Dayvigo (Lemborexant) Safety in Adults 65 and Older

Why Geriatric Insomnia Requires a Different Safety Lens

Insomnia affects 30% to 48% of community-dwelling adults over 65, according to epidemiologic data compiled by the National Institute on Aging. The clinical stakes differ sharply from those in younger populations. A single sedative-related fall in a 75-year-old can trigger a hip fracture, hospitalization, deconditioning, and a cascade of morbidity that extends far beyond the original sleep complaint.

Traditional hypnotics such as benzodiazepines and nonbenzodiazepine Z-drugs (zolpidem, eszopiclone) act on GABA-A receptors, producing broad central nervous system depression. The American Geriatrics Society Beers Criteria explicitly lists these agents as potentially inappropriate in older adults because of documented increases in falls, cognitive impairment, and motor vehicle crashes. That recommendation pushed clinicians toward alternatives. Dual orexin receptor antagonists, which block wakefulness-promoting orexin neuropeptides rather than globally suppressing cortical activity, emerged as a mechanistically distinct option.

Lemborexant received FDA approval in December 2019 for insomnia characterized by difficulty with sleep onset, sleep maintenance, or both. The clinical development program specifically enrolled adults 65 and older and prespecified geriatric safety analyses, setting it apart from older sleep agents whose geriatric data consisted mostly of post-hoc pooled subgroups.

Mechanism of Action and Why It Matters for Older Patients

Lemborexant competitively blocks both orexin-1 (OX1R) and orexin-2 (OX2R) receptors. Orexin neurons in the lateral hypothalamus fire during wakefulness and go silent during sleep. By antagonizing these receptors, lemborexant reduces the wakefulness drive rather than forcing sedation through inhibitory pathways [1].

This distinction matters for geriatric pharmacology in three concrete ways. First, orexin blockade does not impair respiratory drive, which is relevant for the substantial proportion of older adults with comorbid obstructive sleep apnea. A pooled analysis of SUNRISE-1 and SUNRISE-2 found no increase in apnea-hypopnea index with lemborexant 5 or 10 mg. Second, the mechanism spares GABAergic tone, avoiding the muscle relaxation and ataxia that contribute to GABA-agonist falls. Third, orexin antagonism preserves relatively normal sleep architecture, including slow-wave sleep, which declines with age and plays a role in memory consolidation and glymphatic clearance of amyloid-beta [2].

SUNRISE-1: The Key Geriatric Safety Dataset

SUNRISE-1 was a phase 3, randomized, double-blind, placebo- and active-controlled crossover trial in 1,006 adults aged 55 and older with insomnia disorder [3]. The trial used polysomnography-measured endpoints and included an active comparator arm of zolpidem ER 6.25 mg (the FDA-approved geriatric dose). The study is the single most informative trial for evaluating lemborexant head-to-head against an established hypnotic in an older population.

Primary and key secondary endpoints at the end of each treatment period (two consecutive nights of PSG per period) demonstrated that lemborexant 5 mg and 10 mg both significantly reduced wake-after-sleep-onset (WASO) and latency to persistent sleep (LPS) compared to placebo [3].

Next-Morning Postural Stability

The trial's most practice-changing finding for geriatric care was the postural stability assessment. Using a body-sway test performed approximately 8 hours after dosing, investigators found that lemborexant 5 mg was non-inferior to placebo on next-morning balance. Zolpidem ER 6.25 mg was not. The mean change in body sway area from placebo was 1.2 cm² for lemborexant 5 mg versus 7.7 cm² for zolpidem ER (P<0.05 for zolpidem vs. placebo) [3].

For a prescriber weighing fall risk in a 70-year-old, this is a meaningful difference. Residual postural instability eight hours after dosing maps directly onto the window when patients rise for the bathroom or begin morning activities.

Geriatric Subgroup Findings

Among the 132 participants aged 65 and older in SUNRISE-1, lemborexant 5 mg reduced WASO by a mean of 29.5 minutes compared to placebo. The efficacy magnitude was consistent with the broader study population. Adverse event rates in this subgroup did not diverge from younger participants at the 5 mg dose [3]. Somnolence, the most common treatment-emergent adverse event, occurred in 7% of the lemborexant 5 mg group.

SUNRISE-2: Long-Term Safety Over 12 Months

SUNRISE-2 extended the safety evaluation to 12 months in a randomized, double-blind, placebo-controlled trial of 949 adults (including participants ≥65) with insomnia [4]. Lemborexant 5 mg and 10 mg both showed sustained efficacy on patient-reported sleep onset latency and sleep efficiency through month 12, without evidence of dose escalation or tolerance.

