Major
Lamotrigine × Phenytoin
Antiepileptic with dual mechanism×Antiepileptic, hydantoin derivative (sodium channel blocker)
Mechanism
Phenytoin induces UGT1A4. Lamotrigine falls 50%.
Symptoms
Seizure breakthrough.
Management
Double lamotrigine dose.
Check the full regimen, not just this pair
Opens the checker with these two drugs prefilled. Add the rest of the regimen and recompute additive risks.