Adult experience with lamotrigine

Lamotrigine is a phenyltriazine derivative with anticonvulsant properties that initially was tested in adults with partial seizures. Pharmacokinetics in adults includes a volume of distribution of 1.0 to 1.3 L/kg. Plasma protein binding is 55% and none of the metabolites are active as anticonvulsants. The placebo-controlled studies evaluated the responder rate as the percent of patients with 50% or greater seizure reduction when compared to baseline assessment. The responder rate for 300 mg per day was 20% and 36% for 500 mg per day dosages. Adverse events were infrequent but the occurrence of rash appeared to correlate with rapid ascension dosing and comedication with valproic acid. Slow titration is required when initiating treatment with lamotrigine. Accumulating experience in adults suggests that lamotrigine has a broad spectrum of effect; data from further controlled trials should suggest other clinically important forms of epilepsy that respond to lamotrigine.