Effects of phenytoin on amygdaloid kindled seizures in the rat.

The effects of oral phenytoin (0.25 g/kg) on the evolution of amygdaloid seizures were investigated using the kindling technique in rats. By utilizing low intensity stimulation at threshold for after-discharge, it was found that phenytoin produced a 23% increase in threshold for after-discharge and generalized seizures in fully kindled rats with blood levels in the human therapeutic range. Although half of the animals demonstrated a block of after-discharge after phenytoin was started when the stimulation intensity was increased, the phenytoin animals developed generalized seizures in the same manner as controls.