Safety and Efficacy of Zonisamide in Refractory Epilepsy Patients: Clinical Experience from a Tertiary Center

Objectives: Zonisamide (ZnS) is a new generation antiepileptic agent used in the treatment of epilepsy patients with partial and generalized seizures. In this study, we aim to investigate the safety and efficacy of ZnS in the treatment of patients with refractory epilepsy who were being followed. Methods: Forty-five refractory epilepsy patients who received ZnS treatment were included in this study. Patients who received ZnS treatment for less than six months were excluded. Age, sex, types of seizures, examination findings, magnetic resonance imaging and electroencephalography findings, concurrent use of non-ZnS antiepileptic drugs, decrease in the seizure frequency and side effects of the drug were recorded. Results: Thirty-nine patients, whose mean age was 34.3 +/- 9.3 years, were evaluated. Complex partial seizures (CPS) and generalized tonic-clonic seizure (GTCS) were observed in 74.4% of the patients, whereas 10.3% had GTCS alone, 7.7% had CPS alone, 5.2% had GTCS and myoclonia and 2.6% of them had absence and myoclonia. In the follow-up, treatment was observed to be discontinued in 19 of the 39 patients due to drug side effects, or where there was an increase, or no change, in seizure frequency. Twenty patients responded to treatment. Seizure frequency was decreased by 25% in one patient; 50% in five patients, and 75% in seven patients. Three patients were seizure-free. Although there was no change in seizure frequency, seizure duration was shortened in four patients. Treatment-responsive patients were using ZnS at doses that ranged from 100 to 400 mg/day for 7 to 80 months. Conclusion: ZnS is a safe, tolerable and effective option for the additional treatment of refractory epilepsy patients at our center.