MAOIs

Summary

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      • MAOIs should be withdrawn 14 days before starting an SSRI or TCA (and vice versa)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