MK-677 (Ibutamoren) vs Sermorelin
A neutral, side-by-side comparison of two performance & growth hormone peptides — their mechanisms, dosing ranges, administration routes, side effects, and research evidence. For research and educational purposes only.
MK-677 (Ibutamoren)
Oral non-peptide growth hormone secretagogue that mimics ghrelin to stimulate GH and IGF-1 release without injection. Long half-life (~24 hours) enables once-daily oral dosing. Widely researched for body composition, sleep quality, and IGF-1 elevation.
Full profileSermorelin
Sermorelin is a synthetic analog of the first 29 amino acids of GHRH (Growth Hormone-Releasing Hormone). It was FDA-approved for pediatric GH deficiency diagnosis and is widely used off-label in anti-aging and performance medicine. It stimulates pulsatile GH release more physiologically than exogenous GH.
Full profile| MK-677 (Ibutamoren) | Sermorelin | |
|---|---|---|
| Category | Performance & Growth Hormone | Performance & Growth Hormone |
| Also known as | Ibutamoren, Nutrobal, MK677, L-163,191 | GHRH 1-29, GRF 1-29 NH2, Geref |
| Evidence | Research-stage | FDA-approved |
| Dosing range | 10mg–50mg mg, once daily oral | 100mcg–500mcg mcg, once daily (before sleep) |
| Administration | Oral (capsule/liquid) | Subcutaneous injection |
| Key side effects | Water retention, Increased appetite, Elevated fasting glucose (long-term), Fatigue (initial, transient) | Injection site redness, Headache, Flushing, Dizziness |
| Cited sources | 2 references | 1 reference |
Key differences
- Evidence level differs: MK-677 (Ibutamoren) is research-stage, while Sermorelin is fda-approved.
- Administration: MK-677 (Ibutamoren) — Oral (capsule/liquid); Sermorelin — Subcutaneous injection.
- Dosing units differ: MK-677 (Ibutamoren) is dosed in mg, Sermorelin in mcg — they operate at different scales.
- Frequency: MK-677 (Ibutamoren) is typically once daily oral; Sermorelin is once daily (before sleep).
- Research depth: this profile cites 2 sources for MK-677 (Ibutamoren) vs 1 for Sermorelin.
How each works
MK-677 (Ibutamoren)
MK-677 binds the ghrelin receptor (GHS-R1a) to stimulate pulsatile GH release and increase circulating IGF-1. Unlike peptide GHRPs it survives oral administration. Clinical trials demonstrate significant increases in GH pulsatility and IGF-1 without suppression of the endogenous GH axis, though long-term use raises glucose metabolism concerns.
Sermorelin
Sermorelin works by binding pituitary GHRH receptors to stimulate GH secretion within the body's natural feedback loop. Unlike synthetic GH, it does not suppress endogenous production. Clinical studies show improved body composition, sleep quality, and IGF-1 levels in GH-deficient adults. Its short half-life (~10 min) means it requires daily dosing.
This comparison aggregates public research and structured profile data for informational purposes only. It is not medical advice and does not recommend either compound for human use. Consult a qualified healthcare provider before considering any peptide.