Anticonvulsant action of oxcarbazepine, hydroxycarbamazepine, and carbamazepine against metrazol-induced motor seizures in developing rats.

Antimetrazol effects of carbamazepine (CBZ, 5, 12.5, 25, or 50 mg/kg), oxcarbazepine (OCBZ, 5, 10, 30, or 60 mg/kg), and hydroxycarbamazepine (HCBZ, the main human metabolite of OCBZ, 10, 30, or 60 mg/kg) were studied in 7-, 12-, 18-, 25-, and/or 90-day-old laboratory rats. No drug tested affected the incidence of minimal (clonic) metrazol seizures (mMs) in animals aged > or = 18 days; in rats aged 7 or 12 days in which mMs are rare under control conditions, the incidence of mMs was increased by lower doses of CBZ and HCBZ. All drugs tested specifically abolished the tonic phase of major generalized tonic-clonic seizures (MMs) in a dose-dependent manner. In addition, CBZ and OCBZ were able to suppress all phases of MMs in the two youngest groups (7- and 12-day-old). There were no marked differences among the three drugs tested (CBZ, OCBZ, and HCBZ) on their action against metrazol-induced seizures during ontogenesis of rats; i.e., all these drugs appeared to possess an identical profile of anticonvulsant action.