{"title":"YK-11","description":"\u003cp\u003eYK-11, also written YK11 and known chemically as (17alpha,20E)-17,20-[(1-methoxyethylidene)bis(oxy)]-3-oxo-19-norpregna-4,20-diene-21-carboxylic acid methyl ester, is a steroidal compound first described by researchers at Toho University in Japan in 2011 as a partial agonist of the androgen receptor. It is often sold as a SARM and described as a myostatin inhibitor. This page lists every brand of YK-11 stocked at Free Muscle, compared on strength per capsule, capsules per pack and batch testing, and summarises what the published research does and does not show.\u003c\/p\u003e\n\u003ch2\u003eWhat is YK-11?\u003c\/h2\u003e\n\u003cp\u003eUnlike RAD-140, LGD-4033 or ostarine, YK-11 is built on a steroid skeleton: it is a 19-norpregnane derivative related to nandrolone, carrying an unusual orthoester group on its D-ring. In reporter-gene assays it activated the androgen receptor (AR) only partially, accelerated AR movement into the nucleus, and did so without inducing the amino\/carboxyl-terminal (N\/C) interaction that full agonists such as dihydrotestosterone rely on. Because it produced gene-selective effects, the Toho group suggested it might function as a SARM despite its steroidal structure.\u003c\/p\u003e\n\u003cp\u003eThe myostatin claim comes from a single cell-culture finding. In mouse C2C12 myoblasts, YK-11 induced expression of follistatin, an endogenous antagonist of myostatin, and the myogenic differentiation it caused was reversed by an anti-follistatin antibody. This has not been shown in any animal or human. YK-11 has no pharmaceutical developer, was never entered into clinical trials, and has never been approved as a medicine by the MHRA, EMA, FDA or any other regulator. Anti-doping scientists have characterised it from a seized black-market product.\u003c\/p\u003e\n\u003ch2\u003eWhat the published research reports\u003c\/h2\u003e\n\u003cp\u003e\u003cstrong\u003eIdentification as an AR partial agonist (2011).\u003c\/strong\u003e Kanno and colleagues showed in an androgen-response-element luciferase assay that YK11 was a partial agonist of the AR, accelerated its nuclear translocation, did not induce the N\/C interaction and blocked DHT from doing so. Gene expression effects in MDA-MB 453 cells varied by gene context, leading the authors to propose SARM-like behaviour. This is an in vitro study.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eMyogenic differentiation and follistatin (2013).\u003c\/strong\u003e The same group reported that YK11 induced myogenic differentiation of C2C12 myoblasts, with stronger induction of MyoD, Myf5 and myogenin than DHT. YK11, but not DHT, induced follistatin expression, and an anti-follistatin antibody reversed the effect. Again a cell-culture result only.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eOsteoblast proliferation (2018).\u003c\/strong\u003e Yatsu and colleagues found that YK11 and DHT accelerated proliferation and mineralisation of MC3T3-E1 mouse osteoblast cells, increased osteoprotegerin and osteocalcin, and raised phosphorylated Akt, effects attenuated by an AR antagonist.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eMetabolism and detection for doping control (2018).\u003c\/strong\u003e Piper and colleagues, at the Cologne anti-doping laboratory, identified YK11 in a seized black-market product and conducted an elimination study with deuterium-labelled YK11. Fourteen urinary metabolites were detected; no intact YK11 was found in urine, but glucuronidated and sulfated metabolites remained traceable for more than 48 hours, and two were incorporated into routine anabolic-agent screening.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eHippocampal effects in rats (2024).\u003c\/strong\u003e Dahleh and colleagues gave rats YK11 for five weeks with or without swimming exercise. YK11 downregulated BDNF\/TrkB\/CREB signalling in the hippocampus, increased the pro-inflammatory cytokines IL-1beta and IL-6, reduced IL-10, raised p38 MAPK activity and activated the Bax\/Bcl-2\/caspase-3 apoptotic cascade, with impaired aversive memory consolidation. Exercise partly offset some of these changes.\u003c\/p\u003e\n\u003cp\u003eThese findings describe cell lines, laboratory animals and doping-control samples. None of them is a claim about the products listed on this page.\u003c\/p\u003e\n\u003ch2\u003eBrands of YK-11 we stock\u003c\/h2\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eFree Muscle YK-11, 10mg, 60 capsules.