Anti-metrazol effects of nitrazepam during ontogenesis in the rat

Anti-metrazol effect of nitrazepam was studied in male rats aged 7, 12, 18 and 90 days. Nitrazepam protected all age groups against seizures elicited by metrazol (80 mg/kg s.c.); the 50%-protective dose decreased from 165.7 micrograms/kg in adult rats to 70.2 micrograms/kg in 7-day-old animals. The sensitivity of 7-day-old and adult rats to metrazol is nearly the same, so that we may conclude that nitrazepam exhibits higher anti-metrazol potency in 7-day-old rats than in adult ones.