Effectiveness and tolerability of zonisamide in children with epilepsy: A retrospective review

PURPOSE To evaluate the effectiveness and tolerability of zonisamide in children with epilepsy. METHOD Retrospective case note review of young people (less than 19 years) with epilepsy from three UK tertiary centres who received treatment with zonisamide and were followed up for a minimum of 12 months. RESULTS Fifty-seven children were included, aged 1.5-18.5 (median, 12) years. Thirty-three (57.9%) patients had generalised epilepsy, 21 (36.8%) focal epilepsy, and three (5.3%) a mixed, generalised and focal, epilepsy. Fifty-six of the 57 patients had been refractory to at least three previous antiepileptic drugs. The maintenance dose of zonisamide was [range (median)] 0.7-14 (5)mg/kg/day. The median duration of treatment for all patients was 12 (range 0.25-35) months. After 2 months of treatment, 51 patients remained on zonisamide, 18 (35.3%) of whom demonstrated a > or =50% reduction in seizure frequency. At the end of the follow-up period, there was a loss of effect for some patients. Thirteen (25.5%) of the 51 patients continued to demonstrate a > or =50% reduction in seizure frequency whilst two who had become seizure-free started having seizures again. Six (11.8%) had <50% reduction, twenty-four (47%) had no change, and eight (15.7%) had increasing seizures. Twenty-five (43.9%) patients reported unwanted effects although this contributed to the withdrawal of zonisamide in only ten (17.6%) patients. CONCLUSIONS Zonisamide appeared to be a reasonably effective and generally well-tolerated antiepileptic drug in a heterogeneous group of 57 children with poorly controlled epilepsy and provides another treatment option for children with refractory seizures.