Lamotrigine pharmacokinetics adverse effects

Lamotrigine is metabolized primarily to the N-2 glucuronide through the UGT pathway. The half-life of lamotrigine (24–35 hours) is decreased by enzyme-inducing drugs (for example, carbamazepine and phenytoin) and increased by greater than 50 percent with the addition of valproate. Lamotrigine dosages should be reduced when adding valproate to therapy unless the valproate is being added in a small dose to provide a boost to the lamotrigine serum concentration. Rapid titration to high serum concentrations of lamotrigine have been reported to cause a rash, which in some patients may progress to a serious, life-threatening reaction.