Comparative assessment of the anticonvulsant activity of some benzodiazepines, phenobarbitone and diphenylhydantoin against maximal electroshock seizures in rats: a time-distribution study.

The anticonvulsant activity of three benzodiazepines (BZDP) and two standard antiepileptic drugs were investigated comparatively against maximal electroshock seizures in rats in a time-distribution study. While phenobarbitone (PHB) and diphenylhydantoin (DPH) gave marked to moderate protection (100%-67%) against tonic seizures up to 6-7 h post-treatment, the BZDP provided significant protection (100%-60%) only up to 1.5 h, with clonazepam being the strongest and diazepam the weakest. Clonic seizures occurred in all treatment groups, whether tonic seizures preceded them or not, but their duration was longer in the DPH and PHB groups than in the BZDP groups. Total seizure durations were often significantly reduced in the BZDP groups, notably with clonazepam, whereas it was invariably longer in the DPH and PHB groups when compared with the vehicle treated controls. The BZDP treated rats generally required longer time to recover from postictal coma, the effect being dose-related. the DPH and PHB treated rats needed longer recovery time when the treatment-test interval was 18-20 h.