Clozapine and seizures.

Epileptiform EEG changes, myoclonus, and seizures are reported in some patients treated with clozapine. Although these are undesirable side effects, the excitation of specific neuronal networks by clozapine and other neuroleptics may be important for the therapeutic effect of this class of agents. In these experiments, intraperitoneal clozapine 2-16 mg/kg produced dose-related myoclonic jerks in partially restrained rats. Paroxysmal slow waves and spike activity were recorded from implanted electrodes in amygdala, hippocampus, and cortex following higher doses of clozapine, but the EEG abnormalities were not correlated with the myoclonic jerks. Single doses of chlorpromazine (8 and 16 mg/kg) rarely produced myoclonic jerks but provoked generalized tonic seizures in two animals preceded by multiple myoclonic jerks in one. Myoclonus and seizures reflect increased excitability of the central nervous system. It is possible that clozapine and other neuroleptics exert a therapeutic effect by increasing excitability in critical subcortical areas of the brain.