Version July 2025
Dosage guidance:
Dosage form information: Macrilen has been discontinued in the United States for >1 year.
Diagnostic aid, growth hormone deficiency, adult: Note: Correct other pituitary hormone deficiencies prior to administration (Ref). Discontinue growth hormone therapy at least 1 week prior to administration.
BMI ≤40 kg/m2: Oral: 0.5 mg/kg as single dose.
BMI >40 kg/m2: Oral: Dose has not been established.
Dosage adjustment for concomitant therapy: Significant drug interactions exist, requiring dose/frequency adjustment or avoidance. Consult drug interactions database for more information.
There are no dosage adjustments provided in the manufacturer's labeling.
There are no dosage adjustments provided in the manufacturer's labeling.
Refer to adult dosing.
The following adverse drug reactions and incidences are derived from product labeling unless otherwise specified.
1% to 10%:
Cardiovascular: Sinus bradycardia (1%)
Central nervous system: Dizziness (4%), fatigue (4%), headache (4%), feeling hot (1%)
Dermatologic: Hyperhidrosis (1%)
Gastrointestinal: Dysgeusia (5%), hunger (3%), nausea (3%), diarrhea (2%)
Respiratory: Upper respiratory tract infection (2%), nasopharyngitis (1%)
Frequency not defined:
Cardiovascular: Prolonged QT interval on ECG
There are no contraindications listed in the manufacturer's labeling
Concerns related to adverse effects:
• QT prolongation: Prolongation of the QTc interval (~11 msec) has been observed in clinical trials at doses 2- and 4-times the recommended dosage; avoid concurrent use with other agents known to prolong the QT interval.
Disease-related concerns:
• Hypothalamic disease: Growth hormone deficiency due to hypothalamic lesion may not be detected early in the disease process; macimorelin stimulates release of stored growth hormone from the anterior pituitary, which may lead to false negative result. Repeat testing may be necessary.
Macrilen has been discontinued in the United States for >1 year.
Excipient information presented when available (limited, particularly for generics); consult specific product labeling. [DSC] = Discontinued product
Packet, Oral:
Macrilen: 60 mg (1 ea [DSC]) [contains saccharin sodium]
No
Pack (Macrilen Oral)
60 mg (per each): $5,400.00
Disclaimer: A representative AWP (Average Wholesale Price) price or price range is provided as reference price only. A range is provided when more than one manufacturer's AWP price is available and uses the low and high price reported by the manufacturers to determine the range. The pricing data should be used for benchmarking purposes only, and as such should not be used alone to set or adjudicate any prices for reimbursement or purchasing functions or considered to be an exact price for a single product and/or manufacturer. Medi-Span expressly disclaims all warranties of any kind or nature, whether express or implied, and assumes no liability with respect to accuracy of price or price range data published in its solutions. In no event shall Medi-Span be liable for special, indirect, incidental, or consequential damages arising from use of price or price range data. Pricing data is updated monthly.
Oral: Patient must drink entire dose within 30 seconds after fasting for at least 8 hours.
Diagnostic aid, growth hormone deficiency, adult: Diagnosis of adult growth hormone deficiency.
Limitations of use: The safety and diagnostic performance has not been established for patients with BMI >40 kg/m2.
Sound-alike/look-alike issues:
Macimorelin may be confused with tesamorelin
Substrate of CYP3A4 (Major with inducers), CYP3A4 (Minor with inhibitors); Note: Assignment of Major/Minor substrate status based on clinically relevant drug interaction potential;
Note: Interacting drugs may not be individually listed below if they are part of a group interaction (eg, individual drugs within “CYP3A4 Inducers [Strong]” are NOT listed). For a complete list of drug interactions by individual drug name and detailed management recommendations, use the drug interactions program by clicking on the “Launch drug interactions program” link above.
