Clinical presentation

Lamotrigine is rapidly absorbed, with peak effects within 4 hours after ingestion. Toxicity generally resolves within 24 hours but can be prolonged in severe cases. Central nervous system (CNS) effects are common.

Effects of lamotrigine poisoning include:

• gastrointestinal effects—nausea, vomiting
• CNS effects
  • CNS depression (altered conscious state ranging from drowsiness to coma)
  • ataxia, involuntary movements (eg hemiballismus, choreoathetosis, myoclonus)
  • seizures including status epilepticus
• cardiovascular effects
  • sinus tachycardia (most commonly), arrhythmias
  • cardiac conduction abnormalities—QRS widening and sodium channel blockade, Brugada-like electrocardiographic pattern (more than 3 mm R wave in lead aVR, and ST elevation), heart block, sudden cardiovascular collapse with refractory hypotension
• other effects—acute drug-related eruptions.

Due to lamotrigine’s reversible monoamine oxidase inhibitor (MAOI) effect, co-ingestion with other serotonergic drugs can precipitate serotonergic toxidrome and interaction with tyramine-containing foods can induce a tyramine reaction.