Lamotrigine as adjunctive therapy in patients with refractory epilepsy and mental retardation.

This study evaluated the effects of lamotrigine as adjunctive therapy for refractory epilepsy in patients with mental retardation. Patients with epilepsy and mental retardation having uncontrolled seizures despite treatment with other antiepileptic drugs were eligible (n=67). The open-label study comprised a Baseline Phase, an Escalation Phase during which lamotrigine was titrated to a target dose, an 8-week Maintenance Phase during which doses of lamotrigine and concomitant antiepileptic drugs were maintained, and a 12-week Optimization Phase during which doses of lamotrigine and other antiepileptic drugs could be adjusted. Almost half (44%) of patients experienced a 50% reduction in seizure frequency during the Maintenance Phase after addition of lamotrigine; 15% of patients became seizure-free. A similar pattern of results was reported for the Optimization Phase. Investigator-rated clinical status was improved relative to baseline in 66 and 74% of patients at the end of the Maintenance and Optimization Phases, respectively. Most patients experienced improvements in seizure frequency, duration, and intensity during the Maintenance Phase (62 to 72%) and the Optimization Phase (65 to 74%). Many patients were rated as having improved social functioning during the Maintenance Phase (42%) and the Optimization Phase (46%). The Aberrant Behavior Checklist score for lethargy and the mean Habilitative Improvement Scale score were improved at the ends of the Maintenance and Optimization Phases relative to baseline (P< or =0.04). One limitation of this study is its open-label design, which limits the ability definitively to attribute the clinical improvements to lamotrigine. Adjunctive lamotrigine in patients with refractory epilepsy and mental retardation appears to decrease seizure frequency and improve behavior while permitting a reduction in dose of concomitant antiepileptic drugs.