Influence of a new antiepileptic drug ORG 6370 on metrazol-induced seizures in rats during ontogenesis.

The anticonvulsant action of a new antiepileptic drug ORG 6370 (Organon International B.V.) was studied in 217 male albino rats aged 7, 12, 18, 25 and 90 days. Epileptic phenomena induced by a subcutaneous injection of a 100 mg/kg dose of metrazol (isolated myoclonic jerk, minimal metrazol seizures and major, generalized tonic-clonic metrazol seizures) were used as a model. ORG 6370 did not influence myoclonic jerks or minimal metrazol seizures in those age groups where they were regularly elicited. In 12-day-old rats pretreatment with ORG 6370 led to the appearance of minimal metrazol seizures, a phenomenon rarely seen under control conditions. Major seizures were suppressed only in adult rats with a 20 mg/kg dose; on the other hand, ORG 6370 exhibited a selective action against the tonic phase of major seizures at all stages of development. The profile of action of ORG 6370 is almost the same as that of phenytoin.