Abstracts

Zonisamide is a broad- spectrum antiepilepsy drug approved in the United States for the adjunctive treatment of partial seizures in adults with epilepsy. Studies in Japan have established Zonisamide as effective and safe in children, but there is very limited information from United states concerning its use in the pediatric population.A rare side effect of Zonisamide seen in Japnese patients is the development of secondary IgA deficiency. However this has not been reported in the United States. We report a child who developed IgA deficiency secondary to Zonisamide use. A 6 year-old boy with spastic quadruparesis and medically refractory mixed epilepsy developed frequent upper respiratory infections within 6 months after initiation of Zonisamide. Quantitative serum immunoglobulin determination was performed using PEG- enhanced tubimetric immunoassay Ten months after Zonisamide was started, a quantitative immunoglobulin determination revealed low IgA. Within 2 months, the level dropped to zero. At this point Zonisamide was discontinued. Quantitative immunoglobulin determination done four months later showed a normal IgA level. Although rare, Zonisamide can cause secondary immunoglobulin deficiency. In patients treated with Zonisamide who present with recurrent infections, quantitative immunoglobulin determination should be performed. To our knowledge, this is the first report of IgA deficiency developing after Zonisamide use in the United States.