Zonisamide suppresses the tonic phase but not the clonic phase of generalized seizures in developing rats

Zonisamide is increasingly used in pediatric neurology but there are no experimental data for immature animals. Zonisamide (12.5–100 mg/kg i.p.) was tested against pentetrazol-induced seizures in 7-, 12-, 18-, 25- and 90-day-old rats. Minimal clonic seizures were not suppressed by zonisamide. Selective suppression of tonic phase of generalized tonic-clonic seizures was demonstrated in all age groups. This effect indicates possible action of zonisamide against generalized tonic-clonic seizures during brain maturation.