RESEARCH MK-677 12.5MG

Buying MK-677 12.5mg in the UK: legal position and checks

Ibutamoren occupies a narrow legal space in the UK. The MHRA has never granted it a marketing authorisation, so it cannot be sold as a medicine, and it is not an authorised food supplement ingredient, so it cannot be sold for anyone to swallow. What remains is supply as a laboratory research compound to adults aged 18 or over, the only basis on which Free Muscle sells it; see our MK-677 legal status page. A listing that presents it as a supplement, or offers dosing and results, is describing it for human use.

Four checks help when judging any UK supplier:

1. A named UK company. Free Muscle is FreeMuscle LTD of Scunthorpe, reachable through our contact page.
2. A certificate for the batch, not the product. Janoshik Analytical assays every Free Muscle batch, and the certificate matching the batch number on your bottle is emailed on request.
3. No human-use claims. No dosing tables, before-and-after photographs or testimonials presented as outcomes.
4. Delivery and returns in writing. Free tracked UK delivery in plain packaging, same-day processing for orders before 2pm Monday to Friday, three to seven working days to the EU, and 30-day returns on unopened items (shipping, guarantee).

The three Free Muscle strengths by total content

All three bottles hold 60 capsules, so they differ only in strength. To compare value fairly, divide the bottle price by its total milligrams.

Capsules compared with liquids, powders and injectables

Ibutamoren is a small non-peptide molecule, and the published human trials gave it by mouth, so injectable versions have no basis in the clinical literature and raise sterility questions a capsule does not. When liquids, powders or tablets are offered instead, the useful question is what a batch certificate can confirm for each form:

For capsules, the specific question is content uniformity: a single reported figure may come from one capsule or a pooled sample, and the two answer different questions. None of this implies that any form acts differently.

MK-677 compared with ostarine (MK-2866)

Is MK-677 a SARM? No, and ostarine, the most studied SARM, shows why. The two share an "MK" code and are often sold side by side, but little else.

The overlap is in the market rather than the pharmacology. When a US anti-doping laboratory bought 44 products sold online as SARMs, 17 contained no SARM but another unapproved drug, ibutamoren among them (Van Wagoner 2017), so only an identity test separates the two. Reported adverse effects also sit in different systems: for ibutamoren, glucose handling, appetite and fluid retention; for androgen receptor modulators, blood lipids and the body's own testosterone production. See the ostarine collection.

Reading the certificate of analysis for this product

Every batch is assayed by Janoshik Analytical (see lab tests). Once the batch number matches your bottle, three details are specific to ibutamoren:

• Salt or free base. Ibutamoren is often supplied as its mesylate salt, C28H40N4O8S2, molecular weight 624.8, against 528.7 for the free base. About 85 percent of the salt's mass is ibutamoren, so 12.5mg of mesylate holds about 10.6mg of base, while 12.5mg expressed as base needs about 14.8mg of salt. Two listings that both say 12.5mg can therefore differ by roughly 15 percent. The certificate should state its basis; if it does not, ask.
• Identifiers. The free base is CAS 159634-47-6, InChIKey UMUPQWIGCOZEOY-JOCHJYFZSA-N. The mesylate has separate entries, so a different number may simply mean the salt.
• Result against the label. Milligrams found per capsule, set against the 12.5mg claim. A purity figure alone does not show whether capsules were filled correctly.

Method names and chromatograms are explained in How to read a certificate of analysis.

Detection, sport and testing

WADA prohibits ibutamoren at all times under section S2 of the Prohibited List. Strict liability applies, so a positive finding stands whatever the explanation, including a mislabelled product of the kind described above.

The clearest human detection data come from hair: in a forensic hair study, a single exposure in one volunteer was still measurable in hair collected four weeks later, with a limit of detection of 0.1 picograms per milligram, and hair from a repeated user held concentrations more than a hundred times higher (Kintz 2026). That is one volunteer and one case, not a population estimate. For urine we have not found a verified human excretion study, so no window is given here. Anyone subject to UK Anti-Doping rules should assume detection remains possible long after any contact.

