Monoamine oxidase inhibitors (MAOIs) are medications used to treat depression and certain neurological disorders. MAOIs work by blocking monoamine oxidase (MAO), a substance in the cells of most tissues that is involved in processing neurotransmitters such as dopamine, norepinephrine and serotonin. By blocking the action of MAO, the neurotransmitters remain at high levels in the brain.

MAOIs are often used to treat Parkinson’s disease. Patients with Parkinson’s disease experience destruction of the brain cells that produce dopamine, a chemical that is essential to the brain’s ability to direct the body on how and when to move. Some types of MAOIs help prevent the breakdown of dopamine.

Other neurological disorders that can benefit from MAOI treatment include:

• Multiple system atrophy
  
• Cataplexy (sudden loss of muscle tone or strength)
  
• Dopa-responsive dystonia (DRD)
  
• Hypersomnia
  
• Panic disorder

MAOIs should not be used by patients with epilepsy as they can increase the risk of seizures. In addition, individuals who take MAOIs are usually advised to adhere closely to a medication and diet regimen that will reduce the risk of drug interactions and adverse effects on blood pressure. Side effects that can occur include insomnia, nausea, confusion and hallucinations. Symptoms of MAOI overdose can be similar to the medication’s side effects, but are usually more severe.

Patients should consult their physicians before taking any additional prescriptions, over-the-counter medications or nutritional or herbal supplements. Because of the risk of experiencing serious hypertensive side effects, patients taking MAOIs are generally advised to carry identification cards or to wear identification bracelets that indicate that they are taking these medications.

MAOIs are not typically prescribed for children or for adults over the age of 60. Women who are pregnant or are thinking about becoming pregnant should consult their physician before taking these drugs as studies have indicated that MAOIs may cause birth defects.

Monoamine oxidase inhibitors (MAOIs) are one category of antidepressants used to treat some forms of depression and certain neurological (nervous system) disorders. MAOIs were introduced in the 1950s as the first antidepressant. These drugs are now less frequently prescribed for depression because of their potential for severe side effects, which includes an adverse hypertensive (high blood pressure) reaction. However, MAOIs are still used to treat some disorders, particularly Parkinson’s disease, in which case it is sometimes used in conjunction with the dopamine precursor levodopa.

MAOIs work by blocking the action of an enzyme (a protein that catalyzes specific biochemical reactions) called monoamine oxidase (MAO). MAO metabolizes certain neurotransmitters including dopamine, norepinephrine and serotonin. The enzyme comes in two forms, known as MAO type A and MAO type B. Both MAO types A and B break down dopamine. MAO type A is primarily responsible for breaking down serotonin and norepinephrine. MAOI medications are designed to block these actions to allow neurotransmitters to remain at high levels in the brain. This may help to alleviate the symptoms of neurological disorders (e.g., Parkinson’s disease) that are caused by low levels of certain neurotransmitters.

MAOI medications are designed to affect either MAO type A or MAO type B. Type B MAOIs are generally used to treat the movement symptoms of Parkinson’s disease. This is achieved by blocking the breakdown of dopamine, a neurotransmitter responsible for controlling movement and coordination. The MAOI primarily used to treat this disease is selegiline (Emsam, Deprenyl, Eldepryl or Movergan). Selegiline can help reduce motor fluctuations in Parkinson’s patients and increase the effectiveness of levodopa. In 2006, the Food and Drug Administration (FDA) also approved the type B MAOI rasagiline (Azilect) to treat Parkinson’s disease.

Type A MAOIs are used to treat anxiety and depression, which may be caused by low levels of serotonin or norepinephrine. Although type A MAOIs also prevent the breakdown of dopamine, they may be unsuitable for patients with Parkinson’s disease because of the possibility of interactions with other Parkinson’s medications. Type A MAOIs include:

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

Most MAOIs are available in tablet form. However, the FDA recently approved an MAOI in the form of a skin patch that is applied daily. 

It takes time for the enzyme-blocking action of MAOIs to improve patient symptoms. Patients who take MAOIs will usually begin to feel beneficial effects within two to three weeks.

In rare cases, people taking MAOIs (particularly type A MAOIs) may experience a hypertensive crisis, a sudden increase in blood pressure that can result in a stroke. Certain foods and beverages may increase the risk of experiencing this side effect. Therefore, people who are taking type A MAOIs should closely adhere to a medication and diet regimen that will reduce the risk of this type of reaction. They should be advised to carry an identification card that details any foods and beverages that should be avoided. Patients taking any type of MAOI should talk with their physician about which foods and beverages they should avoid.

