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Macrilen

Generic: Macimorelin acetate

Verified·Apr 23, 2026
Manufacturer
Aeterna Zentaris
NDC
58844-130
Route
ORAL
ICD-10 indication
E23.0

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About Macrilen

What is this medication? Macrilen, known generically as macimorelin, is a prescription medication used specifically as a diagnostic tool to identify Adult Growth Hormone Deficiency. Unlike many other treatments that are used to manage long-term conditions, Macrilen is typically administered just once in a clinical setting to help doctors determine if a patient's pituitary gland is producing sufficient amounts of growth hormone. It works by mimicking a natural hormone that triggers the release of growth hormone into the bloodstream, allowing healthcare providers to measure the body's response through a series of blood tests. The medication is provided as a granule that is dissolved in water and taken orally by the patient. After the solution is consumed, medical staff draw blood samples at specific intervals to evaluate how much growth hormone the pituitary gland has released in response to the stimulus. This process provides a more convenient and less invasive alternative to older diagnostic tests that often required intravenous infusions or multiple injections. By analyzing these results, physicians can confirm a diagnosis of growth hormone deficiency and decide on the most appropriate course of further treatment.

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Prescribing information

From the FDA-approved label for Macrilen. Official source: DailyMed (NLM) · Label effective Feb 18, 2026

