GHRP-2 vs GHRP-6
GHRP-2 and GHRP-6 are first-generation synthetic growth hormone releasing hexapeptides acting on the ghrelin receptor. They differ mainly in potency of GH release and the strength of their appetite-stimulating effect.
Side-by-Side Comparison
| Property | GHRP-2 | GHRP-6 |
|---|---|---|
| Category | Growth hormone releasing hexapeptide (ghrelin mimetic) | Growth hormone releasing hexapeptide (ghrelin mimetic) |
| Mechanism of Action | GHSR-1a agonist; stimulates pulsatile GH release and amplifies GHRH signaling | GHSR-1a agonist; stimulates pulsatile GH release with a pronounced ghrelin-like appetite effect |
| Molecular Weight | ~818 Da (D-Ala-D-2-Nal-Ala-Trp-D-Phe-Lys-NH2) | ~873 Da (His-D-Trp-Ala-Trp-D-Phe-Lys-NH2) |
| Primary Research Focus | GH secretion dynamics; used clinically in Japan (pralmorelin) as a GH deficiency diagnostic | GH secretion and appetite/ghrelin signaling research |
| Receptor Target | GHSR-1a; mild transient effects on cortisol and prolactin at higher concentrations | GHSR-1a; mild transient effects on cortisol and prolactin at higher concentrations |
| Half-Life | ~30 minutes (estimated) | ~20-30 minutes (estimated) |
| Key Research Citations | Bowers (1998), Cell Mol Life Sci; Arvat et al. (1997), J Endocrinol Invest | Bowers et al. (1984), Endocrinology; Ghigo et al. (1994), Eur J Endocrinol |
Key Differences
- GHRP-2 is generally reported as the more potent GH secretagogue of the two on a per-microgram basis in comparative studies.
- GHRP-6 produces a markedly stronger appetite stimulus, closely mimicking ghrelin’s orexigenic effect; GHRP-2’s appetite effect is comparatively mild.
- GHRP-2 (as pralmorelin) achieved clinical use in Japan as a diagnostic agent for GH deficiency, giving it a regulatory research history GHRP-6 lacks.
- Neither is selective in the way ipamorelin is: both can transiently elevate cortisol and prolactin at higher concentrations, a consideration when designing hormone-axis studies.
Research Summary
GHRP-2 and GHRP-6 are closely related first-generation ghrelin mimetics that established the growth hormone secretagogue field. GHRP-2 offers somewhat stronger GH release and a clinical diagnostic pedigree; GHRP-6 is distinguished by its potent ghrelin-like appetite stimulation, making it the tool of choice when orexigenic signaling itself is the research subject. Later secretagogues such as ipamorelin traded some potency for the receptor selectivity these two lack.
What is the difference between GHRP-2 and GHRP-6?
Both are hexapeptide ghrelin mimetics acting on GHSR-1a. GHRP-2 is generally the more potent GH secretagogue and saw clinical diagnostic use in Japan as pralmorelin, while GHRP-6 produces a much stronger ghrelin-like appetite stimulus. Both can transiently affect cortisol and prolactin at higher concentrations, unlike the more selective ipamorelin.
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Disclaimer: All compounds referenced on this page are sold for research and laboratory use only. The comparisons presented are based on published scientific literature and are intended for educational and informational purposes. This content does not constitute medical advice. Researchers should consult primary literature and applicable regulations before designing study protocols.