Tricyclic-induced electroencephalogram abnormalities and plasma drug concentrations.

In a double-blind study of 34 randomly assigned depressed inpatients, antidepressant-induced electroencephalogram (EEG) abnormalities were compared in amitriptyline-treated versus bupropion-treated patients. Drug-free baseline EEGs plus one or more repeat EEGs under pharmacokinetic steady state conditions were obtained. Of the 34 patients, eight developed EEG abnormalities. Seven were on amitriptyline and one was on bupropion (chi 2 = 13.77, df = 3, p less than 0.01). All but one of the amitriptyline-treated patients with EEG abnormalities had plasma concentrations above its therapeutic range (150 to 250 ng/ml), whereas all with normal EEGs were within or below this range.