\u003c\/strong\u003e Our own brand, capsule form, 600mg of compound per pack. Every batch is assayed by Janoshik Analytical and the certificate for your batch is available by email on request. \u003ca href=\"\/products\/yk-11-10mg\"\u003eView the Free Muscle YK-11 listing\u003c\/a\u003e.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eiMuscle YK-11, 10mg, 60 capsules.\u003c\/strong\u003e Capsule form, 600mg per pack. A certificate of analysis is shown on the listing only where iMuscle has supplied one for the batch we hold. \u003ca href=\"\/products\/imuscle-yk-11-60-10mg\"\u003eView the iMuscle YK-11 listing\u003c\/a\u003e.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eFree Muscle Research Bundle (MK-677, RAD-140 and YK-11).\u003c\/strong\u003e Three Free Muscle-brand compounds sold together for laboratory work, each from a Janoshik-assayed batch. \u003ca href=\"\/products\/christmas-bulking-bundle\"\u003eView the research bundle\u003c\/a\u003e.\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003ch3\u003eHow to compare them\u003c\/h3\u003e\n\u003cp\u003eBoth single-compound listings contain 600mg per pack (10mg multiplied by 60 capsules), so the quantity is identical and the comparison comes down to cost per milligram and testing. Divide each pack price by 600 to get cost per milligram. Then weigh the certificate: the Free Muscle batch has a Janoshik identity and purity assay available for its lot number, while the iMuscle batch carries a COA only where the manufacturer has supplied one. Given that YK-11 was first identified by anti-doping scientists in an unlabelled black-market product, independent confirmation of identity matters more here than for most compounds. Our guide to \u003ca href=\"\/blogs\/news\/price-per-mg-compare-sarms-peptides\"\u003eprice per milligram\u003c\/a\u003e covers the arithmetic.\u003c\/p\u003e\n\u003ch2\u003eBatch testing and certificates of analysis\u003c\/h2\u003e\n\u003cp\u003eA certificate of analysis (COA) answers the two questions that matter about a YK-11 capsule: is the compound what the label says, and how much is present. A genuine batch certificate is issued by an independent laboratory, names the lot number, and reports identity (by HPLC or mass spectrometry against a reference standard) and assayed purity or content.\u003c\/p\u003e\n\u003cp\u003eEvery Free Muscle-brand batch is assayed by Janoshik Analytical, an independent laboratory, and the certificate for the batch you receive is sent on request by email. For other brands we show a COA only where the manufacturer has supplied one for the batch we hold. A generic PDF with no batch number, or one dated long before the product was made, is not a batch certificate and tells you nothing about the capsules in your hand. Our \u003ca href=\"\/pages\/lab-tests\"\u003elab tests page\u003c\/a\u003e explains how to read a Janoshik certificate and match it to your batch.\u003c\/p\u003e\n\u003ch2\u003eLegal status in the UK\u003c\/h2\u003e\n\u003cp\u003eYK-11 is not a licensed medicine in the United Kingdom. It has never been granted a marketing authorisation by the MHRA, and it is not an authorised food supplement or a permitted novel food ingredient. It cannot legally be sold or labelled for human consumption. Free Muscle sells YK-11 to adults aged 18 or over for laboratory and research purposes only, and every listing states this. YK-11 falls within section S1.2 of the World Anti-Doping Agency Prohibited List (Other Anabolic Agents), which covers all SARMs and substances with similar structure or effect, and is prohibited at all times; the Cologne laboratory has published detection methods for its metabolites. Anyone subject to anti-doping rules should treat any product in this class as prohibited at all times, in and out of competition. For a fuller overview of the class, see our \u003ca href=\"\/blogs\/news\/what-are-sarms-the-2026-research-guide\"\u003eresearch guide to SARMs\u003c\/a\u003e.\u003c\/p\u003e\n\u003ch2\u003eStorage and handling\u003c\/h2\u003e\n\u003cp\u003eKeep YK-11 capsules in the original sealed container in a cool, dry place away from light and heat. Do not decant into unlabelled containers, and record the batch number so that a COA request can be matched to the exact material. Keep out of reach of children and pets, and follow standard laboratory good practice: gloves when handling, no eating or drinking in the work area, and disposal in line with local rules for research chemicals.