GHRP-2
GHRP-2 (pralmorelin) is a synthetic hexapeptide growth hormone secretagogue that activates the ghrelin receptor (GHS-R1a) to stimulate growth hormone release, approved only in Japan as a single-dose diagnostic agent and not FDA-approved.
GHRP-2, known by the International Nonproprietary Name pralmorelin and developmental codes KP-102 and GPA-748, is a synthetic hexapeptide in the growth hormone secretagogue (GHRP) class. Its sequence is D-Ala-D-2-Nal-Ala-Trp-D-Phe-Lys-NH2 — a structure built from D-amino acids, an unnatural 2-naphthylalanine residue at position 2, and a C-terminal amide. The 2-naphthylalanine substitution (replacing the D-Trp found in GHRP-6) is the structural feature most often associated with its relatively high GH-releasing potency.
Mechanistically, GHRP-2 binds and activates the growth hormone secretagogue receptor (GHS-R1a), the receptor for endogenous ghrelin, on anterior pituitary somatotrophs and on hypothalamic neurons. Receptor activation signals primarily through Gq/11 and phospholipase C, driving IP3-mediated intracellular calcium release and pulsatile growth hormone secretion. In human pharmacology studies the effect is not GH-selective: ACTH and cortisol rise in a dose-dependent manner (comparable to corticotropin-releasing hormone), prolactin rises to a smaller degree, and appetite/food intake is stimulated through ghrelin-receptor agonism.
Regulatory status: GHRP-2 is approved in Japan (October 2004, Kaken Pharmaceutical, brand GHRP Kaken 100) solely as a single-dose diagnostic agent for assessing growth hormone deficiency — not as a therapeutic medicine. It is not FDA-, MHRA-, or EMA-approved, and it is explicitly named on the World Anti-Doping Agency Prohibited List under category S2 (Peptide Hormones, Growth Factors, Related Substances and Mimetics). Outside its Japanese diagnostic indication it is supplied only as a research chemical and is not characterized for long-term safety.
Chemistry: molecular formula C45H55N9O6, molecular weight ≈ 818 g/mol, CAS 158861-67-7, PubChem CID 6918245.
GHRP-2 is a synthetic hexapeptide that acts as an agonist at the growth hormone secretagogue receptor (GHS-R1a), the same receptor targeted by the endogenous ligand ghrelin. Activation on anterior pituitary somatotrophs triggers Gq/11-phospholipase C signaling and IP3-mediated intracellular calcium release that promotes pulsatile growth hormone release; in human pharmacology studies it can also dose-dependently raise cortisol, ACTH, and (to a lesser degree) prolactin, and it stimulates appetite via ghrelin-receptor agonism.
- Human evidence
- Human clinical pharmacology and diagnostic-stimulation studies exist (approved as a diagnostic agent in Japan); no controlled therapeutic-efficacy evidence supporting medical use in other markets.
- Regulatory status
- Approved in Japan (October 2004, Kaken Pharmaceutical, brand "GHRP Kaken 100", via the PMDA) only as a single-dose diagnostic agent for assessing growth hormone deficiency. NOT FDA-approved and not licensed as a therapeutic medicine in the US, UK, or EU. Explicitly named as a prohibited substance by the World Anti-Doping Agency under category S2 (Peptide Hormones, Growth Factors, Related Substances and Mimetics). Marketed elsewhere only as a research chemical.
- Used as a pharmacological probe of the GHS-R1a (ghrelin) receptor and the pituitary growth-hormone axis in laboratory studies.
- Serves as a diagnostic stimulation agent for growth-hormone-deficiency assessment (its sole approved use, in Japan).
- Investigated in research models of ghrelin signaling, appetite regulation, and somatotroph function.
- Reference comparator within the classical GHRP peptide family (vs GHRP-6, hexarelin) in secretagogue potency studies.
- Acute dosing in human pharmacology studies can dose-dependently elevate cortisol, ACTH, and prolactin in addition to growth hormone, reflecting non-selective pituitary stimulation (human clinical pharmacology literature; Wikipedia: Pralmorelin).
- Reliably induces hunger and increased food intake via ghrelin-receptor agonism, which may confound research endpoints (Wikipedia: Pralmorelin).
- GH secretagogues can affect glucose handling and insulin sensitivity; relevant for any metabolic research context.
- Prohibited in sport by WADA (S2); not characterized for long-term safety outside the approved single-dose diagnostic use in Japan.
- [1]PubChem Compound: Pralmorelin (GHRP-2), CID 6918245PubChem (NIH)
- [2]Pralmorelin (GHRP-2) - encyclopedia entryWikipedia
- [3]General pharmacology of KP-102 (GHRP-2), a potent growth hormone-releasing peptide (Arzneimittelforschung, 2004)PubMed
- [4]GHRP-2 / Pralmorelin (CAS 158861-67-7) chemical recordChemicalBook