Monoamine oxidase inhibitors (MAOIs) are often used to treat the movement symptoms of Parkinson’s disease. Patients with Parkinson’s disease experience destruction of the brain cells that produce dopamine, a neurotransmitter that is essential for movement. MAOIs help prevent the breakdown of dopamine, enabling what little dopamine that is produced to stay in the brain for longer. Some experts believe that type B MAOIs may also help slow the progression of Parkinson’s disease, but this has not been conclusively established with medical research.

Other neurological disorders that may benefit from MAOI treatment include:

• Multiple system atrophy (MSA). A neurodegenerative disease characterized by symptoms that affect movement, blood pressure and other body functions. MAOIs are used to treat low blood pressure associated with this condition.
  
  
• Cataplexy. A sudden loss of muscle tone or strength often associated with narcolepsy. Antidepressant medications such as MAOIs often help reduce cataplexy.
  
  
• Dopa responsive dystonia (DRD). Genetic disorder most often diagnosed in children between the ages of 6 and 16. It often is evident in a patient’s manner of walking, which may be stiff-legged. Like Parkinson’s disease, it is caused by damage to cells that produce dopamine.
  
  
• Hypersomnia. Condition in which a person experiences excessive sleepiness. In some cases, hypersomnia is the result of neurological damage, which may be treated using MAOIs.
  
  
• Panic disorder. Condition in which patients experience frequent panic attacks, which are episodes of intense fear that unfold within minutes. MAOIs appear to reduce anxiety in patients with this condition.

Patients may not be good candidates for some types of monoamine oxidase inhibitors (MAOIs) treatment if they have been diagnosed with certain neurological conditions, such as epilepsy. MAOIs may increase the occurrence of seizures in people with epilepsy. Other conditions that may preclude the use of MAOIs include the following:

• Alcoholism
  
• Angina (chest pain)
  
• Severe or frequent headaches
  
• Diabetes
  
• Heart or blood vessel disease
  
• Kidney or liver disease
  
• History of recent heart attack or stroke
  

  

• Overactive thyroid
  
• Pheochromocytoma (adrenal gland tumor that may cause hypertension)

It is important for patients to provide a complete family medical history. This should include information on whether other family members have ever had depression or other psychiatric disorders, or if the patient or any members of the patient’s family have ever attempted suicide.

The side effects of monoamine oxidase inhibitors (MAOIs) may range from mild to severe depending on the individual’s dosage and certain lifestyle factors. The most common side effects experienced by patients include:

• Nausea
  
• Sedation
  
• Insomnia
  
• Agitation
  
• Confusion
  
• Orthostatic hypotension
  
• Constipation
  
• Fatigue
  
• Dry mouth
  
• Decreased urine output
  
• Decreased sexual function
  
• Muscle twitching
  
• Increased appetite and weight gain
  
• Blurred vision
  
• Trembling
  
• Increased perspiration

Patients using the selegiline transdermal patch can experience slight redness or a mild rash at the site where the skin patch was applied.

In most cases, the dosage level of MAOI used to treat Parkinson’s disease is low and rarely causes side effects. The most common side effects experienced when MAOIs are used to treat Parkinson’s disease are insomnia and nausea. Less commonly, patients can experience confusion and hallucinations.

Taking some MAOIs, particularly type A MAOIs, in higher dosages can cause adverse hypertensive (high blood pressure) reactions that can have serious health consequences. Patients can reduce their risk of this side effect through diet restriction and avoidance of certain foods (e.g., fermented meats, over-ripe fruits and vegetables).  

Patients should seek immediate medical attention if they experience a severe, pounding headache in the lower back of the skull, which may indicate a hypertensive reaction. Other symptoms associated with this type of hypertensive reaction include sweating, palpitations and increased blood pressure.

Patients should be aware that a physician might need to adjust the dosage or change medications to achieve the best results with minimal side effects. In addition, the FDA has advised that antidepressants can increase the risk of suicidal thinking in some patients. All people being treated with MAOIs should be monitored closely for behavioral changes.

Patients should consult their physicians before taking any additional prescriptions, over-the-counter medications, or nutritional or herbal supplements.

Use of sympathomimetic drugs (medications that stimulate part of the autonomic nervous system) such as decongestants can cause a hypertensive reaction, a sudden increase in blood pressure that can lead to a stroke. Patients should avoid any cold, sinus and allergy medications containing the ingredients pseudoephedrine, phenylephrine or phenylpropanolamine. They should also avoid the following during MAOI therapy and for two weeks afterward:

• Amphetamines
  
• Meperidine (an opioid pain reliever)
  
• Methylphenidate
  
• Carbamazepine
  
• Antidiabetic agents
  
• Antihypertensive medications
  
• Buspirone (anti-anxiety drug)
  
• Diet medications
  
• Disulfiram (alcohol addiction drug)
  
• Isoproterenol (bronchodilator)
  
• Local anesthetic drugs containing ephedrine or cocaine
  
• Certain herbal medications (e.g., St. John’s wort)

Additionally, certain foods may increase the risk of a hypertensive reaction in people who are taking type A MAOIs. Type A MAOIs prevent the amino acid tyramine from being broken down in the body. Tyramine occurs naturally in the body and helps to regulate blood pressure. Certain foods and beverages also contain tyramine. Thus consuming these substances while taking type A MAOIs increases the likelihood of toxicity in the body. Toxic levels of tyramine may lead to a sudden increase in blood pressure. This is a rare occurrence, but in extreme cases it could cause the patient’s death.