\u003c\/p\u003e\n\u003ch2\u003eDelivery and returns\u003c\/h2\u003e\n\u003cp\u003eAll orders are sent from Scunthorpe by FreeMuscle LTD, a UK company, with free tracked UK delivery and plain packaging. Place an order before 2pm Monday to Friday and it is processed that working day; EU orders take 3 to 7 working days to arrive. Unopened items may be returned within 30 days. Customers must be 18 or over. Our \u003ca href=\"\/pages\/shipping\"\u003eshipping page\u003c\/a\u003e and \u003ca href=\"\/pages\/guarantee\"\u003eguarantee page\u003c\/a\u003e have the full terms.\u003c\/p\u003e\n\u003ch2\u003eRelated reading\u003c\/h2\u003e\n\u003cul\u003e\n\u003cli\u003e\u003ca href=\"\/blogs\/news\/what-are-sarms-the-2026-research-guide\"\u003eWhat are SARMs? The 2026 research guide\u003c\/a\u003e\u003c\/li\u003e\n\u003cli\u003e\u003ca href=\"\/blogs\/news\/sarms-explained-how-selective-androgen-receptor-modulators-work-1135-86\"\u003eSARMs explained: how selective androgen receptor modulators work\u003c\/a\u003e\u003c\/li\u003e\n\u003cli\u003e\u003ca href=\"\/blogs\/news\/how-to-read-a-certificate-of-analysis\"\u003eHow to read a certificate of analysis\u003c\/a\u003e\u003c\/li\u003e\n\u003cli\u003e\u003ca href=\"\/blogs\/news\/what-is-janoshik-analytical\"\u003eWhat is Janoshik Analytical?\u003c\/a\u003e\u003c\/li\u003e\n\u003cli\u003e\u003ca href=\"\/blogs\/news\/mk-677-ibutamoren-what-the-research-says\"\u003eMK-677 (Ibutamoren): what the research says\u003c\/a\u003e\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003cp\u003eRelated collections: \u003ca href=\"\/collections\/rad-140\"\u003eRAD-140 (Testolone)\u003c\/a\u003e, \u003ca href=\"\/collections\/mk-677\"\u003eMK-677 (Ibutamoren)\u003c\/a\u003e, \u003ca href=\"\/collections\/market-bundles\"\u003eBundles\u003c\/a\u003e, \u003ca href=\"\/collections\/sarms\"\u003eall SARMs\u003c\/a\u003e.\u003c\/p\u003e\n\u003cp\u003e\u003cem\u003eYK-11 is sold strictly for laboratory research use only. It is not a licensed medicine, has not been evaluated or approved by the MHRA, EMA or FDA, is not a food supplement and is not for human consumption. Buyers must be 18 or over. Nothing on this page is medical advice, dosing advice or a recommendation to use this compound in any way; the published findings summarised above describe study participants and laboratory models, not the products listed.\u003c\/em\u003e\u003c\/p\u003e","products":[{"product_id":"yk-11-10mg","title":"YK-11 — Myostatin Inhibitor · 10mg · 60 Capsules","description":"\u003cp\u003e\u003cstrong\u003eYK-11 — 10mg × 60 capsules.\u003c\/strong\u003e\u003c\/p\u003e\u003cp\u003eYK-11 is structurally a steroid, not a true SARM, although it is usually sold alongside them. It is sometimes described as a myostatin-pathway agent; that description rests largely on a single cell-culture study and there is no human data.\u003c\/p\u003e\u003cp\u003eBecause it has a steroidal backbone, androgenic and liver effects cannot be ruled out. It is \u003cstrong\u003enot authorised for human consumption in the UK or EU\u003c\/strong\u003e and is prohibited in sport by WADA.\u003c\/p\u003e\u003cp\u003eIdentity and purity are verified per batch by Janoshik Analytical, an independent laboratory. Certificate of Analysis available on request. We do not publish dosing schedules, cycle lengths or post-cycle protocols for human use.\u003c\/p\u003e\u003cp\u003e\u003csmall\u003e\u003cstrong\u003eResearch use only.\u003c\/strong\u003e Not a medicine or dietary supplement, not evaluated by the MHRA, EMA or FDA, not for human consumption.\u003c\/small\u003e\u003c\/p\u003e","brand":"FreeMuscle","offers":[{"title":"Default Title","offer_id":46857393144034,"sku":"10000012","price":49.99,"currency_code":"GBP","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0772\/3499\/5426\/files\/yk_11_10mg_60_capsules.jpg?v=1766262356"},{"product_id":"imuscle-yk-11-60-10mg","title":"iMuscle YK-11 — 60 caps, 10mg","description":"\u003cp\u003eiMuscle YK-11 is supplied as 60 capsules stated at 10 mg each, giving 600 mg of YK-11 per pack. YK-11 is a steroidal partial agonist of the androgen receptor that is commonly sold alongside SARMs and is described in cell studies as a follistatin inducer. iMuscle manufactures it and Free Muscle stocks it in the Muscle Market range for laboratory research by adults only.