MK-677 vs ipamorelin
The two most-searched growth-hormone secretagogues — an oral tablet and an injected peptide — compared: how each raises GH, and how differently.
Neither is an approved medicine. Both are sold as unapproved research chemicals and both are banned in sport. This is a factual comparison, not advice or an offer to sell.
| MK-677Ibutamoren, Nutrobal | Ipamorelin | |
|---|---|---|
| Type | Oral secretagogue (not a peptide) | Injectable GHRP (peptide) |
| Route | oral (tablet or capsule); oral bioavailability above 60 percent | subcutaneous (intravenous in study settings) |
| Dosing | Once daily, usually before sleep | 1-3x daily, with at least 3 hours between administrations to limit receptor desensitisation |
| Half-life | ~4–6 h (IGF-1 raised 24 h) | ~2 h; short GH pulse |
| GH pattern | Round-the-clock elevation | Brief, physiological pulse |
| Status | In trials | In trials |
MK-677 (ibutamoren)
An orally active ghrelin-receptor agonist — a tablet, not a peptide. Its selling point is convenience and a steady, round-the-clock rise in GH and IGF-1; its downside is that the same sustained IGF-1 elevation is what tends to bring water retention, increased appetite and, at higher exposure, effects on insulin sensitivity.
Ipamorelin
A selective GHRP given by injection. It triggers a short, clean GH pulse without the cortisol and prolactin rise seen with older GHRPs, which is why it is the most-used of that family. The trade-off is the mirror image of MK-677: a briefer, more physiological signal, but an injection several times a day rather than a single tablet.
So which is “better”?
They are different tools, not two rungs of a ladder. MK-677 offers convenience and continuous IGF-1 at the cost of water retention and a less natural signal; ipamorelin offers a cleaner, pulsed release at the cost of injections and a shorter action. And for either, the claim that raising GH translates into meaningful muscle or performance in healthy adults is not well supported — see each entry for what its trials actually measured.