Cardiovascular effects of phenelzine and amitriptyline in depressed outpatients

Blood pressure and ECG changes were monitored in depressed outpatients treated for 6 weeks with amitriptyline, 150 mg/day, or phenelzine, 60 mg/day, as part of an ongoing double-blind study. Phenelzine produced significant decreases in blood pressure and a significant increase in orthostatic fall in pressure. Amitriptyline produced little overall change in blood pressure. The degree of MAO inhibition in phenelzine-treated patients was significantly correlated with blood pressure. Tricyclic plasma concentrations were also related to some blood pressure measures. Reported dizziness/faintness did not correlate with blood pressure changes in either group. Amitriptyline significantly increased heart rate, while phenelzine produced slowing. Amitriptyline was associated with significant prolongation of QRS and QTc but not PR intervals. Phenelzine produced significant shortening of the QTc interval.