\u003c\/p\u003e\n\u003ch2\u003eThis listing\u003c\/h2\u003e\n\u003cul\u003e\n\u003cli\u003eCompound: YK-11\u003c\/li\u003e\n\u003cli\u003eBrand: iMuscle\u003c\/li\u003e\n\u003cli\u003eForm: capsules\u003c\/li\u003e\n\u003cli\u003ePack size: 60 capsules\u003c\/li\u003e\n\u003cli\u003eStated strength: 10 mg per capsule (manufacturer's label claim)\u003c\/li\u003e\n\u003cli\u003eStated total per pack: 600 mg\u003c\/li\u003e\n\u003cli\u003eIntended use: laboratory research only, not for human consumption\u003c\/li\u003e\n\u003cli\u003eSold to adults aged 18 and over\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003cp\u003eThe strength is the manufacturer's label claim; only a batch certificate confirms it. To compare brands of YK-11, use total milligrams per pack: dividing the listed price by the 600 mg stated here gives the cost per stated milligram, as explained in \u003ca href=\"\/blogs\/news\/price-per-mg-compare-sarms-peptides\"\u003eprice per milligram\u003c\/a\u003e.\u003c\/p\u003e\n\u003ch2\u003eAbout YK-11\u003c\/h2\u003e\n\u003cp\u003eYK-11 is often grouped with SARMs, but it is a steroidal molecule: a 19-nor-pregnane derivative with a methyl ester side chain. It was described in 2011 by a group at Toho University in Japan, who showed in cell assays that it acts as a partial agonist at the androgen receptor, activating the receptor less fully than DHT (Kanno 2011).\u003c\/p\u003e\n\u003cp\u003eThe claim that YK-11 is a myostatin inhibitor comes from a 2013 study in C2C12 mouse myoblast cells, in which YK-11 increased expression of follistatin, a protein that binds myostatin, and promoted myogenic differentiation more than DHT did in that model (Kanno 2013). Both papers are cell-culture work. No human clinical trial of YK-11 has been published, so its pharmacokinetics, hormonal effects and liver tolerance in people are unknown.\u003c\/p\u003e\n\u003ctable\u003e\n\u003cthead\u003e\u003ctr\u003e\n\u003cth\u003eIdentifier\u003c\/th\u003e\n\u003cth\u003eYK-11\u003c\/th\u003e\n\u003c\/tr\u003e\u003c\/thead\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003ctd\u003eCAS number\u003c\/td\u003e\n\u003ctd\u003e1370003-76-1\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eMolecular formula\u003c\/td\u003e\n\u003ctd\u003eC25H34O6\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eMolecular weight\u003c\/td\u003e\n\u003ctd\u003e430.5 g\/mol\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eInChIKey\u003c\/td\u003e\n\u003ctd\u003eKCQHQCDHFVGNMK-PQUNLUOYSA-N\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003ePubChem CID\u003c\/td\u003e\n\u003ctd\u003e119058028\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\n\u003c\/table\u003e\n\u003ch3\u003eAnimal and metabolism studies\u003c\/h3\u003e\n\u003cp\u003eWork in living animals is recent and sparse, and much of the published in vivo work concerns metabolism for doping control (Piper 2018). One study followed rats for five weeks, with and without swimming exercise, to look for unwanted effects in the brain (Dahleh 2024). Animals given YK-11 retained an aversive memory task less well, showed weaker BDNF signalling in the hippocampus, had a cytokine balance tilted towards inflammation and showed activation of proteins that drive programmed cell death. Exercise offset part of this. One rat study cannot say what happens in people, but its findings point towards harm rather than benefit.\u003c\/p\u003e\n\u003cp\u003eThe cell and animal findings summarised here are not claims about this product.\u003c\/p\u003e\n\u003ch2\u003eYK-11 in the UK: buying, legal status and what to check\u003c\/h2\u003e\n\u003cp\u003eYK-11 is not a licensed medicine in the UK, and it has never been licensed in any other country: it has no MHRA marketing authorisation, is not an authorised food supplement, and cannot lawfully be sold for human consumption. Free Muscle supplies it to adults aged 18 or over for laboratory research only. Because it is a synthetic steroid, its status under the Misuse of Drugs Act is less clear-cut than that of non-steroidal SARMs, and buyers should take their own advice. It is prohibited at all times in sport, as the detection section below explains. Buyers are responsible for the rules that apply to them, including any anti-doping code. Background on the class is in \u003ca href=\"\/blogs\/news\/what-are-sarms-the-2026-research-guide\"\u003eWhat are SARMs? The 2026 research guide\u003c\/a\u003e.\u003c\/p\u003e\n\u003ch3\u003eWhat a trustworthy UK listing shows\u003c\/h3\u003e\n\u003cul\u003e\n\u003cli\u003eThe compound named precisely, ideally with its CAS number, not a nickname.\u003c\/li\u003e\n\u003cli\u003eA stated strength per capsule and a capsule count, so total content can be worked out.