MK-777 (Acetamoren) capsules, 60 per bottle, Bioreactive Series

Last reviewed: 16 October 2026 · sources and prices checked by Free Muscle.

Key facts

Where to buy MK-777 in the UK: what to check

Whichever seller you consider, check these five points:

1. Stated strength and capsule count. Here: 60 capsules per bottle.
2. A batch number on the pack. Here: printed on every bottle we ship.
3. A certificate for that batch from a named independent laboratory. Here: Janoshik Analytical; we email the certificate for your batch on request.
4. Tracked delivery in plain packaging and a written returns policy. Here: every order ships in plain packaging, UK delivery is free and tracked, EU delivery usually takes 3 to 7 working days after dispatch, and unopened items can be returned within 30 days.
5. Sold for laboratory research only, to adults aged 18 or over. Here: no instructions for human use are given.

Our UK supplier checklist explains each point, and How we test sets out what a certificate does and does not prove.

Research compounds sold by Free Muscle are supplied for laboratory research use only and are not for human consumption. They are not authorised as medicines by the MHRA, EMA or FDA, are not food supplements, and are sold only to adults aged 18 or over. Nothing on this page is medical or dosing advice.

MK-777 in the UK: buying, legal status and what to check

Searches for "MK-777 UK" and "Acetamoren UK" ask whether it can be bought lawfully and how to know what is in the bottle. MK-777 holds no MHRA marketing authorisation, so it cannot be sold or advertised as a medicine, and it is not an authorised food supplement ingredient or novel food, so it cannot be sold for human consumption. That leaves supply to adults aged 18 or over as a laboratory research compound, the only basis on which Free Muscle sells it; our MK-677 legal status page explains the same framework.

Because Acetamoren is a product designation, not an International Nonproprietary Name, anyone can print "MK-777" on a label, and the letters prove nothing about the contents. A trustworthy listing shows a batch number on the pack, a certificate for that batch from an independent named laboratory, a capsule count, a named seller and a returns policy. Here: 60 capsules per bottle, every batch assayed by Janoshik Analytical, sold by FreeMuscle, a business registered in Andorra with UK operations and dispatch in Scunthorpe. UK delivery is free, tracked and in plain packaging, orders placed before 2pm Monday to Friday are processed the same working day, EU parcels take three to seven working days, and unopened items can be returned within 30 days (see shipping and our guarantee).

Capsules compared with other forms

This listing is supplied as capsules, 60 to a bottle. Between forms, the practical difference is verification, not effect. A capsule is a weighed fill in a sealed shell, and a batch certificate can report what it contained. A liquid's concentration depends on how accurately it was mixed, whether the compound stays dissolved and how the solvent has aged, and a certificate for the starting powder answers none of those questions.

On the "MK-777 peptide" query: ibutamoren was described in 1995 as an orally active non-peptide acting through the same mechanism as the peptide GHRP-6 (Patchett 1995), a distinction that matters because swallowed peptides are largely digested (see Do oral peptides work?). Free Muscle lists MK-777 with its secretagogues rather than its peptides, but no absorption data exist under this name, so its behaviour after oral administration has not been measured.

MK-777 compared with MK-677 (ibutamoren)

"Acetamoren vs ibutamoren" is a common search, and the answer is about what can be verified.

The class description and regulatory position are shared; evidence is not. Ibutamoren has published human measurements of growth hormone, IGF-1, body composition, glucose, cortisol and adverse events. MK-777 has a batch certificate confirming identity and purity, and nothing more. Nor does the prefix signal a shared origin: MK-0677 was a Merck research code, and the code MK-0777 belongs to an unrelated compound, described below. Where a citable literature matters, the MK-677 collection holds the 10mg, 12.5mg and 25mg strengths.

Reading the certificate of analysis for this product

For MK-777 the certificate is the only independent document describing the contents, so it carries more weight than usual. Janoshik Analytical assays every Free Muscle batch; five fields decide whether a certificate means anything.

• Identity: the method, usually liquid chromatography with mass spectrometry (LC-MS), and the substance the laboratory reports finding. With a house designation, the identity result, not the product name at the top, is what the certificate proves.
• Purity: the identified compound as a percentage of total peak area in the chromatogram.
• Content: the measured amount per capsule set against the label claim.
• Batch number: it must match the number on your bottle; a certificate for another batch, or for none, says nothing about your pack.
• Date and reference: the test date and any code the laboratory prints so the document can be checked with it directly.

A missing field makes the document incomplete, and a generic PDF shown for "the product" is marketing, not evidence. See our lab tests page and the guide How to read a certificate of analysis.

Detection, sport and testing

The WADA Prohibited List bans growth hormone secretagogues and their mimetics at all times, in and out of competition, under section S2.2.4, and every substance in S2 is non-Specified. Ibutamoren is named there as an example. MK-777 is not, but that offers no protection: S2 also covers "other substances with similar chemical structure or similar biological effect(s)", and a product listed as a GHS-R1a secretagogue falls within that wording. Strict liability applies. No excretion or metabolism data have been published for MK-777, so the accurate position is that it is prohibited, detectable in principle and without an established detection window; a short window should not be assumed. UK Anti-Doping applies the WADA list across UK sport.

