YK-11

Areas of active research — not promised effects

Each tag links to other compounds with research into that goal. Research use only: these are areas of study, not human-use claims.

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YK-11 has no FDA-approved drug application. It may not be legally marketed, sold, or distributed for human consumption. It is not scheduled under the Controlled Substances Act as of the drafting date but is sold only under 'research chemical' or RUO designations. The FDA has flagged SARMs-containing products as illegal when marketed for human use.

Confirmed high-severity market-integrity event (enforcement / recall / counterfeit)

Transparent blend · bci-1.0 · never paid-placement

Primary name

YK-11

Origin

Synthetic steroidal compound first reported by Yuichiro Kanno in 2011; structurally derived from the steroid scaffold (5α-dihydrotestosterone methyl ester), not isolated from any natural source.

Registry IDs

PubChem CID

119058028

CAS

1370003-76-1

InChIKey

KCQHQCDHFVGNMK-PQUNLUOYSA-N

Molecular formula

C25H34O6

Molar mass

430.5 g/mol

Monoisotopic

430.23553880 Da

InChIKey

KCQHQCDHFVGNMK-PQUNLUOYSA-N

Appearance

White to off-white crystalline powder

Solubility

Soluble in DMSO and ethanol; poorly soluble in water

Sequence not available in current seed.

Stability: Stable as a dry powder under recommended cold-storage conditions; stability in solution is not well-characterised in published literature

Vial sizes

null mg

Purity grades

≥98% (HPLC) / research grade

Salt forms

Free base (primary)

• GHS hazard class on file
• PPE & spill response
• Disposal guidance
• Not-for-human-consumption posture

How much research exists, and of what maturity — never a verdict on whether it works.

Mechanism of action

• YK-11 binds the androgen receptor (AR) as a partial agonist, recruiting only a subset of coactivators compared to DHT, which confers tissue-selective gene activation
• Uniquely among SARMs, YK-11 also upregulates follistatin mRNA in C2C12 myoblasts independently of its AR-agonist activity; follistatin is an endogenous antagonist of myostatin and activins, thereby disinhibiting muscle hypertrophy signaling via ActRIIB
• Both pathways have been characterised exclusively in cell-culture and isolated animal models; no human pharmacodynamic data exist
• YK-11 does not fold the AR N/C terminus as efficiently as DHT, consistent with its partial-agonist profile and potentially reduced androgenic side-effect burden relative to full androgens — though this inference is unvalidated in clinical studies

Pharmacokinetics (ADME)

Half-life

Estimated 6–12 h (community-inferred; no published PK study in humans or animals)

PK–PD note: No peer-reviewed PK/PD data identified. Oral bioavailability is assumed from in-vitro cell-dosing studies. Hepatic first-pass metabolism is suspected given the steroid scaffold; no formal studies conf…

Reading the evidence

• Evidence quality and gaps vary by application — see the cited grades above.
• Indexed-article counts span all evidence tiers, not only completed human trials.
• No first-party human-dosing, efficacy, or benefit claims are made here.

Key reviews & evidence-gap sources

• Kanno Y et al. (2011) YK11 is a partial agonist of the androgen receptor. Biol Pharm Bull 34(3):318-323. PMID 21372378 — Foundational mechanistic characterization; in vitro AR binding/transactivation
• Kanno Y et al. (2013) SARM YK11 regulates myogenic differentiation of C2C12 myoblasts by follistatin expression. Biol Pharm Bull 36(9):1460-1465. PMID 23995658 — Anchoring primary source for follistatin/myostatin mechanism; in vitro
• Lee SJ et al. (2021) Myostatin inhibitor YK11 as a preventative health supplement for bacterial sepsis. Biochem Biophys Res Commun 543:1-7. PMID 33588136 — Animal (mouse) sepsis model; reports reduced mortality/inflammatory markers — not human efficacy
• Dahleh MMM et al. (2024) From gains to gaps? How SARM YK11 impacts hippocampal function: in silico, in vivo, ex vivo. Chem Biol Interact 394:110971. PMID 38521455 — Rat in vivo neurotoxicity/safety signal; PBPK + molecular docking
• Studies on the in vivo metabolism of the SARM YK11: metabolites for doping controls. PMID 30379415 — Doping-control/metabolism characterization; notes YK11 is non-approved for humans
• KoreaMed Synapse review article on YK-11 / myostatin inhibitors (review) — Narrative review discussing YK-11 as steroidal gene-selective partial AR agonist and follistatin-mediated myostatin inhibition; could not fully retrieve page text
• Wikipedia: YK-11 (aggregator entry) — Secondary aggregator; cites Kanno 2011/2013 and Lee 2021; notes Health Canada 2022 advisory

