Macimorelin vs Anamorelin

Both are approved oral ghrelin-receptor agonists in at least one market, but for different jobs. Macimorelin provokes a GH response to diagnose deficiency; anamorelin was trialled to increase appetite and lean mass in cancer cachexia.

HPLC tested · JanoshikJanoshik CertificatesNationwide DeliveryResearch Only

🧪

Macimorelin

An oral ghrelin-receptor agonist approved in the US and EU as a diagnostic test for adult growth-hormone deficiency.

BEST STUDIED FOR

GH secretagogues

Read the cited profile →

🧪

Anamorelin

An orally active, non-peptide ghrelin-receptor agonist approved in Japan for cancer cachexia — the best-trialled molecule in the secretagogue class.

BEST STUDIED FOR

GH secretagogues

Read the cited profile →

SIDE BY SIDE

	Macimorelin	Anamorelin
The key difference	Diagnostic test for GH deficiency	Treatment candidate for cancer cachexia
Class	GH secretagogues	GH secretagogues
Mechanism	Macimorelin stimulates GH release through GHS-R1a after a single oral dose; a low GH peak after stimulation indicates GH deficiency, offering an alternative to the insulin tolerance test.	Anamorelin binds GHS-R1a, increasing appetite signalling and GH/IGF-1 release, studied as a way to counter the muscle and weight loss of cancer anorexia-cachexia.
Status	Approved as a diagnostic agent (adult GHD); also explored in a pilot cancer-cachexia study.	Approved in Japan (2021) for cancer cachexia in several tumour types; two phase 3 trials (ROMANA 1 and 2) are the core dataset.
Reported safety signals	In diagnostic use it is a single dose; the phase 3 trial compared its accuracy with the insulin tolerance test, which carries hypoglycaemia risk.	The phase 3 programme reported it was generally well tolerated; hyperglycaemia and other events were monitored. Meta-analyses summarise effects on body weight and lean mass.
A key study	A phase 3 study compared the oral macimorelin test against the insulin tolerance test for diagnosing adult GHD. (J Clin Endocrinol Metab 2018, PMID 29860473)	Two phase 3 trials measured anamorelin’s effect on lean body mass and other cachexia outcomes in advanced NSCLC. (Lancet Oncol 2016, PMID 26906526)

WHEN TO RESEARCH WHICH

The choice follows the endpoint: GH-stimulation testing for macimorelin, body-weight and appetite endpoints for anamorelin. Both are discussed here strictly as research compounds; nothing on this page is medical advice or a dosing guide.

REFERENCES (PUBMED)

[Macimorelin] Macimorelin as a Diagnostic Test for Adult GH Deficiency — J Clin Endocrinol Metab 2018. PMID 29860473
[Macimorelin] Pilot clinical trial of macimorelin to assess safety and efficacy in patients with cancer cachexia — J Cachexia Sarcopenia Muscle 2023. PMID 36860137
[Macimorelin] Diagnosis and testing for growth hormone deficiency across the ages: a global view of the accuracy, caveats, and cut-offs for diagnosis — Endocr Connect 2023. PMID 37052176
[Anamorelin] Anamorelin in patients with non-small-cell lung cancer and cachexia (ROMANA 1 and ROMANA 2): results from two randomised, double-blind, phase 3 trials — Lancet Oncol 2016. PMID 26906526
[Anamorelin] Anamorelin for cancer anorexia-cachexia syndrome: a systematic review and meta-analysis — Support Care Cancer 2017. PMID 28074289
[Anamorelin] Anamorelin in Japanese patients with cancer cachexia: an update — Curr Opin Support Palliat Care 2023. PMID 37389636

FREQUENTLY ASKED

What is the difference between Macimorelin and Anamorelin?

What is the regulatory status of Macimorelin and Anamorelin?

Macimorelin: Approved as a diagnostic agent (adult GHD); also explored in a pilot cancer-cachexia study. Anamorelin: Approved in Japan (2021) for cancer cachexia in several tumour types; two phase 3 trials (ROMANA 1 and 2) are the core dataset.

What safety signals have been reported?

Macimorelin: In diagnostic use it is a single dose; the phase 3 trial compared its accuracy with the insulin tolerance test, which carries hypoglycaemia risk. Anamorelin: The phase 3 programme reported it was generally well tolerated; hyperglycaemia and other events were monitored. Meta-analyses summarise effects on body weight and lean mass.

Which studies is this comparison based on?

For Macimorelin: “Macimorelin as a Diagnostic Test for Adult GH Deficiency” (PMID 29860473); “Pilot clinical trial of macimorelin to assess safety and efficacy in patients with cancer cachexia” (PMID 36860137); “Diagnosis and testing for growth hormone deficiency across the ages: a global view of the accuracy, caveats, and cut-offs for diagnosis” (PMID 37052176). For Anamorelin: “Anamorelin in patients with non-small-cell lung cancer and cachexia (ROMANA 1 and ROMANA 2): results from two randomised, double-blind, phase 3 trials” (PMID 26906526); “Anamorelin for cancer anorexia-cachexia syndrome: a systematic review and meta-analysis” (PMID 28074289); “Anamorelin in Japanese patients with cancer cachexia: an update” (PMID 37389636).