Storage, stability and handling

No stability study has been published for MK-777, so shelf life should be read from the label and the certificate date rather than assumed. Keep the capsules in the original bottle with the cap closed, which also keeps the batch number with the contents. Store cool, dry and out of direct light, away from heat and damp, and do not combine different batches. In a laboratory, record the batch number and the date the bottle was opened, handle with gloves on a clean surface, and dispose of unused material under local rules. Keep out of reach of children and animals.

What the published research reports

The searches behind the table above, run on PubMed and PubChem for "Acetamoren", "MK-777" and "MK777" in September 2026 and repeated on 2 October 2026, returned no records. Nothing below describes this product.

Class context: MK-677 (ibutamoren), not MK-777

Merck chemists reported ibutamoren in 1995 as a potent, orally active non-peptide that released growth hormone from rat pituitary cells and raised it in dogs after oral administration, with only modest rises in cortisol (Patchett 1995). In a two-year randomised trial in 65 healthy adults aged 60 to 81, growth hormone and IGF-1 rose to young-adult levels and, at one year, fat-free mass had increased by about 1.1 kg against a 0.5 kg fall on placebo. The same trial recorded weight gain, higher fasting glucose, lower insulin sensitivity, raised cortisol, increased appetite, transient mild leg oedema and muscle pain, and no change in strength or function (Nass 2008). In 123 older adults recovering from hip fracture, IGF-1 rose but most functional measures did not improve, and the trial was stopped early after congestive heart failure occurred in a small number of patients (Adunsky 2011).

A lookalike code: MK-0777

Searches for "MK 777 studies" often surface papers on MK-0777, a compound also coded TPA023. It is a GABA-A α2/α3 partial agonist with no relation to growth hormone secretagogues, and a four-week trial in 60 people with schizophrenia found no benefit on the primary cognitive measure (Buchanan 2011). None of the findings in this section is a claim about MK-777 or any Free Muscle product.

More questions

What does MK-777 do?

What MK-777 does has not been measured in any published study, human or animal, so we cannot describe any effect and make no outcome claims. Free Muscle lists it with its growth hormone secretagogues, the class of ibutamoren (MK-677), but no receptor data exist under this name. The ibutamoren trials above are class context only; they describe a different compound and cannot be transferred to this one.

What side effects are reported for MK-777?

None have been reported, because MK-777 has never been the subject of a published study; missing data are not evidence that it is well tolerated. As class context only, trials of ibutamoren, a different ghrelin-receptor compound, recorded increased appetite, transient leg oedema and muscle pain, as well as higher cortisol and fasting glucose with lower insulin sensitivity, and a hip fracture trial was stopped early after cases of congestive heart failure.

Is MK-777 a SARM?

No. SARMs such as RAD-140 and ostarine act at the androgen receptor and sit in section S1.2 of the WADA Prohibited List. Free Muscle lists MK-777 as a growth hormone secretagogue, a class covered by section S2, although no receptor data have been published for it. The confusion comes from the shared "MK" prefix, which ostarine also carries as MK-2866.

Related compounds and reading

Collections: MK-777 (Acetamoren), MK-677 (ibutamoren), ipamorelin, a peptide secretagogue acting at the same receptor, and the Bioreactive Series, which also includes RAD-150. Reading: MK-777 (Acetamoren): what the name means, MK-677: what the research says, MK-677 vs ipamorelin vs HGH, What is Janoshik Analytical? and How to choose a UK supplier.

Glossary

• Acetamoren: Free Muscle's designation for MK-777, unrelated to acetaminophen (paracetamol) despite the similar spelling.
• GHS-R1a: growth hormone secretagogue receptor type 1a, the receptor for the hormone ghrelin.
• Secretagogue: a substance that prompts a gland to release a hormone, here growth hormone from the pituitary.
• International Nonproprietary Name (INN): a generic name assigned through the World Health Organization, such as ibutamoren.
• IGF-1: insulin-like growth factor 1, released mainly by the liver in response to growth hormone.
• Label claim: the quantity per capsule stated on the pack, against which the assay result is compared.
• Non-Specified Substance: a WADA category that leaves less room for a reduced sanction.
• Strict liability: the anti-doping rule that an athlete is responsible for any prohibited substance in their sample.

References

• Patchett AA, et al. Design and biological activities of L-163,191 (MK-0677): a potent, orally active growth hormone secretagogue. Proc Natl Acad Sci U S A. 1995;92(15):7001-7005. PMID: 7624358.
• Nass R, et al. Effects of an oral ghrelin mimetic on body composition and clinical outcomes in healthy older adults: a randomized trial. Ann Intern Med. 2008;149(9):601-611. PMID: 18981485.
• Adunsky A, et al. MK-0677 (ibutamoren mesylate) for the treatment of patients recovering from hip fracture: a multicenter, randomized, placebo-controlled phase IIb study. Arch Gerontol Geriatr. 2011;53(2):183-189. PMID: 21067829.
• Buchanan RW, et al. A randomized clinical trial of MK-0777 for the treatment of cognitive impairments in people with schizophrenia. Biol Psychiatry. 2011;69(5):442-449. PMID: 21145041.

Research compounds sold by Free Muscle are supplied for laboratory research use only and are not for human consumption. They are not authorised as medicines by the MHRA, EMA or FDA, are not food supplements, and are sold only to adults aged 18 or over. Nothing on this page is medical or dosing advice.