MK-677 (Ibutamoren), single vial

Growth hormone secretagogue (ghrelin receptor agonist)

MK-677 (Ibutamoren)

NOT A PEPTIDE — small molecule. A non-peptidic spiro-indoline piperidine compound, not a chain of amino acids.. Supplied for laboratory research use only.

  • Small molecule (ibutamoren) -- not a peptide
  • Merck discontinued development; no NDA ever filed
  • FDA warning letter, Dec 2025, undeclared use in kids' supplement
  • Supplied for laboratory research use only. Not for human or veterinary use.
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Research use only. Not for human or veterinary use or consumption. This product is not approved by the FDA and is not intended to diagnose, treat, cure or prevent any disease.

What it is
CompoundMK-677 (Ibutamoren), also designated Ibutamoren mesylate
ClassGrowth hormone secretagogue (ghrelin receptor agonist)
CompositionNOT A PEPTIDE — small molecule. A non-peptidic spiro-indoline piperidine compound, not a chain of amino acids.
FormCapsules or raw powder, supplied in a vial
OriginatorMerck, originator; development discontinued
Development status

MK-677 (Ibutamoren) is not approved by the FDA for any indication.

Development status is stated above. No efficacy claim is made on this page.

Shipping & returns
ReturnsNinety days from delivery. Contact us and we will refund the purchase price.
MK-677 (Ibutamoren) $239.99

The specifics

The details, if you want them.

DeveloperMerck (originator; discontinued development)
Also known asIbutamoren, MK-0677
ClassGrowth hormone secretagogue (ghrelin receptor agonist)
Molecule typeSmall molecule — not a peptide
FormCapsule or raw powder (not a reconstituted vial)
Receptor target(s)ghrelin receptor (GHS-R1a)
Molecular formulaC27H36N4O5S
Molecular weight528.66 Da

Development

Where it is up to.

Investigated by Merck in clinical trials for several indications; development was discontinued and no New Drug Application was ever filed.

Questions

The questions people actually ask.

What is MK-677?
A small molecule (also called ibutamoren), not a peptide — it's built around a different chemical structure entirely, not a chain of amino acids.
Is MK-677 actually a peptide?
No. Despite being sold in the peptide category, MK-677 is a small molecule with no amino-acid sequence. Describing it as a peptide is inaccurate.
Is MK-677 approved by the FDA?
No. Merck investigated it but never filed for approval. FDA has issued multiple warning letters over unapproved MK-677 products, most recently in Dec 2025.
What does "Research Use Only" mean?
Research Use Only means exactly that: intended for laboratory and research settings only, not for human or animal use, consumption, diagnosis, treatment, cure, or prevention of any disease.
What is your refund policy?
Ninety days from delivery. If you decide against it inside that window, contact hello@getmrpeps.com and we will refund the purchase price. Damaged or incorrect orders are replaced or refunded regardless.