GHRP-2
Research OnlyA synthetic hexapeptide GH secretagogue with the strongest GH-releasing potency in its class. More potent than GHRP-6 with different side effect profile: less appetite stimulation but greater cortisol and prolactin elevation. Approved in Japan as Pralmorelin for GH deficiency diagnosis. Extensively studied in human pharmacology with robust clinical data.
Growth Hormone Releasing Peptide-2 · Pralmorelin · KP-102
18 human studies
- Preclinical
- 37%
- Clinical
- 35%
Based on 52 cited sources
clinically demonstrated · moderate confidence
Demonstrated effect magnitude — not a recommendation or safety claim.
Research Depth 73: ≥2 independent human RCTs/controlled studies (Pandya GHRH-antagonist RCT 9543138, van Dam acipimox crossover RCT 11134132, Tiulpakov 7586605, Frieboes 7617137, Pihoker controlled trial 7559885) plus a low-RoB diagnostic validation study (Chihara 17609397, n=135) — but no GHRP-2 systematic review/meta-analysis, capping 1A at 30 and 1B at 14; cumulative human N ~300-1,000 (1C 9), direct population/route/outcome for GH provocation (1D 13), substantial preclinical program (1E 7). Mechanism 95: GHS-R1a target with high-affinity binding, functional agonism, and GHRH-antagonist abolition of most effect (9543138 → 2A 40); full Gq/11-PLC-IP3-Ca2+ → GH exocytosis pathway plus hypothalamic GHRH amplification (2B 27); human dose-response (Arvat 9285939, 2C 18); in-vivo mammalian confirmation (2D 10). Plausibility 93: mechanism → surrogate (GH peak) → validated diagnostic outcome each supported (3A 34), fully coherent with ghrelin/GH physiology (3B 25), multiple same-class agents replicate the effect (GHRP-6, hexarelin, ipamorelin, MK-677; 3C 20), tightly scoped diagnostic claim (3D 14). Global Coverage 83: reproduced across many independent groups in Japan, USA, Italy, Netherlands, Russia, Spain, Germany (4A 30, 4B 23, 4C 20), approved as Pralmorelin in Japan (4D 10). Community Experience 71: broad multi-year bodybuilding-community discussion (5A 22, 5B 27, 5C 14) with recurring but minor cortisol/prolactin/hunger reports (5D 8) — usage signal only, not efficacy or safety. Effectiveness basis clinical (moderate): the validated indication is GH-deficiency diagnostic provocation (Chihara 17609397) — robust GH separation between GHD patients and controls (~1.4 vs ~85 µg/L) and non-inferior to the insulin tolerance test with a better safety profile; scored on the diagnostic (functional, non-hard) endpoint, with therapeutic/body-composition claims remaining clinically unvalidated.
GHRP-2 is a synthetic hexapeptide that acts as a potent agonist of the ghrelin receptor (GHS-R1a). Human pharmacodynamic studies establish it as the most potent hexapeptide GH secretagogue, approximately 3x more effective than GHRP-6 at stimulating growth hormone release.
How It Works (Simplified)
GHRP-2 triggers growth hormone release by mimicking the hunger hormone ghrelin:
Binds to ghrelin receptors (GHS-R1a) on pituitary somatotrophs with high affinity, triggering intracellular calcium release.
Calcium mobilization triggers exocytosis of GH-containing vesicles, producing the most potent GH release of any hexapeptide GHRP.
Also acts at hypothalamic level to stimulate GHRH neurons, creating supra-additive effects when combined with exogenous GHRH.
Unlike ipamorelin, GHRP-2 significantly increases cortisol and prolactin (more than GHRP-6) while causing less appetite stimulation.
