MAOIs are a class of antidepressants and include the drugs isocarboxazid, phenelzine, and tranylcypromine. These drugs are used to treat depression, although they are not first-line treatments due to their side effects and dangerous food and drug interactions. Notably, MAOIs can cause a hypertensive crisis, especially if patients consume foods containing tyramine, like wine, cheese, and processed meats. MAOIs can also cause serotonin syndrome, a life-threatening condition resulting from overload of serotonin signaling. As such, MAOIs should not be given within 14 days of taking any other serotonin-altering drug.

Key Points

  • Key Drugs
    • Isocarboxazid
    • Phenelzine
    • Tranylcypromine
    • Selegiline
    • Rasagiline
    • Mechanism
      • Antidepressant
        • Inhibits the enzyme monoamine oxidase, thus increasing norepinephrine, serotonin, dopamine, and epinephrine levels in the brain.
    • Clinical Use
      • Depression
        • Because of severe adverse reactions of drug/food interactions, MAOIs are generally only used if other medications have been proved ineffective in treatment
      • Parkinson’s Disease
        • Selegiline and Rasagiline only (MAO-B inhibitors)
    • Side Effects and Adverse Reactions
      • Hypertensive Crisis
        • Extremely high blood pressure that can lead to stroke, often accompanied by symptoms such as headache, tachycardia, neck stiffness, etc.
        • Avoid foods containing tyramine as eating them can lead to a hypertensive crisis
          • Found in aged cheese, processed meats, wine, yogurt, pickled foods, avocados, chocolate, etc.
        • Hypertensive crisis may also occur with concurrent use of vasoconstrictors and cold medications that contain phenylephrine and pseudoephedrine
        • Closely monitor blood pressure and tell patient to report any signs of a hypertensive crisis
        • Educate patient to consult with provider before taking over the counter medications, as MAOIs have several drug interactions
      • Serotonin Syndrome
        • Symptoms include agitation, restlessness, confusion, tachycardia, hypertension, muscle rigidity
        • MAOIs should be withdrawn 14 days before starting an SSRI or TCA (and vice versa)
          • Concurrent use with other serotonin altering medications increases risk for serotonin syndrome
      • Hypoglycemia
        • MAOIs can increase the hypoglycemic effect of insulin and oral diabetic medications
      • Orthostatic hypotension
      • Anticholinergic effects