Ostarine MK-2866 — 60 caps, 15mg

iMuscle Ostarine MK-2866 is a pack of 60 capsules stated at 15 mg each, 900 mg of ostarine in total. Ostarine, also known as enobosarm, MK-2866 or GTx-024, is the most clinically studied compound in the SARM class, having reached Phase 3 trials without approval. iMuscle manufactures it and Free Muscle stocks it in the Muscle Market range for research use by adults aged 18 and over.

About Ostarine (MK-2866)

Ostarine is a non-steroidal selective androgen receptor modulator developed by GTx Inc. for muscle wasting and, later, for breast cancer.

A 2011 Phase 2 trial in 120 healthy elderly men and postmenopausal women reported a placebo-adjusted increase in lean body mass of about 1.3 kg at the 3 mg dose over 12 weeks, alongside improved stair-climb performance, and also recorded falls in HDL cholesterol and modest suppression of testosterone (Dalton et al., 2011). A 2013 randomised Phase 2 trial in patients with cancer-related muscle wasting again found increases in lean body mass (Dobs et al., 2013), but the subsequent Phase 3 POWER trials did not meet their co-primary endpoints and enobosarm was not approved. It remains unlicensed as a medicine in every country.

The adverse findings carry as much weight as the lean mass figure. In the full 2011 report, HDL cholesterol fell with dose, by 27 per cent at the highest dose; in men, SHBG and total testosterone fell, though free testosterone did not change significantly; and eight participants had transient rises in the liver enzyme ALT, one of whom was withdrawn. Outside trials, physicians at the University of British Columbia described a previously healthy man in his early forties admitted with jaundice after two months of taking ostarine bought online, without medical supervision (Bedi et al., 2021). A liver biopsy showed moderate to severe cholestasis consistent with drug-induced liver injury, and his blood tests improved gradually over the following months. He had also been taking two prescribed medicines, and the report describes no analysis of the product. One case cannot show how often such injury occurs, and no long-term human data exist.

The findings above describe the compound in clinical research and case reports and are not claims about this listing. The later breast cancer trial and the wider literature are covered in the ostarine research guide.

This listing

• Compound: Ostarine (MK-2866)
• Brand: iMuscle
• Form: capsules
• Pack size: 60 capsules
• Stated strength: 15 mg per capsule (manufacturer's label claim)
• Stated total per pack: 900 mg
• Intended use: laboratory research only, not for human consumption
• Sold to adults aged 18 and over

The strength is the manufacturer's label claim; only a batch certificate confirms it. To compare brands of Ostarine, use total milligrams per pack, as explained in price per milligram.

Ostarine in the UK: buying, legal status and what to check

Behind "ostarine UK", "MK 2866 buy UK" and "ostarine UK sale" sit two questions: is buying it here lawful, and what separates one listing from another?

The legal position

Ostarine is not a licensed medicine in the UK: it has no MHRA marketing authorisation, is not an authorised food supplement, and cannot lawfully be sold for human consumption. It is not a controlled drug under the Misuse of Drugs Act 1971, and Free Muscle supplies it to adults aged 18 or over for laboratory research only. It is prohibited at all times under section S1 (anabolic agents) of the WADA Prohibited List. Buyers are responsible for the rules that apply to them, including any anti-doping code. Background on the class is in What are SARMs? The 2026 research guide.

Six things a UK listing should show

• Label figures that can be tested. A strength per capsule and a count, as listed above; without them a listing can be neither checked nor compared.
• Who makes it and who sells it. The manufacturer is iMuscle; the seller is FreeMuscle LTD, a UK company based in Scunthorpe.
• A lot number that leads to a certificate. The number printed on the pot ties the capsules to an analysis; how this works for iMuscle stock is set out in the certificate section below.
• Sold for research, to adults. The page gives no directions for use and promises nothing about outcomes, and every buyer must be 18 or over.
• Delivery that can be followed. Every UK order travels free, tracked and in plain packaging; orders placed before 2pm Monday to Friday are processed the same working day, and EU delivery takes 3-7 working days.
• A way back. Unopened items can be returned within 30 days, on the terms given on our delivery and guarantee pages.

Reviews and "ostarine UK reddit" threads can say how fast a parcel arrived, not what the capsules contained; only a laboratory can say that. A longer checklist is in how to choose a SARMs supplier in the UK.

Capsules compared with other forms

"Ostarine tablets UK", "ostarine capsules UK" and "ostarine liquid UK" are all searched. Ostarine is a small synthetic molecule with a molecular weight of 389.3, not a peptide, so the usual objection to swallowed peptides, breakdown by digestive enzymes, does not apply in the same way (see do oral peptides work); the Cologne excretion study described below gave it by mouth. The forms differ in how the amount per unit is fixed and how far a certificate can confirm it; no published study has compared them.

None of this is a claim that one form works better than another; it concerns only how a stated quantity can be verified.

Ostarine compared with LGD-4033

"Ligandrol vs ostarine" sets ostarine against another member of its class; "MK 2866 vs MK 677", a pairing with an unrelated growth hormone secretagogue, is answered in the questions below. Ostarine and LGD-4033 are both non-steroidal SARMs that activate the androgen receptor, and both began as drug candidates that were never approved.

