When people with depression do not respond to common antidepressants like Prozac or cannot tolerate their side effects, doctors may prescribe monoamine oxidase (MAO) inhibitors, a type of drug that targets chemical imbalances in the brain that may cause depression. Sold as a tablet or capsule under a variety of brand names, the drugs reduce the amount of monoamine oxidase, a chemical substance that breaks down neurotransmitters and causes imbalances in the brain. When these neurotransmitters are properly balanced, symptoms of depression often diminish.

Medications such as isocarboxazid (Marplan), phenelzine sulfate (Nardil), and tranylcypromine sulfate (Parnate) are examples of MAO inhibitors. MAO inhibitors are not recommended for children or teens and are usually not the first medicines prescribed for depression in adults because these drugs have serious side effects when combined with certain foods, beverages, or medications. Dangerously high blood pressure can occur, for example, if an MAO inhibitor is taken with fermented foods that have a high tyramine count—such as cheese, meat or sausage, fava beans, sauerkraut, or overripe fruit. Patients should also avoid alcoholic beverages, nonalcoholic beers or wines, and large amounts of caffeine while taking these drugs and for at least 2 weeks after stopping the medication.

Symptoms of unusually high blood pressure include chest pain, enlarged pupils, irregular heartbeat, severe headache, increased sweating, and a stiff or sore neck, and anyone experiencing them should be checked by a doctor immediately. Other side effects of MAO inhibitors can include dizziness, fainting, dry mouth, difficulty sleeping, blurred vision, loss of sexual desire, and appetite or weight changes—especially in older patients. Like all other antidepressants, MAO inhibitors have a black box warning on their labels regarding an increased risk of suicide, and patients should be monitored carefully for suicidal thoughts or behavior.

Research suggests that MAO inhibitors are as effective as other antidepressants in treating severe depression. In addition, they may be more effective than other antidepressants in treating those who have uncommon symptoms such as sleeping and eating too much or being overly sensitive to rejection.

ADDITIONAL FACTS

  1. Two MAO inhibitors, phenelzine and tranylcypromine, are often prescribed off-label to treat chronic headaches, panic disorder, and Parkinson’s disease and for helping with smoking cessation.
  2. Research on pregnant women has shown an increased risk of birth defects when MAO inhibitors are taken during the first 3 months of pregnancy.
  3. A skin patch form of the drug selegiline (Emsam) was approved in 2006. Since the drug doesn’t enter the gastrointestinal tract, this delivery method eliminates the dangers of dietary interactions.