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AMIRAVOResearch Library

Hexarelin vs GHRP-6

Hexarelin and GHRP-6 are closely related synthetic growth hormone-releasing peptides that act at the ghrelin (GHS) receptor 1,9. Hexarelin, also called examorelin, has been studied mainly in Italian endocrinology and cardiology research, including acute cardiac measurements in patients 2,3. GHRP-6 is the earlier hexapeptide His-D-Trp-Ala-Trp-D-Phe-Lys-NH2, studied as a growth hormone provocative test and by intranasal administration in healthy men 6,7. Neither is FDA-approved; GHRP-6 appears in 503B category 2 on the FDA's compounding page, while hexarelin is not listed there, as of 22 April 2026 5,8.

Unbranded reference vial illustrating Hexarelin; not an actual product
Hexarelin
Not approved — research use only
Unbranded reference vial illustrating GHRP-6; not an actual product
GHRP-6
Not approved — research use only

Side by side

FieldHexarelinGHRP-6
ClassSynthetic hexapeptide growth hormone secretagogue (ghrelin receptor agonist); also called examorelin 1,10Synthetic hexapeptide growth hormone-releasing peptide (ghrelin receptor agonist) 7,9
Origin and structurePeptidyl GHS described as non-natural; catalogued in PubChem under the record title Examorelin (CID 6918297), molecular formula C47H58N12O6 1,10His-D-Trp-Ala-Trp-D-Phe-Lys-NH2, one of the earliest GHRPs developed from this peptide series 7
Proposed mechanismStimulates growth hormone at the GHS receptor and also raises prolactin, ACTH and cortisol in humans 1; reported growth hormone-independent cardiac effects 2,3Acts at the GHS receptor as a functional somatostatin antagonist, enhancing pulsatile growth hormone release 9; in healthy men it slightly raised prolactin and cortisol 7
Half-lifeNot located in the sources reviewedNot located in the sources reviewed
Highest human trial phaseNo phase-numbered registered trial located (ClinicalTrials.gov searched 24 October 2026) 11; published work is investigator-initiated physiology and cardiology studies in patients 2,3No phase-numbered registered trial located (ClinicalTrials.gov searched 24 October 2026) 11; published work includes diagnostic testing studies in children and adults 6
FDA statusNot FDA-approved; no Drugs@FDA application record located for hexarelin or examorelin (searched 24 October 2026) 5. Not named on the FDA compounding page as of 22 April 2026 8Not FDA-approved; GHRP-6 is in 503B category 2 on the FDA compounding page (added 29 September 2023), as of 22 April 2026 8
Published human outcomesIn 13 patients with cardiomyopathy, intravenous hexarelin raised growth hormone in both groups and raised ejection fraction in the ischemic but not the dilated group 2; in 24 men undergoing bypass surgery it raised ejection fraction, cardiac index and output while growth hormone, GHRH and placebo did not 3In short-statured children and adults with growth hormone deficiency, growth hormone responses were lower than in controls but overlapped considerably, limiting diagnostic separation 6; in 6 healthy men, intranasal administration raised growth hormone and IGF-I 7
Safety signalsShort-term intranasal or oral administration in elderly volunteers was described as not desensitising the growth hormone response, with no adverse findings reported in the abstract 4; a review of secretagogues notes concern about rising blood glucose from reduced insulin sensitivity 9FDA cites limited safety information with concerns including effects on cortisol and increased blood glucose due to decreased insulin sensitivity 8; repeated intranasal administration was tolerated in 6 healthy men 7
WADA statusNamed under S2.2.4 as examorelin (hexarelin); prohibited at all times (2026 List) 12Named under S2.2.4 as GHRP-6; prohibited at all times (2026 List) 12
Who funded the evidenceAcademic groups, mainly the University of Turin 1,2,3,4Academic groups in Spain and Japan 6,7; one review of secretagogues was authored from Merck Research Laboratories 9

Hexarelin: what the data says

Hexarelin has been used as a research tool for the ghrelin receptor. In 7 healthy young men (humans), hexarelin raised growth hormone and also prolactin, ACTH and cortisol, and its growth hormone response was compared with ghrelin and GHRH in the same subjects 1.

