GHRP-2 — Growth Hormone Releasing Peptide 2 (Research Evidence Summary)

GHRP-2 (also known as pralmorelin or KP-102) is a synthetic hexapeptide ghrelin-receptor agonist developed in the 1980s by Cyril Bowers and colleagues at Tulane University. It is one of the original GH secretagogues and remains among the most-studied compounds in the class in terms of human pharmacokinetics and GH-release pharmacology.

What it is

GHRP-2 is a six-amino-acid peptide (His-D-Trp-Ala-Trp-D-Phe-Lys-NH2) that binds the ghrelin receptor — formally known as GHSR-1a (growth hormone secretagogue receptor 1a). Ghrelin is the endogenous ligand of this receptor; GHRP-2 is a synthetic agonist developed before ghrelin itself was identified (ghrelin was characterised in 1999, six years after GHRP-2 had been in clinical investigation).

Mechanism of action

GHRP-2 acts at the same receptor as ghrelin — see our GHSR-1a glossary entry — and produces the same downstream effects: pulsatile growth hormone release from anterior pituitary somatotropes via a Gαq/PLC/IP3/Ca²⁺ signalling cascade. The pharmacology is distinct from GHRH analogues like CJC-1295 and tesamorelin, which act at the GHRH receptor through Gαs/cAMP. Combining a GHRH analogue with a GHRP produces additive — and in some studies synergistic — GH release, which is the rationale behind the CJC-1295 + Ipamorelin combination literature. See: GH axis mechanism map, CJC-1295 evidence summary, Ipamorelin evidence summary.

Beyond GH release, GHRP-2 — like other GHSR-1a agonists — increases food intake, the appetite-stimulating effect that is the central physiological role of endogenous ghrelin. This orexigenic effect has been demonstrated in human studies (Laferrère 2005).

GHRP-2's short plasma half-life is what drives its multiple-daily-pulse research protocols. See our peptide half-life visualiser for how this decay curve compares to CJC-1295 and other GH-axis peptides.

Human evidence

GHRP-2 has a small but well-characterised human pharmacokinetic and pharmacodynamic literature:

Diagnostic GH-deficiency use in Japan — pralmorelin (GHRP-2) has been used as a single-dose diagnostic agent for adult and paediatric GH deficiency. It is approved by the Japanese regulator (PMDA) for this diagnostic indication. There is no equivalent UK or EU approval.
Phase I PK studies in healthy adults and children (Pihoker 1998), documenting rapid, dose-dependent GH release with a plasma half-life of approximately 15–20 minutes.
Appetite effects in healthy men (Laferrère 2005), establishing that GHRP-2 produces orexigenic effects comparable to those of endogenous ghrelin.

There is no licensed therapeutic indication for GHRP-2 outside the diagnostic GH-deficiency context.

Preclinical evidence

Substantial rodent and in-vitro pharmacology dating from the original Bowers laboratory work in the 1980s. GHRP-2 reliably stimulates GH release in rats, dogs, pigs, and non-human primates. Translation to functional clinical outcomes beyond GH measurement is not established.

UK regulatory status

GHRP-2 is not licensed in the UK for any indication. Research-grade material is permissible for laboratory work strictly within an in-vitro research context. The MHRA has not granted any therapeutic authorisation for the compound.

GHRP-2 is explicitly prohibited under the WADA Code at all times, including out-of-competition periods. Athletes in any tested sport should treat the compound as a competition-ending finding. See: peptides and sports anti-doping.

Safety signals and unknowns

Acute single-dose safety profile is reasonably characterised through the diagnostic-use literature. Reported transient effects include flushing, mild prolactin and cortisol elevations, and orexigenic response.
Chronic dosing safety is not well-characterised in humans. The long-term consequences of sustained GHSR-1a agonism — for body composition, appetite regulation, and downstream IGF-1 elevation — are not established in any registered RCT.
The orexigenic effect is dose-dependent and persists with repeated dosing in published animal studies. This is a feature, not a side effect, of ghrelin-receptor agonism.

Common online claims vs evidence

Claim: "GHRP-2 is the strongest GH secretagogue." Reality: in human comparison studies GHRP-6 and ipamorelin produce GH release of broadly similar magnitude at appropriate doses. Single-rank ordering of GHRPs is marketing, not evidence.
Claim: "GHRP-2 builds muscle without IGF-1 elevation." Reality: GH release through GHSR-1a stimulation leads to downstream IGF-1 production. The compound is not IGF-1-sparing.
Claim: "It's safe because it stimulates endogenous GH, not synthetic." Reality: the somatotropes do not distinguish endogenous from pharmacological stimulation. Endocrine consequences of sustained supra-physiological GH and IGF-1 are the same regardless of route.

GH axis mechanism map
Ipamorelin evidence summary — the principal head-to-head comparison
Ipamorelin vs GHRP-2 — evidence comparison
CJC-1295 evidence summary
Peptides and sports anti-doping

Regulatory and clinical status

UK status: Not UK-approved. Pralmorelin (GHRP-2) has been used as a diagnostic agent for GH deficiency in Japan but is not licensed in the UK. Research-grade material is permissible for laboratory use only. WADA-prohibited at all times.

Read more about how UK regulation applies to peptides in our UK regulation hub and our explanation of what “research use only” means in the UK. PeptideStacks does not make editorial sourcing recommendations within research content; any vendor links elsewhere on this page appear in a clearly-labelled sponsor block (see our conflict-of-interest disclosure).

References

Peer-reviewed sources for the claims above. Where an editor has verified study type, sample size, outcome and limitation, the citation is rendered as a card; otherwise as a plain reference. Links open PubMed or the journal DOI.

Bowers CY, Momany FA, Reynolds GA, Hong A. On the in vitro and in vivo activity of a new synthetic hexapeptide that acts on the pituitary to specifically release growth hormone. Endocrinology. 1984;114(5) :1537-45 · PMID: 6714155
Furuta S, Shimada O, Doi N, et al.. General pharmacology of KP-102 (GHRP-2). Arzneimittelforschung. 2004;54(12) :868-80 · PMID: 15646371
n/a. Pralmorelin: GHRP 2, GPA 748, growth hormone-releasing peptide 2, KP-102 D, KP-102 LN, KP-102 D-LN. Drugs in R&D. 2004;5(4) :236-239 · PMID: 15230633
Sigalos JT, Pastuszak AW. The Safety and Efficacy of Growth Hormone Secretagogues. Sexual Medicine Reviews. 2018;6(1) :45-53 · PMID: 28400207
Semenistaya E, Zvereva I, et al.. Determination of growth hormone releasing peptides metabolites in human urine after nasal administration. Drug Testing and Analysis. 2015;7(10) :919-925 · PMID: 25869809

Published: 2026-05-21Last updated: 2026-05-21Last reviewed: 2026-05-21

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