Selective and nonselective monoamine oxidase inhibitors: behavioral disturbances during their administration to depressed patients.

The occurrence of behavioral disturbances during four-week treatment of depressed patients with the nonselective monoamine oxidase (MAO) inhibitor, phenelzine sulfate (N = 14), the selective MAO-type A inhibitor, clorgyline (N = 12), and the partially selective MAO-type B inhibitor, pargyline hydrochloride (N = 13), was studied. Behavioral disturbances were encountered during treatment with each of the MAO-inhibiting drugs, with an overall incidence of 15% (six of 39 patients). All but one episode met criteria for mania or hypomania. Patients with bipolar illness experienced significantly greater incidences of behavioral disturbances in comparison with patients with unipolar illness (35.3% v 4.5%, respectively). The earliest latency to onset of a behavioral disturbances was 18 days, whereas the mean latencies were 22 to 26 days. Episodes of hypomania were observed after discontinuation of drug treatment in individual patients with unipolar and bipolar illness. Repeated MAO-inhibitor treatment, as part of a crossover study of clorgyline and pargyline, produced an increased severity of behavioral disturbances and a significantly shortened latency to onset.