What Are MAO Inhibitors?

What are MAOIs?
Monoamine oxidase inhibitors (MAOIs) are a class of medication used to treat depression. They were introduced in the 1950s as the first drugs for depression. Today, they’re less popular than other depression medications, but some people benefit from their use.

Read on to learn more about MAOIs, including how they work, who they might help, and what foods to avoid while taking them.

How do MAOIs work?
MAOIs work with the chemicals in your brain called neurotransmitters that allow brain cells to communicate with each other. Depression is thought to be caused by low levels of the neurotransmitters dopamine, serotonin, and norepinephrine, which collectively are called monoamines. A chemical found naturally in the body, monoamine oxidase, removes these neurotransmitters.

By inhibiting monoamine oxidase, MAOIs allow more of these neurotransmitters to remain in the brain, thus elevating mood through improved brain cell communication.

Tyramine and foods to avoid
One downside to MAOIs is that they come with dietary restrictions because of the elevated tyramine levels in the blood.

When this class of drug first entered the market, no one knew about the concerns over tyramine and blood pressure. This caused a wave of deaths that prompted further research. Now we know that certain foods contain excess tyramine, and these should be avoided when taking MAOIs.

The more food ages, the more concentrated the levels of tyramine become. This is true for aged meats, cheeses, and even leftovers in your fridge. Foods with dangerously high levels of tyramine include:

soy sauce and other fermented soy products
salami and other aged or cured meats
Other foods that contain high levels of tyramine are:

aged cheeses, such as Brie, cheddar, Gouda, Parmesan, Swiss, and blue cheese
alcohol, especially chianti, vermouth, and beers
fava beans
raisins, dates, and other dried fruits
all nuts

Other precautions
Besides blood pressure problems, people taking MAOIs should also beware of a condition called serotonin syndrome. Symptoms can include:

irregular or rapid heartbeat
dilated pupils
occasional unconsciousness
The condition can manifest if a person on MAOIs takes other antidepressants or the herbal supplement St. John’s wort.

To avoid serotonin syndrome, people taking MAOIs shouldn’t take anything for two weeks when ending MAOI treatment and starting another.

Types of MAOIs
These days, MAOIs are rarely the first choice of prescription medication to treat depression. However, the U.S. Food and Drug Administration (FDA) — the regulating agency of all prescription medication — has approved the following MAOIsTrusted Source:

isocarboxazid (Marplan): can take three to six weeks to fully take effect
phenelzine (Nardil): can take up to four weeks to fully work
tranylcypromine (Parnate): can take up to 3 weeks to achieve its desired effects

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