Zonisamide Efficacy And Tolerability As Adjunctive Therapy In Asian Children With Refractory Epilepsy

Objective:Approximately one third of epileptic children do not achieve complete seizure improvement. Zonisamide is a new antiepileptic drug which is effective as adjunctive therapy in treatment of refractory epilepsy. The purpose of the current study was to evaluate the effectiveness, tolerability and retention of zonisamide in Asian children with intractable seizures.Materials & Methods:From February 2011 to September 2014,81 children who referred to Children’s Hospital of Chongqing Medical University due to refractory epilepsy (failure of seizure control with the use of two or more antiepileptic drugs) entered the study. The children were treated with zonisamide by dose of 8～12 mg/kg daily in addition to their previous medication. The underlying illness, seizure types, previous and concomitant antiepileptic drugs, the number of failed anticonvulsant drugs prior the study and adverse events of the drug were collected. We followed the children first three or four weeks after the initiation based on daily frequency of seizures, then followed the children every two to three months. Efficacy of zonisamide was evaluated on the basis of seizure reduction rates. During the follow-up, equal and more than fifty percent reduction in seizure frequency was known as response to the drug.Results:In this study 81 children (49 boys and 36 girls) were reviewed. Mean maintenance dose of ZNS was 9.66±2.07 mg/kg/day (range,4.17～15.30 mg/kg/day). The retentions of ZNS at one month and six month were 82.7% and 42.0%, respectively. The retention of ZNS in children with intellectual disabled (93.5%) was higher than that in children with intellectual normal (68.6%) one month after initiation. The efficacy of ZNS at one month and six month were 46.2% and 67.6%, respectively, and no significant difference was found between efficacy and age group. The highest response to ZNS adjunctive therapy was in seizure type of generalized tonic-clonic seizure (66.7%). Among children with specific syndromes, response rate was 23.1% (3/13) in IS,37.5% (9/24) in Lennox-Gastaut syndrome,50% (3/6) in Dravet syndromes. Adverse events were noticed in 12 (17.9%) children and anepithymia was the most common side effect.Conclusion:This study confirms the short term efficacy and safety of zonisamide in children with refractory epilepsies. ZNS adjunctive therapy was an appropriate choice for toddlers with intractable epilepsy.