Aspirin: Coadministration of Aspirin and Macimorelin may alter diagnostic results. Risk X: Avoid
Atropine (Systemic): Coadministration of Atropine (Systemic) and Macimorelin may alter diagnostic results. Risk X: Avoid
Bosentan: Coadministration of Bosentan and Macimorelin may alter diagnostic results. Risk C: Monitor
CloNIDine: Coadministration of CloNIDine and Macimorelin may alter diagnostic results. Risk X: Avoid
Corticosteroids (Systemic): Coadministration of Corticosteroids (Systemic) and Macimorelin may alter diagnostic results. Risk X: Avoid
CYP3A4 Inducers (Strong): May decrease serum concentration of Macimorelin. Risk X: Avoid
Efavirenz: Coadministration of Efavirenz and Macimorelin may alter diagnostic results. Risk C: Monitor
Etravirine: Coadministration of Etravirine and Macimorelin may alter diagnostic results. Risk C: Monitor
Haloperidol: QT-prolonging Agents (Indeterminate Risk - Avoid) may increase QTc-prolonging effects of Haloperidol. Risk C: Monitor
Insulin: Coadministration of Insulin and Macimorelin may alter diagnostic results. Risk X: Avoid
Levodopa-Foslevodopa: Coadministration of Levodopa-Foslevodopa and Macimorelin may alter diagnostic results. Risk X: Avoid
Levoketoconazole: QT-prolonging Agents (Indeterminate Risk - Avoid) may increase QTc-prolonging effects of Levoketoconazole. Management: Monitor for QTc interval prolongation and ventricular arrhythmias when these agents are combined. Patients with additional risk factors for QTc prolongation may be at even higher risk. Risk C: Monitor
Modafinil: Coadministration of Modafinil and Macimorelin may alter diagnostic results. Risk C: Monitor
Nonsteroidal Anti-Inflammatory Agents: Coadministration of Nonsteroidal Anti-Inflammatory Agents and Macimorelin may alter diagnostic results. Risk X: Avoid
Products that Affect Growth Hormone: Coadministration of Products that Affect Growth Hormone and Macimorelin may alter diagnostic results. Risk X: Avoid
Propylthiouracil: Coadministration of Propylthiouracil and Macimorelin may alter diagnostic results. Risk X: Avoid
QT-prolonging Agents (Highest Risk): QT-prolonging Agents (Indeterminate Risk - Avoid) may increase QTc-prolonging effects of QT-prolonging Agents (Highest Risk). Management: Monitor for QTc interval prolongation and ventricular arrhythmias when these agents are combined. Patients with additional risk factors for QTc prolongation may be at even higher risk. Risk C: Monitor
Somatostatin Analogs: Coadministration of Somatostatin Analogs and Macimorelin may alter diagnostic results. Risk X: Avoid
St John's Wort: May decrease serum concentration of Macimorelin. Risk X: Avoid
Liquid meal decreased macimorelin Cmax and AUC by 55% and 49% respectively. Patient should fast for at least 8 hours prior to macimorelin administration.
Animal reproduction studies have not been conducted.
It is not known if macimorelin is present in breast milk. According to the manufacturer, the decision to breastfeed following administration should consider the risk of infant exposure, the benefits of breastfeeding to the infant, and benefits of treatment to the mother.
Serum growth hormone at 30, 45, 60, and 90 minutes following administration
According to the manufacturer, serum growth hormone (GH) levels <2.8 ng/mL (SI: <2.8 mcg/L) at 30, 45, 60, and 90 minutes following macimorelin administration confirm the presence of adult GH deficiency. However, using a GH cutoff level <5.1 ng/mL (SI: <5.1 mcg/L) may more optimally balance sensitivity and specificity (Garcia 2018).
Stimulates GH release by activating GH secretagogue receptors in the pituitary and hypothalamus.
Metabolism: Hepatic via CYP3A4
Half-life elimination: 4.1 hours
Time to peak (plasma): 0.5 to 1.5 hours
