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MK-677 (Ibutamoren)

B
best evidence
Small molecule (non-peptide)⚠ WADA-banned
also called — MK-677 · MK-0677 · Ibutamoren (mesylate) · Merck code L-163,191 · pediatric development name LUM-201. INCI: none. Not a peptide and not a SARM (see below)
GH secretagogue (oral)body compositionslow-wave sleepappetite (research / gray-market)

Reference entry — not sold here. The oral, non-peptide sibling of the injectable GHRPs: same ghrelin-receptor mechanism, but a pill. Included because the demand is enormous and it sits right next to the GH-peptide cluster — honestly tagged as not a peptide. No dosing published here.

In brief

MK-677 (ibutamoren) is an oral, non-peptide ghrelin-receptor agonist — the pill version of the injectable GHRPs. Across ~30 years of trials it reliably raises GH and IGF-1 and deepens slow-wave sleep, and it modestly increases lean mass — but without improving strength or physical function, and at a real metabolic cost (insulin resistance / elevated blood glucose). It's not FDA-approved (the FDA is recalling consumer products that contain it), it carries a congestive-heart-failure safety signal from an elderly trial, and it's banned in sport. It is not a peptide and not a SARM.

Legal standing, by region
European Union
Not approved

not approved.

United States · your region
Not approved

Not FDA-approved for any indication (30 years on, still unapproved; Merck shelved it, and Lumos's LUM-201 is in pediatric development, not approved). The FDA is actively enforcing against unapproved consumer products — a consumer alert on "iKids-Growth" (Sept 2025) and a recall of "Agebox" products containing undeclared ibutamoren (March 2026). It is not a scheduled substance, but selling it in supplements is unlawful.

⚠ WADA-prohibited in sportSport: WADA-prohibited at all times — Section S2 (GH secretagogues / ghrelin mimetics); directly detectable.
Evidence, by outcome

An honest grade per outcome — drawn from the evidence, not any catalogue. Hype and undemonstrated marketing claims grade low.

OutcomeEvidence base · effectGrade
GH / IGF-1 elevation
Well-established biomarker effect — which is not the same as a clinical benefit
~30 years of trials (Chapman 1996; Svensson 1998; many) · Sustained rise in GH & IGF-1
B
Slow-wave (deep) sleep
A genuine, often most-noticed effect
Documented across trials · Meaningful increase in stage-IV sleep
B
Fat-free (lean) mass
No strength or functional improvement — the key honest limit
Nass 2008 (Ann Intern Med, 2 yr, n=65): FFM +1.1 kg · Modest lean-mass gain
C
Anti-aging / physique / strength (the popular use)
The FFM gain ≠ performance; ghrelin-driven hunger causes fat gain in physique use
Lean-mass gain doesn't translate to function; appetite drives fat gain · Not demonstrated for these goals
F
Failed / halted indications
The congestive-heart-failure signal in elderly is a serious flag
Alzheimer's (Sevigny 2008 — no effect); hip-fracture trial (Adunsky 2011) terminated early on a CHF signal · Negative / safety-halted
Safety
Insulin resistance / elevated fasting glucose (primary risk); lower-extremity edema; appetite → fat gain; modest prolactin rise; theoretical oncogenic concern (sustained IGF-1); CHF signal; WADA-banned
Multiple trials · Real concerns

Identity a non-peptide small molecule — a spiroindanylpiperidine (~529 Da), chemically closer to a conventional drug than to a peptide. Synthesised in 1995 by Arthur Patchett's team at Merck (Patchett, PNAS 1995; Smith, Science 1997) as an orally active growth-hormone secretagogue. It is a long-acting (~24 h, once-daily) agonist of the ghrelin receptor (GHS-R1a) — the same receptor as the injectable GHRPs (GHRP-6 #24, GHRP-2 #23, Ipamorelin #17, Hexarelin #21), but taken by mouth. ## Mechanism (as proposed) binds GHS-R1a (the ghrelin receptor) on hypothalamic and pituitary somatotrophs → pulsatile GH release (mimicking the body's natural overnight pattern) → hepatic IGF-1, which drives the downstream muscle/fat/bone/sleep effects. It also mimics ghrelin's appetite signal (relentless hunger). Its oral, small-molecule nature and long half-life are what distinguish it from the injectable GHRPs — as is its tendency to raise blood glucose with sustained use.

Sources — 5 cited
01Patchett AA, et al. (A nonpeptidyl growth hormone secretagogue.) PNAS. 1995; Smith RG, et al. Science. 1997.
02Chapman IM, et al. (Stimulation of the GH/IGF-1 axis by oral MK-677.) J Clin Endocrinol Metab. 1996.
03Nass R, et al. Effects of an oral ghrelin mimetic on body composition in healthy older adults. Ann Intern Med. 2008. (FFM +1.1 kg, no strength gain.)
04Sevigny JJ, et al. (MK-677 — no clinical effect on Alzheimer's progression.) Neurology. 2008; Adunsky A, et al. (Hip-fracture trial terminated on CHF signal.) 2011.
05Lumos Pharma — LUM-201 (OraGrowtH210/212) pediatric GHD Phase 2.
Review status
Not yet reviewed

A credentialed reviewer (PharmD / PhD / MD) will be named before this entry is finalised. Until then, treat it as a working draft. Last updated July 2026.

Grades reflect the published evidence, not our interest. No dosing, reconstitution, or administration is published for research compounds — that restraint is deliberate.

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MK-677 (Ibutamoren) — evidence, the oral-GH story & status · Vallydia