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MK-677

66
evidence score
gh secretagogue
Research Only
110 studies
IbutamorenIbutamoren MesylateL-163,191+1 more

MK-677 (Ibutamoren) is an oral, non-peptide ghrelin receptor agonist that stimulates pulsatile GH and IGF-1 secretion from the pituitary. Unlike exogenous HGH, MK-677 works through the body's own GH axis, maintaining physiologic pulsatility. Phase II trials in elderly subjects and GH-deficient populations demonstrated significant increases in IGF-1 (up to 60–80% above baseline), lean mass gains, and improved bone density. Also increases deep sleep (slow-wave). 24-hour coverage from single daily oral dose. Does not suppress natural GH secretion. Main concerns: insulin resistance, cortisol elevation, water retention, and increased appetite (via ghrelin pathway). Not FDA-approved.

Evidence

Moderate evidence

Safety

Unknown safety profile

Clinical Status

Phase II

Last Sync

Feb 19, 2026

Last Reviewed

Not reviewed yet

Dosing

Typical
25 mg
10 mgRange50 mg
FrequencyOnce daily oral (evening preferred for sleep/GH pulse alignment)

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Pharmacology

Half-life~24 hours
OnsetElevated IGF-1 within days; sleep improvement within 1–2 weeks; body composition changes over months
DurationEffects persist during dosing; IGF-1 returns to baseline within days of cessation
Routes
oral

Evidence Score

66
Level B — Moderate
110 studies indexed
Scoring Factors
Volume(24%)~41/100
Quality(24%)~40/100
Sample Size(12%)~89/100
Consistency(14%)~89/100
Replication(8%)~89/100
Recency(18%)~89/100

Scores estimated from study counts. Exact breakdown computed after research sync.

Evidence Levels
AScore ≥75 with at least 1 meta-analysis and 3+ RCTs
BScore ≥50 with at least 1 RCT or meta-analysis
CScore ≥25 — observational or animal evidence only
DScore <25 — very limited or preclinical data

Plain-English Snapshot

MK-677 is currently categorized as a gh secretagogue compound.

Evidence is moderate (66/100): promising signal from 110 indexed studies, but context and population still matter.

Safety scoring is incomplete. Start conservatively and monitor carefully.

Core mechanism

Ghrelin receptor (GHSR-1a) agonist; stimulates pulsatile GH release from anterior pituitary; elevates IGF-1 without suppressing endogenous GH axis

Practical Context

Strongest current signals

  • Level C: LGD-4033 and MK-677 use impacts body composition, circulating biomarkers, and skeletal muscle androgenic hormone and receptor content: A case report.
  • Level D: 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.
  • Level D: Hepatotoxicity induced by MK-677.

Compound Profile