Mayo Clinic Health Manager

Get free personalized health guidance for you and your family.

Get Started

Free

E-Newsletter

Subscribe to receive the latest updates on health topics. About our newsletters

  • Housecall
  • Alzheimer's caregiving
  • Living with cancer

Monoamine oxidase inhibitors (MAOIs)

MAOIs have the longest history of all the antidepressant classes. Discover how the recently developed MAOI skin patch for depression works and what side effects and risks MAOIs may cause.

By Mayo Clinic staff

Monoamine oxidase inhibitors (MAOIs) were the first type of antidepressant in use, dating back to the 1950s.

How MAOIs work

Researchers believe MAOIs relieve depression by preventing the enzyme monoamine oxidase from metabolizing the neurotransmitters norepinephrine (nor-ep-ih-NEF-rin), serotonin (ser-oh-TOE-nin) and dopamine (DOE-puh-mene) in the brain. As a result, these levels remain high in the brain, boosting mood.

Antidepressants, in general, may also work by playing a neuroprotective role in how they relieve anxiety and depression. It's thought that antidepressants may increase the effects of brain receptors that help nerve cells keep sensitivity to glutamate — an organic compound of a nonessential amino acid — in check. This increased support of nerve cells decreases glutamate sensitivity, providing protection against the glutamate overwhelming and exciting key brain areas related to anxiety and depression.

Therapeutic effects of antidepressants may vary in people, due in part to each person's genetic makeup. It's thought that people's sensitivity to antidepressant effects, especially selective serotonin reuptake inhibitor effects, can vary depending on:

  • How each person's serotonin reuptake receptor function works
  • His or her alleles — the parts of chromosomes that determine inherited characteristics, such as height and hair color, that combine to make each person unique

Antidepressant medications are often the first treatment choice for adults with moderate or severe depression, sometimes along with psychotherapy. Although antidepressants may not cure depression, they can help you achieve remission — the disappearance or nearly complete reduction of depression symptoms.

MAOIs approved to treat depression

Here are the MAOIs that have been specifically approved by the Food and Drug Administration to treat depression, with their generic, or chemical, names followed by available brand names in parentheses:

  • Phenelzine (Nardil)
  • Tranylcypromine (Parnate)
  • Isocarboxazid (Marplan)
  • Selegiline (Emsam)

Emsam is the first skin (transdermal) patch for depression. You apply a new Emsam patch to your torso, thigh or upper arm each day, allowing the medication to be absorbed into your bloodstream over a 24-hour period.

Some of these medications may also be used to treat conditions other than depression.

Side effects of MAOIs

Because they can cause serious side effects and safety concerns, MAOIs are usually reserved for people whose depression doesn't improve with other antidepressant medications they've tried first.

Side effects of MAOIs include:

  • Drowsiness
  • Constipation
  • Nausea
  • Diarrhea
  • Stomach upset
  • Fatigue
  • Dry mouth
  • Dizziness
  • Low blood pressure
  • Lightheadedness, especially when getting up from a lying or sitting position
  • Decreased urine output
  • Decreased sexual function
  • Sleep disturbances
  • Muscle twitching
  • Weight gain
  • Blurred vision
  • Headache
  • Increased appetite
  • Restlessness
  • Shakiness
  • Trembling
  • Weakness
  • Increased sweating
Next page
(1 of 2)
References
  1. Questions and answers on antidepressant use in children, adolescents, and adults. U.S. Food and Drug Administration. http://www.fda.gov/cder/drug/antidepressants/QA20070502.htm. Accessed Sept. 29, 2008.
  2. FDA proposes new warnings about suicidal thinking, behavior in young adults who take antidepressant medications. U.S. Food and Drug Administration. http://www.fda.gov/bbs/topics/NEWS/2007/NEW01624.html. Accessed Sept. 12, 2008.
  3. Hall-Flavin DK (expert opinion). Mayo Clinic, Rochester, Minn. Sept. 25, 2008.
  4. Ultram (prescribing information). Mississaugo, Ontario, Canada: Biovail Corp.; 2007. http://www.ortho-mcneil.com/ortho-mcneil/shared/pi/ultramer.pdf. Accessed Oct. 5, 2008.
  5. Single interactions table. Micromedex Healthcare Series. http:www.micromedex.com. Accessed Oct. 14, 2008.
  6. Demerol (prescribing information). Bridgewater, N.J.: Sanofi-Aventis; 2007. http://products.sanofi-aventis.us/demerol/demerol.pdf. Accessed Oct. 15, 2005.
  7. Single interactions table. Micromedex Healthcare Series. http:www.micromedex.com. Accessed Oct. 14, 2008.
  8. Monoamine oxidase inhibitors. Drug Facts & Comparisons. http://online.factsandcomparisons.com/MonoDisp.aspx?monoID=fandc-hcp11283&inProdGen=true&quick=monoamine%20oxidase%20inhibitors&search=monoamine%20oxidase%20inhibitors. Accessed Oct. 21, 2008.
  9. Nardil (prescribing information). New York, N.Y.: Pfizer; 2007. http://media.pfizer.com/files/products/uspi_nardil.pdf. Accessed Oct. 21, 2008.
  10. Antidepressants: Selecting one that's right for you. MayoClinic.com. http://www.mayoclinic.com/health/antidepressants/HQ01069. Accessed Oct. 16, 2008.

MH00072

Dec. 10, 2008

© 1998-2009 Mayo Foundation for Medical Education and Research (MFMER). All rights reserved. A single copy of these materials may be reprinted for noncommercial personal use only. "Mayo," "Mayo Clinic," "MayoClinic.com," "EmbodyHealth," "Reliable tools for healthier lives," "Enhance your life," and the triple-shield Mayo Clinic logo are trademarks of Mayo Foundation for Medical Education and Research.

Print Share Reprints

Text Size: smaller largerlarger