No registered human trials found for this compound.

Status

No registered trials found

Summary (literature)

No clinical safety data in humans exist. YK-11 carries a steroidal scaffold that is C17-methylated, raising concern for hepatotoxicity analogous to 17α-alkylated androgens; elevated liver enzymes have been reported in the broader SARM literature. At least one case report of liver…

WADA status

Prohibited at all times (in- and out-of-competition) under WADA Prohibited List 2026, Section S1.2 — Other Anabolic Agents; specifically named alongside other S…

Dominant research route: Oral (PO) — the only route with peer-reviewed in vivo data (equine, murine, and a single human elimination study).

Equine in vivo metabolism study: three daily oral doses of 50 mg administered to two Thoroughbred horses; parent YK-11 and seven phase I metabolites detected in plasma, 11 phase I metabolites in urine.

Bioavailability: Parent YK-11 was detectable in plasma (non-conjugated) following oral dosing, indicating systemic absorption in the horse; urine was dominated by mono- and di-O-demethylated breakdown products rather than intact drug.

Anti-doping metabolism study; not a human protocol. Demonstrates oral absorption and extensive phase I/II metabolism in horses.

Mouse in vivo study: YK11 administered orally to mice for 10 days (6 h/3 times/day) in a sepsis-induced muscle-wasting model.

Bioavailability: Oral administration produced pharmacodynamic effects (reduced pro-inflammatory cytokines, organ damage markers, and mortality) in septic mice, consistent with systemic exposure; no plasma PK values reported in abstract.

Preclinical efficacy study in mice; route was oral but no bioavailability fraction quantified.

Human elimination study: six-fold deuterated YK11 administered to a human volunteer; urinary metabolites characterized over >48 h.

Bioavailability: No intact YK-11 was observed in post-administration urine; 14 deuterated metabolites (unconjugated, glucuronidated, sulfoconjugated) detected. Unconjugated metabolites cleared within 24 h; conjugated metabolites traceable >48 h.

Single-subject human metabolism/elimination study for doping-control purposes; not a therapeutic trial. Abstract does not explicitly state administration route.

No peer-reviewed PK study of injectable YK-11 located; vendor product pages market an injectable format claimed to bypass hepatic first-pass metabolism.

Bioavailability: Vendor asserts injectable format 'bypasses hepatic first-pass metabolism, allowing the compound to enter systemic circulation unmodified'; no cited PK data supporting this claim.

Layer B community/vendor claim; no controlled study retrieved. RUO — no first-party efficacy assertion.

Animal & human figures are kept visibly separate so studied animal doses are never misread as human guidance.

Sorted A–Z by vendor — never by price

Weekly median $/mg from the live vendor crawl.

Researched storefront prices, bucketed

p25 $0.168 · median $0.235 · p75 $0.268 · 8 researched vendors

Legit, COA-backed band: $0.130–$0.300/mg.

Value rule: don't just buy the cheapest — a price under $3/mg is a red flag. Pair price with COA and independent-test grade.

Estimated cost of research (10 mg)

Vial (best researched price)

$1

Bacteriostatic water (generic estimate)

$6

Syringes / supplies (generic estimate)

$12

What each test proves — general guidance, plus this compound's researched purity data

Purity on the current market (researched)

No independent, compound-specific YK-11 purity range was sourced from a retrievable lab report. Vendor self-claims (e.g., Chemyo stating ≥99% raw material purity and finished liquid within 10% of labeled mg/mL) are first-party marketing and not cited as independent evidence.

