Adverse interaction between cimetidine and chlorpromazine in two cases of chronic schizophrenia

The treatment of two chlorpromazine-medicated chronic schizophrenics with cimetidine resulted in excessive sedation, which necessitated a reduction in chlorpromazine dosage. Eventual discontinuation of cimetidine therapy led to a return of schizophrenic symptoms, which responded to an increase in chlorpromazine dosage to previous levels.