YK-11 Research Overview (also known as YK11, Myostatin inhibitor SARM)
YK-11 is an experimental steroidal androgen-receptor ligand commonly described as a selective androgen receptor modulator (SARM) and as a compound that may influence the myostatin–follistatin pathway. Evidence is limited primarily to laboratory research, with no well-established human pharmacokinetic, efficacy, or safety profile; advertised doses and cycle protocols should not be interpreted as clinically validated guidance.
What Is YK-11?
YK-11 is an experimental synthetic steroidal compound that is widely discussed online as both a selective androgen receptor modulator and a myostatin-pathway modulator. Popular descriptions commonly attribute its discovery or synthesis to Japanese researcher Yuichiro Kanno in 2011 and identify it as a derivative or analogue of dihydrotestosterone (DHT). The compound is structurally different from the non-steroidal SARMs that dominate pharmaceutical research. It is often marketed as unusually potent because it is proposed to combine androgen-receptor signaling with increased follistatin expression and consequent reduction of myostatin signaling. Those descriptions are based mainly on preclinical findings, secondary reporting, and commercial claims rather than on adequately controlled human trials.
YK-11 is sometimes described as a partial androgen-receptor agonist, although the available public evidence is too limited to define its receptor pharmacology, tissue selectivity, dose-response relationship, oral bioavailability, metabolism, or clinical potency with confidence. A frequently repeated estimate places its half-life at approximately 6–10 hours, but this figure is not supported by a robust, publicly established human pharmacokinetic study and should not be treated as a validated parameter. The compound has no approved therapeutic indication, no established safe human dose, and no reliable evidence that it produces a clinically meaningful or safe reduction in myostatin activity. Because it may affect androgen signaling and because its long-term effects are unknown, it should be regarded as an advanced research compound rather than a supplement or a proven performance-enhancing medicine.
Research Indications
Myogenic Signaling
Follistatin expression in cell culture
YK-11 increased follistatin expression during differentiation of C2C12 mouse myoblasts in an in-vitro study; this is not evidence of a clinical muscle-building effect in humans.
Androgen receptor-mediated activity
Preclinical work suggests partial agonist activity at the androgen receptor with signaling behavior distinct from testosterone in the studied cell model.
Body Composition Research
No controlled human YK-11 trials
There are no established peer-reviewed controlled clinical trials demonstrating YK-11 efficacy for lean mass, strength, fat loss, or athletic performance.
Class-level SARM findings are not transferable
Human data from other investigational SARMs cannot establish comparable efficacy, pharmacokinetics, or safety for YK-11.
Pharmacology and Toxicology Gaps
Human pharmacokinetics are not established
Absorption, metabolism, half-life, tissue exposure, and active metabolites have not been adequately characterized in published human studies.
Long-term risk is unknown
Potential endocrine, hepatic, lipid, cardiovascular, reproductive, and psychiatric effects remain inadequately defined for YK-11.
Research Protocols
As reported in cited literature and research-community logs (see Research Citations below) — not a personal dosing recommendation.
| Research Application | Dose | Frequency | Route |
|---|
| Human clinical research | No established dose | Not established | Oral |
| Body-composition claims | No evidence-based dose | Not established | Oral |
| Preclinical mechanism study | In-vitro only; not translatable | Not applicable | Oral |
Timing
No evidence-based timing schedule exists for YK-11. Published YK-11 work is primarily cellular and does not establish an oral human dosing regimen, dosing interval, cycle duration, or monitoring schedule.
Peptide Interactions
Avoid concurrent use: alcohol can add hepatic stress and complicate interpretation of liver-related symptoms or laboratory abnormalities.
Use caution with potentially hepatotoxic medicines. Human interaction studies with YK-11 have not been published.
Concurrent androgenic agents may compound endocrine suppression, lipid changes, blood-pressure effects, and other poorly characterized risks.
Stacking investigational SARMs lacks clinical safety evidence and may increase androgen-receptor, endocrine, lipid, and hepatic uncertainty.
Potential lipid effects could obscure treatment assessment; medication changes should only be directed by the prescribing clinician.
YK-11 reproductive and endocrine effects are unknown; avoid use during pregnancy, breastfeeding, fertility treatment, or when hormonal status requires reliable management.
Reported Research Timeline
01Days 1–7 (reported in cited studies): no clinically validated onset profile exists. Subjective changes reported outside research cannot establish pharmacologic effect or safety.
02Weeks 2–4 (reported in cited studies): human effects on strength, recovery, body composition, mood, libido, or endocrine markers remain uncharacterized for YK-11.
