What is the recommended dosage reduction and rate of Lamotrigine (an anticonvulsant medication) when starting Electroconvulsive Therapy (ECT) from a dose of 200mg?

Lamotrigine Reduction Before ECT

For patients on lamotrigine 200mg who are starting ECT, the recommended approach is to gradually taper lamotrigine by 25-33% every week over 4 weeks, reducing to 150mg, then 100mg, then 50mg, before discontinuing completely. 1

Rationale for Tapering Lamotrigine Before ECT

Lamotrigine requires careful tapering before ECT for several reasons:

• Lamotrigine affects seizure threshold, which is critical for ECT efficacy
• Abrupt discontinuation increases risk of withdrawal seizures, even in patients taking it for mood disorders 1
• The brain needs time to readjust to the absence of lamotrigine's effects on voltage-sensitive sodium channels 1

Recommended Tapering Schedule

For a patient on 200mg lamotrigine:

1. Week 1: Reduce to 150mg daily (25% reduction)
2. Week 2: Reduce to 100mg daily (50% of original dose)
3. Week 3: Reduce to 50mg daily (75% reduction)
4. Week 4: Discontinue completely

This follows the American Academy of Neurology recommendation for gradual discontinuation over 4 weeks with 25-33% reductions each week 1.

Special Considerations

• Higher risk patients: Consider a more gradual 6-8 week taper with 25% reductions every 2 weeks 1
• Concurrent valproate: If the patient is also taking valproate, a more gradual taper may be necessary due to valproate's effect on lamotrigine clearance 1
• Monitoring: During tapering, closely monitor for:
  • Emergence of mood symptoms
  • Withdrawal symptoms
  • Seizure activity

Important Precautions

• Lamotrigine typically takes 4-6 weeks to reach therapeutic effectiveness due to its required slow titration schedule 1
• The risk of serious rash with lamotrigine is approximately 1.1% and is dose-related 2
• Females are at higher risk of developing rash than males (relative risk 1.8) 2

After ECT Completion

If lamotrigine needs to be restarted after ECT:

• Follow the standard titration schedule to minimize risk of serious rash
• Start at 25mg/day and gradually increase to target dose
• Consider the original 200mg dose may need adjustment based on ECT response

This approach balances the need to optimize ECT effectiveness while minimizing risks associated with lamotrigine withdrawal and reintroduction.