Phenelzine is effective in patients with depression clinically characterized as atypical, nonendogenous, or neurotic; these patients often have mixed anxiety and depression and phobic or hypochondriacal features. Less conclusive evidence that drug is useful in severely depressed patients with endogenous features.
Because of potential for serious adverse effects and necessity of dietary restrictions, MAO inhibitors (e.g., phenelzine, tranylcypromine) generally are not used as initial therapy for major depressive disorder, but are reserved for carefully selected patients who can be closely supervised and who have depression refractory to other antidepressants (e.g., SSRIs, SNRIs, TCAs) or in whom other therapies are contraindicated.
Eating Disorders
Phenelzine has been used with some success in the management of bulimia nervosa†.
However, MAO inhibitors are potentially dangerous (e.g., risk of hypertensive crisis) in patients with eating disorders and should be used with caution in patients with chaotic binge eating and purging behaviors. MAO inhibitors currently are not recommended as first-line therapy in the management of bulimia nervosa.
Dosage and Administration
General
Allow at least 2 weeks to elapse between discontinuance of phenelzine therapy and initiation of a TCA or buspirone or discontinuance of another MAO inhibitor and initiation of phenelzine.
Allow at least 2 weeks to elapse between discontinuance of an SSRI and initiation of phenelzine and vice versa. Also allow at least 5 weeks to elapse when switching from fluoxetine.
Allow at least 2 weeks to elapse between discontinuance of phenelzine and initiation of bupropion.
Allow at least 5 or 7 days to elapse between discontinuance of duloxetine or venlafaxine, respectively, and initiation of phenelzine and at least 2 weeks between discontinuance of phenelzine and initiation of duloxetine or venlafaxine.
Patients receiving phenelzine should be monitored for possible worsening of depression, suicidality, or unusual changes in behavior, especially at the beginning of therapy or during periods of dosage adjustment. (See Worsening of Depression and Suicidality Risk under Cautions.)
Administration
Oral Administration
Administer orally.
Dosage
Available as phenelzine sulfate; dosage expressed in terms of phenelzine.
Individualize dosage carefully according to individual requirements and tolerance; use lowest possible effective dosage.
Adults
Major Depressive Disorder
Oral
Usual initial dosage: 15 mg 3 times daily; dosage should then be increased fairly rapidly, depending on the patient’s tolerance and therapeutic response, to ≥60 mg daily. Dosages ≤90 mg daily may be required in some patients to obtain sufficient MAO inhibition. Many patients do not respond clinically until receiving 60 mg daily for ≥4 weeks.
Maintenance dosage: After maximum benefit is obtained, usually in 2–6 weeks, slowly reduce dosage over several weeks to a maintenance level. Maintenance dosage may be as low as 15 mg daily or every other day.
Eating Disorders
Oral
Dosages used for management of bulimia nervosa† have been similar to those used for the treatment of major depressive disorder. (See Major Depressive Disorder under Dosage and Administration.)
Special Populations
Geriatric Patients
Select dosage cautiously, usually starting with dosage at the lower end of recommended range since renal, hepatic, and cardiovascular function and concomitant disease and other drug therapy are more common. (See Geriatric Use under Cautions.)
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