Peptide Comparison
MacimorelinvsCapromorelin
FDA-approved diagnostic test for adult growth hormone deficiency
An oral ghrelin agonist originally developed by Pfizer that stimulates growth hormone and appetite. FDA-approved for veterinary use (Entyce and Elura) and investigated in human trials for age-related muscle wasting and appetite support.
At a Glance
Quick
comparison
Dose Range
Macimorelin
25–60 mg
Capromorelin
3–30 mg
Frequency
Macimorelin
As needed
Capromorelin
Once daily
Administration
Macimorelin
Oral (reconstituted solution)
Capromorelin
Oral (capsule or tablet)
Cycle Length
Macimorelin
4-6 weeks
Capromorelin
4-6 weeks
Onset Speed
Macimorelin
Rapid (hours to days)
Capromorelin
Moderate (1-2 weeks)
Evidence Level
Macimorelin
Strong human trials (Phase 3 or FDA approved)
Capromorelin
Moderate human trials (Phase 1-2)
Efficacy
Benefit
ratings
Diagnostic Accuracy
Safety & Tolerability
Convenience & Patient Experience
GH & IGF-1 Stimulation
Physical Function
Oral Convenience
Technical Data
Compound
specifications
Macimorelin
Molecular Formula
C26H30N6O3
Molecular Weight
474.6 g/mol
Half-Life
4.1 hours
Bioavailability
Oral; food decreases Cmax and AUC by approximately 50-55% — must be administered fasting
CAS Number
381231-18-1
Capromorelin
Molecular Formula
C28H35N5O4
Molecular Weight
505.6 g/mol
Half-Life
1-2.4 hours in humans
Bioavailability
Good oral bioavailability
CAS Number
193273-66-4
Applications
Best
suited for
Macimorelin
Diagnosis of Adult Growth Hormone Deficiency
Macimorelin is FDA-approved specifically for diagnosing AGHD in adults. It replaces the insulin tolerance test (ITT) as a safer, more convenient, and equally accurate diagnostic option. Phase 3 trials showed 87% sensitivity and 96% specificity.
Patients Intolerant or Contraindicated for ITT
For patients who cannot safely undergo insulin tolerance testing due to cardiac risk, seizure history, or other contraindications, macimorelin offers an evidence-based non-invasive alternative.
Clinical Confirmation Testing
With 97% reproducibility on retesting, macimorelin can reliably confirm GH deficiency diagnoses and monitor therapeutic responses over time with excellent consistency.
Capromorelin
Age-Related Muscle Wasting
Capromorelin showed significant improvements in physical function — including tandem walk and stair climb — in elderly adults, making it a strong candidate for combating sarcopenia.
Appetite Stimulation
As an FDA-approved veterinary appetite stimulant, capromorelin has extensive real-world evidence for boosting food intake and body weight in mammals.
Growth Hormone Research
One of the best-studied oral ghrelin agonists with human Phase 2 data, offering researchers a well-characterized tool for studying GH/IGF-1 pathways.
Safety Profile
Side
effects
Macimorelin
Common
- Dysgeusia (abnormal taste)
- Dizziness
- Headache
- Fatigue
- Nausea
- Increased Appetite
Serious
- Cardiovascular events
Capromorelin
Common
- Appetite stimulation
- Fluid retention and weight gain
Uncommon
- Joint and muscle aches
- Fatigue or lethargy
- Peripheral edema (swelling)
Serious
- Hyperglycemia
Research Status
Safety
& evidence
Macimorelin
Evidence Level
Strong human trials (Phase 3 or FDA approved)
FDA Status
FDA approved for this use
Safety Overview
Macimorelin is well-tolerated with an excellent safety profile in clinical trials. No serious adverse events were reported in Phase 3 studies (n=154). Most side effects are mild and transient. QT prolongation of approximately 11 msec occurs but is generally not clinically significant. However, avoid combining with other QT-prolonging drugs.
Contraindications
- xPatients with QT prolongation or QT/RR prolongation disorder
- xConcurrent use with drugs known to prolong QT interval
- xPatients with critical illness (acute medical or surgical illness)
- xKnown hypersensitivity to macimorelin or any components
- xPatients unable to fast or follow fasting requirements
Capromorelin
Evidence Level
Moderate human trials (Phase 1-2)
FDA Status
FDA approved for this use
Safety Overview
Capromorelin was generally well-tolerated in Phase 2 human trials involving nearly 400 elderly participants. Most side effects were mild to moderate. Its FDA-approved veterinary use provides additional long-term safety data in mammalian species.
Contraindications
- xActive cancer or history of cancer (GH may stimulate growth)
- xUncontrolled diabetes or severe metabolic disorders
- xSevere liver or kidney disease
- xPregnancy and lactation
Decision Guide
Which is
right for you?
Choose Macimorelin if...
- Diagnosing adult growth hormone deficiency (AGHD)
- Patients who cannot tolerate or are contraindicated for insulin tolerance test
- Clinical settings requiring convenient, repeatable hormone testing
- Healthcare providers seeking FDA-approved diagnostic alternatives
Choose Capromorelin if...
- Stimulating growth hormone production in elderly adults
- Supporting appetite and weight gain in wasting conditions
- Improving muscle mass and physical performance
- Anti-aging and longevity optimization