The table invites a head-to-head reading the evidence cannot support. Ostarine's Phase 2 trials enrolled older adults and people with cancer over roughly twelve to sixteen weeks; the only LGD-4033 trial enrolled young, healthy men for three weeks. No study has given both compounds to comparable participants, so any ranking by strength or tolerability has no trial behind it, and a milligram of one molecule is not equivalent to a milligram of the other.

What they share is status: unlicensed everywhere, sold here for laboratory research only, and prohibited under the same WADA section. Brands of LGD-4033 are compared in the LGD-4033 (Ligandrol) collection, and its trial is summarised in LGD-4033 (ligandrol): trials, findings and UK status.

Reading the certificate of analysis for this product

iMuscle is a third-party brand, so any certificate of analysis (COA) for this pack is the manufacturer's, not ours. Where iMuscle supplies a COA for the batch we hold, we show it; 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 a certificate is available, check each field against the table.

Where a field is blank on the certificate for our current batch, ask us through the contact page what is known before relying on that batch. Further detail is in how to read a COA and on our lab tests page.

Detection, sport and testing

Ostarine is named in section S1.2 (other anabolic agents) of the WADA Prohibited List, banned in and out of competition, and is the SARM most frequently detected in anti-doping analyses. Under strict liability an athlete answers for any prohibited substance in their sample, whatever its source, and supplements contaminated with minute amounts of ostarine have become a major concern for athletes and the authorities that manage results.

That concern prompted a controlled study at the German Sport University Cologne, where single and repeated oral amounts of 1, 10 and 50 micrograms of ostarine were given and urine was analysed by LC-MS/MS (Walpurgis et al., 2020). A single 1 microgram amount could be detected for up to nine days, depending on whether ostarine itself or its glucuronide was the target, while hydroxylated metabolites gave considerably shorter windows. Peak urine levels and detection times rose with the amount given and varied widely between individuals.

No verified study we can cite gives a detection window after milligram quantities such as the 15 mg stated per capsule here, so the accurate statement for this product is: detectable, window not established. Because detection time increased with the amount, the microgram figures are not an upper limit. Anyone subject to an anti-doping code should treat any contact with ostarine as a risk of an adverse finding.

Storage, stability and handling

We can cite no published stability study of ostarine capsules, so we quote no shelf life. Work to the expiry date on the iMuscle pot; a certificate reflects the batch only on its test date.

• Container. Keep the capsules in the original pot, closed fully after each opening; the pot carries the lot number, and decanting into an unlabelled container breaks the link to any certificate.
• Conditions. A cool, dry, dark place away from heat and direct sunlight. Kitchens and bathrooms are poor choices, as capsule shells take up moisture and can soften or stick together.
• Records. Note the lot number and the date the seal was broken, and label any sample taken for analysis with compound, lot and date.
• Handling. Use gloves with opened capsules or loose powder, keep the material away from food and drink and out of reach of children and pets, and dispose of it as chemical waste rather than in household bins or drains.

Breaking the seal also ends the 30-day return option, which applies to unopened items only.

Glossary

• Enobosarm: the International Nonproprietary Name for ostarine, used in clinical publications; MK-2866 and GTx-024 are development codes for the same molecule.
• Selective androgen receptor modulator (SARM): a non-steroidal androgen receptor activator whose developers aimed for effects on muscle and bone with less action on the prostate.
• Aryl-propionamide: the chemical family ostarine belongs to, which also includes andarine (S-4) and S-23.
• Lean body mass: body weight minus fat, measured in the ostarine trials by dual-energy X-ray absorptiometry (DXA); it includes water and organs as well as muscle.
• Co-primary endpoint: one of the main outcomes, set in advance, that a trial must meet to count as a success; the POWER trials fell short on theirs.
• SHBG: sex hormone-binding globulin, which binds testosterone in the blood, so total testosterone tends to fall when SHBG does.
• ALT: alanine aminotransferase, a liver enzyme whose blood level rises when liver cells are damaged.
• Cholestasis: reduced flow of bile from the liver, which can cause jaundice; the pattern seen in the ostarine case report.
• Glucuronide: a compound joined to glucuronic acid by the body so it can be excreted in urine; anti-doping methods can target it.

Related

• All brands of Ostarine (MK-2866), compared on strength, pack size and batch testing
• Ostarine (MK-2866): the most-studied SARM, what trials found
• All iMuscle products stocked at Free Muscle
• LGD-4033 (Ligandrol) and all SARMs
• Delivery and returns

This 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.

References

1. Dalton JT, et al. 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. J Cachexia Sarcopenia Muscle. 2011;2(3):153-161. PMID: 22031847.
2. Dobs AS, et al. Effects of enobosarm on muscle wasting and physical function in patients with cancer: a double-blind, randomised controlled phase 2 trial. Lancet Oncol. 2013;14(4):335-45. PMID: 23499390.
3. Bedi H, et al. Drug-Induced Liver Injury From Enobosarm (Ostarine), a Selective Androgen Receptor Modulator. ACG Case Rep J. 2021;8(1):e00518. PMID: 34368386.
4. Walpurgis K, et al. Elimination profiles of microdosed ostarine mimicking contaminated products ingestion. Drug Test Anal. 2020;12(11-12):1570-1580. PMID: 32959982.