Last updated
Ipamorelin and GHRP-2 are both GHRPs on the same ghrelin receptor, and they are the two most common first choices in GH-secretagogue research. The split between them is the recurring GHRP trade-off in its mildest form: ipamorelin for a clean, selective pulse; GHRP-2 for more growth hormone per dose, at the cost of a little selectivity.
Research reference only. Not medical advice, prescribing guidance, or a product recommendation.
| Dimension | Ipamorelin | GHRP-2 |
|---|---|---|
| Class | Pentapeptide GHRP | Hexapeptide GHRP (2nd-generation) |
| Receptor | GHS-R1a (ghrelin receptor) | GHS-R1a (ghrelin receptor) |
| GH potency | Moderate | Higher — more GH per dose |
| Selectivity | High — minimal ACTH / cortisol / prolactin | Lower — can raise cortisol / prolactin at higher doses |
| Appetite | Minimal | Mild (much less than GHRP-6) |
| Regulatory status | None — research compound | Approved in Japan as a GH-deficiency diagnostic (pralmorelin) |
| Characterizing work | Raun et al., 1998 | Second-generation GHRP (from GHRP-6) |
| Molecular weight | 711.9 Da | 818.0 Da |
| FDA approval | None | None (US) |
Ipamorelin’s whole identity is selectivity. It was characterized as the first GHRP to release growth hormone without meaningfully raising ACTH, cortisol, or prolactin (Raun et al., 1998) — a clean profile that also shows less receptor desensitization over repeated exposure. It is not the strongest secretagogue in the family; it is the tidiest, which is why it is the default when a pure GH signal is the goal.
GHRP-2 (pralmorelin) trades a little of that cleanliness for output. As a second-generation GHRP tuned from GHRP-6, it releases more growth hormone per dose and provokes only mild appetite (far less than GHRP-6’s hallmark hunger), but at higher doses it can transiently raise cortisol and prolactin. It also carries something no other GHRP here has: an actual regulatory approval, used in Japan as a single-injection diagnostic of pituitary GH reserve. So against ipamorelin, GHRP-2 is the more potent, slightly less selective option with a real clinical pedigree — a gentler version of the same trade-off ipamorelin makes against the far more potent, far less selective hexarelin.
If the research goal is a clean GH pulse with minimal off-target hormones, ipamorelin’s selectivity is the reason to pick it; if it is maximal GH release per dose, GHRP-2 is stronger and has the added distinction of an approved diagnostic use in Japan. Both act on the same receptor, both are commonly studied alongside a GHRH analog for complementary release, and neither is FDA-approved in the US. This page is a research and educational reference.
Both are GHRPs that release growth hormone via the ghrelin receptor. Ipamorelin is prized for selectivity — it releases GH with minimal cortisol, prolactin, or appetite. GHRP-2 (pralmorelin) is more potent, raises appetite mildly, can nudge cortisol and prolactin at higher doses, and is an approved GH-deficiency diagnostic in Japan.
Ipamorelin. It was characterized as the first GHRP to release GH without meaningfully raising ACTH, cortisol, or prolactin, and it shows less receptor desensitization. GHRP-2 is stronger but less selective.
Much less. GHRP-2 was tuned from GHRP-6 for more GH and less appetite; it raises hunger only mildly, whereas GHRP-6’s sharp appetite spike is its hallmark. Ipamorelin’s effect on appetite is minimal.
No. GHRP-2 is approved in Japan as a diagnostic (pralmorelin) but not by the FDA; ipamorelin is a research compound. This page is a research and educational reference.
Mechanism, evidence, and trade-offs between Ipamorelin and GHRP-2 — citation-backed answers grounded in PubMed, PubChem, and ClinicalTrials.gov.