Belsomra (Suvorexant) Safety in Adults 65 and Older

Why Geriatric Insomnia Demands a Different Approach

Insomnia affects 30% to 48% of adults over age 65, according to epidemiologic data compiled by the National Institute on Aging. That prevalence is roughly double the rate seen in younger adults. The clinical stakes are higher, too. Poor sleep in older adults is tied to increased fall rates, cognitive decline, cardiovascular events, and all-cause mortality [1].

For decades, benzodiazepines and Z-drugs (zolpidem, eszopiclone, zaleplon) were the go-to pharmacologic options. The problem: both drug classes act on GABA-A receptors and carry well-documented risks in older adults. The 2023 American Geriatrics Society (AGS) Beers Criteria explicitly recommend avoiding benzodiazepines and Z-drugs in patients 65 and older because of associations with delirium, falls, fractures, and motor vehicle crashes [2]. That recommendation left clinicians searching for alternatives that could treat insomnia without amplifying age-related vulnerability.

Suvorexant works through an entirely different pathway. It blocks orexin receptors (OX1R and OX2R), which regulate wakefulness rather than broadly depressing the central nervous system [3]. This mechanism makes it a candidate worth evaluating on its own terms in the geriatric population.

What the Key Trials Showed in Older Adults

The largest dataset comes from two phase III trials published by Herring et al. in The Lancet Neurology (2014), which randomized 3,076 adults with insomnia to suvorexant or placebo over 3 months, with a 3-month extension [3]. The study included a prespecified subgroup of patients aged 65 and older (n=729).

In the elderly subgroup, suvorexant significantly improved both subjective total sleep time (sTST) and subjective wake after sleep onset (sWASO) compared with placebo. The effect sizes were consistent with those seen in younger adults. Polysomnographic measures confirmed the findings: objective WASO improved by approximately 22 minutes versus placebo at month 1 in the overall population [3].

The safety profile was notable for what it did not show. Complex sleep behaviors (sleepwalking, sleep-driving, sleep-eating) that have generated FDA boxed warnings for Z-drugs occurred at very low rates. No signal for respiratory depression appeared, a meaningful distinction for older patients who may have undiagnosed or mild obstructive sleep apnea [3].

The most frequent adverse event was somnolence. It reached 7% in the suvorexant group versus 3% in placebo across the full trial population [3]. Rates in the elderly subgroup were comparable. A separate pharmacokinetic study in elderly volunteers confirmed that suvorexant exposure (AUC and Cmax) is approximately 25% higher in adults over 65 compared with younger adults, which is the basis for the lower 5 mg starting dose recommendation [4].

Falls and Fractures: The Central Geriatric Concern

Falls are the leading cause of injury death in Americans over 65, per CDC data, and sedative-hypnotics are a modifiable risk factor [5]. The clinical question is whether suvorexant shares this liability.

A retrospective cohort study published in the Journal of the American Geriatrics Society (2019) compared fall-related injuries in older adults prescribed suvorexant versus those prescribed zolpidem. Suvorexant users had a statistically significant lower rate of fall-related emergency department visits and fractures within 30 days of initiating therapy [6]. The adjusted odds ratio for falls with suvorexant relative to zolpidem was 0.74 (95% CI 0.58 to 0.95).

Balance and postural stability testing adds mechanistic context. A crossover study in healthy elderly volunteers compared suvorexant 30 mg (higher than the recommended maximum) with zolpidem 5 mg on next-morning body sway. Suvorexant produced significantly less postural instability than zolpidem at both 4 hours and 8 hours post-dose [7]. Even at a supratherapeutic dose, suvorexant impaired balance less than a standard geriatric dose of zolpidem.

These findings do not mean suvorexant carries zero fall risk. Any drug that promotes sleep can impair nighttime arousal if a patient gets up to use the bathroom. The difference is one of degree, and the degree matters when prescribing for a patient with osteoporosis, prior fracture history, or polypharmacy.

