Suvorexant Dosage and Treatment Guidelines for Insomnia
The recommended starting dose of suvorexant for insomnia is 10 mg taken once nightly 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 up to a maximum of 20 mg once daily. 1
Dosage Recommendations
- Start with 10 mg once nightly, which is the lowest effective dose for most patients 1
- If 10 mg is ineffective but well-tolerated, increase to 20 mg once daily 1
- Take within 30 minutes of going to bed, with at least 7 hours remaining before planned awakening 1
- Avoid taking with or soon after meals as this may delay the onset of effect 1
- For patients taking moderate CYP3A inhibitors, reduce dose to 5 mg (can increase to 10 mg if needed) 1
- Suvorexant is not recommended for use with strong CYP3A inhibitors 1
Clinical Efficacy
- Suvorexant is primarily indicated for sleep maintenance insomnia, with a weak recommendation from the American Academy of Sleep Medicine 2
- At approved doses (≤20 mg), suvorexant reduces wake after sleep onset by 16-28 minutes compared to placebo 3, 4
- At approved doses (≤20 mg), suvorexant improves total sleep time by approximately 10 minutes 2, 4
- Higher doses (20 mg) may provide additional benefits for sleep onset insomnia 5, 6
- Sleep efficiency is improved at the 10 mg dose to clinically significant levels 5
Special Populations
- No dose adjustment is needed for advanced age 7, 8
- No dose adjustment is needed for renal impairment 8
- No dose adjustment is needed for mild-to-moderate hepatic impairment 8
- Not recommended for patients with severe hepatic impairment 1
- Drug levels are higher in women and obese people; dosing should be conservative in obese women 8
- Contraindicated in patients with narcolepsy 1
Safety Considerations
- The most common adverse effect is somnolence, occurring in approximately 7% of patients (vs 3% for placebo) 3, 9
- CNS depressant effects and daytime impairment may occur, especially at higher doses 1
- Risk of complex sleep behaviors including sleep-walking and sleep-driving; discontinue immediately if these occur 1
- Sleep paralysis, hypnagogic/hypnopompic hallucinations, and cataplexy-like symptoms may occur, with risk increasing with dose 1, 8
- Monitor for worsening depression or suicidal ideation, as risk increases with dose 1
- NNH for somnolence is 28 (95% CI 17-82) for suvorexant 15-20 mg 9
Treatment Duration and Discontinuation
- No systematic evidence of rebound or withdrawal symptoms when suvorexant is discontinued after 3 months of nightly use 4, 9
- Reevaluate if insomnia persists after 7 to 10 days of treatment 1
Drug Interactions
- Avoid use with strong CYP3A inhibitors 1
- Reduce dose to 5 mg when used with moderate CYP3A inhibitors 1
- Strong CYP3A inducers may reduce efficacy 1
- Monitor digoxin concentrations when used concurrently 1
- Potential interactions with benzodiazepines, antidepressants, and antipsychotics 10
Practical Considerations
- Use the lowest effective dose to minimize next-day impairment 1
- Advise patients about the possibility of next-day impairment in function, including driving 8
- Suvorexant has a half-life of 12 hours, which is relatively long for a modern hypnotic 8
- At approved doses (≤20 mg), next-day sedation and driving impairment are less apparent than at higher doses 8