  • 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 2.
  • 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, which the authors interpreted as a growth hormone-independent effect 3.
  • In elderly volunteers (humans), short-term intranasal or oral administration did not reduce the growth hormone response, and IGF-I did not change significantly while IGFBP-3 rose 4.

GHRP-6: what the data says

GHRP-6 is one of the original growth hormone-releasing peptides and is described in reviews as acting at the GHS receptor as a functional somatostatin antagonist, enhancing pulsatile growth hormone release 9.

  • In short-statured children and in adults diagnosed with growth hormone deficiency by conventional testing (humans), growth hormone responses to intravenous GHRP-6 were lower than in controls, but individual values overlapped; responses were almost absent in pituitary stalk transection 6.
  • In 6 healthy men (humans), intravenous and intranasal administration raised plasma growth hormone, and repeated intranasal administration raised IGF-I without loss of response 7.
  • FDA states it identified limited safety information for GHRP-6, with concerns about cortisol effects and increased blood glucose from decreased insulin sensitivity 8.

Key research differences

  • FDA compounding listing: GHRP-6 is in 503B category 2 on the FDA page, whereas hexarelin is not named there as of 22 April 2026 8.
  • Research focus: hexarelin's distinctive human literature is cardiac, including ejection-fraction changes during bypass surgery 3, while GHRP-6's human literature is mainly diagnostic growth hormone testing 6.
  • Comparative data: hexarelin has been compared directly with ghrelin and GHRH in the same healthy volunteers 1; no equivalent three-way comparison with GHRP-6 was located.
  • Pharmacokinetics: no half-life was located for either peptide in the sources reviewed 5,11.

Where the evidence is limited

No head-to-head human trial of hexarelin versus GHRP-6 was located, and neither has a registered trial on ClinicalTrials.gov 11. Both literatures are small, mostly from the 1990s and early 2000s, and consist of single-administration physiology studies rather than outcome trials 1,6,7. The hexarelin cardiac studies were small and measured acute haemodynamic variables, not clinical outcomes 2,3. No pharmacokinetic parameters were located for either, so the two cannot be compared on exposure 5,11.

Frequently asked questions

Are hexarelin and GHRP-6 the same class?
Yes. Both are synthetic hexapeptide growth hormone-releasing peptides acting at the ghrelin (GHS) receptor 1,9.
Is either FDA-approved?
No. No Drugs@FDA record was located for hexarelin or examorelin 5, and GHRP-6 appears in 503B category 2 on the FDA's compounding page as of 22 April 2026 8.
Did hexarelin affect the heart independently of growth hormone?
In 24 men undergoing bypass surgery, hexarelin raised ejection fraction, cardiac index and output while recombinant growth hormone, GHRH and placebo did not; the authors described this as growth hormone-independent, in a small single-administration study 3.
Can hexarelin and GHRP-6 be compared directly?
No head-to-head trial was located, and their human studies addressed different questions, cardiac measures for hexarelin and diagnostic testing for GHRP-6 3,6.

References

  1. 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
  2. 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
  3. Effects of acute hexarelin administration on cardiac performance in patients with coronary artery disease during by-pass surgery European Journal of Pharmacology. 2002
  4. 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
  5. Drugs@FDA (openFDA) queries for active ingredients hexarelin and examorelin: no matches FDA openFDA. 2026
  6. Growth hormone releasing hexapeptide-6 (GHRP-6) test in the diagnosis of GH-deficiency Journal of Pediatric Endocrinology & Metabolism. 1996
  7. Intranasal administration of His-D-Trp-Ala-Trp-D-Phe-LysNH2 (growth hormone releasing peptide) increased plasma growth hormone and insulin-like growth factor-I levels in normal men Endocrinologia Japonica. 1991
  8. 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
  9. Growth hormone secretagogues: mechanism of action and use in aging Growth Hormone & IGF Research. 1998
  10. PubChem compound record for examorelin (hexarelin), CID 6918297 PubChem (NCBI). 2026
  11. ClinicalTrials.gov API searches for hexarelin and GHRP-6 (0 studies returned, 24 October 2026) ClinicalTrials.gov. 2026
  12. 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.