Effects of certain antiepileptics on cephaloridine- and cefazolin-induced seizures in rats.

Effects of phenobarbital, phenytoin and diazepam on cephaloridine-induced spiking activity (focal seizure) and cefazolin-induced violent seizure appearing repeatedly in EEG and general behavior (repeated generalized seizure) were studied in rats with chronically implanted electrodes. Phenobarbital, phenytoin and diazepam showed remarkable inhibition on cephaloridine-induced focal seizure and the ED50 values were 4.52 mg/kg, 9.41 mg/kg and 0.86 mg/kg, respectively. Phenobarbital and diazepam also inhibited cefazolin-induced repeated generalized seizure. The ED50s to inhibit seizure pattern in EEG were 30.5 mg/kg and 3.4 mg/kg, respectively and the ED50 values to suppress seizure behavior were 49.0 mg/kg and 4.7 mg/kg. However, phenytoin did not suppress repeated generalized seizure even at 100 mg/kg. From these results, cephaloridine-induced focal seizure and cefazolin-induced generalized seizure are thought to be useful models for evaluating the inhibitory effect of test compounds on cortical seizure and status epilepticus, respectively.