Storage, stability and handling

A certificate describes the batch on the day it was tested; storage decides whether that still holds. Capsule shells soften in humid air and turn brittle when very dry, so bathrooms, kitchens and sunny window sills are poor places for the bottle. If it is refrigerated, let it reach room temperature before opening so condensation does not settle on the capsules. Check the seal and batch label on arrival, keep any desiccant sachet in the bottle, and never move capsules into pill organisers or unlabelled pots, which separates them from their certificate. Use gloves and a clean surface, record the batch and opening date, and never dispose of capsules down household drains. Keep out of the reach of children and animals.

What the published research reports

The most cited trials studied older adults, obesity, hip fracture and Alzheimer's disease; our overview MK-677: what the research says is the place to start. Less quoted papers add three points.

• Kidney failure. In a randomised, double-blind crossover study, 22 of 26 haemodialysis patients completed three months each on MK-0677 and placebo. IGF-1, the primary outcome, rose about 65 percent more on the drug, and no serious adverse effects were attributed to it. Only a blood marker was measured; lean mass, strength, quality of life and survival were untested (Campbell 2018).
• Liver. A 2025 case report described an otherwise healthy man in his early thirties who developed raised liver enzymes while using MK-677 bought as a performance product; values returned to normal after he stopped. One case cannot establish cause, and the authors called such reports scarce (Cobani 2025).
• Product quality. Of the 44 online products described above, only 18 (41 percent) matched their label for amount, 11 (25 percent) held unlisted substances and 4 (9 percent) held no active compound (Van Wagoner 2017).

None of these findings describes this product or suggests any use for it.

Related compounds and reading

Every strength and brand is compared on the MK-677 collection page. Related: ipamorelin, MK-777 (Acetamoren) and the SARMs range.

• MK-677 vs ipamorelin vs somatropin
• Ostarine (MK-2866): what trials found
• Choosing a UK SARMs or peptide supplier
• What are SARMs? The 2026 research guide
• What is Janoshik Analytical?

Glossary

• Free base: the ibutamoren molecule alone, without a salt-forming acid.
• Mesylate: shorthand for methanesulfonate; ibutamoren mesylate has a molecular weight of 624.8, against 528.7 for the base.
• CAS Registry Number: a unique identifier for a chemical substance; salts and bases usually have separate numbers.
• InChIKey: a fixed-length code derived from molecular structure, used to match database records.
• Content uniformity: how closely individual capsules in a batch agree in content.
• Limit of detection: the smallest amount a method can reliably distinguish from zero.
• Strict liability: the anti-doping rule that athletes answer for any prohibited substance found, whatever its source.
• Crossover trial: a study in which each participant receives both the test substance and placebo in turn.

Supplied for laboratory research only, never for human consumption. Ibutamoren holds no UK marketing authorisation, has not been assessed by the MHRA, EMA or FDA, and is not a food supplement. Orders are accepted from adults aged 18 and over. This page contains no medical, dosing or protocol advice.

References

• Campbell GA, et al. Oral ghrelin receptor agonist MK-0677 increases serum insulin-like growth factor 1 in hemodialysis patients: a randomized blinded study. Nephrol Dial Transplant. 2018;33(3):523-530. PMID: 28340044.
• Cobani E, et al. Hepatotoxicity induced by MK-677. BMJ Case Rep. 2025;18(7):e265728. PMID: 40675653.
• Van Wagoner RM, et al. Chemical composition and labeling of substances marketed as selective androgen receptor modulators and sold via the internet. JAMA. 2017;318(20):2004-2010. PMID: 29183075.
• Kintz P, Gheddar L. Knowing the minimal detectable dose can facilitate the interpretation of a hair test result: II. Case example with ibutamoren (MK-677), a growth hormone secretagogue. Clin Chim Acta. 2026;578:120578. PMID: 40882886.