Influences of histamine H1 receptor antagonists on maximal electroshock seizure in infant rats

The influences of histamine H1 receptor antagonists on maximal electroshock seizure were studied using infant rats. In this study, electroconvulsion was induced by stimulating rats using ear-clip electrodes, and the durations of electroencephalogram (EEG) seizure, tonic extensor (TE) seizure and clonic (CL) seizure induced by maximal electroshock were measured. Diphenhydramine, chlorpheniramine, cyproheptadine and ketotifen caused a dose-dependent and significant prolongation of both EEG seizure and TE seizure induced by maximal electroshock. On the other hand, epinastine and fexofenadine caused no such effects, even at a dose of 50 mg/kg. All drugs used in this study showed no significant effect on CL seizure induced by maximal electroshock. From these findings, it is suggested that epinastine and fexofenadine may cause no harmful influence on epilepsy, even when used in a little child.