\u003c\/li\u003e\n\u003cli\u003eA batch number on the pack, and a certificate of analysis carrying that number from a named laboratory.\u003c\/li\u003e\n\u003cli\u003eA plain statement when no certificate exists for the batch in stock, instead of a generic PDF.\u003c\/li\u003e\n\u003cli\u003eA named UK company, an 18+ restriction, plain packaging and tracked delivery.\u003c\/li\u003e\n\u003cli\u003eNo instructions for human use and no outcome promises.\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003ch3\u003eHow this listing measures up\u003c\/h3\u003e\n\u003cp\u003eThe 10 mg and 60-capsule figures are iMuscle's label claim, not a figure we have assayed. A certificate is shown only where iMuscle supplies one for the batch we hold, and we tell you when there is none. Testing is the real difference from Free Muscle's own-brand \u003ca href=\"\/products\/yk-11-10mg\"\u003eYK-11 10 mg\u003c\/a\u003e, which carries the same label strength and capsule count but is assayed batch by batch at Janoshik Analytical. Orders ship from FreeMuscle LTD in Scunthorpe by free tracked UK delivery in plain packaging; orders placed before 2pm Monday to Friday are processed the same working day, EU delivery takes 3 to 7 working days, and unopened items can be returned within 30 days (\u003ca href=\"\/pages\/shipping\"\u003edelivery\u003c\/a\u003e, \u003ca href=\"\/pages\/guarantee\"\u003ereturns\u003c\/a\u003e). Our \u003ca href=\"\/blogs\/news\/how-to-choose-a-sarms-supplier-uk-checklist\"\u003eUK supplier checklist\u003c\/a\u003e covers each test in more detail.\u003c\/p\u003e\n\u003ch2\u003eCapsules compared with other forms\u003c\/h2\u003e\n\u003cp\u003eYK-11 is offered as capsules, as solutions in dropper bottles and as loose powder, and injectable versions are widely searched for. No study has compared these forms and none has been evaluated in a clinical trial, so the differences below concern what can be measured and kept stable, not effect. This listing is capsules.\u003c\/p\u003e\n\u003ctable\u003e\n\u003cthead\u003e\u003ctr\u003e\n\u003cth\u003eForm\u003c\/th\u003e\n\u003cth\u003eWhat fixes the amount per unit\u003c\/th\u003e\n\u003cth\u003eWhat a certificate can confirm\u003c\/th\u003e\n\u003cth\u003eMain stability concern\u003c\/th\u003e\n\u003c\/tr\u003e\u003c\/thead\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003ctd\u003eCapsule\u003c\/td\u003e\n\u003ctd\u003eFill weight set at manufacture\u003c\/td\u003e\n\u003ctd\u003eContent per capsule and purity, if finished capsules are tested\u003c\/td\u003e\n\u003ctd\u003eHumidity once the container is opened\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eSolution\u003c\/td\u003e\n\u003ctd\u003eConcentration, and whether the compound stays evenly dissolved\u003c\/td\u003e\n\u003ctd\u003eConcentration per millilitre on the test date\u003c\/td\u003e\n\u003ctd\u003eConstant contact with solvent\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003ePowder\u003c\/td\u003e\n\u003ctd\u003eWeighing by the researcher\u003c\/td\u003e\n\u003ctd\u003ePurity of the bulk material\u003c\/td\u003e\n\u003ctd\u003eHumidity and handling losses\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eInjectable\u003c\/td\u003e\n\u003ctd\u003eConcentration, carrier and sterility\u003c\/td\u003e\n\u003ctd\u003eUsually concentration only; sterility needs separate testing\u003c\/td\u003e\n\u003ctd\u003eNo published characterisation for YK-11\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\n\u003c\/table\u003e\n\u003cp\u003eTwo points follow from the chemistry. First, the Cologne anti-doping group described the orthoester-derived group on the D-ring of YK-11 as arguably labile and found no unchanged YK-11 in urine after administration (Piper 2018). Groups that break down readily in the body are also exposed to hydrolysis in a solution containing water or acid, one reason a dry fill is the easier form to store and assay. Second, YK-11 is not a peptide but a small steroid, so the argument that peptides are largely digested when swallowed, discussed in \u003ca href=\"\/blogs\/news\/do-oral-peptides-work\"\u003eDo oral peptides actually work?\u003c\/a\u003e, does not apply. That is a point about chemistry, not a claim about what a capsule does. Fill accuracy is itself a manufacturing variable, which is why the certificate section below asks whether finished capsules or raw powder were tested.\u003c\/p\u003e\n\u003ch2\u003eYK-11 compared with RAD-140\u003c\/h2\u003e\n\u003cp\u003eRAD-140 (testolone) is the compound most often set beside YK-11, and iMuscle sells both in the same format: \u003ca href=\"\/products\/imuscle-testolon-rad-140-60-10mg\"\u003eiMuscle Testolone RAD-140\u003c\/a\u003e is also labelled 10 mg per capsule, 60 capsules. Identical label arithmetic hides two different molecules with very different evidence bases.\u003c\/p\u003e\n\u003ctable\u003e\n\u003cthead\u003e\u003ctr\u003e\n\u003cth\u003ePoint\u003c\/th\u003e\n\u003cth\u003eYK-11\u003c\/th\u003e\n\u003cth\u003eRAD-140\u003c\/th\u003e\n\u003c\/tr\u003e\u003c\/thead\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003ctd\u003eChemical class\u003c\/td\u003e\n\u003ctd\u003eSteroid, 19-nor-pregnane derivative\u003c\/td\u003e\n\u003ctd\u003eNon-steroidal SARM\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFormula and molecular weight\u003c\/td\u003e\n\u003ctd\u003eC25H34O6, 430.5\u003c\/td\u003e\n\u003ctd\u003eC20H16ClN5O2, 393.8\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eOrigin\u003c\/td\u003e\n\u003ctd\u003eAcademic group, Toho University, 2011\u003c\/td\u003e\n\u003ctd\u003ePharmaceutical programme, Radius Health\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eAction at the androgen receptor\u003c\/td\u003e\n\u003ctd\u003ePartial agonist in cell assays; induced follistatin in mouse muscle cells\u003c\/td\u003e\n\u003ctd\u003eAgonist designed for tissue selectivity, characterised in rats and monkeys\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003ePublished human data\u003c\/td\u003e\n\u003ctd\u003eNo clinical trial\u003c\/td\u003e\n\u003ctd\u003eOne phase 1 study in 22 women with advanced breast cancer\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eMain adverse findings\u003c\/td\u003e\n\u003ctd\u003eMemory, inflammatory and cell-death changes in rat hippocampus\u003c\/td\u003e\n\u003ctd\u003eRaised liver enzymes, the most frequent adverse events in the phase 1 study\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eUK status\u003c\/td\u003e\n\u003ctd\u003eNot a licensed medicine; steroid structure makes its drugs-law status less clear-cut\u003c\/td\u003e\n\u003ctd\u003eNot a licensed medicine; research use only\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eWADA\u003c\/td\u003e\n\u003ctd\u003eSection S1, prohibited at all times\u003c\/td\u003e\n\u003ctd\u003eSection S1, prohibited at all times\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\n\u003c\/table\u003e\n\u003cp\u003eThe evidence gap is the main difference. RAD-140's human data come from one oncology study in patients with advanced disease (LoRusso 2022), yet that study still produced a measured half-life and a documented liver-enzyme signal. YK-11 has neither, so any statement about how it behaves in people rests on nothing published. The regulatory picture differs for a structural reason: a steroid backbone brings YK-11 closer to the anabolic steroids that UK drugs law already controls, whereas RAD-140 is chemically unrelated to them. Neither compound is approved anywhere, both are banned in sport, and nothing here ranks one above the other for any purpose. Brands of RAD-140 are compared on the \u003ca href=\"\/collections\/rad-140\"\u003eRAD-140 collection page\u003c\/a\u003e, and its research is summarised in \u003ca href=\"\/blogs\/news\/rad-140-testolone-what-the-research-says\"\u003eRAD-140 (Testolone): what the research says\u003c\/a\u003e.\u003c\/p\u003e\n\u003ch2\u003eReading the certificate of analysis for this product\u003c\/h2\u003e\n\u003cp\u003eiMuscle is a third-party brand, so any certificate of analysis is the manufacturer's, not ours. Where iMuscle supplies a COA for the batch we hold, we show it or send it by email on request; where none exists for the batch in stock, we say so rather than show a generic document. Free Muscle-brand compounds are assayed batch by batch at Janoshik Analytical; that programme does not cover iMuscle. When an iMuscle certificate is available, these are the fields to check.\u003c\/p\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eBatch or lot number\u003c\/strong\u003e: the same number as the one printed on your pack.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eIdentity\u003c\/strong\u003e: the method (HPLC against a YK-11 reference standard, LC-MS, or both) and a result consistent with C25H34O6, molecular weight 430.5. YK-11 has a defined E geometry at its side-chain double bond, and an isomer would share its mass, so a retention-time match to a reference standard is stronger evidence than mass alone.