Safety and Efficacy of Zonisamide in Patients with Epilepsy: A Post-Marketing Surveillance Study

BACKGROUND AND PURPOSE Zonisamide (ZNS) is one of new antiepileptic drug, which is known to inhibit seizure through multiple mechanisms of action. In Korea, ZNS was approved as an antiepileptic drug in 1992 and has been used for epilepsy patients with partial and generalized seizures. The objective of this study was to investigate the efficacy and tolerability of ZNS in patients with epilepsy and to identify the incidence of adverse events in real clinical setting. METHODS This study was carried out in patients who received ZNS for epilepsy. Patients who were observed for at least 12 weeks after treatment with ZNS were included as evaluable subjects. Information regarding the status and type of adverse events occurring during the course of treatment with ZNS was obtained regardless of causal relationship to ZNS and efficacy was assessed by the study physicians and patients at 12 weeks post dose of ZNS. RESULTS A total of 1,948 patients were included in the study, and ZNS efficacy was evaluated in 1,744 patients. ZNS was used as a monotherapy in 1,095 patients and as an adjunctive drug in 853 patients. Of the total patients, 1,345 (69.1%) patients had partial seizure, 563 patients had generalized seizure, and 40 patients were undetermined. Adverse events were reported in 65 patients (3.34%) including 1 case of Stevens-Johnson syndrome, but no incidence of serious unexpected adverse drug reactions were reported. 755 patients (43.29%) became seizure free with ZNS treatment, and additional 322 patients (18.41%) experienced marked improvement with ZNS treatment. CONCLUSIONS Our study shows the safety and tolerability of ZNS treatment in patients with epilepsy in real clinical setting. In addition, ZNS was found to be an effective option as a monotherapy or in patients with generalized seizure.