SYS · ONLINE│PASS · 63.0%
Open Assay
Independent Testing / Est. 2026
BATCH04·26·B
PASS63.0%
N27
Peptides›GH secretagogue›MK-677

MK-677

/ Non-peptide spiroindoline small molecule; oral ghrelin / GHS-R1a receptor agonist
TIER 2 · TranslationalN = 0 · TESTING PENDINGLAST REVIEW 2026·04·20

ALIAS · Ibutamoren · MK-0677

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Research use onlyAny dose figures below describe what specific cited studies used, reported factually. Nothing on this page is guidance for human use.READ FIRST →

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§ A · Identity
Primary sequence— sequence not captured —
MW · —CLASS · Non-peptide spiroindoline small molecule; oral ghrelin / GHS-R1a receptor agonistCATEGORY · GH secretagogue

Merck developed through Phase 3 for frailty and Alzheimer’s; halted ~2007 without approval after a failed Alzheimer trial (Sevigny 2008) and a CHF/edema signal in frail elderly.

§ B · Mechanism of action

MK-677 is a non-peptide, orally bioavailable spiroindoline small molecule that acts as a ghrelin/GHS-R1a receptor agonist, mimicking ghrelin to stimulate pulsatile GH and IGF-1 release. Oral bioavailability and long duration (~24 hours) distinguish it from injectable ghrelin mimetics. Increases appetite via the same receptor.

§ C · Human clinical evidence

Never FDA-approved. Merck developed ibutamoren for frailty, sarcopenia, and hip-fracture recovery through Phase 3. Program halted ~2007, reportedly after a failed Phase 3 Alzheimer’s disease study (Sevigny 2008) and CHF/edema signals in frail elderly populations.

§ D · Primary literature
PubMed19075206Nass R et al. — Effects of an oral ghrelin mimetic on body composition and clinical outcomes in healthy older adults: a randomized trial · Annals of Internal Medicine · human-phase-2Two-year randomized trial in 65 healthy older adults. MK-677 restored GH and IGF-1 levels to young-adult range. Increased lean mass by 1.1 kg vs placebo. Fasting glucose rose ~0.3 mmol/L.Limitations: Modest sample size; functional outcomes (strength, stair climb) did not reach significance. Subsequent trials in frail elderly flagged CHF exacerbation signal.2008
PubMed18094333Sevigny JJ et al. — Growth hormone secretagogue MK-677: no clinical effect on AD progression in a randomized trial · Neurology · human-phase-3-rct12-month randomized trial in mild-to-moderate Alzheimer's disease found no cognitive benefit from MK-677 despite increases in GH and IGF-1.Limitations: Negative trial; effectively halted MK-677 development in this indication.2008
§ F · Safety signal

Common adverse events: increased appetite, weight gain, fluid retention / peripheral edema, transient muscle pain, mild fasting hyperglycemia / insulin resistance, fatigue. Serious signal: CHF exacerbation noted in frail elderly populations; not recommended in that population in trial protocols. Elevated fasting glucose and HbA1c are consistent findings.

§ H · Regulatory status

Regulatory status

FDA status:
Not FDA-approved
Compounding:
Not eligible for compounding (approved, not in shortage)
§ I · Notable gaps and controversies

MK-677 is not a pharmacopeial API and is not on any FDA positive compounding list. It is sold predominantly through gray-market research-chemical suppliers. FDA has issued warning letters regarding products marketed as dietary supplements containing MK-677 — it does not meet the DSHEA definition of a dietary ingredient. WADA-prohibited.