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Comparison

GHRP-2 vs Macimorelin

Both are gHRPs & ghrelin mimetics, so the meaningful differences are in kinetics, evidence and regulatory status.

On published evidence alone, Macimorelin is the better documented of the two (regulator approved). That is a statement about the state of the literature, not a recommendation.

GHRP-2 Macimorelin
Class GHRPs & ghrelin mimetics GHRPs & ghrelin mimetics
Evidence Clinical trials Regulator approved
Human trials ~12 ~8
Half-life ~30 minutes ~4 hours
Reported range 100-300 mcg 500 mg
Frequency 2-3x daily Single 0.5 mg/kg diagnostic dose
Routes Subcutaneous, Intramuscular, Intranasal Oral
FDA approved No Yes
Research use only Yes No
Banned in sport Yes Yes
Studied for GH secretory testing, Growth hormone elevation, Appetite stimulation Diagnosis of adult growth hormone deficiency
Reported side effects Increased appetite, Elevated cortisol and prolactin, Water retention, Tiredness Dysgeusia, Dizziness, Headache, Fatigue, QT prolongation

GHRP-2

GHRP-2 is a synthetic hexapeptide agonist at the growth hormone secretagogue receptor. It produces a larger GH pulse than ipamorelin at comparable doses, but with measurable increases in cortisol and prolactin, which is the trade-off that defines its position in the class. It is approved in Japan under the name pralmorelin as a diagnostic test of pituitary GH reserve.

Macimorelin

Macimorelin is an orally active growth hormone secretagogue receptor agonist approved as a single-dose diagnostic test for adult growth hormone deficiency. Administered as an oral solution, it produces a reliable GH rise in subjects with intact pituitary function, so a blunted response identifies deficiency. It replaced the insulin tolerance test in many settings because it avoids induced hypoglycaemia.

GHRP-2 vs Macimorelin: common questions

What is the difference between GHRP-2 and Macimorelin?

Both are gHRPs & ghrelin mimetics. GHRP-2: A potent ghrelin-receptor agonist approved in Japan as a diagnostic agent, with a stronger GH pulse than ipamorelin and more hormonal spillover. Macimorelin: An orally administered ghrelin-receptor agonist and the only compound in this class with a current FDA approval.

Which has stronger evidence, GHRP-2 or Macimorelin?

Macimorelin has the stronger evidence base (regulator approved, about 8 human studies) compared with GHRP-2 (clinical trials).

Are GHRP-2 and Macimorelin FDA approved?

Only Macimorelin is FDA approved (Diagnosis of adult growth hormone deficiency (Macrilen)). GHRP-2 is not approved for any indication.

References

Regulatory and primary sources

  1. PubChem compound record (CID 6918245) ↗ · structure, identifiers, synonyms
  2. WADA Prohibited List ↗ · current year
  3. FDA: Unapproved drugs and "research use only" products ↗ · regulatory status of non-approved products
  4. CAS Registry Number 158861-67-7 ↗ · chemical identity
  5. PubChem compound record (CID 9804938) ↗ · structure, identifiers, synonyms
  6. DailyMed: FDA-approved labeling for Macimorelin ↗ · indications, dosing, warnings as approved
  7. FDA Drugs@FDA database ↗ · approval history
  8. CAS Registry Number 381231-18-1 ↗ · chemical identity

Published literature

  1. Ghigo E, Arvat E, Muccioli G, et al.. Growth hormone-releasing peptides.Eur J Endocrinol 1997.PubMed 9186261 · doi:10.1530/eje.0.1360445
  2. Fukuda I, Hizuka N, Muraoka T, et al.. Adult growth hormone deficiency: current concepts.Neurol Med Chir (Tokyo) 2014.PubMed 25070016 · doi:10.2176/nmc.ra.2014-0088
  3. Pralmorelin: GHRP 2, GPA 748, growth hormone-releasing peptide 2, KP-102 D, KP-102 LN, KP-102D, KP-102LN.Drugs R D 2004.PubMed 15230633 · doi:10.2165/00126839-200405040-00011
  4. Camanni F, Ghigo E, Arvat E. Growth hormone-releasing peptides and their analogs.Front Neuroendocrinol 1998.PubMed 9465289 · doi:10.1006/frne.1997.0158
  5. Vodnik M, Štrukelj B, Lunder M. Ghrelin Receptor Ligands Reaching Clinical Trials: From Peptides to Peptidomimetics; from Agonists to Antagonists.Horm Metab Res 2016.PubMed 26551992 · doi:10.1055/s-0035-1564149
  6. Muccioli G, Broglio F, Valetto MR, et al.. Growth hormone-releasing peptides and the cardiovascular system.Ann Endocrinol (Paris) 2000.PubMed 10790589
  7. Celichowska M, Miedziaszczyk M, Lacka K. Pharmacotherapy in Cachexia: A Review of Endocrine Abnormalities and Steroid Pharmacotherapy.J Pain Palliat Care Pharmacother 2022.PubMed 35758863 · doi:10.1080/15360288.2022.2063469
  8. Argente J, García-Segura LM, Pozo J, et al.. Growth hormone-releasing peptides: clinical and basic aspects.Horm Res 1996.PubMed 8950613 · doi:10.1159/000185015
  9. Refardt J, Atila C, Christ-Crain M. New insights on diagnosis and treatment of AVP deficiency.Rev Endocr Metab Disord 2024.PubMed 38087160 · doi:10.1007/s11154-023-09862-w
  10. Arlien-Søborg MC, Radovick S, Boguszewski MCS, et al.. Consensus and controversies about diagnosing GH deficiency: a Delphi survey by the GH research society.Pituitary 2025.PubMed 40335774 · doi:10.1007/s11102-025-01526-z
  11. Tritos NA. Growth hormone deficiency in adults with Cushing's disease.Best Pract Res Clin Endocrinol Metab 2021.PubMed 33272904 · doi:10.1016/j.beem.2020.101474
  12. Agrawal V, Garcia JM. The macimorelin-stimulated growth hormone test for adult growth hormone deficiency diagnosis.Expert Rev Mol Diagn 2014.PubMed 24834478 · doi:10.1586/14737159.2014.915746
  13. Garcia JM, Biller BMK, Korbonits M, et al.. Macimorelin as a Diagnostic Test for Adult GH Deficiency.J Clin Endocrinol Metab 2018.PubMed 29860473 · doi:10.1210/jc.2018-00665
  14. Tritos NA, Biller BMK. Current concepts of the diagnosis of adult growth hormone deficiency.Rev Endocr Metab Disord 2021.PubMed 32959175 · doi:10.1007/s11154-020-09594-1
  15. Herodes M, Anderson LJ, Shober S, et al.. Pilot clinical trial of macimorelin to assess safety and efficacy in patients with cancer cachexia.J Cachexia Sarcopenia Muscle 2023.PubMed 36860137 · doi:10.1002/jcsm.13191
  16. Cuboni D, Caputo M, Ghigo E, et al.. Once upon a time: the glucagon stimulation test in diagnosing adult GH deficiency.J Endocrinol Invest 2024.PubMed 38461479 · doi:10.1007/s40618-024-02322-5

Literature retrieved from PubMed on October 16, 2026, favouring human studies and reviews. Numbered markers in the text show which paper supports which statement; uncited entries are background reading.

Read this first This page compares published reference data. It is not medical advice and not a recommendation to use either compound. Several compounds documented on this site are not approved for human use.