Tolerance to the anti-pentylenetetrazole effects of diazepam in the mouse.

The protective effects of acute and chronic diazepam administration (4 mg/kg) against seizures induced by pentylenetetrazole (PTZ) and picrotoxin were investigated. Considering the incidence of tonic-clonic convulsions, tolerance to the protective effects of diazepam was evident by day 5 if the mice were challenged with PTZ (120 mg/kg), by day 10 if the challenge was picrotoxin (8 mg/kg) and by day 20 if the challenge was PTZ (105 mg/kg). Diazepam retained its protective effects against tonic-clonic convulsions induced by PTZ (90 and 60 mg/kg) for 45 days, but the incidence of myoclonic jerks revealed tolerance after 5 days.