What is the recommended dosage and treatment approach for Belsomra (suvorexant) in patients with insomnia?

Belsomra (Suvorexant) Dosing and Treatment Approach for Insomnia

Start with 10 mg taken once nightly within 30 minutes of bedtime (with at least 7 hours remaining before planned awakening), and increase to a maximum of 20 mg only if the 10 mg dose is well-tolerated but ineffective. 1

Recommended Dosing

• Initial dose: 10 mg once nightly 1
• Maximum dose: 20 mg once nightly if 10 mg is well-tolerated but not effective 1
• Timing: Within 30 minutes of bedtime with at least 7 hours remaining before planned awakening 1
• Avoid taking with or soon after meals, as food delays absorption and reduces effectiveness 1

Specific Clinical Indication

Suvorexant is specifically indicated for sleep maintenance insomnia (difficulty staying asleep), not primarily for sleep onset problems 2, 3

• Reduces wake after sleep onset by 16-28 minutes compared to placebo 2, 3
• Improves total sleep time by 10 minutes objectively (though subjective improvements range 22-50 minutes) 2
• The American Academy of Sleep Medicine provides a WEAK recommendation for suvorexant in sleep maintenance insomnia, reflecting limitations in the evidence base rather than lack of efficacy 2

Dose Adjustments for Special Populations

Obese women require particular caution due to significantly increased drug exposure 1

• Consider maintaining the 10 mg dose in obese women before escalating, given increased exposure-related adverse effects 1
• No dose adjustment needed for advanced age, renal impairment, or mild-to-moderate hepatic impairment 4
• Not recommended in severe hepatic impairment 1

Drug Interactions Requiring Dose Modification

With moderate CYP3A inhibitors: Start at 5 mg (generally should not exceed 10 mg) 1

• Avoid use with strong CYP3A inhibitors (e.g., ketoconazole, clarithromycin, ritonavir) 1
• Strong CYP3A inducers may reduce efficacy 1
• When combined with other CNS depressants, consider dose reduction of suvorexant and/or the other agent 1

Treatment Duration and Monitoring

Reevaluate after 7-10 days if insomnia persists to rule out comorbid conditions 3, 1

• Suvorexant has been studied for up to 12 months of nightly use without evidence of rebound insomnia or withdrawal effects upon discontinuation 5
• No evidence of physical dependence with chronic use 6, 5

Critical Safety Warnings

Patients taking 20 mg should be cautioned against next-day driving due to documented impairment in driving ability studies 1

• CNS depressant effects may persist for several days after discontinuation 1
• Discontinue immediately if complex sleep behaviors occur (sleep-walking, sleep-driving, engaging in activities while not fully awake) 1
• Contraindicated in narcolepsy 1

Common Adverse Effects

Somnolence is the most common adverse effect (≥5% incidence, at least twice placebo rate) 1, 5

• Number needed to harm for somnolence: 13 for higher doses (30-40 mg), 28 for approved doses (15-20 mg) 5
• Dose-related effects include abnormal dreams, sleep paralysis, and rarely suicidal ideation 1, 4
• Potential for cataplexy-like symptoms and REM sleep behavior disorder given mechanism of action 4

Mechanism and Advantages

Suvorexant is a dual orexin receptor antagonist, the first in its class, working by blocking wake-promoting orexin signaling rather than enhancing sleep-promoting systems 4, 6

• This mechanism differs fundamentally from benzodiazepines and Z-drugs, potentially offering advantages in cognitive and psychomotor impairment profiles 6
• Does not carry the same risks of amnesia, confusion, or gait disturbance seen with benzodiazepine receptor agonists 6