Lamotrigine overdose in an adult

Lamotrigine is an antiepileptic agent that has been shown to be an effective adjunctive treatment for refractory partial and generalized seizures. It is now licensed in more than 70 countries for this indication. There is very little published material about the effects of acute overdose with lamotrigine.

We describe the findings in a patient following the deliberate ingestion of a large amount of lamotrigine (stated 4.5 g, absorbed estimated 2.9 g), in excess of that previously described in the literature. The main clinical features were ataxia and rotary nystagmus. Electrocardiogram was unremarkable. Peak measured concentration of lamotrigine was 35.8 mg/L and half-life 19.5 hours, suggesting linear kinetics in overdose.