Compound Profile · GH Secretagogue
MK-677 / Ibutamoren
MK-677 (ibutamoren) is an oral ghrelin receptor agonist and GH secretagogue studied in research for its effects on growth hormone and IGF-1 release, muscle growth and sleep quality.
Peptide Score
Evidence
Safety
Regulatory
Transparency
Quick verdict
Orally active GH secretagogue — mechanistically interesting, but never reached human approval. Insulin resistance and water retention signals in trials.
Reality check
What this isn't
- Never approved by any regulatory body
- Insulin resistance signal in Phase II trials
- Water retention and peripheral oedema common
- WADA prohibited (S2 — peptide hormones, growth factors)
- Oral bioavailability advantage over injectable peptides, but not safer
- Long-term human safety unknown
- Educational research review only — not medical advice
GH/IGF-1 elevation
Mean increase in growth hormone and IGF-1
16
Weeks
Phase II
Trial phase
What this means: Demonstrated GH and IGF-1 elevation in Phase II human trials with oral bioavailability. Development halted before Phase III — insulin resistance and metabolic side-effect signals contributed to stalled approval pathway.
What participants experienced
- 1
Dose titration
GH/IGF-1 elevation confirmed in Phase II
- 2
Week 2–4
GH and IGF-1 plateau established
- 3
Weeks 4–16
Persistent GH elevation; water retention and appetite effects observed
- 4
Post-trial
Development paused; no Phase III trials initiated; research context interest only
Full MK-677 / Ibutamoren review
MK-677 is a non-peptide ghrelin receptor agonist. Unlike GH secretagogues that are peptides, ibutamoren is administered orally.
It stimulates pulsatile GH and IGF-1 release by mimicking ghrelin's action on the growth hormone secretagogue receptor.
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