Clozapine induced increase of human plasma norepinephrine.

Four psychotic patients and 5 controls were treated with clozapine (200--400 mg/day during 30 days, patients, respectively 100 mg/day during 7 days, controls) and plasma norepinephrine (NE) concentration was measured. In the morning, shortly after end of sleep, plasma NE concentration was significantly increased under clozapine treatment in both populations. The effects of clozapine were explained with a direct pharmacological action of the drug on NE receptors.