Key Research: Arvat et al. (Italy, 1997) established GHRP-2 as the most potent hexapeptide secretagogue with highest cortisol/prolactin effects. PMID:9285939
Important Limitations
- More potent GH release comes with less selectivity (cortisol/prolactin elevation)
- Paradoxically causes less appetite stimulation than GHRP-6 despite same receptor
- Short half-life (~30 minutes) requires frequent dosing for sustained effects
- No therapeutic trials completed - only diagnostic use validated
- Long-term safety data limited to repeat diagnostic administrations
Reported positives
- Strong GH release and improved recovery reported
- Enhanced appetite useful for muscle building goals
- Improved sleep quality noted
- Fast-acting effects felt within minutes of injection
Reported negatives
- Intense hunger increase can be difficult to manage
- Cortisol and prolactin elevation concerns
- Water retention and bloating
- Desensitization with prolonged use reported
“Potent GH secretagogue popular in bodybuilding. FDA Category 2 restricted from compounding.”
Self-reported, unverified accounts — not clinical evidence and no substitute for the cited research. Anecdotes are prone to selection bias and placebo effects.
Peak GH release occurs rapidly following subcutaneous or IV administration. Human studies consistently show maximal serum GH concentrations within this window. Cortisol and prolactin also begin rising.
PMID:7586605GH levels remain elevated above baseline. Despite GHRP-2's short half-life (~30 minutes), the triggered GH secretion persists for 2-3 hours. Cortisol and prolactin return toward baseline.
PMID:9285939GH levels return to baseline. The acute secretory response is complete. Repeated dosing would be required for sustained elevation, though tachyphylaxis (reduced response) may develop.
PMID:17609397Long-term effects not systematically studied. Theoretical concerns include HPA axis effects from repeated cortisol stimulation and potential tachyphylaxis. No approved therapeutic dosing protocols exist.
Research-based observations
This timeline reflects observations from published clinical and preclinical studies. Individual responses may vary significantly. This is not a guarantee of effects or a dosing schedule. Consult qualified healthcare providers for personalized guidance.
Good Signs (7 indicators)
Warning Signs (5 indicators)
Bad Signs (7 indicators)
For Research Evaluation Only
These quality indicators are general guidelines based on typical peptide characteristics. Professional laboratory testing (HPLC, mass spectrometry) provides definitive quality verification. This checklist is for initial visual evaluation only.
CJC-1295
SynergisticGHRH+GHRP synergy is well-documented. GHRP-2 initiates GH pulse while CJC-1295 amplifies release. Combined effect exceeds either agent alone.
Sermorelin
SynergisticClassic synergistic combination. Sermorelin (GHRH) and GHRP-2 act through complementary receptor pathways for enhanced GH secretion.
Tesamorelin
SynergisticTesamorelin (FDA-approved GHRH analog) may synergize with GHRP-2 through complementary GHRH/GHRP pathways. No direct combination studies.
GHRP-6
CompatibleSame receptor target (GHS-R1a). GHRP-2 is more potent with different cortisol/prolactin profile. No established rationale for combining.
Ipamorelin
CompatibleBoth are GHRPs with different selectivity profiles. Ipamorelin cleaner; GHRP-2 more potent. No clear benefit to combination.
MK-677
CompatibleBoth stimulate GH via ghrelin pathway. MK-677 oral with sustained effect. Potentially redundant but may complement timing.
Semaglutide
CautionGHRP-2 affects cortisol and may influence glucose metabolism. Monitor parameters carefully if combining with GLP-1 agonists.
Research Note: Interaction data is based on published literature, mechanistic understanding, and theoretical considerations. Most peptide combinations lack direct clinical study. This information is for educational purposes only and does not constitute medical advice. Always consult qualified healthcare providers.
Key Studies Cited
Full reference list available on request. All citations link to PubMed for verification.
This dossier synthesizes available evidence from peer-reviewed literature, regulatory documents, and clinical trial registries. Evidence strength ratings follow a modified GRADE approach.
For complete methodology details, see our Methodology page.
Important Disclaimer
This dossier is for educational purposes only and does not constitute medical advice. Always consult a qualified healthcare provider before making health decisions.
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