The safety profile remained stable over the full treatment period. Treatment-emergent adverse events leading to discontinuation occurred in 4.6% of the lemborexant 5 mg group, 8.4% of the lemborexant 10 mg group, and 3.0% of the placebo group [4]. Falls were reported as adverse events in 2.3% of patients on lemborexant 5 mg versus 1.5% on placebo across the full population. In the geriatric subgroup, the difference was not statistically significant, though the subgroup sample size limits the power to detect small differences [4].

No withdrawal syndrome or rebound insomnia was observed upon discontinuation of lemborexant at the 6-month mark (a prespecified assessment). This finding has practical relevance for geriatric prescribing, where clinicians routinely need to stop, switch, or taper sleep medications during hospitalizations, surgical episodes, or transitions between care settings [4].

Dosing in Older Adults: What the Label Says and What Clinicians Do

The FDA-approved prescribing information recommends a starting dose of 5 mg taken immediately before bedtime with at least 7 hours of intended sleep remaining. No dose adjustment is required solely on the basis of age, mild-to-moderate hepatic impairment, or any degree of renal impairment.

In clinical practice, many geriatricians start at 5 mg and remain there indefinitely, reserving the 10 mg dose for patients who show inadequate response after 7 to 14 nights and who tolerate 5 mg without next-day somnolence. The label explicitly states that 10 mg may be used if 5 mg is tolerated but not effective.

Dr. Phyllis Zee, Professor of Neurology at Northwestern University Feinberg School of Medicine, has noted: "The dual orexin receptor antagonists represent a shift in how we think about treating insomnia in older adults. Rather than sedating the brain, we are turning down the wake signal, and that has meaningful implications for the safety profile in a population where falls are the leading cause of injury-related death."

Renal and Hepatic Considerations

Lemborexant is primarily metabolized by CYP3A4 with minor contributions from CYP3A5. The parent drug and metabolites are excreted mainly through feces (57.4%) and to a lesser extent through urine (29.1%) [5]. Since renal clearance is not the dominant elimination pathway, age-related decline in glomerular filtration rate does not meaningfully alter drug exposure.

For hepatic impairment, pharmacokinetic studies showed approximately 50% higher AUC in moderate hepatic impairment (Child-Pugh B). The maximum recommended dose in these patients is 5 mg [5]. Severe hepatic impairment (Child-Pugh C) is a contraindication.

Drug-Drug Interactions in Polypharmacy-Prone Patients

Adults over 65 take a median of 5 prescription medications. Lemborexant's reliance on CYP3A4 metabolism creates interaction risks that require active management.

Contraindicated combination: Strong CYP3A inhibitors (itraconazole, ketoconazole, clarithromycin, ritonavir) are contraindicated with lemborexant. Coadministration with itraconazole increased lemborexant AUC approximately 4-fold in a pharmacokinetic study, which would proportionally increase sedation and fall risk [6].

Dose-limited combinations: Moderate CYP3A inhibitors (fluconazole, erythromycin, verapamil, diltiazem, grapefruit juice) require limiting the lemborexant dose to 5 mg. Diltiazem and verapamil are commonly prescribed in older adults for hypertension and atrial fibrillation. Prescribers must check for these before writing for lemborexant [5].

Reduced efficacy: Strong or moderate CYP3A inducers (carbamazepine, rifampin, phenytoin, St. John's wort) reduce lemborexant exposure and may render it ineffective. The label recommends avoiding coadministration.

CNS depressants: Concomitant use with other CNS depressants, including alcohol, benzodiazepines, and opioids, increases the risk of daytime somnolence and impaired psychomotor function. In the geriatric population, this category includes gabapentin and pregabalin, which are frequently prescribed for neuropathic pain and also carry independent fall risk [5].

A practical medication reconciliation checklist for geriatric lemborexant prescribing should include: stopping any existing Z-drug or benzodiazepine, reviewing the CYP3A inhibitor list against the current medication profile, and confirming that the patient is not using over-the-counter diphenhydramine (commonly sold as a "PM" sleep aid), which would add anticholinergic burden without benefit.

Comparison With Other Sleep Agents in Older Adults

Lemborexant vs. Suvorexant

Suvorexant (Belsomra), the first FDA-approved DORA, has a longer half-life (approximately 12 hours vs. 17 hours for lemborexant). Both drugs target OX1R and OX2R. Head-to-head trial data do not exist. However, lemborexant has a higher binding selectivity ratio for OX2R relative to OX1R, which may contribute to its sleep-maintenance effects [7]. The SUNRISE-1 trial provides more strong geriatric postural stability data than the suvorexant development program offered.

Lemborexant vs. Zolpidem ER

SUNRISE-1 directly compared lemborexant 5 mg and 10 mg against zolpidem ER 6.25 mg. Both drugs improved sleep outcomes versus placebo, but lemborexant 5 mg demonstrated superior next-morning postural stability [3]. The Beers Criteria list zolpidem as potentially inappropriate; no DORA currently appears on the Beers list [8].

