BELSOMRA
Clinical safety rating: caution
Comprehensive clinical and safety monograph for BELSOMRA (BELSOMRA).
Selective orexin receptor antagonist that binds to OX1R and OX2R, inhibiting orexin neuropeptide signaling to promote sleep initiation and maintenance.
| Metabolism | Primarily metabolized by CYP3A4; also involves CYP2C19 to a minor extent. |
| Excretion | Primarily hepatic metabolism via CYP3A4 and CYP2C9; 83% excreted in feces (as metabolites), 6% in urine (as unchanged drug and metabolites). |
| Half-life | Terminal elimination half-life approximately 1 hour for suvorexant; clinical context: duration of action is longer due to high receptor binding affinity and slow dissociation. |
| Protein binding | 99% bound; primarily to albumin. |
| Volume of Distribution | Approximately 1.3 L/kg; indicates extensive tissue distribution. |
| Bioavailability | Oral: approximately 82%. |
| Onset of Action | Oral: 30 minutes to 2 hours; peak effect at 0.5-2 hours. |
| Duration of Action | Approximately 7-8 hours for sleep maintenance; clinical notes: residual sedation may persist beyond 8 hours, especially with higher doses. |
10 mg orally once nightly, within 30 minutes of bedtime; maximum dose 20 mg.
| Dosage form | TABLET |
| Renal impairment | No dose adjustment required for mild to moderate renal impairment (eGFR ≥30 mL/min). For severe renal impairment (eGFR <30 mL/min), not recommended. |
| Liver impairment | Child-Pugh A: 5 mg; Child-Pugh B: not recommended; Child-Pugh C: contraindicated. |
| Pediatric use | Not approved for use in pediatric patients (safety and efficacy not established). |
| Geriatric use | Initial dose 5 mg; maximum dose 10 mg due to increased risk of adverse effects. |
| 1st trimester | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
Comprehensive clinical and safety monograph for BELSOMRA (BELSOMRA).
| Breastfeeding | Excretion into breast milk unknown; M/P ratio not determined. Caution advised; consider risk of infant sedation or respiratory depression. |
| Teratogenic Risk | First trimester: Limited human data; animal studies show no teratogenicity at clinically relevant doses. Second and third trimesters: No known risk; avoid late pregnancy due to potential neonatal respiratory depression or sedation. |
| Fetal Monitoring |
■ FDA Black Box Warning
BELSOMRA can cause complex sleep behaviors such as sleep-driving, making phone calls, preparing and eating food, and other activities while not fully awake. Discontinue immediately if such behaviors occur.
| Serious Effects |
["Hypersensitivity to suvorexant or any component","Narcolepsy","Coadministration with strong CYP3A4 inhibitors (e.g., ketoconazole)"]
| Precautions | ["Complex sleep behaviors","Impaired alertness and motor coordination (including next-day impairment)","Worsening of depression or suicidal ideation","Respiratory depression risk in patients with compromised respiratory function","Use in elderly patients: increased risk of falls and cognitive impairment"] |
| Food/Dietary | Avoid grapefruit and grapefruit juice as they may increase the concentration of suvorexant in the blood, raising the risk of adverse effects. High-fat meals can delay the absorption and reduce the peak concentration of BELSOMRA; take on an empty stomach or avoid heavy fatty meals close to dosing. |
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| Monitor for maternal excessive sedation, sleepwalking, or complex behaviors. Fetal monitoring not routinely indicated; assess neonatal respiratory status if used near term. |
| Fertility Effects | No known impact on human fertility; animal studies show no adverse effects on reproduction at clinically relevant doses. |
| Clinical Pearls | BELSOMRA (suvorexant) is a dual orexin receptor antagonist (DORA) used for insomnia. It has low abuse potential compared to benzodiazepines or Z-drugs. Onset of action is within 30 minutes; advise patients to take only if they have at least 7 hours before planned awakening. Avoid concurrent use with strong CYP3A4 inhibitors (e.g., ketoconazole) or inducers (e.g., rifampin) due to significant changes in exposure. Dose adjustment required for concomitant moderate CYP3A4 inhibitors (reduce to 5 mg). Contraindicated in narcolepsy. Rare but serious side effects include complex sleep behaviors (e.g., sleep-driving) and daytime somnolence; monitor for next-day impairment. Maximum recommended dose is 20 mg once daily; however, 10 mg is the usual therapeutic dose for most patients. |
| Patient Advice | Take BELSOMRA only if you are able to stay in bed for a full night (at least 7 hours) before being active again. · Do not take this medicine unless you plan to go to bed immediately. · Avoid driving, operating machinery, or performing hazardous tasks the day after taking BELSOMRA until you know how it affects you. · Do not consume alcohol while taking this medication as it can increase the risk of side effects. · Tell your doctor if you have a history of depression, mental illness, or substance abuse; this medication may worsen these conditions. · Seek immediate medical attention if you experience unusual behaviors such as sleep-driving, preparing/eating food, making phone calls, or having sex while not fully awake. · This medicine may cause daytime drowsiness; take caution until you understand your response. |