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Draft entry. Written from the cited papers but not yet reviewed by a person. Check the references before relying on any claim.
Ghrelin / GHS-receptor agonist

MK-777

also Acetamoren · MK 777

MK-777, sold as "acetamoren", is offered as an orally active growth hormone secretagogue and a successor to MK-677. There is no published research on it. A search of PubMed for MK-777 and for acetamoren returns nothing: no pharmacology paper, no animal study, no human data, no pharmacokinetics, no structure. It has no PubChem entry under either name. Everything asserted about it — its potency, its selectivity, its supposed advantages over MK-677 — originates from sellers, not from any source that can be checked.

A product name with no published science behind it of any kind. Nothing here can be verified, including whether the vials contain what the label says.

No PubChem structure on file.
No evidence4 papers · 2008–2021 · 4 journals · 3 in humans
  • meta-analysis
  • RCT
  • trial
  • observational
  • preclinical / case
  • review / patent / other
  • retracted
2008 · RCT · Effects of an oral ghrelin mimetic on body composition and clinical outcomes in healthy older adults: a randomized trial.2009 · RCT · Effects of an oral growth hormone secretagogue in older adults.2018 · other · Analysis of new growth promoting black market products.2021 · review · The ups and downs of growth hormone secretagogue receptor signaling.
in its favour
  • + No benefit has been demonstrated in any published study
watch for
  • − No published pharmacology, toxicology or human data exists
  • − The compound's structure is not publicly documented
  • − Nothing is known about what is actually in products sold under the name

Overview

MK-777 appears on peptide retailer catalogues as an oral growth hormone secretagogue, usually presented as a newer or stronger relative of MK-677. The "MK" prefix is Merck's internal compound code, and the name is presumably meant to suggest continuity with MK-677 (ibutamoren), which Merck did develop and test extensively in humans [1].

Searching the published literature for MK-777 or acetamoren returns nothing at all. There is no synthesis paper, no receptor binding data, no animal study, no pharmacokinetics and no clinical trial. This is different from a compound with weak evidence, such as Ipamorelin, where at least the animal pharmacology is published and checkable. Here there is no starting point.

Without a published structure it is also impossible to say what relationship, if any, the material sold under this name bears to any characterised molecule. Analyses of grey-market growth products have repeatedly found contents that do not match their labels [2].

This entry exists to record that absence. If pharmacology for this compound is ever published, it will be added here.

Mechanism

No mechanism has been published for MK-777. It is marketed as an agonist at the growth hormone secretagogue receptor GHS-R1a, the receptor that ghrelin, MK-677 and the GH-releasing peptides use [3], but no binding or functional data for this compound have been reported.

Formulation

how the form changes blood levels

No published structure, molecular formula or molecular weight exists for MK-777 under that name or under "acetamoren", and it has no PubChem record. It is sold as an oral product.

Dosing

as studied or commonly reported; not a recommendation

No doses are listed for this compound.No peer-reviewed human dosing data.

Notes
No human or animal dose has been studied. No dose can be given here, because there is no published study of this compound at any dose by any route.

Safety

risks and cautions, not medical advice

Nothing is known. No toxicology study, no adverse event data, no human exposure has been published under this name. The class it is marketed as belonging to has well-documented effects on blood glucose — MK-677 raised fasting glucose and HbA1c measurably over 12 months [1] and capromorelin did the same [4] — but it cannot be assumed that an uncharacterised compound shares either the benefits or the risks of drugs it is named after.

Adverse effects
reported, not universal
  • Unknown; no safety data have been published
Cautions
who should think twice
  • Nothing about this compound has been independently verified
  • Grey-market growth products frequently do not contain what their labels claim [2]
Limits of the evidence
what has not been shown
  • No published study of this compound exists, of any kind
  • No published structure, so the identity of material sold under this name cannot be confirmed
  • Marketing claims of superiority over MK-677 have no published basis

Interactions

documented pairs only, not exhaustive

No interaction data exist.

FAQ

Is MK-777 stronger than MK-677?
There is no way to know. No study of MK-777 has ever been published, so there is nothing to compare.
What is acetamoren?
It is the trade-style name used for MK-777. Neither name appears in the published literature or in PubChem.

References

entry last reviewed 2026-09-19
  1. [1]
    Effects of an oral ghrelin mimetic on body composition and clinical outcomes in healthy older adults: a randomized trial.
    Nass R, Pezzoli SS, Oliveri MC et al.Ann Intern Med 2008RCT · humanPMID 18981485◌ unreviewed
  2. [2]
    Analysis of new growth promoting black market products.
    Krug O, Thomas A, Malerød-Fjeld H et al.Growth Horm IGF Res 2018other · humanPMID 29864719◌ unreviewed
  3. [3]
    The ups and downs of growth hormone secretagogue receptor signaling.
    Cornejo MP, Mustafá ER, Cassano D et al.FEBS J 2021reviewPMID 33460513◌ unreviewed
  4. [4]
    Effects of an oral growth hormone secretagogue in older adults.
    White HK, Petrie CD, Landschulz W et al.J Clin Endocrinol Metab 2009RCT · humanPMID 19174493◌ unreviewed