Growth Hormone Secretagogues
GHRP-2
Pralmorelin; KP-102; GPA-748
10 min read · Updated June 25, 2026 · 9 references
GHRP-2 (pralmorelin) is a synthetic ghrelin-receptor agonist that triggers a strong growth hormone pulse but also raises cortisol, prolactin, and appetite; it is approved in Japan only as a diagnostic agent for growth hormone deficiency and is not an approved therapeutic in the US or EU.
Evidence: Approved in some countries; not by the FDA or EMA.
Approved in: Japan only, for diagnostic use only. Not FDA- or EMA-approved, and not approved as a therapeutic anywhere
- Synthetic hexapeptide agonist of the ghrelin receptor (GHS-R1a)
- Releases a strong GH pulse from the pituitary
- Also raises ACTH, cortisol, prolactin, and appetite
- Approved in Japan only as a GH-deficiency diagnostic
- Not an approved therapeutic in the US or EU; WADA-prohibited (S2)
A synthetic hexapeptide and agonist of the ghrelin / growth-hormone-secretagogue receptor (GHS-R1a) that strongly stimulates growth hormone release. Unlike the more selective ipamorelin, it also modestly raises ACTH, cortisol, and prolactin and increases appetite. Approved in Japan (as pralmorelin) only as a diagnostic agent for growth hormone deficiency; not approved as a therapeutic in the US or EU.
Overview
GHRP-2 (generic name pralmorelin; development codes KP-102 and GPA-748) is a synthetic hexapeptide that acts as an agonist of the ghrelin / growth-hormone-secretagogue receptor (GHS-R1a). It belongs to the family of growth-hormone-releasing peptides (GHRPs) that also includes GHRP-6 and hexarelin. Like the endogenous hormone ghrelin, GHRP-2 binds GHS-R1a and triggers a strong, transient pulse of growth hormone (GH) release from the pituitary.
GHRP-2 is notable as essentially the only GHRP to have obtained any regulatory approval: in Japan it is marketed by Kaken Pharmaceutical as pralmorelin (brand name "GHRP Kaken 100"), a single-dose diagnostic agent used to provoke GH release when assessing growth hormone deficiency. It is not approved as a therapeutic drug in the United States, the European Union, or other major markets, and it is not approved anywhere for anti-aging, body-composition, or performance uses.
A defining contrast with the more selective ipamorelin is that GHRP-2 is not GH-selective: in human studies it also modestly raises ACTH, cortisol, and prolactin, and it reliably increases appetite and food intake.
Approved only as a diagnostic, not a therapeutic
GHRP-2 (pralmorelin) is approved in Japan only as a diagnostic agent for growth hormone deficiency. It is not an approved treatment anywhere, and it is not FDA- or EMA-approved for any indication. Outside its Japanese diagnostic use, material sold as "GHRP-2" is handled as a research chemical. Nothing here is medical advice.
Chemistry and structure
GHRP-2 is a small, fully synthetic peptide built partly from D-configured and non-natural amino acids, which contribute to receptor activity and metabolic stability relative to naturally occurring peptides.
| Property | Value |
|---|---|
| Class | Synthetic hexapeptide |
| Amino acid sequence | D-Ala-D-2-Nal-Ala-Trp-D-Phe-Lys-NH₂ |
| Molecular formula | C₄₅H₅₅N₉O₆ (free base) |
| Molecular weight | ~817.99 g/mol (free base) |
| CAS number | 158861-67-7 |
| PubChem CID | 6918245 |
| Generic name | Pralmorelin |
| C-terminus | Amidated (–NH₂) |
The sequence includes D-2-Nal (D-2-naphthylalanine), D-Phe (D-phenylalanine), and D-Ala (D-alanine). These residues distinguish GHRP-2 from endogenous ghrelin, which is a 28-residue peptide that carries an essential octanoyl (acyl) modification. GHRP-2 requires no acylation to activate the receptor. The drug substance used in the Japanese diagnostic product is the dihydrochloride salt, which has a higher formula weight than the free base.
GHRP-2 and ghrelin both act at the GHS-R1a receptor, but they are structurally very different: ghrelin is a 28-amino-acid acylated peptide, whereas GHRP-2 is a six-residue synthetic mimetic.
Mechanism of action
GHRP-2 binds and activates GHS-R1a, the receptor for endogenous ghrelin, which is expressed in the anterior pituitary and the hypothalamus. Activation drives the release of stored GH from pituitary somatotrophs, producing a discrete GH pulse rather than a sustained elevation. In animal models (KP-102 / GHRP-2), its GH-releasing activity acted at both hypothalamic and pituitary sites and was more potent than exogenously injected growth-hormone-releasing hormone (GHRH).