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003ePurity\u003c\/strong\u003e: the main peak as a percentage of everything the HPLC detected. The remainder may be synthesis by-products or breakdown products.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eContent per capsule\u003c\/strong\u003e: the milligrams found in finished capsules, to set against the stated 10 mg; a raw-powder result is not the same measurement.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eTest date and laboratory\u003c\/strong\u003e: when and by whom the analysis was run.\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003cp\u003eFor this brand, a missing field has a specific meaning. With no certificate for the batch in stock, nothing independent confirms identity, purity or content, and the 10 mg figure stays a label claim. Without a content figure, a certificate confirms what the material is but not the fill; without a batch number, it cannot be tied to your pack; without a named laboratory, it cannot be checked with the lab that issued it. Email us through the \u003ca href=\"\/pages\/contact\"\u003econtact page\u003c\/a\u003e with the product name and the batch number on your pack and we will tell you what we hold. See \u003ca href=\"\/pages\/lab-tests\"\u003elab tests\u003c\/a\u003e and \u003ca href=\"\/blogs\/news\/how-to-read-a-certificate-of-analysis\"\u003ehow to read a COA\u003c\/a\u003e.\u003c\/p\u003e\n\u003ch2\u003eDetection, sport and testing\u003c\/h2\u003e\n\u003cp\u003eYK-11 is prohibited at all times, in and out of competition, under section S1 (anabolic agents) of the WADA Prohibited List, which UK Anti-Doping applies in the UK. Under the strict liability principle of the anti-doping code, an athlete is responsible for any prohibited substance found in their sample, whatever the product label said.\u003c\/p\u003e\n\u003cp\u003eLaboratories can find it. In an elimination study with deuterium-labelled YK-11, the Cologne anti-doping laboratory identified fourteen urinary metabolites and no unchanged YK-11 in urine. Unconjugated metabolites had gone within 24 hours, while glucuronide and sulfate conjugates were still traceable after more than 48 hours, and two glucuronidated metabolites were added to the laboratory's routine screen for anabolic agents (Piper 2018). The study itself was prompted by the detection of YK-11 in a seized black-market product.\u003c\/p\u003e\n\u003cp\u003eThose timings describe how long metabolites were traced in one study; they are not a detection window. With no published human pharmacokinetic study, there is no established half-life for YK-11 in people and the full window is unknown. The reliable statement is that YK-11 is detectable.\u003c\/p\u003e\n\u003ch2\u003eStorage, stability and handling\u003c\/h2\u003e\n\u003cp\u003eNo stability study of YK-11 capsules has been published, so storage practice rests on general chemistry and the manufacturer's label. Water can cleave the ester and orthoester-derived groups in the molecule, and heat and light degrade most organic research materials.\u003c\/p\u003e\n\u003cul\u003e\n\u003cli\u003eKeep the capsules in the original closed container, cool, dry and away from direct sunlight and heat.\u003c\/li\u003e\n\u003cli\u003eClose the lid promptly and leave any desiccant sachet in place; humidity is the main avoidable threat.\u003c\/li\u003e\n\u003cli\u003eKeep the label intact: the batch number links the capsules to any certificate and to any quality query.\u003c\/li\u003e\n\u003cli\u003eRecord the date of receipt and any printed expiry date; without one, a certificate's test date is the only dated reference.\u003c\/li\u003e\n\u003cli\u003eSoft, sticky, discoloured or clumped capsules suggest moisture damage; note the batch number and contact us.\u003c\/li\u003e\n\u003cli\u003eKeep out of reach of children and pets, handle with gloves in a clean area free of food and drink, and dispose of unwanted material under local chemical-waste rules.\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003cp\u003eIf you might return the item, leave it sealed: returns are accepted within 30 days on unopened items only.\u003c\/p\u003e\n\u003ch2\u003eGlossary\u003c\/h2\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003ePartial agonist\u003c\/strong\u003e: a ligand whose maximum effect at a receptor stays below that of a reference hormone; for YK-11 in cell assays the reference was DHT.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eDHT (dihydrotestosterone)\u003c\/strong\u003e: a potent androgen made from testosterone in tissues such as skin and prostate.