Teratogenicity of lamotrigine

QUESTION: One of my female patients has epilepsy and is currently receiving lamotrigine monotherapy. She has recently found that she is 6 weeks pregnant and is concerned about possible side effects of lamotrigine on her fetus. How should I advise her and should I switch to another antiepileptic drug? ANSWER: Lamotrigine (LTG) has not been associated with an increased risk for major malformations in monotherapy in most available studies. Risk of major malformations has been suggested when LTG was taken in doses higher than 200 mg/d and when clefts not caused by any known syndrome have been associated with LTG treatment. Therefore, safety for the fetus cannot yet be proven or rejected, although the drug does not appear to be a major human teratogen.