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AMIRAVOResearch Library

GHRP-2 (pralmorelin) vs Hexarelin

GHRP-2 and hexarelin are both synthetic growth hormone-releasing peptides acting at the ghrelin (GHS) receptor, and both raise ACTH and cortisol in addition to growth hormone 5,6. GHRP-2, generic name pralmorelin, is approved in Japan as a diagnostic agent for growth hormone secretion deficiency and has been marketed there since February 2005 1. Hexarelin (examorelin) has no approval identified, and its human literature consists of small Italian studies of acute cardiac measures 7,8,10. Neither is FDA-approved; GHRP-2 is in 503B category 2 on the FDA's compounding page while hexarelin is not named there, as of 22 April 2026 11.

Unbranded reference vial illustrating GHRP-2; not an actual product
GHRP-2
Approved outside the US
Unbranded reference vial illustrating Hexarelin; not an actual product
Hexarelin
Not approved — research use only

Side by side

FieldGHRP-2Hexarelin
ClassSynthetic growth hormone-releasing peptide / ghrelin receptor agonist; generic name pralmorelin 1,2Synthetic hexapeptide growth hormone secretagogue (ghrelin receptor agonist); also called examorelin 6
Origin and structureDeveloped from work on small GHRP analogues at Tulane University; marketed in Japan as pralmorelin hydrochloride 2Described as a non-natural peptidyl growth hormone secretagogue 6
Proposed mechanismStimulates growth hormone at the GHS receptor; in conscious rats it raised growth hormone more than injected GHRH and also raised ACTH and corticosterone 5Stimulates growth hormone at the GHS receptor and in humans also raises prolactin, ACTH and cortisol 6; separate reports describe growth hormone-independent cardiac effects 7,8
Half-lifeElimination half-life of about 0.42 to 0.69 hours in 18 healthy men after intravenous administration, with plasma protein binding of 83 to 86%, per the Japanese package insert 1Not located in the sources reviewed
Highest human trial phaseApproved diagnostic product in Japan; validation study in 77 healthy subjects and 58 patients with growth hormone deficiency 1,3No phase-numbered registered trial located; published work is investigator-initiated physiology and cardiology studies 7,8,9
FDA statusNot FDA-approved; GHRP-2 for injectable and nasal routes is in 503B category 2 (added 29 September 2023), as of 22 April 2026 11Not FDA-approved; no Drugs@FDA application record located for hexarelin or examorelin (searched 24 October 2026) 10. Not named on the FDA compounding page as of 22 April 2026 11
Published human outcomesPeak growth hormone was much lower in patients with growth hormone deficiency than in healthy subjects, supporting diagnostic use 3; in 7 healthy men, infusion was followed by greater food intake than saline 4In 13 patients with cardiomyopathy, ejection fraction rose in the ischemic but not the dilated group despite similar growth hormone rises 7; in 24 men during bypass surgery, ejection fraction, cardiac index and output rose while growth hormone, GHRH and placebo had no effect 8
Safety signalsFDA is aware of reports of serious adverse events in patients who received GHRP-2, including increased insulin requirement, deaths of critically ill study subjects, infection and pancreatitis, with causality not established 11Short-term intranasal or oral administration in elderly volunteers did not reduce the growth hormone response, with no adverse findings reported in the abstract 9; no regulatory safety assessment was located 10,11
WADA statusNamed under S2.2.4 as GHRP-2 (pralmorelin); prohibited at all times (2026 List) 13Named under S2.2.4 as examorelin (hexarelin); prohibited at all times (2026 List) 13
Who funded the evidencePreclinical characterisation came from Kaken Pharmaceutical, which holds the Japanese product 1,5; the food-intake study was supported by US NIH grants 4Academic groups, mainly the University of Turin 6,7,8,9

GHRP-2: what the data says

GHRP-2 is marketed in Japan as pralmorelin hydrochloride (GHRP Kaken 100 Injection) for the diagnosis of growth hormone secretion deficiency, approval number 21600AMZ00573, with sales from February 2005 1.

  • In a validation study of 77 healthy subjects and 58 patients with growth hormone deficiency (humans), peak growth hormone was markedly lower in patients, and the authors proposed a diagnostic cut-off 3.
  • In rats and dogs (animal data), GHRP-2 raised growth hormone, and in conscious rats it also raised ACTH and corticosterone 5.
  • In 7 lean healthy men (humans), subcutaneous infusion was followed by about 36% greater intake at a buffet meal than saline 4.
  • A 2004 drug profile records that development rights passed between companies and that the Japanese diagnostic indication was the lead use 2.

Hexarelin: what the data says

Hexarelin has mainly been used as a research tool. In 7 healthy young men (humans), it raised growth hormone along with prolactin, ACTH and cortisol, and its growth hormone response was compared with ghrelin and GHRH in the same subjects 6.

