Anticonvulsant effects of zonisamide and phenytoin on seizure activity of the feline visual cortex.

The acute anticonvulsant effects of zonisamide (ZNS) and phenytoin (PHT) on seizure activity produced by electrical stimulation of the feline visual cortex were studied. The intravenous administration of ZNS 60 mg/kg reduced kindled generalized seizures into partial seizures, with marked reduction in the afterdischarge duration. ZNS also suppressed focal seizure activity of the visual cortex and produced a dose-related increase in the afterdischarge threshold. The anticonvulsant effect of ZNS (60 mg/kg) was comparable to that of PHT (15 mg/kg) and was observed in the absence of neurological toxicity and background EEG changes. The present findings demonstrated that ZNS possesses potent anticonvulsant action against focal seizure and its secondary generalization from the visual cortex.