Independent labs cited for this compound

No FDA-enforced recall specific to YK-11 products was found. The GE Labs Ykarine advisory (FDA lab finding of undeclared trendione + YK-11, linked to a stroke adverse event) is a consumer warning to discard, not a formal recall entry. Honest result: none found in FDA recall databases.

Buyer red-flag checklist

• YK-11 is named on the WADA Prohibited List under S1.2 Other Anabolic Agents (SARMs class), prohibited at all times.
• FDA confirmed a commercial YK-11 product (GE Labs Ykarine) was adulterated with undeclared trendione, a Schedule III anabolic steroid, linked to a consumer stroke adverse event.
• FDA has pursued criminal actions against distributors of SARMs products (per FDA Consumer Update and Fraudulent Products page).
• Independent JAMA study found 59% of internet-sold SARMs products had amounts differing from label and 9% contained no active substance (class-wide).
• YK-11 is not FDA-approved for any use; all U.S. marketing as a drug or dietary supplement is illegal per FDA.
• YK-11 is structurally a steroidal compound (not a classic non-steroidal SARM), increasing risk of misidentification and substitution in gray-market products.

GMP vs research-grade: the chemistry (SPPS + HPLC + MS) is identical — the difference is the quality system.

Underdosing / mislabeling: No YK-11-specific underdosing prevalence from independent labs was retrievable. SARMs-class-wide data (Van Wagoner et al., JAMA 2017, n=44 products) found 59% of internet-sold SARMs products had substance amounts differing from label claims and 9% contained no active substance; this is class-level, not YK-11-isolated.

• FDA Import Alert 66-41 'Detention Without Physical Examination of Unapproved New Drugs Promoted In The U.S.' applies to unapproved new drugs marketed/promoted in the U.S. SARMs including YK-11 meet the unapproved-new-drug criteria (section 505(a) FD&C Act). This is a class-level alert, not a YK-11-specific Red List entry.66-41
• An RUO label is not an import exemption — CBP judges actual intended use.
• Lyophilized powder is ambient-stable in transit; temperature control needed for > 7-day transit.
• US-warehouse vendors dodge import scrutiny — they cost more but ship more reliably.

Every item dated & sourced

Prohibited at all times (in- and out-of-competition) under S1.2 Other Anabolic Agents — Selective Androgen Receptor Modulators (SARMs); classified as a non-Specified Substance. Named explicitly on the 2026 Prohibited List (e.g., andarine, enobosarm/ostarine, LGD-4033/ligandrol, RAD140, S-23 and YK-11).

No granted patents identified in current seed. Composition-of-matter coverage is limited given the peptide's synthetic origin.

• IACUC / IRB research context
• RUO buyer responsibilities & documentation
• Veterinary / alternative-use where lawful
• Jurisdiction-aware "who may lawfully obtain"

What people discuss

Reported concerns — discussion, not established effects

Reading caveats

• self-selection bias: only active users tend to post
• anecdotal only; no controlled dosing or bloodwork standardization
• bodybuilding-community skew toward performance framing
• source-affiliated posters and vendor promotion present
• negative experiences over-represented relative to silent majority

Manually researched from reddit, youtube— theme weights are research estimates, not live counts; aggregated & de-identified. No individual posts, quotes, or usernames are ever shown.

Relative research / market volume — populated once the activity stream is wired

Inline tooltips for lyophilized, RUO, EU/mg, SPPS, 503A and more.

Toggle plain-language ↔ scientific in the header.

• How to read a COA
• Free base vs acetate
• Understanding evidence grades

Steroidal SARM that acts as a partial androgen receptor agonist and induces follistatin expression to suppress myostatin in preclinical models. Approximately 7 articles are indexed (literature last scanned 2026-05-29). US regulatory status: Research use only; not approved for human use. Research use only.

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