Abstracts

Zonisamide is a broad-spectrum antiepileptic drug with multiple mechanisms of action. The drug has been available in Japan since 1989 and has been used there to treat a variety of seizure types. Zonisamide is approved in the United States for the adjunctive treatment of partial seizures in adults with epilepsy. Few data from the United States exist regarding zonisamide[apos]s effects in patients with absence seizures. This chart review study investigates the use of zonisamide in treating patients with absence seizures.
This retrospective chart review study included zonisamide-treated adult and pediatric patients with absence seizures. Zonisamide[apos]s efficacy was assessed via subjective patient and/or caregiver reports and with use of seizure diaries. Safety was assessed via reports of adverse events. Patient weights were measured at the time of zonisamide therapy initiation and at subsequent clinic visits. In most cases, efficacy, safety, and tolerability were assessed 1 month after the initiation of zonisamide therapy.
The charts of 9 patients (6 females and 3 males) were reviewed. Mean patient age was 12.6 years (range=5.6 to 23.0 years). Zonisamide was used as adjunctive therapy in 5 patients and as monotherapy in 4 patients. Mean zonisamide dosage was 366.7 mg/d (range=300 to 600 mg/d). Mean length of time on zonisamide therapy was 28.9 weeks (range=2.0 to 77.4 weeks). Two patients had a moderate response to zonisamide, 2 patients had a good response, 1 patient experienced significant improvement, and 3 patients achieved seizure freedom. Five patients reported adverse events, including decreased appetite (n=2), restlessness (n=1), sleeplessness and incontinence (n=1), and thinking problems (n=1). For the 6 patients who had their body weight recorded both at the time of zonisamide initiation and during zonisamide therapy, mean weight was 29.7 kg (range=12.6 to 46.6 kg) at initiation and 30.7 kg (range=12.7 to 50.6 kg) during therapy.
Data from this small cohort suggest that zonisamide can be useful in treating patients with absence seizures. All patients with available efficacy assessments had at least a moderate response to zonisamide, and 3 patients achieved seizure freedom. No serious adverse events were reported. Further investigation is warranted to assess the use of zonisamide in patients with absence seizures.
[Supported by: Elan Pharmaceuticals, Inc.]