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

Abstract

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.