A large body of evidence supports the role of L-type calcium channels in 
epileptogenesis. The aim of the present study was to study the efficacy of the 
specific L-type calcium channel blocker nifedipine on seizure activity induced 
by picrotoxin (PTX). Adult female Sprague-Dawley rats were used in these 
experiments. The intraperitoneal administration of nifedipine (5 mg/kg) did not 
significantly alter the latency to onset of clonic seizure induced by 
intraperitoneal injection of PTX (4 mg/kg). Higher doses of the drug (10 and 20 
mg/kg) significantly increased the latency of onset of clonic seizure in a 
dose-dependent manner. Nifedipine (10 mg/kg) did not reduce the incidence of 
clonic seizures in the animals injected with PTX, but inhibited tonic seizure 
and the progression of clonic seizures into maximal tonic seizures in four of 
eight of the animals. The drug (20 mg/kg) inhibited clonic seizure in four of 
six of the animals and abolished minimal or maximal tonic seizures in all the 
animals. In conclusion, our study provides further evidence on the antiepileptic 
effect of L-type calcium channel blocker nifedipine by showing its protective 
effect on seizure activity induced by PTX.