Transitioning from Levetiracetam to Lamotrigine in a Patient with Suspected PNES
For a patient weighing 308 pounds with suspected PNES, you should gradually taper levetiracetam while simultaneously titrating lamotrigine slowly over 6-8 weeks to minimize risk of withdrawal seizures and lamotrigine-related adverse effects, particularly rash.
Tapering Levetiracetam Schedule
Levetiracetam can be tapered relatively quickly compared to other antiepileptic drugs as it has fewer withdrawal concerns:
- Weeks 1-2: Reduce levetiracetam from 1500mg to 1000mg daily
- Weeks 3-4: Further reduce to 500mg daily
- Weeks 5-6: Discontinue levetiracetam completely
Lamotrigine Titration Schedule
Lamotrigine requires slow titration to minimize risk of serious rash:
- Weeks 1-2: Start with 25mg daily
- Weeks 3-4: Increase to 50mg daily
- Weeks 5-6: Increase to 100mg daily
- Weeks 7-8: Increase to 200mg daily
- Further titration as needed based on clinical response
Key Considerations
Weight-Based Dosing
For this 308-pound (140kg) patient, the target lamotrigine dose would be approximately 200-400mg daily. The maximum dose can be calculated at approximately 1-1.5mg/kg/day for adults 1.
Monitoring Parameters
- Watch for signs of lamotrigine-associated rash, particularly during the first 8 weeks
- Monitor for neuropsychiatric symptoms during the transition
- Assess for breakthrough seizures during the tapering process
Special Precautions
- Lamotrigine carries a significant risk of serious rash, especially if titrated too quickly 1
- Do not load lamotrigine in a patient not previously on the medication due to risk of serious rash 1
- Levetiracetam withdrawal is generally well-tolerated but can occasionally lead to withdrawal seizures 1
Rationale for Medication Change
For patients with suspected PNES (Psychogenic Non-Epileptic Seizures), lamotrigine may be preferred over levetiracetam due to:
- Levetiracetam's association with psychiatric side effects (irritability, mood changes) which may worsen PNES symptoms 2
- Lamotrigine's mood-stabilizing properties which may benefit patients with underlying mood disorders that can contribute to PNES 1
Follow-up Recommendations
- Schedule follow-up visits every 2 weeks during the transition period
- Consider EEG monitoring if diagnosis remains uncertain
- Evaluate for improvement in suspected PNES events
- Assess for any adverse effects from either medication
Remember that while transitioning between these medications, the primary goal is to maintain seizure control while minimizing adverse effects. The slow titration of lamotrigine is critical to avoid potentially serious rash, while the gradual taper of levetiracetam helps prevent withdrawal seizures.