Verapamil and flunarizine inhibit phencyclidine-induced effects: an EEG and behavioural study in rats.

The influence of verapamil and flunarizine on phencyclidine-induced effects has been studied in adult male rats. Both verapamil (25 and 100 micrograms/10 microliters, i.c.v.) and flunarizine (40 and 60 mg/kg, i.p.) significantly reduced behavioural (mean intensity of ataxia, mean duration of head weaving) and the EEG (increase in the mean voltage of background activity of the EEG) effects induced by phencyclidine 5 mg/kg (i.p.). It was reported previously that nimodipine and diltiazem significantly potentiate effects induced by phencyclidine. The contrasting results obtained with verapamil and flunarizine, suggest that these drugs may modulate effects induced by phencyclidine by acting at sites other than NMDA receptor-coupled "L"-type calcium channel.