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Macimorelin (Macrilen)

Peptide

Macimorelin is an oral ghrelin receptor agonist peptidomimetic. FDA-approved in 2017 as first oral diagnostic for adult GH deficiency. Single dose 0.5 mg/kg. Phase 3: 82-87% sensitivity, 92-96% specificity at 2.7-5.1 ng/mL GH cutoff. Comparable accuracy to insulin tolerance test without hypoglycemia risk.

Quick Answer

What it is

Macimorelin is an oral ghrelin receptor agonist peptidomimetic. FDA-approved in 2017 as first oral diagnostic for adult GH deficiency.

Key findings

  • Grade A: GH Deficiency Diagnosis (Growth Hormone Deficiency)
  • Grade A: GH Stimulation Response (Growth Hormone Deficiency)
  • Grade A: Diagnostic Safety (Growth Hormone Deficiency)

Safety

  • Comparable accuracy to insulin tolerance test without hypoglycemia risk.
  • No hypoglycemia risk unlike ITT.
⚠ī¸ Research Notice

This peptide information is for educational and research purposes only. Peptides may not be FDA-approved for human use and may only be legally available for research purposes. Consult qualified healthcare professionals before considering any peptide compounds.

ℹī¸ Quick Facts: Macimorelin (Macrilen)

Quick Facts: Macimorelin (Macrilen)

  • Best Evidence:Grade A
  • Conditions Studied:1
  • Research Outcomes:5
  • Grade A Findings:3
  • Key Effect:Growth Hormone Deficiency
A3
B0
C2
D0
1 conditions ¡ 5 outcomes

Detailed Outcomes

A
GH Deficiency Diagnosis
Phase 3: 82-87% sensitivity, 92-96% specificity for AGHD diagnosis. Optimal GH cutoff 2.7-5.1 ng/mL. Accuracy comparable to insulin tolerance test (ITT). First FDA-approved oral GH stimulation test.
large↑Improves
A
GH Stimulation Response
Robust GH release in healthy subjects. Peak response at 30-90 minutes. Reproducible test with low inter- and intra-individual variability. Blunted response (<5.1 ng/mL) indicates GH deficiency.
large↑Improves
A
Diagnostic Safety
No hypoglycemia risk unlike ITT. Well-tolerated single oral dose. Contraindicated only with strong CYP3A4 inhibitors. Can be used in patients where ITT is contraindicated (elderly, cardiovascular disease, seizure history).
large↑Improves
C
Hormone Levels
10 preclinical studies support this finding. Primarily preclinical evidence.
moderate↑Improves
C
Seizure Activity
3 preclinical studies support this finding. Primarily preclinical evidence.
small↓Improves

Research Citations (23)

Molecular recognition of two approved drugs Macimorelin and Anamorelin by the growth hormone secretagogue receptor.
(2025)
PMID: 40542284
Macimorelin Acetate for the Diagnosis of Childhood-onset Growth Hormone Deficiency
(2023)
PMID: 36694890
Pilot clinical trial of macimorelin to assess safety and efficacy in patients with cancer cachexia
(2023)
PMID: 36860137
Diagnosis and testing for growth hormone deficiency across the ages: a global view of the accuracy, caveats, and cut-offs for diagnosis.
(2023)
PMID: 37052176
Safety, Tolerability, Pharmacokinetics, and Pharmacodynamics of Macimorelin in Children with Suspected Growth Hormone Deficiency: An Open-Label, Group Comparison, Dose-Escalation Trial
(2021)
PMID: 34438400
Current concepts of the diagnosis of adult growth hormone deficiency.
(2021)
PMID: 32959175
Growth hormone deficiency in adults with Cushing's disease.
(2021)
PMID: 33272904
Translational potential of the ghrelin receptor agonist macimorelin for seizure suppression in pharmacoresistant epilepsy.
(2021)
PMID: 34157194
Sensitivity and specificity of the macimorelin test for diagnosis of AGHD
(2020)
PMID: 33320108
Safety, tolerability, pharmacokinetics, and pharmacodynamics of macimorelin in healthy adults: Results of a single-dose, randomized controlled study
(2020)
PMID: 32325373

Related Peptides

CJC-1295

Peptide

1 shared condition ¡ 10 outcomes

CJC-1295 is a synthetic analog of growth hormone-releasing hormone (GHRH) consisting of 29 amino acids with modifications to extend its biological half-life. Developed by ConjuChem Biotechnologies, it exists in two forms: CJC-1295 with DAC (Drug Affinity Complex) which binds to albumin for an extended half-life of 6-8 days, and Modified GRF (1-29) without DAC with a half-life of approximately 30 minutes. Clinical trials demonstrated sustained, dose-dependent increases in growth hormone and IGF-1 levels in healthy adults. Development was discontinued after Phase II trials, and it remains an investigational compound not approved by the FDA.