Abstracts

RATIONALE: Zonisamide (ZNS) is a novel anticonvulsant that has recently been approved in the United States but has been available in Japan since 1989. There is substantial open label experience with ZNS in the treatment of pediatric epilepsy in Japan. No comprehensive review of this experience has previously been reported. METHODS: 14 Japanese studies examining the efficacy and safety of ZNS in children with partial or generalized epilepsy were evaluated. ZNS was used either exclusively as monotherapy (n=5), solely as adjunctive therapy (n=5), or as either adjunctive therapy or monotherapy (n=4). Efficacy was assessed by responder rates (percentage of patients with a ? 50% decrease in seizure frequency). ZNS adverse events occurring with a frequency greater than 5% were analyzed. RESULTS: The overall efficacy of ZNS in children with partial or generalized epilepsy was 59% (730/1237); there was a 63% response rate for patients with partial seizures (578/912) compared with 47% for patients with generalized seizures (152/325). In ZNS monotherapy studies, 76% of children with partial seizures responded and 71% of children with generalized seizures responded. The responder rate for ZNS adjunctive therapy was 35% in children with partial seizures, 14% in children with generalized seizures. In studies examining a mixture of patients on ZNS monotherapy and adjunctive therapy, 66% of children with partial seizures responded compared to 50% of children with generalized seizures. Similar to adults, the most common ZNS adverse events in children were drowsiness/sleepiness [ranging from 12-18% in monotherapy studies to 14-36% in adjunctive trials and 23-50% in mixed studies], anorexia, ataxia, sluggishness/decreased activity, lightheadedness/dizziness and cognitive impairment. Side effects were more commonly noted in adjunctive therapy trials compared to monotherapy trials. CONCLUSIONS: Zonisamide is well tolerated and effective against both partial and generalized seizures in open label experience in Japanese children. Effectiveness is greater when ZNS is used as monotherapy and for partial seizures. Side effects are fewer when ZNS is used in monotherapy.