Anticonvulsant effect of nimodipine alone and in combination with diazepam and phenytoin in a mouse model of status epilepticus

The effect of nimodipine alone and in combination with diazepam or phenytoin was tested in the electroshock-induced mouse model of status epilepticus. Status epilepticus was induced by transauricular electrical stimulation with a stimulus of 15 mA at 0.5, 3, 10, 20 and 30 min, starting half an hour after intraperitoneal administration of vehicle/drug. The median effective doses of diazepam and phenytoin alone and in combination with a fixed dose of nimodipine (24 mg/kg) was calculated. The ED50s of diazepam and phenytoin were found to be 10.5 and 9 mg/kg, respectively. When nimodipine was combined with diazepam or phenytoin, the ED50 values decreased to 3.77 mg/kg and 7.15 mg/kg, respectively. The severity of seizures was also decreased by combination with nimodipine as compared to diazepam and phenytoin given alone. To study the effect of nimodipine on psychomotor impairments produced by diazepam and phenytoin three tests were performed: rotarod, behavioral despair and hole board. Nimodipine did not show protective effects on its own but potentiated the anticonvulsant effects of diazepam and phenytoin. Furthermore, the combination of nimodipine with diazepam and phenytoin produced lesser impairment of psychomotor functions.