Efficacy and tolerability of tranylcypromine versus phenelzine: a double-blind study in antidepressant-refractory depressed inpatients

Background: The aim of this study was to examine whether phenelzine is a suitable alternative to tranylcypromine in antidepressant-resistant depression. Method: A total of 77 severely depressed inpatients, meeting the DSM-IV criteria for major depressive disorder, who failed to respond to fixed plasma level treatment with either tricyclic antidepressants or fluvoxamine were withdrawn from psychotropic medication and included in a double-blind flexible-dose 5-week comparison of tranylcypromine and phenelzine. Results: Of the 77 patients, 67 (87%) completed the trial, of whom 35 (52%) responded. No significant differences in response between both drugs were observed. Seventeen (44%) of 39 patients responded to tranylcypromine and 18 (47%) of 38 to phenelzine (≥ 50% reduction in Hamilton Rating Scale for Depression [HAM-D] score). The mean reduction in HAM-D score was 10.4 ± 8.3 for the tranylcypromine sample versus 8.3 ± 8.4 for the phenelzine-treated patients. Only a few patients (10%) used concomitant psychotropic medication. A substantial number of patients experienced severe side effects, mainly dizziness, agitation, and insomnia; the incidence was the same in both samples (21%). Conclusion: No difference in efficacy was observed between both monoamine oxidase inhibitors in a sample of patients with severe antidepressant-refractory depression. Phenelzine appears to be a suitable alternative to tranylcypromine.

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