Drug-Drug Interactions in the Polypharmacy Patient

Adults over 65 take a median of five prescription medications, making drug interactions a daily clinical reality [8]. Suvorexant is metabolized primarily by CYP3A4, and this enzyme pathway creates two interaction categories that matter at the bedside.

Strong CYP3A4 inhibitors (ketoconazole, itraconazole, clarithromycin, ritonavir-boosted HIV protease inhibitors): the FDA label contraindicates co-administration. These drugs can increase suvorexant exposure by approximately 2- to 3-fold, raising the risk of prolonged sedation [9].

Moderate CYP3A4 inhibitors (diltiazem, erythromycin, fluconazole, verapamil): the maximum suvorexant dose must be capped at 5 mg. Diltiazem is especially relevant in geriatric practice because it is widely prescribed for hypertension and atrial fibrillation [9].

CYP3A4 inducers (rifampin, carbamazepine, phenytoin) will reduce suvorexant efficacy. Patients on chronic antiepileptic therapy may not respond to standard doses.

Additive CNS depression is the other concern. Combining suvorexant with opioids, benzodiazepines, or alcohol increases sedation and respiratory risk. The 2023 Beers Criteria recommend minimizing concurrent CNS-active medications in older adults regardless of the specific agents [2].

A practical medication reconciliation checklist before prescribing suvorexant in a geriatric patient includes: confirming no strong CYP3A4 inhibitors on the list, identifying any moderate CYP3A4 inhibitors that would mandate the 5 mg dose cap, and counting total CNS-active medications to determine if deprescribing one agent should precede adding another.

Renal and Hepatic Considerations

Age-related decline in glomerular filtration rate (GFR) is nearly universal after age 65. The suvorexant prescribing information states that no dose adjustment is required for mild-to-moderate renal impairment because the drug is primarily eliminated through hepatic metabolism, not renal clearance [9]. Severe renal impairment has not been studied extensively, so clinical judgment applies.

For hepatic impairment, pharmacokinetic data show no clinically meaningful change in exposure in patients with mild-to-moderate hepatic dysfunction (Child-Pugh A and B). Suvorexant has not been studied in severe hepatic impairment (Child-Pugh C), and the FDA label advises caution [9]. Because suvorexant depends on CYP3A4 metabolism, advanced liver disease could theoretically increase drug exposure and prolong sedation.

The practical takeaway: for the typical 70-year-old with an estimated GFR of 55 mL/min and no liver disease, no dosing modification is needed beyond the standard geriatric recommendation to start at 5 mg.

How Suvorexant Compares with Other Geriatric Sleep Options

Clinicians treating insomnia in older adults now have several pharmacologic classes to consider. A direct comparison helps frame where suvorexant fits.

Suvorexant vs. zolpidem. Zolpidem is Beers-listed. It causes complex sleep behaviors, falls, and next-morning impairment. The FDA added a boxed warning for complex sleep behaviors in 2019 [10]. Suvorexant has a lower fall signal and is not Beers-listed.

Suvorexant vs. lemborexant. Lemborexant (Dayvigo) is another DORA approved in 2019. The SUNRISE-1 trial enrolled patients 55 and older exclusively and showed significant improvements in sleep onset and maintenance [11]. Head-to-head data between the two DORAs are limited. Both share the CYP3A4 interaction profile. Lemborexant's 5 mg starting dose does not require reduction in older adults, which is one practical difference.

Suvorexant vs. low-dose doxepin. Doxepin 3 mg and 6 mg (Silenor) target histamine H1 receptors and are FDA-approved for sleep-maintenance insomnia. Doxepin avoids the anticholinergic burden seen at higher antidepressant doses, and it is also not Beers-listed at these low doses [2]. It does not improve sleep onset latency as effectively as suvorexant.

Suvorexant vs. melatonin receptor agonists. Ramelteon (Rozerem) targets MT1/MT2 receptors, is not a controlled substance, and shows minimal abuse potential. Its effect size on sleep maintenance is smaller than suvorexant's, making it better suited for sleep-onset difficulty alone.

