Growth Hormone Protocol
MacimorelinComplete Dosing & Administration Guide
FDA-approved diagnostic test for adult growth hormone deficiency
Dose Range
25-60mg
Frequency
As needed
Route
Oral (reconstituted solution)
Cycle Length
4-6 weeks
Dosing
How much
do I take?
Timing
Best time to take
Early morning, after fasting overnight for at least 4 hours
With food?
Must be taken on an empty stomach. Food decreases absorption by 50-55%. Do not eat for at least 1 hour before and 30 minutes after administration.
If stacking
This is a single-use diagnostic test, not a compound to be stacked. Administered once with baseline and stimulated GH measurements at 30, 45, and 60 minutes post-dose.
Adjusting Your Dose
Increase if
- +Initial test is inconclusive and retesting is clinically indicated
- +Patient weight changes significantly between test administrations
- +Clinical suspicion remains high despite initial negative result
Decrease if
- -Not applicable — single fixed dose based on weight
- -Dose is calculated once at 0.5 mg/kg body weight
Signs of right dose
- ✓Clear GH response meeting diagnostic criteria at 2-minute interval
- ✓GH level above 2.8 ng/mL threshold (positive test)
- ✓Minimal side effects or patient tolerability issues
Dosing Calculator
Calculate Your Exact Dose
Step 1: Peptide Weight
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The peptide weight is printed on the label
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The weight is on the label
Administration
How do I
use it?
Reconstitution
What you need
- •Macrilen powder vial (25 mg or 50 mg)
- •Sterile water for injection (pharmaceutical grade)
- •Small glass of water (8 oz) for dilution
- •Graduated cylinder or syringe for measuring
- •Small spoon or stirring device
Injection
Route
Not applicable — oral solution only
Best sites
- •Not applicable (oral administration)
Technique
- 1.Reconstitute powder with sterile water according to package instructions
- 2.Stir gently until completely dissolved
- 3.Solution should be clear and colorless
- 4.Drink entire solution immediately or within specified timeframe
- 5.Do not inject or inhale
Storage
Signs of degradation
Sample Daily Schedule
Safety
Is it
safe?
Safety Profile
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.
Safety data from Phase 3 clinical trial (NCT02558829, 157 subjects) and FDA approval process demonstrating efficacy and safety equivalent to insulin tolerance test with superior convenience and tolerability.
Common Side Effects
Experienced by some users
Dysgeusia (abnormal taste)
Metallic or unpleasant taste in mouth affecting 4.5% of patients. Often described as a bitter or medicinal aftertaste. Occurs within minutes of taking the dose and typically resolves within 1-2 hours.
Management: Eat something sweet or drink a flavored beverage after the required fasting window. Swish mouth with water. Taste usually resolves spontaneously. Does not interfere with test results.
Dizziness
Mild dizziness or lightheadedness in 3.9% of patients. Usually mild and transient, resolving within 1-2 hours. May be related to fasting state and GH stimulation.
Management: Sit or lie down if dizziness occurs. Stay well-hydrated. Avoid sudden position changes. Dizziness resolves as GH levels normalize. No intervention usually needed.
Headache
Mild to moderate headache in 3.9% of patients. Typically mild and non-throbbing. Occurs within first few hours after dosing. Similar incidence to placebo in some analyses.
Management: Rest in a quiet, dark environment. Over-the-counter pain relief (acetaminophen or ibuprofen) is safe if needed. Drink plenty of water. Usually resolves within 2-4 hours without intervention.
Fatigue
Mild fatigue or tiredness in 3.9% of patients. May be related to morning testing and fasting state. Typically mild and short-lived.
Management: Schedule test when able to rest afterward. Avoid strenuous activity immediately after testing. Fatigue usually resolves within 2-4 hours. Eat a light meal after the testing window concludes.
Nausea
Mild nausea in 3.2% of patients. Rarely progresses to vomiting (less than 1% of cases). Related to fasting state and GH stimulation. Transient and mild when it occurs.
Management: Remain still and breathe deeply. Avoid sudden movements. Eat bland foods after testing window. Ginger tea or peppermint may help. Does not typically interfere with diagnostic test.
Increased Appetite
Hunger or increased appetite stimulation in 3.2% of patients. Expected physiologic response since macimorelin stimulates ghrelin/hunger pathways. Occurs during test window.
Management: This is expected during the diagnostic test. Eat a meal immediately after the 60-minute testing window concludes. Hunger resolves once food is consumed. Does not affect test validity.
Stop and Seek Help If
- ×Test has been completed and diagnostic results obtained (single-use diagnostic tool)
- ×Patient develops signs of QT prolongation or cardiac arrhythmias
- ×Patient experiences severe hypersensitivity reaction
- ×Contraindications emerge that preclude continued testing
- ×Physician determines additional testing is not clinically warranted
Macimorelin is a single-dose diagnostic test, not an ongoing therapy. Once administered and blood samples collected, the diagnostic protocol is complete. Additional testing requires a separate administration if clinically indicated by the healthcare provider.
Interactions
With other peptides
- !Should not be combined during diagnostic testing as it will confound results
- !Discontinue GH therapy 4+ weeks before testing if possible to avoid false negatives
With medications
- !QT-prolonging drugs (quinidine, disopyramide, amiodarone, sotalol, dofetilide, antipsychotics, antiemetics) - Increases risk of QT prolongation and torsades de pointes. Avoid combination or use extreme caution with ECG monitoring.
- !CYP3A4 inhibitors (ketoconazole, clarithromycin, ritonavir) - May increase macimorelin exposure and side effects. Monitor for increased QT prolongation.
- !Medications affecting electrolytes (diuretics, amphotericin B) - Electrolyte abnormalities increase QT prolongation risk. Ensure normal K+ and Mg+ before testing.
- !Corticosteroids or opioids - May blunt GH response to macimorelin. Discontinue if possible before testing.
With supplements
- ✓Supplements affecting heart rhythm (stimulants with high caffeine) - Extreme caffeine intake before testing may increase arrhythmia risk. Recommend abstinence 24 hours before test.
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View the complete Macimorelin research profile including mechanism of action, clinical studies, effectiveness timeline, and FAQ.
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