Zonisamide in children and young adults with refractory epilepsy: an open label, multicenter Italian study

To report on the first multicenter Italian experience with zonisamide as an add-on drug for refractory generalised or partial epilepsy in children, adolescents and young adults.

The patients were enrolled in a prospective, add-on, open-label treatment study from eight Italian centres for children and adolescent epilepsy care. Eighty-two young patients (45 males, 37 females), aged between 3 and 34 years (mean 13.1 years), all affected by partial (47) or generalised (35) refractory epilepsy, were enrolled in the study. ZNS was added to the baseline therapy at a starting dose of 1 mg/kg/day twice daily. This dose was increased by 2 mg/kg every 1-2 weeks over a period of up 3 months, according to the patient's response and tolerability, up to a maximum dose of 12 mg/kg. ZNS was given at the mean daily dose of 5.7/mg/kg/24 h (range 1-12 mg/kg).

After a mean follow-up period of 11.9 months (range 2-64 months), 9 patients (10.9%) were seizure-free. The number of seizures decreased by 50-99% in 31 cases (37.8%), by 25-49% in 5 cases (6.1%), remained the same in 29 cases (35.4%) and increased in 8 cases (9.7%). After 15 months of follow-up, 61 patients (74.4%) were still taking ZNS, while the remaining 21 (25.6%) had stopped. Twenty-two patients (26.8%) reported adverse effects while taking ZNS. They generally appeared during the first weeks of treatment, and were mild to moderate. The most frequent adverse effects were irritability and a reduced appetite.

ZNS effectively reduced seizure frequency in this pediatric population with both partial and generalised crypto/symptomatic refractory epilepsy. Its overall tolerability was good.