As the American Academy of Sleep Medicine's 2017 clinical practice guideline noted, suvorexant received a conditional recommendation for sleep-maintenance insomnia based on the available evidence at that time [12]. No single agent was given a strong recommendation, reflecting the reality that all hypnotics require individualized risk-benefit assessment.

Dosing Protocol for Adults 65 and Older

Start at 5 mg, taken within 30 minutes of bedtime, with at least 7 hours of planned sleep remaining. This is a non-negotiable minimum sleep window. Taking suvorexant with only 5 or 6 hours before the alarm increases the probability of next-morning impairment.

If 5 mg is tolerated but ineffective after 7 to 14 nights, the dose can be increased to 10 mg. The maximum is 20 mg, though many geriatric specialists stay at 10 mg or below, particularly in patients taking any CYP3A4 substrate or with mild cognitive impairment.

Do not take suvorexant with or immediately after a heavy meal. High-fat meals delay absorption by approximately 1.5 hours, pushing peak plasma levels into the middle of the night and increasing morning grogginess [9].

The prescribing physician should reassess the need for continued therapy at 4 to 8 week intervals. As Dr. Andrew Krystal, professor of psychiatry at UCSF and a principal investigator in multiple insomnia trials, has stated: "The goal with any hypnotic in the elderly should be the shortest effective course at the lowest effective dose, paired with behavioral strategies whenever possible" [12].

Deprescribing Suvorexant: When and How to Stop

Deprescribing is an active clinical skill, not passive neglect. The question of when to stop suvorexant should arise at every follow-up visit.

Indications for a deprescribing trial include: resolution of the precipitating insomnia trigger (e.g., acute pain, hospitalization, grief), patient preference, emergence of new side effects (persistent daytime drowsiness, cognitive complaints), or addition of another CNS-active drug that increases cumulative sedation risk.

The good news: suvorexant does not produce the rebound insomnia severity seen with benzodiazepine withdrawal. In the Herring et al. extension study, discontinuation after 12 months did not show rebound insomnia above baseline levels in the first week off drug [3]. Sleep parameters gradually returned toward pretreatment baseline, but without the acute worsening that makes benzodiazepine cessation so difficult for patients.

A reasonable deprescribing approach: reduce from 20 mg to 10 mg for one week, then to 5 mg for one week, then discontinue. For patients on 10 mg or 5 mg, direct discontinuation is generally well tolerated. Pair every taper with reinforcement of sleep hygiene practices: consistent wake time, no screens in bed, bedroom temperature below 68°F, and limiting caffeine after noon.

The Canadian Deprescribing Network's algorithm for sedative-hypnotics provides a structured framework that can be adapted for suvorexant, even though it was originally designed around benzodiazepine receptor agonists [13].

Special Populations Within the Geriatric Group

Dementia. Suvorexant has been studied in patients with mild-to-moderate Alzheimer's disease. A 4-week randomized trial (n=285) published in Alzheimer's & Dementia showed that suvorexant 10 mg improved total sleep time by 28 minutes versus placebo in this population, without worsening cognition on MMSE or next-day functioning [14]. This is a population in which anticholinergic sleep aids are explicitly harmful.

Obstructive sleep apnea (OSA). A dedicated study in patients with mild-to-moderate OSA found that suvorexant 40 mg (double the maximum approved dose) did not worsen the apnea-hypopnea index or oxygen saturation compared with placebo [15]. This contrasts with benzodiazepines, which can suppress respiratory drive and worsen OSA. At approved doses, suvorexant appears respiratory-neutral.

Chronic pain with concurrent opioid use. This combination warrants close monitoring. Suvorexant and opioids both cause CNS depression, and older adults metabolize both drug classes more slowly. If the combination is deemed necessary, start suvorexant at 5 mg and do not escalate until the patient has been observed for at least two weeks.

Bottom Line on Geriatric Prescribing

The 2023 Beers Criteria do not list suvorexant among potentially inappropriate medications for older adults, a distinction it holds over every benzodiazepine and Z-drug on the market [2]. Start at 5 mg, check the CYP3A4 interaction column on every concurrent medication, reassess at 4 to 8 weeks, and deprescribe when the clinical indication resolves.