Anti-metrazol action of R 57720 during postnatal development in rats

The effects of an experimental antiepileptic drug R 57720 (Janssen Pharmaceutica) on metrazol-induced seizures were studied in rats aged 7, 12, 18, 25 and 90 days. R 57720 exhibited a marked dose-dependent anticonvulsant effect against major, generalized tonic-clonic seizures in all the age groups studied. Similar action on minimal metrazol seizures (mMS) was present in rats aged 18 days and more. In the two youngest groups where metrazol did not induce mMS under control conditions, the combination of the 5- and 10-mg/kg doses of R 57720 and metrazol led to the appearance of mMS, whereas mMS failed to appear after the highest dose of R 57720 used (20 mg/kg).