This mechanism is distinct from that of GHRH analogs such as CJC-1295 and tesamorelin, which act on the separate GHRH receptor. Because the two receptor pathways are complementary, ghrelin-receptor agonists and GHRH analogs are frequently discussed together in research on the GH/IGF-1 axis.
A key pharmacological point is that GHRP-2 is not selective for GH. Beyond GH release, GHS-R1a activation and downstream signaling also engage:
- the HPA axis, producing modest, transient rises in ACTH and cortisol; and
- prolactin secretion (a slight increase); and
- appetite, consistent with ghrelin's role in stimulating hunger and food intake.
Animal work (Hirotani et al., 2005) suggested the ACTH-releasing activity of GHRP-2 in rats is mediated mainly through release of corticotropin-releasing factor (CRF), while human data in pituitary-disorder patients (Kimura et al., 2010) provided evidence that GHRP-2 can also stimulate ACTH more directly.
Research and evidence
It is useful to separate animal/pharmacology data from the human clinical evidence.
Animal and in-vitro evidence
- Potency and characterization (Doi et al., 2004). Pharmacological characterization of KP-102 (GHRP-2) showed potent GH release acting at both hypothalamic and pituitary sites, more potent than exogenous GHRH in conscious rats.
- HPA-axis mechanism (Hirotani et al., 2005). In rats, the ACTH-releasing activity of KP-102 (GHRP-2) appeared to be mediated mainly by release of CRF, consistent with hypothalamic involvement in its cortisol-related effects.
Human evidence
| Study | Type | Population | Key outcome |
|---|---|---|---|
| Arvat et al. 1997 (Peptides) | Pharmacodynamic | Healthy young adults | GHRP-2 1 µg/kg IV produced a strong GH response greater than GHRH; modest rises in PRL, ACTH, and cortisol (PRL lower than TRH; ACTH/cortisol similar to hCRH) |
| Laferrère et al. 2005 (JCEM) | Randomized, double-blind crossover | 7 lean healthy men | GHRP-2 infusion increased food intake by ~36% vs placebo and raised GH |
| Kimura et al. 2010 (Endocr J) | Diagnostic comparison | Hypothalamic-pituitary disorder patients | Evidence that GHRP-2 can directly stimulate ACTH; compared with CRH and insulin hypoglycemia |
- Hormone profile in man (Arvat et al., 1997). In healthy young adults, intravenous GHRP-2 produced a GH response stronger than maximal-dose GHRH, while also producing modest increases in prolactin, ACTH, and cortisol. The prolactin effect was lower than that of TRH, and the ACTH/cortisol effect was comparable to that of human CRH.
- Appetite (Laferrère et al., 2005). In a randomized, double-blind crossover study, seven lean healthy men ate roughly 36% more at an ad libitum meal after GHRP-2 infusion than after saline, confirming a ghrelin-like appetite-stimulating effect in humans.
- Diagnostic use. GHRP-2 is used as a provocative stimulus for GH secretion. In Japan it is approved (as pralmorelin) for GH-deficiency testing; published cutoffs have been used to distinguish GH-sufficient from GH-deficient individuals, and the test avoids the hypoglycemia of the insulin tolerance test.
There are no large, long-term, controlled human trials supporting GHRP-2 as a therapy for anti-aging, body composition, athletic performance, or other popularly marketed uses; its established human role is as a diagnostic GH stimulus.
Safety and risks
Human exposure data come largely from single-dose diagnostic use and small pharmacodynamic studies. In those settings, single diagnostic doses have generally been described as tolerated. However, GHRP-2's broader hormonal activity raises specific considerations:
- Cortisol and ACTH. GHRP-2 modestly and transiently raises ACTH and cortisol, engaging the stress-hormone (HPA) axis. This contrasts with the selectivity reported for ipamorelin, which spares ACTH/cortisol in studies. Repeated or chronic stimulation of this axis is not well characterized.
- Prolactin. A slight increase in prolactin has been reported in human studies.
- Appetite and food intake. GHRP-2 reliably increases hunger and caloric intake in humans, which is relevant to any chronic use.
- GH/IGF-1 axis. As a GH secretagogue, class-level concerns associated with raising GH/IGF-1 signaling (for example, effects on glucose handling, insulin sensitivity, fluid retention, or the theoretical unmasking of occult conditions) are relevant considerations.
