GHRP-2 vs Hexarelin

Synthetic hexapeptide that stimulates pulsatile growth hormone release from the anterior pituitary by acting on the ghrelin receptor (GHSR-1a). Commonly stacked with GHRH analogs such as CJC-1295 or Sermorelin to amplify GH output synergistically.

GHRP-2 (growth hormone-releasing peptide-2; pralmorelin; KP-102) is a synthetic hexapeptide (D-Ala-D-2Nal-Ala-Trp-D-Phe-Lys-NH2) and potent ghrelin receptor (GHS-R1a) agonist developed as a GH secretagogue with established efficacy in stimulating pulsatile GH release from pituitary somatotrophs, characterized by potent GH stimulation alongside non-selective co-stimulation of cortisol and prolactin secretion. As a first-generation GHRP, GHRP-2 achieves its GH-secretory effect through direct GHS-R1a agonism with amplification by endogenous GHRH; it is distinguished from later selective GHRPs such as ipamorelin by its non-selective endocrine profile, and synergistic GH stimulation is observed when combined with GHRH analogs in diagnostic protocols. GHRP-2 has been validated as a diagnostic agent for the GHRP-2 stimulation test used in Japan to assess GH secretion capacity in adults with suspected hypopituitarism or post-surgical pituitary dysfunction, with published human clinical data supporting its reliability as a GH stimulation tool in endocrine diagnostic practice. GHRP-2 has no FDA approval for any therapeutic or diagnostic indication in the United States; it is used diagnostically in Japan and as a research compound elsewhere, with no approved indication for GH enhancement, performance, or anti-aging applications, and its non-selective endocrine stimulation profile represents a relevant consideration versus more selective GH secretagogues. GHRP-2 dosage in research contexts: doses of 100–300 mcg per subcutaneous injection are documented across research protocols, typically administered 2–3 times daily. Co-administration with a GHRH analog (such as CJC-1295 or sermorelin) produces synergistic GH release and is studied in combination protocols for this reason. Administration is by subcutaneous injection following reconstitution with bacteriostatic water. GHRP-2 vs GHRP-6 vs ipamorelin: GHRP-2 produces potent GH release but with co-stimulation of cortisol and prolactin, similar to GHRP-6. The key distinguishing feature of GHRP-6 is stronger appetite stimulation (ghrelin-like effect); GHRP-2 produces less appetite stimulation with comparable or slightly greater GH output per dose. Both are non-selective compared to ipamorelin, which was developed specifically to achieve GH stimulation without the cortisol and prolactin co-elevation that characterizes first-generation GHRPs. For research contexts prioritizing GH selectivity, ipamorelin is generally preferred; GHRP-2 is used where its diagnostic validation and potent GH stimulation profile are the research objectives.

Potent synthetic GHRP; strongest GH secretagogue in its class; also activates CD36 scavenger receptor for cardioprotective effects

Hexarelin is a synthetic hexapeptide GH secretagogue that acts as an agonist at the ghrelin receptor (GHS-R1a) and is among the most potent GHRP-class peptides characterized in human studies, producing robust GH release at low doses via a mechanism that synergizes with endogenous GHRH and partially suppresses somatostatin. In addition to its pituitary GHS-R1a effects, hexarelin has been shown to engage CD36 receptor-mediated pathways in cardiac tissue, suggesting biological activity beyond GH secretion, though the cardiac pharmacology has not been developed into an approved clinical application. Human endocrine studies have directly compared hexarelin-induced GH release with ghrelin and GHRH in healthy volunteers, confirming its potent pituitary activity; repeated administration produces progressive attenuation of the GH response consistent with receptor desensitization. Hexarelin is not FDA-approved for any indication; it is used as a research tool for characterizing the GH secretagogue receptor system and has not been evaluated for safety or efficacy in performance enhancement contexts. Research interest in hexarelin centers on two distinct biological roles: its potent GH-secreting activity — relevant to muscle recovery and body composition research contexts — and its cardiac tissue effects via CD36 receptor pathways, which distinguish it mechanistically from simpler GHRPs such as GHRP-2 and GHRP-6. Hexarelin dosage in research contexts: published human studies have used intravenous doses of 1–2 mcg/kg to characterize GH secretion kinetics. In clinical research protocols, subcutaneous doses of 100–200 mcg per injection are most commonly cited, typically administered once or twice daily. Hexarelin's potency relative to other GHRPs means lower doses are required for equivalent GH stimulation; however, receptor desensitization with repeated dosing is more pronounced than with selective peptides such as ipamorelin, which has driven research interest in cycling protocols and combination approaches. Administration is by subcutaneous injection. Hexarelin vs ipamorelin: the two peptides differ substantially in selectivity and desensitization profile. Hexarelin is a non-selective GHRP that stimulates GH alongside modest elevations in cortisol, prolactin, and ACTH — effects documented in human challenge studies. Ipamorelin, by contrast, is one of the most selective GHRPs characterized, producing GH secretion with minimal cortisol or prolactin co-stimulation. For research focused specifically on GH secretion with a cleaner hormonal background, ipamorelin is generally preferred; hexarelin is studied in contexts where its dual CD36/GHS-R1a pharmacology is the research focus. Providers offering hexarelin are listed in the PeptideBase directory.