Peptide Comparison
MacimorelinvsIpamorelin
FDA-approved diagnostic test for adult growth hormone deficiency
A uniquely selective growth hormone booster that tells your pituitary to release more GH without messing with your cortisol or other hormones—making it the 'clean' choice among growth hormone peptides.
At a Glance
Quick
comparison
Dose Range
Macimorelin
25–60 mg
Ipamorelin
100–300 mcg
Frequency
Macimorelin
As needed
Ipamorelin
Multiple times daily
Administration
Macimorelin
Oral (reconstituted solution)
Ipamorelin
Subcutaneous injection
Cycle Length
Macimorelin
4-6 weeks
Ipamorelin
8-12 weeks
Onset Speed
Macimorelin
Rapid (hours to days)
Ipamorelin
Moderate (1-2 weeks)
Evidence Level
Macimorelin
Strong human trials (Phase 3 or FDA approved)
Ipamorelin
Moderate human trials (Phase 1-2)
Efficacy
Benefit
ratings
Diagnostic Accuracy
Safety & Tolerability
Convenience & Patient Experience
GH Selectivity
Recovery Support
Safety Profile
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
Ipamorelin
Molecular Formula
C38H49N9O5
Molecular Weight
711.85 g/mol
Half-Life
2 hours
Bioavailability
High when injected subcutaneously
CAS Number
170851-70-4
Protocols
Dosing
tiers
Macimorelin
Ipamorelin
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.
Ipamorelin
Clean GH Boost Seekers
If you want the benefits of increased growth hormone without spiking cortisol or other stress hormones, Ipamorelin is uniquely selective. Unlike GHRP-2 or GHRP-6, it won't raise your cortisol levels even at doses 200 times higher than needed for GH release.
Recovery-Focused Athletes
Ipamorelin shines for athletes who want better recovery between training sessions. The GH boost helps repair muscle tissue faster, and since it doesn't mess with other hormones, you can use it consistently without the rollercoaster effects.
Anti-Aging Enthusiasts
Growth hormone naturally declines as we age, contributing to muscle loss, fat gain, and reduced vitality. Ipamorelin offers a gentle way to restore more youthful GH levels without the risks of actual HGH therapy.
Those Recovering from Steroid Use
Research shows Ipamorelin can help counteract the muscle and bone-weakening effects of glucocorticoid medications. If you've been on steroids for medical reasons, this peptide may help you rebuild what you've lost.
Safety Profile
Side
effects
Macimorelin
Common
- Dysgeusia (abnormal taste)
- Dizziness
- Headache
- Fatigue
- Nausea
- Increased Appetite
Serious
- Cardiovascular events
Ipamorelin
Common
- Mild headache
- Injection site reactions
- Water retention
- Increased appetite
Uncommon
- Tingling in hands or feet
- Joint stiffness
Serious
- Allergic reaction
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
Ipamorelin
Evidence Level
Moderate human trials (Phase 1-2)
FDA Status
Research compound
Safety Overview
Ipamorelin has shown a favorable safety profile in both animal and human studies. What makes it stand out is its remarkable selectivity—it releases growth hormone without significantly affecting cortisol, ACTH, or other hormones. In clinical trials, it was well-tolerated with mostly mild, temporary side effects. Phase 2 trials in patients recovering from surgery showed no significant safety concerns compared to placebo.
Contraindications
- xActive cancer or history of cancer
- xPregnancy or breastfeeding
- xPituitary disorders or tumors
- xKnown allergy to peptide components
- xChildren and adolescents (growth plates still open)
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 Ipamorelin if...
- Muscle recovery and growth
- Anti-aging and vitality
- Body composition improvement
- Sleep quality enhancement