Monoamine oxidase inhibitors (MAOIs) were the first antidepressants found to be effective in clinical use. Their discovery was serendipitous; the anti-tuberculosis agent, iproniazid, was noted to improve depressive symptoms in patients with tuberculosis. It was found that the antidepressant effect was related to inhibition of monoamine oxidase (MAO) (1-3). Currently, four MAOIs are approved and marketed for treatment of depression in the United States: phenelzine, tranylcypromine, transdermal selegiline, and isocarboxazid. Off-label “high-dose” selegiline is also considered a classic MAOI (4). Rasagiline, safinamide, and “low-dose” oral selegiline (10mg daily or less) are selective MAO Type B inhibitors approved for treatment of Parkinson’s disease. Iproniazid, while widely used initially, was removed from the market because of hepatotoxicity. An additional MAOI, moclobemide, is approved for the treatment of depression in Europe, Canada, and Australia. While methylene blue, linezolid, and procarbazine also have MAOI properties, further discussion is outside the scope of this toolkit. The toolkit provides information on:
