Mechanism of Action
GHRP-2 is a full agonist at the growth hormone secretagogue receptor (GHSR-1a), producing robust pulsatile GH release.
GHSR-1a Agonism
GHRP-2 binds GHSR-1a with high affinity, activating Gq-mediated phospholipase C signaling in pituitary somatotrophs. This raises intracellular calcium and diacylglycerol, triggering GH vesicle exocytosis. The GH pulse produced is larger than Ipamorelin at equivalent doses due to greater receptor efficacy.[1]HPA Axis Activation
Unlike Ipamorelin, GHRP-2 also stimulates cortisol and acth/" class="wiki-internal-link">ACTH release through hypothalamic CRH pathways. This HPA activation is mild at standard doses (100-300 mcg) but relevant for stress-sensitive individuals and distinguishes GHRP-2 from more selective GHRPs. Prolactin is also mildly elevated.[2]GHRH Synergy
GHRP-2 is synergistic with GHRH analogs (CJC-1295, Sermorelin). The combination produces GH pulses far exceeding either compound alone, a robust pharmacological synergy exploited in GH stimulation testing and in research protocols.[1]Research Overview
GH Stimulation and IGF-1 Elevation
Most StudiedGHRP-2 is a standard pharmacological GH stimulation test agent in Japan (Pralmorelin). At 1-2 mcg/kg IV, it produces a standardized GH peak within 45-60 min, superior to GHRP-6 in GH peak amplitude. Chronic use elevates IGF-1 by 30-60% over 4-8 week protocols.[1]
Body Composition
Moderate EvidenceGH elevation from GHRP-2 drives lipolysis and lean mass support. Studies in GH-deficient adults show improved body composition (reduced fat, maintained muscle) with GHRP-2 protocols. Healthy subject data is primarily observational.[2]
GI Motility
Moderate EvidenceLike other GHRPs, GHRP-2 activates peripheral ghrelin/" class="wiki-internal-link">ghrelin receptors in the enteric nervous system, promoting gastric emptying and GI motility. Research in postoperative ileus models shows accelerated bowel function recovery.[3]
Calculate your GHRP-2 dose Vial strength, BAC water, exact syringe draw in IU. Free, no signup. Open Calc →
Research Protocols
| Goal | Dose | Frequency | Route |
|---|---|---|---|
| GH pulse | 200–300 µg | Before bed or 2× daily | Subcutaneous |
| Stacked with CJC-1295 | 200 µg GHRP-2 + 1 mg CJC-1295 | GHRP-2 daily, CJC-1295 weekly | Subcutaneous |
| Conservative start | 100 µg | Once daily | Subcutaneous |
Fasted administration (2-3h post-meal) maximizes GH pulse amplitude. Bedtime dosing synergizes with physiological nocturnal GH peak. GHRP-2 produces more cortisol than Ipamorelin, if cortisol sensitivity is a concern, prefer Ipamorelin instead.
Research protocols only. Not medical advice.
Peptide Interactions
Safety Profile
GHRP-2 has an established safety profile from clinical diagnostic use.
WADA: Prohibited as a peptide hormone and growth factor.
Cortisol/prolactin elevation: Mild at standard doses. May cause slight fatigue, water retention, or mood changes at high or frequent dosing. Monitor in stress-sensitive individuals.
Water retention: GH-related sodium retention common. Usually mild.
Approved diagnostic agent: Pralmorelin (GHRP-2) is approved in Japan for GH stimulation testing, providing a clinical safety reference.
References
- [1]Bowers CY. "GH releasing peptides, structure and kinetics." J Pediatr Endocrinol. 1993;6(1):21-31.
- [2]Arvat E, et al. "GHRP-2: a potent GH secretagogue." J Clin Endocrinol Metab. 1997;82(8):2439-2445.
- [3]Sanger GJ. "Ghrelin and the gut-brain axis: New insights and emerging therapies." Front Neurosci. 2012;6:19.