-inositol trispyrophosphate, sometimes written myo-inositol tripyrophosphate or OXY111A in NormOxys trial documents) is a small-molecule allosteric effector of hemoglobin designed to increase the amount of oxygen red blood cells release to tissues.
LGD-4033 (Ligandrol)
PerformancePhase 2LGD-4033, usually sold as ligandrol, is a nonsteroidal selective androgen receptor modulator that Viking Therapeutics took into clinical development under the code VK5211 (NCT02578095).
Ostarine (Enobosarm, MK-2866)
PerformancePhase 3Ostarine is the market name for enobosarm, a nonsteroidal selective androgen receptor modulator first developed by GTx Inc under the codes GTx-024, MK-2866 and S-22.
PEG-MGF
PerformancePreclinicalPEG-MGF (Pegylated Mechano Growth Factor) is a synthetic, PEGylated form of Mechano Growth Factor (MGF) — an alternatively spliced variant of IGF-1 produced locally in muscle and other tissues in response to mechanical loading or damage.
RAD-140 (Testolone)
PerformancePhase 1RAD-140, sold as testolone and given the international nonproprietary name vosilasarm, is a nonsteroidal selective androgen receptor modulator developed at Radius Health, whose scientists reported the first-in-human trial (PMID: 34565686), and first described in the medicinal chemistry literature as a compound with an oxadiazole core designed for oral androgen receptor activity with tissue selectivity (PMID: 24900290).
SLU-PP-332
PerformancePreclinicalSLU-PP-332 is the first-generation synthetic pan-agonist of the estrogen-related receptors (ERRα, ERRβ, ERRγ) developed by the laboratory of Thomas Burris at Saint Louis University and reported in a landmark 2023 publication that established ERR pan-agonism as a pharmacologically tractable exercise-mimetic drug mechanism.
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Protocols, calculator & safety for YK-11
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All PostsResearch Score
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Quality Indicators
Data Completeness
63%Quick Facts
Half-Life
Not established. In a human elimination study using deuterium-labeled YK-11, no intact parent compound was seen in urine; unconjugated metabolites disappeared within 24 hours and glucuronidated and sulfated metabolites remained traceable beyond 48 hours (PMID: 30379415)
Molecular Weight
430.5 g/mol
Administration
Oral
CAS Number
1370003-76-1
Trial Phase
Preclinical
Research Disclaimer
This information is for educational and research purposes only. Not intended as medical advice. Consult a healthcare professional before use.
Frequently Asked Questions
What is YK-11 used for in research?
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).
What forms does YK-11 come in?
YK-11 is available in capsule, liquid forms.
How much does YK-11 cost?
Prices start at $79.99 across 1 verified vendor.
How do I compare YK-11 vendors?
Compare prices, payment methods, shipping, and COA scores across 1 vendor.
Research Tools
Related Compounds
View AllITPP
PerformancePreclinicalITPP (myo-inositol trispyrophosphate, sometimes written myo-inositol tripyrophosphate or OXY111A in NormOxys trial documents) is a small-molecule allosteric effector of hemoglobin designed to increase the amount of oxygen red blood cells release to tissues.
LGD-4033 (Ligandrol)
PerformancePhase 2LGD-4033, usually sold as ligandrol, is a nonsteroidal selective androgen receptor modulator that Viking Therapeutics took into clinical development under the code VK5211 (NCT02578095).
Ostarine (Enobosarm, MK-2866)
PerformancePhase 3Ostarine is the market name for enobosarm, a nonsteroidal selective androgen receptor modulator first developed by GTx Inc under the codes GTx-024, MK-2866 and S-22.
PEG-MGF
PerformancePreclinicalPEG-MGF (Pegylated Mechano Growth Factor) is a synthetic, PEGylated form of Mechano Growth Factor (MGF) — an alternatively spliced variant of IGF-1 produced locally in muscle and other tissues in response to mechanical loading or damage.
RAD-140 (Testolone)
PerformancePhase 1RAD-140, sold as testolone and given the international nonproprietary name vosilasarm, is a nonsteroidal selective androgen receptor modulator developed at Radius Health, whose scientists reported the first-in-human trial (PMID: 34565686), and first described in the medicinal chemistry literature as a compound with an oxadiazole core designed for oral androgen receptor activity with tissue selectivity (PMID: 24900290).
SLU-PP-332
PerformancePreclinicalSLU-PP-332 is the first-generation synthetic pan-agonist of the estrogen-related receptors (ERRα, ERRβ, ERRγ) developed by the laboratory of Thomas Burris at Saint Louis University and reported in a landmark 2023 publication that established ERR pan-agonism as a pharmacologically tractable exercise-mimetic drug mechanism.
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