In an elderly patient with emotional agitation during sundowning, should lamotrigine (Lamictal) or oxcarbazepine (Trileptal) be used first, and what are the recommended dosing and monitoring guidelines?

Neither Trileptal nor Lamictal Should Be Used for Sundowning

Neither oxcarbazepine (Trileptal) nor lamotrigine (Lamictal) should be used as first-line treatment for emotional agitation during sundowning in elderly patients with dementia. The evidence does not support anticonvulsants for this indication, and current guidelines strongly recommend antipsychotics (specifically oral quetiapine) or nonpharmacologic approaches instead 1.

Why Anticonvulsants Are Not Recommended

The evidence base for anticonvulsants in dementia-related agitation is weak and largely negative:

• Oxcarbazepine has failed in controlled trials: A multicenter, randomized, double-blind, placebo-controlled trial of 103 institutionalized dementia patients found no significant effect of oxcarbazepine on agitation and aggression 2. This is the only controlled trial available for oxcarbazepine in this population, and it was negative.

• Lamotrigine lacks any controlled data: There are only small case series and anecdotal reports for lamotrigine in dementia-related agitation 3, 4. No rigorous trials exist to support its use.

• Carbamazepine has the best evidence among anticonvulsants, but even this is limited and concerns about tolerability restrict its use 3, 4. Since you're asking about oxcarbazepine and lamotrigine specifically, neither approaches carbamazepine's evidence level.

What Should Be Used Instead

Based on the most recent 2025 guidelines for geriatric agitation 1:

First-line approach:

• Nonpharmacologic interventions (person-centered communication, sensory therapy) should always be attempted first 1

If medication is necessary:

• Oral quetiapine has the best safety profile among medications studied for severe agitation in older adults 1
• Start with the lowest effective dose to minimize adverse events 1
• Oral formulations are strongly preferred over parenteral routes 1

Critical safety considerations:

• Serious adverse events occurred in 16.8% of older adults receiving antipsychotics or anxiolytics for agitation 1
• Benzodiazepines (especially midazolam) pose excessive risk and should be avoided 1
• Benefits of antipsychotics are "at best small" but can be appropriate for dangerous agitation 5

Clinical Algorithm for Sundowning

1. Assess for reversible causes: Delirium, pain, infection, medication effects
2. Implement nonpharmacologic strategies first: Environmental modifications, consistent routines, adequate lighting
3. If pharmacologic intervention needed: Start oral quetiapine at low dose (12.5-25 mg)
4. Monitor closely for adverse effects including oversedation, falls, respiratory depression, and QTc prolongation
5. Reassess regularly and discontinue if ineffective or causing harm

Common Pitfalls to Avoid

• Do not use anticonvulsants based on anecdotal success: The controlled trial data does not support this practice 2
• Do not assume "mood stabilizers" help behavioral symptoms: The mechanism of sundowning is not primarily mood-related
• Do not combine antipsychotics with benzodiazepines in older adults due to excessive adverse event risk 1
• Do not use parenteral medications unless oral administration has been refused and safety is immediately threatened 1

Why This Matters for Sundowning Specifically

Sundowning represents agitated behavior occurring at specific times of day, typically evening hours 6. The 1997 review noted that fewer than 20 studies examining agitation in dementia even measured time-of-day effects 6. The anticonvulsant trials did not specifically target or measure sundowning patterns 2. Therefore, extrapolating from general agitation studies (which themselves show no benefit) to sundowning is particularly problematic.

The FDA labeling for Trileptal indicates it is approved only for partial-onset seizures 7, not behavioral disturbances. Using it off-label for sundowning lacks evidence and exposes elderly patients to risks including hyponatremia, serious dermatological reactions, and cognitive/neuropsychiatric adverse effects 7.