YK-11
Experimental steroid with anabolic potential From Wikipedia, the free encyclopedia
YK-11 is a synthetic, steroidal selective androgen receptor modulator (SARM) structurally derived from dihydrotestosterone (DHT). It is currently classified as an experimental compound and has not been approved for medical use in humans. Despite this, it has been widely researched in preclinical settings for its potent anabolic effects on muscle cells.
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| Other names | Myostine; YK-11; 17α-methyl-δ2-17β-hydroxyestra-4,9-dien-3-one |
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| Formula | C25H34O6 |
| Molar mass | 430.541 g·mol−1 |
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Overview
YK-11 is distinct among SARMs due to its steroidal structure, setting it apart from most non-steroidal SARMs like Ostarine or LGD-4033. It binds to the androgen receptor (AR), similar to anabolic steroids, but its downstream activity differs significantly.
Mechanism of action
YK-11 functions as a partial agonist of the androgen receptor. It activates the receptor but not to the full extent like natural androgens such as testosterone or DHT. It does not promote the typical N/C-terminal interaction within the AR, which is required for full transcriptional activation.[1]
Instead, YK-11 induces muscle growth through a secondary mechanism: it significantly increases the expression of follistatin, a potent inhibitor of myostatin—a protein that suppresses muscle growth.[2] By blocking myostatin indirectly via follistatin upregulation, YK-11 may enhance muscle hypertrophy beyond what is seen with conventional SARMs or even testosterone.
In vitro and animal studies
Laboratory studies on mouse and human myoblasts (muscle precursor cells) have shown that:
- YK-11 increases muscle cell differentiation and growth more potently than DHT.[2]
- It exhibits strong anabolic activity without stimulating androgenic effects on non-muscle tissue (though this has only been evaluated in vitro so far).
- In animal models, it has demonstrated protective effects against muscle wasting due to sepsis, suggesting potential therapeutic uses.[3]
Risks and safety profile
YK-11 has never undergone clinical trials in humans, so its long-term safety, side effects, or optimal dosage are unknown.
Possible risks include:
- Liver toxicity, as suspected from its methylated structure (similar to oral anabolic steroids).
- Hormonal suppression, possibly affecting endogenous testosterone production.
- Unknown cardiovascular or prostate risks.
- No data exists on neurotoxicity or cancer risk.
Users have reported side effects such as joint pain, aggression, and testosterone suppression, although these are anecdotal.
Use in bodybuilding and doping context
Despite lacking medical approval, YK-11 is commonly sold online as a "research chemical" and marketed for muscle-building purposes. It is popular in bodybuilding communities due to its claimed ability to:
- Increase lean muscle mass
- Enhance strength
- Reduce fat mass while preserving muscle
YK-11 is banned by the World Anti-Doping Agency (WADA) and included on its list of prohibited substances under SARMs. Athletes found using it can face sanctions.
Legal status
YK-11 is not approved by the FDA, EMA or any other regulatory agency. Its legal status varies by country:
- In many jurisdictions, it is legal to buy/sell for research purposes, but not for human consumption.
- It may fall under "designer steroid" or "gray area drug" legislation.
See slso
- Selective androgen receptor modulators
- Myostatin inhibitors
- Ostarine (MK-2866)
- LGD-4033
- MK-4541
References
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