Comparison
Anamorelin 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.
| Anamorelin | Macimorelin | |
|---|---|---|
| Class | GHRPs & ghrelin mimetics | GHRPs & ghrelin mimetics |
| Evidence | Clinical trials | Regulator approved |
| Human trials | ~18 | ~8 |
| Half-life | ~7 hours | ~4 hours |
| Reported range | 50-100 mg | 500 mg |
| Frequency | Once daily | Single 0.5 mg/kg diagnostic dose |
| Routes | Oral | Oral |
| FDA approved | No | Yes |
| Research use only | Yes | No |
| Banned in sport | Yes | Yes |
| Studied for | Cancer cachexia, Appetite stimulation, Lean mass preservation | Diagnosis of adult growth hormone deficiency |
| Reported side effects | Hyperglycaemia, Nausea, Elevated hepatic enzymes, Headache | Dysgeusia, Dizziness, Headache, Fatigue, QT prolongation |
Anamorelin
Anamorelin is a non-peptide small molecule agonist at the growth hormone secretagogue receptor with oral bioavailability, which separates it from the injectable hexapeptides. In phase III cancer-cachexia trials it increased lean body mass and appetite, though it did not consistently improve handgrip strength, which is why its regulatory path diverged between Japan and the US and Europe. Its oral route and long half-life make it pharmacologically closer to MK-677 than to GHRP-2.
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.
Anamorelin vs Macimorelin: common questions
What is the difference between Anamorelin and Macimorelin?
Both are gHRPs & ghrelin mimetics. Anamorelin: An orally active ghrelin-receptor agonist approved in Japan for cancer cachexia, and the most clinically advanced compound in the class. Macimorelin: An orally administered ghrelin-receptor agonist and the only compound in this class with a current FDA approval.
Which has stronger evidence, Anamorelin or Macimorelin?
Macimorelin has the stronger evidence base (regulator approved, about 8 human studies) compared with Anamorelin (clinical trials).
Are Anamorelin and Macimorelin FDA approved?
Only Macimorelin is FDA approved (Diagnosis of adult growth hormone deficiency (Macrilen)). Anamorelin is not approved for any indication.
References
Regulatory and primary sources
- PubChem compound record (CID 9828911) ↗ · structure, identifiers, synonyms
- WADA Prohibited List ↗ · current year
- FDA: Unapproved drugs and "research use only" products ↗ · regulatory status of non-approved products
- CAS Registry Number 249921-19-5 ↗ · chemical identity
- PubChem compound record (CID 9804938) ↗ · structure, identifiers, synonyms
- DailyMed: FDA-approved labeling for Macimorelin ↗ · indications, dosing, warnings as approved
- FDA Drugs@FDA database ↗ · approval history
- CAS Registry Number 381231-18-1 ↗ · chemical identity
Published literature
- Anamorelin for cancer cachexia.Drugs Today (Barc) 2022.PubMed 35274629 · doi:10.1358/dot.2022.58.3.3381585
- What is next after anamorelin?.Curr Opin Support Palliat Care 2017.PubMed 28957883 · doi:10.1097/SPC.0000000000000299
- The effect of anamorelin (ONO-7643) on cachexia in cancer patients: Systematic review and meta-analysis of randomized controlled trials.J Oncol Pharm Pract 2023.PubMed 37525932 · doi:10.1177/10781552231189864
- [Overview of Cancer-Associated Cachexia].Gan To Kagaku Ryoho 2019.PubMed 31879394
- Anamorelin for the Treatment of Cancer Anorexia-Cachexia Syndrome.Curr Oncol Rep 2024.PubMed 38771469 · doi:10.1007/s11912-024-01549-y
- Anamorelin in Japanese patients with cancer cachexia: an update.Curr Opin Support Palliat Care 2023.PubMed 37389636 · doi:10.1097/SPC.0000000000000658
- Clinical results in cachexia therapeutics.Curr Opin Clin Nutr Metab Care 2016.PubMed 26974316 · doi:10.1097/MCO.0000000000000274
- Anamorelin hydrochloride for the treatment of cancer-anorexia-cachexia in NSCLC.Expert Opin Pharmacother 2015.PubMed 25945893 · doi:10.1517/14656566.2015.1041500
- New insights on diagnosis and treatment of AVP deficiency.Rev Endocr Metab Disord 2024.PubMed 38087160 · doi:10.1007/s11154-023-09862-w
- 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
- 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
- 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
- Macimorelin as a Diagnostic Test for Adult GH Deficiency.J Clin Endocrinol Metab 2018.PubMed 29860473 · doi:10.1210/jc.2018-00665
- Current concepts of the diagnosis of adult growth hormone deficiency.Rev Endocr Metab Disord 2021.PubMed 32959175 · doi:10.1007/s11154-020-09594-1
- 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
- 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.