SINGULAIR
Clinical safety rating: caution
Comprehensive clinical and safety monograph for SINGULAIR (SINGULAIR).
Selective leukotriene receptor antagonist; inhibits cysteinyl leukotriene (LTC4, LTD4, LTE4) at the CysLT1 receptor, reducing bronchoconstriction, mucus secretion, and eosinophilic inflammation.
| Metabolism | Primarily metabolized by CYP2C8 and CYP3A4; minor contribution from CYP2C9. Metabolites are excreted in bile. |
| Excretion | Primarily hepatic metabolism; 86% eliminated in feces via bile, <0.2% unchanged in urine. Minor renal excretion of metabolites. |
| Half-life | 2.7-5.5 hours (mean 3-4 hours). No significant accumulation with once-daily dosing; extended effect due to receptor binding kinetics. |
| Protein binding | >99% bound primarily to albumin; minor binding to other plasma proteins. |
| Volume of Distribution | 10-20 L (approximately 0.14-0.29 L/kg). Indicates extensive tissue distribution, consistent with intracellular target (cysteinyl leukotriene receptor). |
| Bioavailability | Oral: 64% (10 mg tablet). Food reduces rate and extent of absorption; administered without regard to meals. |
| Onset of Action | Oral: 3-4 hours for detectable improvement in FEV1; maximal bronchodilation observed within 24 hours of first dose. |
| Duration of Action | 24 hours for clinical effect (once-daily dosing). Note: Duration exceeds plasma half-life due to sustained receptor occupancy; continuous coverage over 24 hours. |
| Action Class | Leukotriene antagonists |
| Brand Substitutes | Vitamont 10mg Tablet, Solukast 10mg Tablet, Ebmont 10mg Tablet, Lasma 10 Tablet, Symkast DX 10mg Tablet |
10 mg orally once daily in the evening, with or without food.
| Dosage form | GRANULE |
| Renal impairment | No dosage adjustment required for renal impairment, including end-stage renal disease. |
| Liver impairment | No dosage adjustment required for mild-to-moderate hepatic impairment (Child-Pugh A or B). Not studied in severe hepatic impairment (Child-Pugh C). |
| Pediatric use | 6 to 23 months: 4 mg (chewable tablet or oral granules) once daily; 2 to 5 years: 4 mg (chewable tablet) once daily; 6 to 14 years: 5 mg (chewable tablet) once daily; 15 years and older: 10 mg tablet once daily. |
| Geriatric use | No specific dose adjustment; use with caution due to potential age-related renal or hepatic function decline. |
| 1st trimester | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
Comprehensive clinical and safety monograph for SINGULAIR (SINGULAIR).
| Breastfeeding | Montelukast is excreted in human breast milk in small amounts. The milk-to-plasma ratio is approximately 0.13. Data from a small study (n=6) found infant dose <0.4% of maternal weight-adjusted dose. Based on limited data, it is considered compatible with breastfeeding. Use caution, especially in preterm infants or those with renal impairment. Alternative agents may be preferred if risk to infant is a concern. |
| Teratogenic Risk | Montelukast is classified as FDA Pregnancy Category B. Animal studies have not demonstrated fetal harm, and there are no adequate and well-controlled studies in pregnant women. Use only if clearly needed. No known risk of major birth defects or miscarriage based on limited human data; first trimester exposure not associated with increased risk of congenital anomalies in large cohort studies. Second and third trimester: no specific risks identified. However, monitor as part of routine prenatal care. |
■ FDA Black Box Warning
No FDA black box warning.
| Serious Effects |
["Hypersensitivity to montelukast or any component of the formulation"]
| Precautions | ["Neuropsychiatric events (agitation, depression, suicidal behavior)","Eosinophilic conditions (Churg-Strauss syndrome)","Acute asthma attacks (not for reversal of bronchospasm)","Aspirin sensitivity (avoid in aspirin-sensitive patients)"] |
Loading safety data…
| Fetal Monitoring | No specific fetal monitoring required beyond routine obstetric care. Monitor maternal asthma control and adjust therapy as needed. Evaluate for potential adverse effects including neuropsychiatric events (e.g., mood changes, agitation) which may indicate need dose adjustment or discontinuation. |
| Fertility Effects | No known adverse effects on human fertility. Animal studies showed no impairment of fertility at clinically relevant doses. No specific monitoring required. |