GHRP-2 (Pralmorelin): Growth Hormone-Releasing Peptide-2
Synthetic hexapeptide ghrelin mimetic. Used in some countries as a diagnostic for GH deficiency; not approved for therapeutic use in most.
👥 Human studies
- Full name
- GHRP-2 / Pralmorelin (KP-102)
- Class
- Ghrelin receptor (GHS-R) agonist — peptide
- Half-life
- ~15–20 minutes
- Route
- Subcutaneous, intranasal, or oral
- Developer
- Kaken / Wyeth
- Regulatory status
- Approved as GH-stimulation diagnostic in Japan; not approved for therapeutic use in US/EU; WADA-banned
What it is
GHRP-2 is a synthetic hexapeptide (D-Ala-D-βNal-Ala-Trp-D-Phe-Lys-NH2) that activates the ghrelin receptor on pituitary somatotrophs, producing a sharp pulse of GH. It is more potent than GHRP-6 and produces less hunger.
How it works
Binding GHS-R1a triggers IP3/DAG signalling in somatotrophs and increases intracellular calcium, evoking a GH pulse within minutes. Effects are synergistic with endogenous GHRH — co-administration produces additive GH release.
Because of its short half-life, GHRP-2 can be used as a diagnostic stimulus for GH secretion. Chronic therapeutic use is limited by tachyphylaxis and the availability of better-studied alternatives.
What the research shows
Most published studies are short-term pharmacodynamic or diagnostic trials.
Bowers CY et al. (1997) — GH pulse characterisation
Bowers C.Y. et al., J Clin Endocrinol Metab 1997;82:3452–3458. 👥 Human studies
Healthy adults received GHRP-2 and GHRP-2 + GHRH.
GH peaks were 5–10× higher than GHRH alone; the combination evoked physiologically supranormal pulses without somatostatin interference.
Limitations: Acute pharmacodynamics only; no long-term outcomes.
Japanese diagnostic registry (pralmorelin test)
Chihara K. et al., Endocr J 2007;54:751–758. 👥 Human studies
Pralmorelin 100 μg IV was compared with insulin tolerance test in children with suspected GH deficiency.
Test performance supported regulatory approval in Japan as a safer alternative to insulin-induced hypoglycaemia.
Limitations: Diagnostic use only; not therapeutic approval.
Safety and limitations
Well tolerated acutely: mild flushing, transient cortisol and prolactin rises (smaller than GHRP-6), occasional nausea. Chronic data are limited.
Unregulated market peptides sold as GHRP-2 vary in purity. Banned by WADA.