Safety And Efficacy of Zonisamide in Refractory Epilepsy Patients: Clinical Experience from A Tertiary Center

Abstract

Objectives: Zonisamide (ZNS) is a newer generation antiepileptic drug used against partial and generalized seizures. The aim of this study was to investigate the safety and efficacy of ZNS in refractory epilepsy patients under clinical follow-up in our center.Methods: A total of 45 patients were found eligible. Six patients observed for less than six months were excluded. Age, gender, seizure types, neurological examination, magnetic resonance imaging, EEG features, number of concomitant antiepileptic drugs, seizure reduction, and adverse effects were noted. Results:The remaining 39 patients, with a mean age of 34.3±9.3 years, were evaluated. The seizure types were complex partial seizure (CPS) and generalized tonic-clonic seizure (GTCS) in 74.4%, GTCS in 10.3%, CPS in 7.7%, GTCS and myoclonia in 5.2%, and GTCS, absence and myoclonia in 2.6% patients. Nineteen of the 39 patients stopped treatment due to aggrevated seizures, unchanged seizure frequency, or side effects. A seizure frequency reduction of 25% was noted in 1, 50% in 5, and 75% in 7 patients. Three patients became seizure-free. Shortening of the seizure period was noted in four patients. Good clinical response was achieved in between 7-80 months' long treatment with 100-400 mg/day doses. Conclusion:ZNS is used as a safe, tolerable, and effective add-on alternative therapy for refractory epilepsy patients in our center.

Scoping review of rational polytherapy in patients with drug‐resistant epilepsy

“…Three studies also used the term “uncontrolled” or “not adequately controlled,” referring to seizures 23,24,26 . Among non‐RCTs ( n = 23), “refractory” epilepsy was used in 15 studies 13,15,17,18,21,22,28,30,33–35,39,40,42,43 . Two studies specifically highlighted “medically refractory epilepsy” 38 and “treatment‐resistant epilepsy.” 14 Four studies did not specifically define DRE 37,41,44,45 .…”

“…Definitions of DRE varied between studies. Two studies specifically referenced the ILAE definition of DRE 39,42 . Four studies highlighted if previous therapy failed to control seizures 15,21,26,38 .…”

“… 23 , 24 , 25 , 26 , 27 , 29 , 31 , 32 Additionally, eight studies reported if seizure frequency was increased or exacerbated. 16 , 19 , 21 , 28 , 29 , 34 Sixteen studies addressed safety outcomes, 14 , 15 , 16 , 17 , 19 , 20 , 24 , 25 , 26 , 27 , 28 , 29 , 31 , 36 , 38 , 39 while seven studies reported plasma concentrations of the study drug 13 , 24 , 26 , 27 and/or all ASMs taken by patients. 22 , 28 , 36 …”

“…[23][24][25][26][27]29,31,32 Additionally, eight studies reported if seizure frequency was increased or exacerbated. 16,19,21,28,29,34 Sixteen studies addressed safety outcomes , [14][15][16][17]19,20,[24][25][26][27][28][29]31,36,38,39 while seven studies reported plasma concentrations of the study drug 13,24,26,27 and/or all ASMs taken by patients. 22,28,36 Outcomes evaluating specific ASM combinations were not part of the primary outcomes but were generally reported with or without statistical analysis.…”

“…23,24,26 Among non-RCTs (n = 23), "refractory" epilepsy was used in 15 studies. 13,15,17,18,21,22,28,30,[33][34][35]39,40,42,43 Two studies specifically highlighted "medically refractory epilepsy" 38 and "treatment-resistant epilepsy." 14 Four studies did not specifically define DRE.…”