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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

Research Sync

Feb 19, 2026

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(40%)~41/100
Quality(30%)~40/100
Sample Size(10%)~100/100
Consistency(10%)~100/100
Replication(5%)~100/100
Recency(5%)~100/100

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