Indications and usage
1 INDICATIONS AND USAGE MACRILEN is indicated for the diagnosis of adult growth hormone deficiency (AGHD). MACRILEN is a growth hormone (GH) secretagogue receptor agonist indicated for the diagnosis of adult growth hormone deficiency ( 1 ). Limitations of Use : The safety and diagnostic performance has not been established for subjects with BMI > 40kg/m 2 ( 1 ). Limitations of Use The safety and diagnostic performance of MACRILEN have not been established for subjects with a body mass index (BMI) > 40 kg/m 2 .
Dosage and administration
2 DOSAGE AND ADMINISTRATION Recommended dose is 0.5 mg/kg as a single oral dose, after fasting for at least 8 hours ( 2.1 ). See Full Prescribing Information for important preparation and administration instructions ( 2.3 ). Discontinue therapy with strong CYP3A4 inducers, growth hormones and drugs that affect GH release for an adequate length of time before administering MACRILEN ( 2.2 ). Adequately replace other hormone deficiencies before administering MACRILEN ( 2.2 ). 2.1 Recommended Dose The recommended dose is a single oral dose of 0.5 mg/kg of macimorelin. The dose is administered as a reconstituted solution [see Dosage and Administration ( 2.3 )] in patients fasted for at least 8 hours. 2.2 Important Recommendations Before MACRILEN Use Discontinue strong CYP3A4 inducers prior to MACRILEN use [see Warning and Precautions ( 5.2 ) and Drug Interactions ( 7.2 )]. Discontinue growth hormone (GH) therapy at least one week before administering MACRILEN [see Drug Interactions ( 7.3 )] . Avoid the use of MACRILEN with drugs known to affect pituitary GH secretion [see Drug Interactions ( 7.3 )] . For patients with deficiencies in sex hormones, thyroid hormone and/or glucocorticoid, adequately replace each of the missing hormones before administering MACRILEN. Ensure that the patient has fasted for at least 8 hours before MACRILEN use. 2.3 Directions for Preparation and Administration Prepare and administer by a healthcare professional exactly as follows. Prepare the MACRILEN solution: Weigh the patient in kilograms (i.e., kg) . Determine the number of MACRILEN pouches needed to prepare the dose: i. For a patient weighing up to 120 kg, use 1 pouch. ii. For a patient weighing more than 120 kg, use 2 pouches. Use a glass or transparent plastic container with graduation in milliliters (i.e., mL) to dissolve the entire contents of the pouch(es) in the appropriate volume of water. i. For 1 pouch dissolve in 120 mL of water (corresponds to 60 mg/120 mL). ii. For 2 pouches dissolve in 240 mL of water (corresponds to 120 mg/240 mL). Stir the MACRILEN solution gently for about 2 to 3 minutes (a small amount of un-dissolved particles will remain). The solution will have a final concentration of 0.5 mg/mL . Use the MACRILEN solution within 30 minutes after preparation. Discard any unused MACRILEN solution. Determine the volume of MACRILEN solution needed for the test: Determine the recommended dose to be administered by multiplying the patient weight in kilogram by 0.5 mg/kg. For example, a 70 kg patient will need a 35 mg dose. Determine the volume of prepared MACRILEN solution to be administered by dividing the recommended dose by 0.5 mg/mL. For example, a patient requiring a dose of 35 mg will need 70 mL of reconstituted MACRILEN solution. Use a syringe (without a needle) with graduations in mL to measure the exact volume of MACRILEN solution to be administered and transfer the required volume of MACRILEN solution into a drinking glass. Administer the MACRILEN solution and perform the test: Have the patient being tested drink the entire volume of MACRILEN solution in the drinking glass (i.e., the dose) within 30 seconds . Observe the patient being tested per routine for the duration of the test. Draw venous blood samples for GH determination at 30 minutes, 45 minutes, 60 minutes and 90 minutes after administration of MACRILEN. Prepare serum samples and send to a laboratory for growth hormone determinations. 2.4 Interpretation of MACRILEN Test Results Clinical studies have established that a maximally stimulated serum GH level of less than 2.8 ng/mL (i.e., at the 30, 45, 60 and 90 minute timepoints) following MACRILEN administration confirms the presence of adult growth hormone deficiency.
Contraindications
4 CONTRAINDICATIONS None None ( 4 )
Warnings and precautions
5 WARNINGS AND PRECAUTIONS QT Prolongation: QT prolongation can lead to development of torsade de pointes-type ventricular tachycardia. Avoid the concomitant use of MACRILEN with drugs that are known to prolong QT interval ( 5.1 , 7.1 ). Potential for False Positive Test Results with Use of Strong CYP3A4 Inducers: Discontinue and washout strong CYP3A4 inducers before testing ( 5.2 , 7.2 ). Potential for False Negative Test Results in Recent Onset Hypothalamic Disease: Consider repeat testing if indicated ( 5.3 ). 5.1 QT Prolongation MACRILEN causes an increase of about 11 msec in the corrected QT (QTc) interval [see Clinical Pharmacology ( 12.2 )] . QT prolongation can lead to development of torsade de pointes-type ventricular tachycardia with the risk increasing as the degree of prolongation increases. The concomitant use of MACRILEN with drugs that are known to prolong the QT interval should be avoided [see Dosage and Administration ( 2.2 ) and Drug Interactions ( 7.1 )] . 5.2 Potential for False Positive Test Results with Use of Strong CYP3A4 Inducers Concomitant use of strong CYP3A4 inducers with MACRILEN can decrease macimorelin plasma levels significantly and thereby lead to a false positive result [see Drug Interactions ( 7.2 )] . Strong CYP3A4 inducers should be discontinued and enough time should be given to allow washout of CYP3A4 inducers prior to test administration [see Dosage and Administration ( 2.2 )]. 5.3 Potential for False Negative Test Results in Recent Onset Hypothalamic Disease Adult growth hormone (GH) deficiency caused by a hypothalamic lesion may not be detected early in the disease process. Macimorelin acts downstream from the hypothalamus and macimorelin stimulated release of stored GH reserves from the anterior pituitary could produce a false negative result early when the lesion involves the hypothalamus. Repeat testing may be warranted in this situation.