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003e19-nor steroid\u003c\/strong\u003e: a steroid missing the carbon atom usually found at position 19, the skeleton YK-11 shares with nandrolone.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eFollistatin\u003c\/strong\u003e: a glycoprotein that captures myostatin and activin outside the cell; the 2013 C2C12 study reported a rise in its expression, the basis of the myostatin-inhibitor label.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eC2C12 cells\u003c\/strong\u003e: a mouse muscle precursor line that fuses into muscle-like fibres in culture.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eHydrolysis\u003c\/strong\u003e: cleavage of a chemical bond by water, the main storage risk for the ester and orthoester-derived groups in YK-11.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eLabel claim\u003c\/strong\u003e: the amount a manufacturer prints per capsule, here 10 mg, unconfirmed until a content assay is run.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eRetention time\u003c\/strong\u003e: how long a compound takes to pass through an HPLC column, compared against a reference standard to support identity.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eConjugated metabolite\u003c\/strong\u003e: a breakdown product linked to glucuronic acid or sulfate for excretion; these were the longest-traced YK-11 markers in the Cologne study.\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003ch2\u003eRelated\u003c\/h2\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003ca href=\"\/collections\/yk-11\"\u003eAll brands of YK-11\u003c\/a\u003e, compared on strength, pack size and batch testing\u003c\/li\u003e\n\u003cli\u003e\n\u003ca href=\"\/collections\/brand-imuscle\"\u003eAll iMuscle products\u003c\/a\u003e stocked at Free Muscle\u003c\/li\u003e\n\u003cli\u003e\u003ca href=\"\/blogs\/news\/yk-11-what-is-known\"\u003eYK-11: a steroidal compound sold as a SARM, what is actually known\u003c\/a\u003e\u003c\/li\u003e\n\u003cli\u003e\n\u003ca href=\"\/collections\/rad-140\"\u003eRAD-140 (testolone)\u003c\/a\u003e and the full \u003ca href=\"\/collections\/sarms\"\u003eSARMs range\u003c\/a\u003e\n\u003c\/li\u003e\n\u003cli\u003e\n\u003ca href=\"\/pages\/shipping\"\u003eDelivery\u003c\/a\u003e and \u003ca href=\"\/pages\/guarantee\"\u003ereturns\u003c\/a\u003e\n\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003cp\u003e\u003cem\u003eThis product is supplied for laboratory research use only. It is not a medicine, has not been evaluated by the MHRA, EMA or FDA, and is not for human consumption. Sold to adults aged 18 and over. Nothing on this page is medical, dosing or usage advice.\u003c\/em\u003e\u003c\/p\u003e\n\u003ch2\u003eReferences\u003c\/h2\u003e\n\u003col\u003e\n\u003cli\u003eKanno Y, et al. (17alpha,20E)-17,20-[(1-methoxyethylidene)bis(oxy)]-3-oxo-19-norpregna-4,20-diene-21-carboxylic acid methyl ester (YK11) is a partial agonist of the androgen receptor. Biol Pharm Bull. 2011;34(3):318-23. PMID: 21372378.\u003c\/li\u003e\n\u003cli\u003eKanno Y, et al. Selective androgen receptor modulator, YK11, regulates myogenic differentiation of C2C12 myoblasts by follistatin expression. Biol Pharm Bull. 2013;36(9):1460-5. PMID: 23995658.\u003c\/li\u003e\n\u003cli\u003ePiper T, et al. Studies on the in vivo metabolism of the SARM YK11: Identification and characterization of metabolites potentially useful for doping controls. Drug Test Anal. 2018;10(11-12):1646-56. PMID: 30379415.\u003c\/li\u003e\n\u003cli\u003eDahleh MMM, et al. From gains to gaps? How Selective Androgen Receptor Modulator (SARM) YK11 impact hippocampal function: In silico, in vivo, and ex vivo perspectives. Chem Biol Interact. 2024;394:110971. PMID: 38521455.\u003c\/li\u003e\n\u003cli\u003eLoRusso P, et al. A First-in-Human Phase 1 Study of a Novel Selective Androgen Receptor Modulator (SARM), RAD140, in ER+\/HER2- Metastatic Breast Cancer. Clin Breast Cancer. 2022;22(1):67-77. PMID: 34565686.\u003c\/li\u003e\n\u003c\/ol\u003e","brand":"iMuscle","offers":[{"title":"Default Title","offer_id":48468980400354,"sku":null,"price":53.99,"currency_code":"GBP","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0772\/3499\/5426\/files\/YK11_720x_d356e17a-105c-480a-834b-d0c2826f4875.jpg?v=1789931421"}],"url":"https:\/\/freemuscle.co.uk\/collections\/yk-11.oembed","provider":"Free Muscle","version":"1.0","type":"link"}