Ipamorelin vs MK-677
Side-by-side comparison of Ipamorelin, MK-677 — mechanism, dosing, half-life, side effects, and research status.
| Attribute | Ipamorelin Ipamorelin (Selective GHRP) Growth Hormone | MK-677 MK-677 (Ibutamoren) — Oral GH Secretagogue Growth Hormone |
|---|---|---|
| Basics | ||
| Molecular type | Growth Hormone Releasing Peptide (GHRP) | Non-Peptide GH Secretagogue |
| Amino acids | 5 | — |
| Molecular weight | 711.9 Da | 624.8 Da |
| Half-life | ~2 hours | ~24 hours |
| Route(s) | Subcutaneous, Intramuscular | Oral |
| Mechanism & Research | ||
| Primary mechanism | Ipamorelin activates growth hormone secretagogue receptors (GHSR-1a) in the pituitary, triggering pulsatile GH release. Unlike first-generation GHRPs (GHRP-6, GHRP-2), ipamorelin's selectivity for GHSR-1a is high enough … | MK-677 mimics ghrelin's binding to GHSR-1a receptors, activating the same signalling cascade that endogenous ghrelin uses to stimulate GH release. As a small non-peptide molecule, it resists enzymatic degradation and is … |
| Research status | Research Compound | Research Compound |
| Evidence summary | Ipamorelin was among the first highly selective GHRPs to enter research. Phase 1 trials confirmed its clean hormonal profile. It remains a reference GHRP in comparative studies and is widely used as the GHRP component in… | MK-677 has one of the most extensive clinical datasets of any non-approved GH secretagogue, with Phase 1/2 trials across multiple populations including GH-deficient adults, elderly frail patients, and post-hip-fracture p… |
| Protocol & Dosing | ||
| Typical dose | 100–300 mcg per injection | 10–25 mg/day |
| Frequency | 2–3x daily (or 1x at bedtime) | Once daily |
| Duration | 8–12 weeks on, 4 weeks off | 8–16 weeks; some protocols run 6 months |
| Timing | Fasted state or 2+ hours post-meal for maximum GH response; bedtime dosing utilises natural nocturnal GH pulse | Bedtime (maximises nocturnal GH pulse; also reduces daytime appetite impact) |
| Safety | ||
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| Anti-doping | Prohibited (WADA S2) | Prohibited (WADA S2) |
| Deeper reading | ||
| Related peptides | CJC-1295, GHRP-2, Sermorelin, Tesamorelin | Ipamorelin, CJC-1295, GHRP-6 |
| Full profile | Read full Ipamorelin profile → | Read full MK-677 profile → |
Comparison data is compiled from each peptide’s individual profile. All values are drawn from peer-reviewed research and regulatory sources. For educational use only — not medical advice. Verify any protocol with a qualified healthcare provider.