  • In 13 patients with ischemic or dilated cardiomyopathy (humans), intravenous hexarelin raised growth hormone similarly in both groups, but ejection fraction rose only in the ischemic group 7.
  • In 24 men with coronary artery disease during bypass surgery (humans), hexarelin raised ejection fraction, cardiac index and cardiac output while recombinant growth hormone, GHRH and placebo did not 8.
  • In elderly volunteers (humans), short-term intranasal or oral administration did not reduce the growth hormone response; IGF-I did not change significantly while IGFBP-3 rose 9.

Key research differences

  • Approval: GHRP-2 is an approved diagnostic product in Japan 1; no approval was located for hexarelin 10.
  • Pharmacokinetics: an elimination half-life of about 0.42 to 0.69 hours is documented for intravenous pralmorelin in healthy men 1, while no half-life was located for hexarelin.
  • Research focus: GHRP-2's human data concern diagnostic growth hormone testing and appetite 3,4, while hexarelin's distinctive human data are acute cardiac measures 7,8.
  • FDA compounding listing: GHRP-2 is in 503B category 2, whereas hexarelin is not named on the FDA page as of 22 April 2026 11.
  • Direct comparison: hexarelin has been compared with ghrelin and GHRH in the same volunteers 6; a side-by-side comparison with GHRP-2 was located only in animal work describing both relative to GHRP-6 12.

Where the evidence is limited

No head-to-head human trial of GHRP-2 and hexarelin was located. GHRP-2's human evidence is diagnostic, with a defined cut-off rather than treatment outcomes 3, while hexarelin's is a set of small single-administration cardiac and endocrine studies, mostly from one centre and from the 1990s and early 2000s 6,7,8. No half-life was located for hexarelin, so exposure cannot be compared 10. The food-intake finding for GHRP-2 came from 7 participants 4, and the cardiac findings for hexarelin from 13 and 24 patients 7,8.

Frequently asked questions

Is GHRP-2 approved anywhere?
Yes, in Japan, as pralmorelin hydrochloride for diagnosing growth hormone secretion deficiency, marketed since February 2005 1. It is not FDA-approved 11.
Do GHRP-2 and hexarelin affect cortisol?
Both have been reported to raise ACTH and cortisol: GHRP-2 in conscious rats 5 and hexarelin in healthy men 6.
Can GHRP-2 and hexarelin be compared directly?
No head-to-head human trial was located; their published human studies addressed different questions 3,8.
What is known about their half-lives?
The Japanese package insert reports an elimination half-life of about 0.42 to 0.69 hours for intravenous pralmorelin in 18 healthy men 1. No half-life for hexarelin was located in the sources reviewed.

References

  1. Package insert: GHRP Kaken 100 Injection (pralmorelin hydrochloride), 3rd revision July 2025 PMDA (Japan). 2025
  2. Pralmorelin: GHRP 2, GPA 748, growth hormone-releasing peptide 2, KP-102 Drugs in R&D. 2004
  3. A simple diagnostic test using GH-releasing peptide-2 in adult GH deficiency European Journal of Endocrinology. 2007
  4. Growth hormone releasing peptide-2 (GHRP-2), like ghrelin, increases food intake in healthy men Journal of Clinical Endocrinology and Metabolism. 2005
  5. Pharmacological characteristics of KP-102 (GHRP-2), a potent growth hormone-releasing peptide Arzneimittel-Forschung. 2004
  6. Endocrine activities of ghrelin, a natural growth hormone secretagogue (GHS), in humans: comparison and interactions with hexarelin, a nonnatural peptidyl GHS, and GH-releasing hormone Journal of Clinical Endocrinology and Metabolism. 2001
  7. GH-independent cardiotropic activities of hexarelin in patients with severe left ventricular dysfunction due to dilated and ischemic cardiomyopathy European Journal of Heart Failure. 2002
  8. Effects of acute hexarelin administration on cardiac performance in patients with coronary artery disease during by-pass surgery European Journal of Pharmacology. 2002
  9. Short-term administration of intranasal or oral Hexarelin, a synthetic hexapeptide, does not desensitize the growth hormone responsiveness in human aging European Journal of Endocrinology. 1996
  10. Drugs@FDA (openFDA) queries for active ingredients hexarelin and examorelin: no matches FDA openFDA. 2026
  11. Certain Bulk Drug Substances for Use in Compounding that May Present Significant Safety Risks (content current as of 04/22/2026) FDA (Human Drug Compounding). 2026
  12. Ipamorelin, the first selective growth hormone secretagogue European Journal of Endocrinology. 1998
  13. Prohibited List 2026 (in force 1 January 2026) World Anti-Doping Agency. 2026

For research use only. Not for human or veterinary use. Not a drug, food, or dietary supplement. This page compares published research and is not medical advice or a recommendation.