Zonisamide: The Arizona Experience (Report‪)‬

INTRODUCTION Epilepsy has an age adjusted prevalence of 0.625 per 1000 [1]. Estimates of people with the condition in the US range from 1.5 to 3 million [2]. Clinicians treating patients with epilepsy were acutely aware of the fact that the traditional antiepileptic drugs (AEDs) did not provide complete seizure control for all and that treatment may result in serious side effects in some. The first major attempt at comparing the efficacy of these drugs was the VA co-operative study [3]. It showed that the majority of patients with seizures may be treated successfully by a single anti-epileptic drug, but that 32% of the patients enrolled in the study dropped out because of side effects of the drug or due to lack of seizure control. Thus the study demonstrated the need for more effective and less toxic anti-epileptic drugs. The search was on and zonisamide became the, first AED to be clinically tried in this country, 15 years after the marketing of valproic acid. However, with the report of renal stones, marketing attempts were abandoned in USA and Europe. However, the Japanese experience where it was in use since 1989, caused a renewed interest in bringing the drug to the USA. The newly completed studies in the USA resulted in the FDA granting an approvable status to the drug in March 1998. It is available for general prescription use, as add-on therapy for partial seizures in this country, since April 2000.