Lemborexant vs. Trazodone

Trazodone 25 to 50 mg is the most commonly prescribed off-label sleep aid in older adults. No randomized controlled trial has compared trazodone to lemborexant. Trazodone carries risks of orthostatic hypotension (especially with alpha-1 blockade), QTc prolongation, and serotonin syndrome when combined with SSRIs or SNRIs. For patients on antidepressants, a DORA may represent a safer coadministration profile than adding trazodone to an existing serotonergic regimen.

Falls, Fractures, and Real-World Evidence

Pooled data from the lemborexant clinical program (SUNRISE-1, SUNRISE-2, and a phase 2 study) recorded falls as adverse events. At the 5 mg dose, the incidence was numerically similar to placebo across age groups [9]. The 10 mg dose showed a small numerical increase in fall-related events, though not statistically significant.

Post-marketing pharmacovigilance data from Japan, where lemborexant was approved and launched earlier than in most markets, have not identified a falls safety signal disproportionate to background rates in treated insomnia populations. A retrospective cohort analysis published in 2022 examined DORA prescriptions in Japanese adults ≥65 and found lower rates of hip fracture compared to benzodiazepine receptor agonist prescriptions, though residual confounding limits causal inference [10].

The absence of evidence is not evidence of absence. Clinicians should still assess gait, use the Timed Up and Go test, review home fall hazards, and ensure adequate vitamin D status before and during lemborexant therapy. The drug's safety advantage over Z-drugs in postural stability testing does not eliminate fall risk. It reduces one contributor.

Deprescribing and Transitions of Care

Geriatric patients frequently move between home, hospital, rehabilitation facility, and long-term care. Each transition creates an opportunity for medication errors and for sleep medications to be continued indefinitely without reassessment.

Lemborexant has two properties that simplify deprescribing compared to benzodiazepines and Z-drugs. First, it does not produce physical dependence or withdrawal symptoms. SUNRISE-2 showed no rebound insomnia after discontinuation at 6 months [4]. Second, it is not a scheduled controlled substance in most jurisdictions outside the United States (it is Schedule IV in the US, like suvorexant and the Z-drugs).

A reasonable deprescribing protocol for geriatric patients on lemborexant:

1. Reassess insomnia severity and contributing factors every 3 months.
2. If the patient reports consistent sleep satisfaction for 4 or more weeks, attempt a direct stop (no taper required per labeling).
3. Monitor for return of insomnia symptoms over 2 weeks post-discontinuation.
4. If insomnia recurs, restart at 5 mg and address any new contributing factors (pain, nocturia, medication changes) before assuming the drug must continue long-term.

The American Academy of Sleep Medicine 2023 clinical practice guideline conditionally recommends DORAs (suvorexant and lemborexant) for insomnia treatment in adults, including older adults, citing a favorable benefit-risk profile compared to benzodiazepine receptor agonists [11].

Special Populations Within the Geriatric Group

Dementia and Cognitive Impairment

The orexin system is implicated in Alzheimer's disease pathophysiology. Cerebrospinal fluid orexin-A levels correlate with amyloid and tau burden in some studies [12]. Whether chronic orexin blockade affects dementia trajectory remains unknown. Lemborexant is not FDA-approved for, and clinical trials excluded patients with, moderate-to-severe dementia. Prescribing in mild cognitive impairment requires clinical judgment and informed consent from both the patient and caregiver.

Nursing Home Residents

Nursing home residents face both high insomnia prevalence and high fall risk. The CMS Beers Criteria-based quality measures penalize facilities for benzodiazepine and Z-drug use. DORAs are not currently flagged by these measures. Some long-term care pharmacists have incorporated lemborexant into formulary as a preferred sleep agent, though cost (approximately $400/month without insurance) remains a barrier in many facilities.

Patients on Anticoagulants

Lemborexant does not have clinically significant interactions with warfarin, apixaban, rivarelbanan, or other anticoagulants. CYP3A4 metabolism does not overlap with the warfarin CYP2C9 pathway. This is a practical advantage over trazodone, which can affect INR through CYP2D6 interactions [5].

Cost and Access

Lemborexant carries a wholesale acquisition cost of approximately $400 for a 30-day supply. Most Medicare Part D plans cover it with prior authorization, typically requiring documentation that the patient has tried and failed or has a contraindication to a generic alternative (usually zolpidem or eszopiclone). Some plans require a step through suvorexant first.

Eisai offers a copay savings program for commercially insured patients. For Medicare beneficiaries, the manufacturer's patient assistance program may cover full cost for those meeting income thresholds.

The 5 mg and 10 mg tablets cannot be split (they are not scored), so dose titration requires separate prescriptions for each strength.