In a patient with a history of seizures who was taking olanzapine 5 mg daily and now feels clearer‑headed after being switched to lacosamide, should lacosamide be continued and how should the olanzapine be tapered?

Continue Lacosamide and Discontinue Olanzapine

If this patient's improved mental clarity coincides with switching from olanzapine to lacosamide for seizure management, lacosamide should be continued as the primary antiseizure medication, and olanzapine should be discontinued unless there is a separate psychiatric indication requiring antipsychotic treatment.

Clinical Reasoning

Lacosamide as Seizure Treatment

Lacosamide is an effective and well-tolerated antiseizure medication for focal-onset seizures. The evidence supports its use:

• Efficacy: Lacosamide 400-600 mg/day provides median seizure reductions of 37-38% compared to 21% with placebo, with responder rates (≥50% reduction) of 38-41% 1, 2
• Tolerability: Most common adverse effects are dizziness (31%), nausea (11%), and diplopia (11%), which are generally dose-related and occur primarily during titration 3
• Real-world effectiveness: Retention rates are 80% at 6 months and 68% at 1 year, with 31% achieving ≥50% seizure reduction and 9% becoming seizure-free 4
• Cognitive profile: Lacosamide shows no significant cognitive impairment with chronic administration and does not result in clinically meaningful driving impairment 5

Olanzapine and Seizure Risk

The FDA label for olanzapine explicitly warns about seizure risk 6:

• Seizures occurred in 0.9% (22/2500) of olanzapine-treated patients during premarketing trials
• Olanzapine should be used cautiously in patients with a history of seizures or conditions that lower the seizure threshold 6
• The drug exhibits anticholinergic effects and can cause somnolence (26% vs 15% placebo), which may contribute to cognitive clouding 6

The "Clear-Headed" Improvement

The patient's subjective improvement in mental clarity after switching to lacosamide likely reflects:

1. Removal of olanzapine's sedating effects: Somnolence is a dose-related adverse effect occurring in 26% of olanzapine patients 6
2. Lacosamide's favorable cognitive profile: Unlike many antiseizure medications, lacosamide does not impair cognitive function with continued use 5
3. Elimination of inappropriate antipsychotic use: If olanzapine was being used for seizure management rather than a psychiatric indication, this represents inappropriate prescribing

Management Algorithm

If Olanzapine Was Used for Seizure Control (Inappropriate Use):

1. Continue lacosamide at current therapeutic dose
2. Discontinue olanzapine immediately - no taper needed if used briefly and at low dose (5 mg)
3. Monitor for seizure control over the next 4-6 weeks to ensure lacosamide provides adequate seizure suppression
4. Optimize lacosamide dosing if needed, targeting 200-400 mg/day for balance of efficacy and tolerability 1, 3

If Olanzapine Was Used for a Psychiatric Indication:

1. Continue lacosamide for seizure management
2. Reassess psychiatric indication for antipsychotic treatment with the patient's psychiatrist
3. If antipsychotic needed: Switch to an agent with lower seizure risk and less sedation (e.g., aripiprazole, risperidone at low doses) 7, 8
4. If no current psychiatric symptoms: Taper olanzapine over 1-2 weeks (e.g., 5 mg → 2.5 mg × 1 week → discontinue) while monitoring for psychiatric symptom recurrence

Monitoring During Transition:

• Seizure frequency: Document any breakthrough seizures
• Cardiac monitoring: Lacosamide can cause PR interval prolongation and bradycardia, particularly in older adults or those on other cardiac medications 9, 10. Obtain baseline ECG if not already done
• Mental status: Continue to assess cognitive clarity and mood
• Adverse effects: Watch for dizziness, nausea, or diplopia during lacosamide titration 3

Critical Caveats

Lacosamide cardiac risks: While generally well-tolerated, lacosamide has been associated with bradycardia, hypotension, and conduction abnormalities, especially with oral dosing in older adults or those on beta-blockers or other cardiac medications 9, 10. This patient should have ECG monitoring and caution with any medications affecting cardiac conduction.

Psychiatric monitoring: If olanzapine is discontinued and was being used for a psychiatric condition, close monitoring for symptom recurrence is essential. Levetiracetam, another common antiseizure medication, is associated with psychiatric side effects 11, but lacosamide has a more favorable psychiatric profile.

Dose optimization: The improved mental clarity suggests the current regimen is appropriate. Lacosamide 400 mg/day provides optimal efficacy-tolerability balance; 600 mg/day may offer additional benefit but with increased adverse effects 1.