What is the recommended dosage and treatment plan for Belsomra (suvorexant) for insomnia?

Recommended Dosage and Treatment Plan for Belsomra (Suvorexant) for Insomnia

The recommended dose for Belsomra (suvorexant) is 10 mg taken once per night within 30 minutes of going to bed, with at least 7 hours remaining before planned awakening. If the 10 mg dose is well-tolerated but not effective, the dose can be increased to a maximum of 20 mg once per night. 1

Dosing Algorithm

1. Initial Dosing:

   • Start with 10 mg once nightly 1
   • Take within 30 minutes of going to bed
   • Ensure at least 7 hours remain before planned awakening
   • Take on an empty stomach (food delays absorption) 2

2. Dose Adjustment:

   • If 10 mg is ineffective but well-tolerated → increase to 20 mg once nightly
   • Maximum recommended dose: 20 mg once nightly 1
   • Always use the lowest effective dose 1

3. Special Populations:

   • Obese patients (especially women): Consider lower doses due to increased drug exposure 1, 2
   • With moderate CYP3A inhibitors: Reduce to 5 mg once nightly (not to exceed 10 mg) 1
   • With strong CYP3A inhibitors: Not recommended 1
   • Elderly patients: No specific dose adjustment required, but use caution 2
   • Renal/mild-to-moderate hepatic impairment: No dose adjustment needed 2

Efficacy and Mechanism

Belsomra is a dual orexin receptor antagonist (DORA), the first in its class for treating insomnia 2. It works by:

• Blocking orexin signaling, which promotes wakefulness
• Reducing time to achieve persistent sleep
• Reducing wake after sleep onset 2

At FDA-approved doses (≤20 mg), Belsomra:

• Has more effect on sleep maintenance than sleep onset due to its slow absorption 3
• Shows improvement in both objective (polysomnography) and subjective sleep measures 4
• Maintains efficacy for at least 3 months without evidence of tolerance 4

Monitoring and Follow-up

• Assess for improvement within 2-4 weeks of starting treatment 5
• Monitor for side effects, particularly:
  • Daytime sedation
  • Driving impairment (especially at 20 mg dose) 1, 2
  • Abnormal dreams, sleep paralysis 2
• No rebound insomnia or withdrawal effects observed after discontinuation at 3 or 12 months 4

Important Precautions

• CNS depression: Can impair daytime wakefulness even when used as prescribed 1
• Driving: May impair driving skills; patients should be cautioned about next-day driving 1
• Contraindication: Narcolepsy 1, 2
• Drug interactions: Avoid combining with other CNS depressants or dose reduction may be necessary 1
• Timing: Effects may be delayed if taken with or soon after a meal 1

Clinical Pearls

• Belsomra has a half-life of approximately 12 hours, which is relatively long for a modern hypnotic 2
• Japanese post-marketing data showed that 74% of patients experienced improvement in sleep quality 6
• Unlike some other hypnotics, Belsomra works through a different mechanism (orexin antagonism) rather than GABA enhancement 2, 7
• For patients who discontinue due to improvement, the mean treatment duration was about 2 months (62 days) in real-world use 6

Common Side Effects

• Most common (≥5% and at least twice placebo rate): somnolence 1
• Other notable side effects: dizziness, nightmares 6
• Side effects are generally dose-related, with higher incidence at doses above the currently recommended range 4

Remember that Belsomra should be used as part of a comprehensive insomnia treatment plan, with consideration of cognitive behavioral therapy for insomnia (CBT-I) as a first-line approach for chronic insomnia 5.