MAOIs – Monoamine oxidase inhibitors

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

Safety concerns with MAOIs
MAOIs can cause dangerous interactions with certain foods and beverages. If you take MAOIs, you’ll face dietary restrictions that require you to limit consumption of foods that contain a high level of tyramine, such as many cheeses, pickled foods, chocolates, certain meats, beer, wine, and alcohol-free or reduced-alcohol beer and wine. The interaction of tyramine with MAOIs can cause a dangerously high increase in blood pressure, which can lead to a stroke. Your doctor can give you a complete list of dietary restrictions.

Emsam may offer a way to avoid these dietary restrictions. At its lowest dose of 6 milligrams a day, you don’t need to follow those dietary restrictions. At higher doses of Emsam, you do, though. Talk to your doctor or mental health provider to see if this may be an option for you.

MAOIs can also cause serious reactions when you take them while you’re also taking certain other medications. Examples of medications to avoid include other antidepressants, certain pain medications such as tramadol (Ultram) and meperidine (Demerol) over-the-counter decongestants and herbal weight-loss products, and St. John’s wort. Always check with your doctor or pharmacist before taking any new prescription medication, over-the-counter medication or supplement while taking MAOIs.

Serotonin syndrome and MAOIs
A rare but potentially life-threatening side effect of MAOIs is serotonin syndrome. This condition, characterized by dangerously high levels of serotonin in the brain, can occur when an MAOI interacts with another type of antidepressant called selective serotonin reuptake inhibitors (SSRIs). Because of this, don’t take any MAOIs while you’re taking any SSRIs or within two weeks of each other. Serotonin syndrome requires immediate medical treatment.

Signs and symptoms of serotonin syndrome include:
* Confusion
* Restlessness
* Hallucinations
* Extreme agitation
* Fluctuations in blood pressure
* Increased heart rate
* Nausea and vomiting
* Fever
* Seizures
* Coma

Stopping treatment with MAOIs
Discontinuation of MAOIs has been associated with nausea, vomiting and malaise. Rarely, discontinuation has caused an uncommon withdrawal syndrome involving vivid nightmares with agitation, psychosis and convulsions. The syndrome is treated with a low-dose MAOI and more gradual tapering off. Talk to your doctor before stopping treatment with MAOIs.

Suicidal feelings and MAOIs
In some cases, antidepressants may be associated with worsening symptoms of depression or suicidal thoughts or behavior in those ages 18 to 24. It’s likely to occur in the first one to two months of treatment or when you change your dosage. Be sure to talk to your doctor about any changes in your symptoms. You may need more careful monitoring when beginning or changing treatment, or you may need to stop the medication if your symptoms worsen. Adults age 65 and older taking antidepressants have a decreased risk of suicidal thoughts.
To nix your irritability, sadness, guilt or anger, work with your doctor or a mental health provider in considering the use of MAOIs to work when other antidepressant medication types haven’t. Feel good again.

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