Suvorexant (Belsomra) Dosing and Treatment Approach for Insomnia
The recommended dosage 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 Considerations
Initial Dosing
- Start with 10 mg once nightly (lowest effective dose)
- Take within 30 minutes of bedtime with at least 7 hours remaining before planned awakening
- May be delayed if taken with or soon after a meal 1
Dose Adjustments
- If 10 mg is well-tolerated but ineffective, increase to maximum of 20 mg once nightly
- For patients taking moderate CYP3A inhibitors: 5 mg once nightly (not to exceed 10 mg)
- Not recommended for use with strong CYP3A inhibitors 1
Special Populations
- Obese patients (particularly women): Consider increased risk of exposure-related adverse effects before increasing dose
- Patients with severe hepatic impairment: Not recommended 1
- When used with other CNS depressants: Dosage reduction of Belsomra and/or other CNS depressants may be necessary 1
Clinical Indication
Suvorexant is primarily indicated for sleep maintenance insomnia, with a weak recommendation from the American Academy of Sleep Medicine 2. The FDA has approved it for insomnia characterized by difficulties with both sleep onset and/or sleep maintenance 1.
Efficacy Profile
- Most effective for sleep maintenance insomnia 3
- At 10 mg and 20 mg doses:
- Clinically significant reduction in wake after sleep onset (objective measurement)
- Improvement in subjective total sleep time (though not reaching clinical significance)
- Improvements in sleep efficiency near or above clinical significance 2
- At 20 mg dose: Clinically significant reduction in sleep latency, suggesting improved sleep onset 2
Safety and Adverse Effects
- Most common adverse effect: Somnolence (reported in ≥5% of patients and at least twice the placebo rate) 1
- CNS depressant effects may persist for several days after discontinuation 1
- Can impair driving skills and increase risk of falling asleep while driving
- Patients using 20 mg should be cautioned against next-day driving
- Patients on lower doses should also be cautioned about potential driving impairment 1
- No evidence of significant daytime residual or withdrawal symptoms 2
- NNH for somnolence vs. placebo: 28 for 15/20 mg doses 4
Treatment Approach
Evaluate appropriateness:
- Confirm diagnosis of insomnia with sleep onset and/or maintenance difficulties
- Rule out narcolepsy (contraindication) 1
- Consider patient factors (obesity, hepatic function, concurrent medications)
Initiate therapy:
- Begin with 10 mg once nightly
- Advise taking 30 minutes before bedtime with at least 7 hours available for sleep
- Caution about next-day impairment, particularly with driving
Monitor and follow-up:
- Assess effectiveness within 2-4 weeks 3
- Monitor for adverse effects, particularly daytime sedation
- If 10 mg is ineffective but well-tolerated, consider increasing to 20 mg
Long-term considerations:
Important Caveats
- Suvorexant is classified as a Schedule IV controlled substance due to its abuse potential, though studies suggest possibly lower abuse liability than zolpidem 6
- Patients should be cautioned about complex sleep behaviors (sleep-walking, sleep-driving) and to discontinue immediately if these occur 1
- May cause sleep paralysis, hypnagogic/hypnopompic hallucinations, and cataplexy-like symptoms, with risk increasing with dose 1
- Consider effects on respiratory function in vulnerable patients 1
Suvorexant represents a novel approach to treating insomnia as the first dual orexin receptor antagonist, offering an alternative mechanism of action compared to traditional hypnotics like benzodiazepines and Z-drugs 5.