Efficacy and safety of zonisamide: results of a multicenter study

Abstract The safety and efficacy of zonisamide (ZNS), a new antiepileptic drug, was tested in 167 adult participants who entered a historical-controlled 16-week open label, multicenter study. The median percent reduction from baseline of partial seizures was 51.8% in the fourth month of the study (baseline median=11.5 sz/month; treatment weeks 13–16 = 5.5 sz/month). Persons completing the efficacy study successfully were eligible for a long-term safety study; 113 entered this study. Adverse effects involved principally the CNS and were similar to those seen with other antiepileptic drugs. Four persons (3.7%) developed kidney stones and were withdrawn from the study 250–477 days after starting ZNS. Because of the high percentage of kidney stones, development of ZNS was stopped in the United States but was continued in Japan.