Drug interactions
7 DRUG INTERACTIONS 7.1 Drugs that Prolong QT Interval Co-administration of MACRILEN with drugs that prolong the QT interval (such as antipsychotic medications (e.g., chlorpromazine, haloperidol, thioridazine, ziprasidone), antibiotics (e.g., moxifloxacin), Class 1A (e.g., quinidine, procainamide) and Class III (e.g., amiodarone, sotalol) antiarrhythmic medications or any other medications known to prolong the QT interval) may lead to development of torsade de pointes-type ventricular tachycardia. Avoid concomitant use of MACRILEN with drugs that prolong the QT interval. Sufficient washout time of drugs that are known to prolong the QT interval prior to administration of MACRILEN is recommended [see Dosage and Administration ( 2.2 ) and Warnings and Precautions ( 5.1 )] . 7.2 Cytochrome P450 (CYP) 3A4 Inducers Co-administration of a strong CYP3A4 inducer with MACRILEN (e.g., carbamazepine, enzalutamide, mitotane, phenytoin, rifampin, St. John's wort, bosentan, efavirenz, etravirine, modafinil, armodafinil, rufinamide) may reduce the plasma macimorelin concentrations and may lead to false positive test results. Discontinue strong CYP3A4 inducers prior to MACRILEN use. Sufficient washout time of strong CYP3A4 inducers prior to administration of MACRILEN is recommended [see Dosage and Administration ( 2.2 ) and Warnings and Precautions ( 5.2 )] . 7.3 Drugs Affecting Growth Hormone Release The following drugs may impact the accuracy of the MACRILEN diagnostic test. Avoid concomitant use of MACRILEN with the following [see Dosage and Administration ( 2.2 )] : Drugs that directly affect the pituitary secretion of growth hormone (such as somatostatin, insulin, glucocorticoids, and cyclooxygenase inhibitors such as aspirin or indomethacin). Drugs that may transiently elevate growth hormone concentrations (such as clonidine, levodopa, and insulin). Drugs that may blunt the growth hormone response to MACRILEN (such as muscarinic antagonists: atropine, anti-thyroid medication: propylthiouracil, and growth hormone products). Discontinue growth hormone products at least one week before administering the MACRILEN diagnostic test. Sufficient washout time of drugs affecting growth hormone release prior to administration of MACRILEN is recommended.
Adverse reactions
6 ADVERSE REACTIONS to report suspected adverse reactions 1-800-332-1088 to report suspected adverse reactions , contact Aeterna Zentaris GmbH at 1-843-900-2332, or FDA at 1‑800-332-1088 or www.fda.gov/medwatch. to report suspected adverse reactions 1-800-332-1088 to report suspected adverse reactions , contact Aeterna Zentaris GmbH at 1-843-900-2332, or FDA at 1‑800-332-1088 or www.fda.gov/medwatch. The most common adverse reactions were dysgeusia, dizziness, headache, fatigue, nausea, hunger, diarrhea, upper respiratory tract infection, feeling hot, hyperhidrosis, nasopharyngitis, and sinus bradycardia ( 6.1 ). 6.1 Clinical Studies Experience to report suspected adverse reactions 1-800-332-1088 to report suspected adverse reactions , contact Aeterna Zentaris GmbH at 1-843-900-2332, or FDA at 1‑800-332-1088 or www.fda.gov/medwatch. Because clinical trials are conducted under widely varying conditions, adverse reaction rates observed in the clinical trials of a drug cannot be directly compared to rates in the clinical trial of another drug and may not reflect the rates observed in practice. The data in Table 1 are derived from an open-label, randomized, cross-over study that compared the diagnostic performance of MACRILEN to the insulin tolerance test (ITT) for the diagnosis of adult growth hormone deficiency [see Clinical Studies ( 14 )]. A total of 154 subjects with a high to low pre-test probability of having adult growth hormone deficiency received a single oral dose of 0.5 mg/kg MACRILEN. Out of 154 subjects, 58% were male, 42% female, and 86% of white origin. Median values were for age 41 years (range: 18 – 66 years) and body mass index was 27.5 kg/m 2 (range: 16 – 40 kg/m 2 ). Common adverse reactions presented in Table 1 were adverse reactions that were not present at baseline and occurred during MACRILEN dosing in at least two individuals. Table 1: Common Adverse Reactions Reported in at Least Two Individuals Dosed with MACRILEN in an Open-Label Study Number of Subjects (n = 154) Proportion of Subjects (%) Dysgeusia 7 4.5 Dizziness 6 3.9 Headache 6 3.9 Fatigue 6 3.9 Nausea 5 3.2 Hunger 5 3.2 Diarrhea 3 1.9 Upper respiratory tract infection 3 1.9 Feeling hot 2 1.3 Hyperhidrosis 2 1.3 Nasopharyngitis 2 1.3 Sinus bradycardia 2 1.3 The safety of Macrilen was evaluated in 126 pediatric patients. The overall safety profile in the pediatric population was consistent with that observed in adults.
Use in pregnancy
8.1 Pregnancy Risk summary There are no available data with MACRILEN use in pregnant women to inform a drug associated risk for adverse developmental outcomes. Animal reproduction studies have not been conducted with MACRILEN. MACRILEN is indicated as a single dose which limits the risk of adverse developmental outcomes from exposure to MACRILEN. The estimated background risk of major birth defects and miscarriage for the indicated populations is unknown. All pregnancies have a background risk of birth defect, loss, or other adverse outcomes. In the U.S. general population, the estimated background risk of major birth defects and miscarriage in clinically recognized pregnancies is 2 – 4% and 15 – 20%, respectively.

Label text is reproduced as-is from the FDA-approved label. We do not paraphrase, summarize, or omit. Content above is for informational purposes only and is not medical advice. Always consult your prescribing clinician or pharmacist before making decisions about your medication.

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How this page is sourced

  • Drug identity verified against openFDA NDC Directory.
  • Label text (when shown) originates from NLM DailyMed.
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