- Long-term safety. Published human data center on single-dose or short-term use. Long-term safety of repeated GHRP-2 administration in humans is not established.
- Product quality. Material sold as "GHRP-2" in the research-chemical market is not subject to pharmaceutical quality control; purity, identity, and sterility cannot be assumed.
This section is descriptive, not a safety endorsement, and no dosing guidance is provided.
Regulatory status
- Japan. Pralmorelin (GHRP-2) is approved as a diagnostic agent for assessing growth hormone deficiency, marketed by Kaken Pharmaceutical (brand "GHRP Kaken 100"). This is a diagnostic indication (provoking a GH response for testing), not a therapeutic approval.
- United States. Not FDA-approved for any indication, therapeutic or diagnostic. Distributed as a research chemical and commonly labeled "not for human consumption."
- European Union. Not EMA-approved for any indication.
- General. The Japanese diagnostic approval does not translate into therapeutic approval elsewhere; outside that specific diagnostic context there is no recognized human-therapeutic channel for GHRP-2 in most jurisdictions.
The distinction matters: a diagnostic approval (using a single dose to provoke a measurable GH response for testing) is not the same as a therapeutic approval (chronic or repeated dosing to treat a condition). GHRP-2 has the former in Japan and the latter nowhere.
How it compares
GHRP-2 is one of several agents that raise GH through related but distinct mechanisms. The comparison below is factual and not a recommendation.
| Compound | Receptor / mechanism | Selectivity | Regulatory status |
|---|---|---|---|
| GHRP-2 (pralmorelin) | Ghrelin receptor (GHS-R1a) agonist | Non-selective: also raises ACTH, cortisol, prolactin, appetite | Diagnostic-approved in Japan; not approved therapeutically (US/EU); WADA-prohibited |
| Ipamorelin | Ghrelin receptor (GHS-R1a) agonist | More selective: spares ACTH/cortisol/prolactin in studies | Not approved anywhere; WADA-prohibited |
| GHRP-6 | Ghrelin receptor (GHS-R1a) agonist | Non-selective: notable appetite stimulation; raises cortisol/prolactin | Not approved anywhere; WADA-prohibited |
| CJC-1295 | GHRH-receptor analog | Acts on a different (GHRH) receptor | Not approved anywhere; WADA-prohibited |
| Tesamorelin | GHRH-receptor analog | Acts on the GHRH receptor | FDA-approved for HIV-associated lipodystrophy; WADA-prohibited |
The principal point of contrast: GHRP-2 and ipamorelin act at the same receptor, but GHRP-2 is the less selective of the two, additionally engaging the cortisol/prolactin and appetite pathways, whereas ipamorelin was characterized specifically for sparing those. GHRH analogs such as CJC-1295 and tesamorelin act on a different receptor entirely.
Legal status
- Anti-doping (sport). GHRP-2 is prohibited at all times (in and out of competition) under the World Anti-Doping Agency (WADA) Prohibited List, within Section S2 (Peptide Hormones, Growth Factors, Related Substances and Mimetics), which explicitly covers growth hormone secretagogues and ghrelin-receptor agonists/mimetics. Athletes in WADA-governed sport must not use it.
- United States. Not FDA-approved; sold as a research chemical.
- General. Regulatory and legal status varies by country. Japan's diagnostic approval is an exception specific to that use; it does not create a legitimate therapeutic channel elsewhere.
WADA's S2 category names growth hormone secretagogues and their mimetics, including GHRP-2 alongside agents such as GHRP-6, hexarelin, ipamorelin, and MK-677 (ibutamoren), as prohibited substances at all times for athletes.
Common misconceptions
| Claim | Reality |
|---|---|
| "GHRP-2 is an FDA-approved peptide drug." | It is not FDA- or EMA-approved. Its only approval is as a diagnostic agent in Japan, not a therapeutic. |
| "It's the same as the selective peptide ipamorelin." | Both act at GHS-R1a, but GHRP-2 is less selective — it also raises ACTH, cortisol, prolactin, and appetite. |
| "It only raises growth hormone." | In humans it also modestly raises ACTH, cortisol, and prolactin and increases food intake. |
| "It's the same as ghrelin." | It activates the same receptor (GHS-R1a) but is a small synthetic hexapeptide, structurally unlike the 28-residue acylated ghrelin hormone. |
| "Japanese approval means it's an approved treatment." | The Japanese approval is for diagnostic GH-deficiency testing, not for chronic therapeutic use. |
| "It's allowed in sport if used therapeutically." | It is on the WADA Prohibited List (S2) at all times; use in sanctioned sport is a doping violation. |
GHRP-2 is frequently discussed alongside the GHRH analog CJC-1295 and the more selective ipamorelin because these compounds act on complementary or related parts of the GH axis. Combination-use claims widely circulated online are not supported by controlled human efficacy trials.
