Diphenylhydantoin potentiates the protective effect of diazepam against pentylenetetrazol but not against bicuculline and isoniazid-induced seizures in mice

The anticonvulsant activity of diazepam alone, or in combination with diphenylhydantoin was studied in pentylenetetrazol-, bicuculline- and isoniazid-induced Scizures. Alone, diphenylhydantoin did not influence the chemically-induced convulsions but enhanced the antipentylenetetrazol action of diazepam whilst failing to affect the protective effect of the benzodiazepine against bicuculline- and isoniazid-induced convulsions. It is suggested that a diphenylhydantoin-induced increase in the total number of specific benzodiazepine binding sites might be responsible for the enhancement of the antipentylenetetrazol activity of diazepam. The anticonvulsant action of diazepam against bicuculline and isoniazid-induced Scizures does not seem to involve an interaction with benzodiazepine receptors.