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Fitness & muscle

MK-677 (Ibutamoren)

Orally active ghrelin mimetic that raises growth hormone and IGF-1 without injections. Not actually a peptide, but a fixture of GH-secretagogue discussions.

Discontinued (safety signal) Fitness & muscle

Reviewed 2026-09-12
Full name
Ibutamoren (not a peptide — an orally active small-molecule ghrelin receptor agonist, included here because it's routinely grouped with GH-secretagogue peptides)
Also known as
Ibutamoren, Ibutamoren Mesylate, Nutrobal
Regulatory status
Was investigated by pharmaceutical companies (Merck and others) for GH deficiency, sarcopenia and hip fracture recovery in the elderly, but never received FDA approval for any indication and development was discontinued. Sold today only as a research chemical/grey-market product.

Origin

A small synthetic molecule, not a peptide, developed as an orally bioavailable ghrelin receptor agonist. The appeal: a daily pill instead of daily injections for GH-axis stimulation.

Mechanism

Activates the same ghrelin/GH secretagogue receptor as injectable GHRPs like Ipamorelin, but produces a sustained GH/IGF-1 elevation over roughly 12-24 hours per dose instead of the sharper, shorter pulse from injectables. Because it mimics ghrelin, the hunger hormone, it reliably increases appetite — a plus for some users, a problem for others.

Research summary

Evidence

Human trial data is more substantial than for most research peptides. Studies in the elderly showed increased lean body mass and improved some muscle function markers, with the clearest benefit in people who actually had low GH to begin with — a caveat for younger, GH-replete users expecting the same results. A hip fracture trial was stopped early over safety concerns: increased congestive heart failure and edema in the treatment group. That trial is a big part of why it never reached approval.

Evidence tier: Discontinued (safety signal) — see the methodology note for how this is assessed.

Citations

Reported benefits

  • Increased appetite (often deliberately used for this reason during muscle-gain phases)
  • Improved sleep quality, commonly and consistently reported
  • Reported improvements in skin, hair and nail quality with extended use, attributed to sustained IGF-1 elevation
  • Reported strength/recovery benefits, more consistently in older or lower-baseline-GH individuals per the available trial data

Dosing protocols reported in the literature & community

These are protocols reported by compounding pharmacies, published trials, or self-experimentation communities — not a prescription. Start low, especially for anything new.

Reported dosing protocols
RouteReported protocol
Oral, once dailyCommonly cited doses range from 10-25 mg once daily, typically taken at night given its sedating/sleep-promoting effect and to align with nighttime GH release; many self-experimenters start at the lower end (10 mg) to assess tolerance, particularly for blood-sugar and water-retention effects before increasing.

Side effects

  • Increased appetite/hunger — often significant and sometimes unwanted
  • Water retention, mild edema, especially in the hands/feet/face — a known dose-related effect
  • Elevated blood glucose / reduced insulin sensitivity reported with sustained use — worth monitoring, especially for anyone with pre-diabetes
  • The hip-fracture trial safety signal (increased heart failure/edema rates) is a genuine red flag, particularly for anyone with existing cardiovascular disease
  • Lethargy or grogginess reported by some users the morning after dosing

Safety notes

Safety: MK-677 has real human efficacy data, unusual for this class, but the same trial history includes a safety signal serious enough to halt a study: increased heart failure and edema in hip fracture patients. That's one of the most clearly documented risk signals in this wiki, especially relevant for anyone with existing cardiovascular risk factors.
Community & reddit notes (anecdotal — not clinical evidence)

Popular because it's oral, no injections, and reliably improves sleep and appetite, which appeals to people trying to gain muscle. Water retention and blood sugar effects get discussed often. The community generally knows about the cardiovascular signal from the discontinued hip-fracture trial, though not everyone treats it with real caution.