References
- 1.Effects of GHRP-2 and hexarelin, two synthetic GH-releasing peptides, on GH, prolactin, ACTH and cortisol levels in man. Comparison with the effects of GHRH, TRH and hCRH — Arvat E, di Vito L, Maccagno B, Broglio F, Boghen MF, Deghenghi R, Camanni F, Ghigo E, Peptides, 1997. source
- 2.Growth Hormone Releasing Peptide-2 (GHRP-2), like ghrelin, increases food intake in healthy men — Laferrère B, Abraham C, Russell CD, Bowers CY, Journal of Clinical Endocrinology & Metabolism, 2005. source
- 3.Pharmacological characteristics of KP-102 (GHRP-2), a potent growth hormone-releasing peptide — Doi N, Hirotani C, Ukai K, Shimada O, Okuno T, Kurasaki S, Kiyofuji T, Ikegami R, Futamata M, Nakagawa T, Ase K, Chihara K, Arzneimittelforschung, 2004. source
- 4.ACTH releasing activity of KP-102 (GHRP-2) in rats is mediated mainly by release of CRF — Hirotani C, Oki Y, Ukai K, Okuno T, Kurasaki S, Ohyama T, Doi N, Sasaki K, Ase K, Naunyn-Schmiedeberg's Archives of Pharmacology, 2005. source
- 5.Concordant and discordant adrenocorticotropin (ACTH) responses induced by growth hormone-releasing peptide-2 (GHRP-2), corticotropin-releasing hormone (CRH) and insulin-induced hypoglycemia in patients with hypothalamopituitary disorders — Kimura T, Shimatsu A, Arimura H, Mori H, Tokitou A, Fukudome M, Nakazaki M, Tei C, Endocrine Journal, 2010. source
- 6.Pralmorelin — National Center for Advancing Translational Sciences (NCATS) Inxight Drugs, NCATS Inxight Drugs, 2026. source
- 7.Pralmorelin (Compound Summary, CID 6918245) — National Center for Biotechnology Information, PubChem, 2026. source
- 8.
- 9.The Prohibited List (S2. Peptide Hormones, Growth Factors, Related Substances and Mimetics) — World Anti-Doping Agency, WADA, 2026. source
Legal status (Europe)
17 major European markets we track — not an exhaustive list of Europe · as of June 2026
Research-reagent classification only, dated June 2026 — not legal advice. “No specific ban” means a compound is not specifically prohibited, never that human use is lawful.
Prohibited in sport (WADA). Listed on the World Anti-Doping Agency Prohibited List, so it can cause a competing athlete to fail a drug test. This is a sporting-eligibility matter, separate from the legal status above: it does not change that status, and human use is treated as an unauthorised medicine regardless of sporting status.
See the full European legality map for how this is classified, what each label means, and the sources.
Frequently asked questions
- What is GHRP-2?
- A synthetic hexapeptide and agonist of the ghrelin / growth-hormone-secretagogue receptor (GHS-R1a) that strongly stimulates growth hormone release. Unlike the more selective ipamorelin, it also modestly raises ACTH, cortisol, and prolactin and increases appetite. Approved in Japan (as pralmorelin) only as a diagnostic agent for growth hormone deficiency; not approved as a therapeutic in the US or EU.
- Is GHRP-2 approved as a medicine, and where?
- GHRP-2 is approved in some countries but not by the US FDA or the European Medicines Agency (EMA). Specifically: Japan only, for diagnostic use only. Not FDA- or EMA-approved, and not approved as a therapeutic anywhere.
- What is GHRP-2 studied for?
- GHRP-2 is most often discussed in the context of muscle & growth hormone. Research has examined Ghrelin/GHS-R receptor pharmacology, GH/IGF-1 axis and GH-deficiency diagnosis, and Appetite and HPA-axis (ACTH/cortisol) responses. Being studied for an area does not mean it is proven or approved for it.
- Does GHRP-2 have human clinical trials?
- Yes. GHRP-2 has been studied in human clinical trials and is an approved medicine in at least some regions.
Educational disclaimer. This article summarizes published research for informational purposes and is not medical advice. GHRP-2 is a research chemical not approved for human use, and is specifically restricted in several European markets. Consult a qualified healthcare professional before making health decisions.