03Weeks 4–8 (reported in cited studies): unknown cumulative exposure may increase uncertainty around liver enzymes, lipids, blood pressure, and hormone regulation.
04Weeks 8–12 (reported in cited studies): there is no evidence-based duration considered effective or safe. Continued use cannot be evaluated against an established human risk threshold.
05After discontinuation (reported in cited studies): the time course for endocrine recovery, laboratory normalization, and persistence of adverse effects is not established.
06Long term (reported in cited studies): no human longitudinal data define cardiovascular, reproductive, hepatic, or cancer-related outcomes for YK-11 exposure.
Safety Notes
Included for harm-reduction awareness only, in the event this compound is encountered outside its labeled research use. Inclusion here does not imply RUO Codes endorses, recommends, or instructs human use.
YK-11 is an investigational, non-approved androgen receptor modulator with extremely limited published human data.
Avoid during pregnancy, breastfeeding, attempts to conceive, or in adolescents; reproductive and developmental risks are unknown.
Potential androgen-related endocrine disruption, including suppression of endogenous hormone signaling, has not been adequately assessed in humans.
Individuals with liver disease, dyslipidemia, cardiovascular disease, hormone-sensitive conditions, or psychiatric illness should avoid unsupervised exposure.
Products marketed as YK-11 may be mislabeled, adulterated, or contain a different amount or compound than stated on the label.
Seek Medical Attention If:
You develop yellowing of the skin or eyes, dark urine, pale stools, persistent nausea, severe abdominal pain, or unusual fatigue.
You experience chest pain, shortness of breath, fainting, severe headache, new neurologic symptoms, or a markedly irregular heartbeat.
You develop severe mood changes, agitation, depression, suicidal thoughts, or symptoms of mania.
You have signs of a serious allergic reaction, including facial swelling, widespread rash, wheezing, or difficulty breathing.
Quality Indicators
Verified Marker
Lot-specific certificate of analysis
A credible COA identifies the exact lot, test date, analyte, laboratory, method, result, and authorized signatory or report identifier.
Verified Marker
Identity confirmation by LC-MS or NMR
Identity testing should distinguish YK-11 from structurally related steroids, undeclared SARMs, and other potential adulterants.
Verified Marker
Quantitative HPLC or UPLC assay
For oral products, the report should state quantitative assay results and chromatographic method details rather than only claiming a generic purity percentage.
Acceptable Range
Tablet or capsule mass uniformity
Oral units should have documented content-uniformity or dosage-uniformity testing; gross unit-weight variation is not a substitute for active-ingredient accuracy.
Quality Concern
Marketing-only documents or unverifiable COAs
Avoid products with reused reports, missing lot numbers, absent analytical methods, implausibly perfect results, or certificates not traceable to an independent laboratory.
Research Citations
- Selective androgen receptor modulator, YK11, regulates myogenic differentiation of C2C12 myoblasts by follistatin expression.
Kanno, Y., Hikosaka, K., Iqbal, J., et al., 2011, Biological & Pharmaceutical Bulletin - The safety, pharmacokinetics, and effects of LGD-4033, a novel nonsteroidal oral selective androgen receptor modulator, in healthy young men.
Basaria, S., Jasuja, R., Huang, G., et al., 2013, The Journals of Gerontology: Series A - The selective androgen receptor modulator GTx-024 (enobosarm) improves lean body mass and physical function in healthy elderly men and postmenopausal women: results of a double-blind, placebo-controlled phase II trial.
Dalton, J. T., Barnette, K. G., Bohl, C. E., et al., 2011, Journal of Cachexia, Sarcopenia and Muscle - The effects of supraphysiologic doses of testosterone on muscle size and strength in normal men.
Bhasin, S., Storer, T. W., Berman, N., et al., 1996, New England Journal of Medicine
Research Focus
myostatin inhibition, muscle hypertrophy, androgen receptor, DHT derivative
Frequently Asked Questions
What should researchers watch for with YK-11?
Included for harm-reduction awareness only, in the event this compound is encountered outside its labeled research use. Inclusion here does not imply RUO Codes endorses, recommends, or instructs human use.
What should researchers expect over time with YK-11?
Days 1–7 (reported in cited studies): no clinically validated onset profile exists. Subjective changes reported outside research cannot establish pharmacologic effect or safety.
How is YK-11 typically administered in research?
As reported in cited literature and research-community logs (see Research Citations below) — not a personal dosing recommendation.
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