YK11 is a steroidal Selective Androgen Receptor Modulator (SARM). Where as most SARMs are removed from traditional AAS structurally, YK11 is built on the same common steroid backbone. It is still quite unique, however, and does not closely resemble any common anabolic steroid. This unusual structure may afford it some level of selectivity in action, similarto other SARMs. YK11 is described as a partial AR agonist. It appears to activate the androgen receptor, though in some tissues may not result in full transcribing activity. As such, it could have a reduced level of relative androgenicity. Admittedly though, the classification of YK11 as a SARM is a tenuous one. This drug is in an early stage of research. Thus far, it has only been subject to in-vitro (cell incubation) studies. These investigations did report several interesting findings, however. First, YK11 did bind and activate the androgen receptor similar to traditional AAS (dihydrotestosterone). It was found to be a partial agonist of this receptor though, and displayed gene-selective activity. Its profile could resemble that of a classic non-steroidal SARM. As such, it might augment anabolic processes, but with muted androgenic activity. YK11 was also shown to strongly stimulate the release of follistatin. This is an important protein for muscle growth, as it strongly antagonizes myostatin, a growth inhibitor. Some AAS also share this activity, though it was particularly noteworthy in this case. YK11 appears to have certain favorable properties on paper. This could be an effective steroidal muscle builder, with reduced SARM-like androgenicity in certain tissues. However, not having been subject to even animal testing at this point, it is far too early to speculate on it-s efficacy and safety in humans. In spite of this, YK11 is popular in the fitness community, where it is used as a muscle-building alternative to anabolic steroids. Of course, there are other drugs in the SARM category with similar anabolic effects and a significantly larger body of research behind them. We recommend a full review of this category.

Brand name YK-11

YK-11 Key Points

  • Steroidal SARM
  • No Human or Animal Studies
  • Efficacy and Safety Unknown

YK-11 History

YK11 was first described in 2011 by Kanno et al. It has appeared in a couple of cell incubation studies, where it demonstrated selective SARM-like effects. It is unclear if this drug is on track for development as a medicine at this time. YK11 is on the WADA banned substance list, and is detectable in doping controls.

Structural Characteristics of YK-11

YK11 is a synthetic steroidal ligand for the androgen receptor (SARM). It has the chemical name (17a ,20E)-17,20-[(1-Methoxyethylidene)bis(oxy)]-3-oxo-19-norpregna-4,20-diene-21-carboxylic Acid Methyl Ester. Its serum half-life is unknown.

How is YK-11 Supplied

YK11 is not available as a pharmaceutical product. Standard dosage information is currently unavailable. Gray market preparations commonly contain 4-5 mg per capsule, or varying concentrations in oral solution.

YK-11 Warnings/Side Effects

YK11 is an unapproved new drug. A thorough understanding of its safety and propensity for side effects in humans is lacking at this time. This drug is steroidal in structure and activity. As such, it is likely to have some side effects in common with other anabolic steroids. Use of YK11 has never been studied in humans, however. It is unknown what shared or unique side effects it may actually have, or if there is any unusual toxicity.

YK-11 Administration

YK11 is given orally. This substance has not been approved for use in humans. Prescribing guidelines are unavailable.

When used for physique- or performance-enhancing purposes, YK 11 is commonly used at a dosage of 5-10 mg per day (men). Women usually opt for 1-5 mg daily, as its propensity for virilizing side effects is unknown.The total daily dose is usually given in one application, though some do opt to split this into two episodes given uncertainties about half-life.

Cycles of YK11 usually last 4 to 8 weeks. Anecdotal reports do suggest this drug has a distinct anabolic effect, and it is often regarded as being among the more potent drugs in the SARM class for gaining lean mass and strength. Beyond that, we are not in a position to categorize its effects.

YK-11 Availability

YK11 is not available as a prescription drug product. It is sold exclusively as a "research compound" or gray market supplement. Note that the quality of gray market products can be difficult to assure.


Wlliam Llewellyn (2017) - Anabolics

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