Because the tyramine content in foods increases as they age, foods should be eaten when they are freshest, and leftovers and foods prepared hours earlier should be avoided. Foods that are high in tyramine and should not be consumed during MAOI therapy (and for two weeks afterward) include:

• Smoked fish or fish eggs
  
• Fermented, aged or smoked meats and sausage
  
• Over-ripe fruits and vegetables of any kind (especially avocado, banana, raisins, figs)
  
• Sauerkraut
  
• Beef bouillon
  
• Soy sauce
  
• Cheeses, yogurt, sour cream
  
• Pickled foods
  
• Chocolates
  
• Fava beans
  
• Food or beverages containing caffeine
  
• Beer, including alcohol-free varieties
  
• Wine, including alcohol-free varieties

Certain foods and beverages may be safe for people taking MAOIs when eaten in moderation (e.g., fresh bread, caffeine, avocados, bananas). In addition, patients taking low doses of type B MAOIs, including the lowest available doses of the selegiline patch (6 milligrams per 24 hours), generally do not have to restrict their diets as they would if they were taking type A MAOIs in tablet form or receiving higher doses of the drug. However, patients are urged to consult their physician about whether it is safe to consume tyramine while taking any form of MAOI.

MAOIs should not be taken with other forms of MAOI or other antidepressants, especially selective serotonin reuptake inhibitors (SSRIs). Combining MAOIs with other antidepressants can lead to serotonin syndrome, a potentially fatal condition marked by fever, confusion, fluctuations in heart rhythms and blood pressure, increased perspiration, muscle rigidity, seizures, and problems with the liver or kidneys.

Patients who switch from using MAOIs to using another antidepressant are usually required to allow at least 14 days to elapse before beginning therapy with the new drug to avoid potentially serious side effects. Similar caution must be exercised when switching from another antidepressant to MAOI therapy.

Patients taking MAOIs should avoid elective surgery requiring general anesthesia because of the increased risk of side effects from the anesthetic. MAOIs should be discontinued at least 10 days prior to elective surgery.

Smoking tobacco may reduce the effectiveness of MAOIs. Therefore, patients should inform the physician if they smoke or use other tobacco products.

Symptoms of monoamine oxidase inhibitor (MAOI) overdose can be similar to the medication’s side effects, but are usually more severe. They may start slowly over a period of 24 to 48 hours and can persist for two weeks. They may progress to coma and, in some cases, death. Patients exhibiting any of these signs and symptoms should contact their physician immediately:

• Agitation
  
• Flushing
  
• Tachycardia (rapid heart rate)
  
• Hypotension (low blood pressure) or hypertension (high blood pressure)
  
• Palpitations
  
• Increased motor activity
  
• Twitching
  
• Increased deep tendon reflexes
  
• Seizures
  
• Hyperpyrexia (abnormally high fever)
  
• Cardiorespiratory arrest

Women who are pregnant, contemplating pregnancy, and women who are breastfeeding should consult a physician before using monoamine oxidase inhibitors (MAOIs).

Some studies have indicated that MAOIs can cause an increased rate of birth defects when taken during the first three months of pregnancy. In animal studies, these drugs caused a slowing of growth and an increase in excitability in newborns when administered in large doses.

Some types of MAOIs (e.g., tranylcypromine) pass into breast milk. It is unknown whether or not other MAOIs also pass into breast milk.

Preparing questions in advance can help patients to have more meaningful discussions with healthcare professionals regarding their condition. Patients may wish to ask their doctor the following questions related to monoamine oxidase inhibitors (MAOIs):

1. Why do you believe that an MAOI would be a good treatment for my neurological condition?
   
   
2. I’ve heard that MAOIs have significant health risks. What do these risks include?
   
   
3. Does my medical condition preclude the use of certain MAOIs?
   
   
4. Which MAOI are you prescribing for me?
   
   
5. Are there any foods or beverages that I should avoid while taking MAOIs?
   
   
6. Are there any over-the-counter drugs that I should avoid while taking MAOIs?
   
   
7. Are there any prescription medications that I should avoid while taking MAOIs?
   
   
8. Will MAOI treatment affect my pregnancy?
   
   
9. Which side effects, if any, should I report immediately to you?
   
   
10. What should I do if I miss a dose?