Monoamine oxidase inhibitors

Monoamine oxidase inhibitors (MAOIs) are a unique class of antidepressants used mainly for treatment-resistant depression and certain neurological conditions. They were among the first antidepressants developed and are still prescribed today when other antidepressant medications have not worked. MAOIs affect brain chemicals that influence mood, movement, and alertness. While effective, they require careful use because of food interactions, drug interactions, and safety concerns. With proper guidance from healthcare providers and pharmacists, MAOIs can be a helpful option for selected patients.

Monoamine oxidase inhibitors (MAOIs) are a type of antidepressant that changes how the brain breaks down neurotransmitters. Neurotransmitters such as serotonin, dopamine, and norepinephrine play a major role in mental health and mood regulation. MAOIs are sometimes used for major depressive disorder, atypical depression, bipolar disorder (off-label), and Parkinson’s disease. Because of safety risks, MAOIs are usually prescribed by specialists in psychiatry or neurology.

Monoamine oxidase inhibitors (MAOIs) work by blocking the monoamine oxidase enzyme. This enzyme normally breaks down amines like serotonin, dopamine, and norepinephrine in the central nervous system (CNS). There are two main forms of the enzyme: monoamine oxidase A (MAO-A) and monoamine oxidase B (MAO-B). MAO-A mainly breaks down serotonin and norepinephrine, while MAO-B mainly affects dopamine.

By inhibiting these enzymes, MAOIs increase levels of neurotransmitters in the brain. This mechanism of action can improve mood, energy, and focus. Some MAOIs are non-selective and block both MAO-A and MAO-B, while others are selective MAO-B inhibitors used mainly in the treatment of Parkinson’s disease. Because MAOIs work differently from selective serotonin reuptake inhibitors (SSRIs) or other classes of antidepressants, they may help when other treatments fail.

There are several MAOIs available, including oral medications and a skin patch:

• Phenelzine (Nardil)
• Tranylcypromine (Parnate)
• Isocarboxazid (Marplan)
• Selegiline (Emsam skin patch, oral forms for Parkinson’s disease)
• Rasagiline (Azilect)
• Safinamide (Xadago)
• Moclobemide (not available in the U.S.)

Phenelzine, tranylcypromine, and isocarboxazid are non-selective MAOIs used mainly for depression. Selegiline, rasagiline, and safinamide are selective MAO-B inhibitors commonly used in Parkinson’s disease.

Monoamine oxidase inhibitors are used primarily for the treatment of depression, especially treatment-resistant depression and atypical depression. They may be considered when SSRIs, SNRIs, tricyclic antidepressants, or other antidepressants are not effective.

Other uses include:

• Treatment of Parkinson’s disease
• Off-label use for certain anxiety or mood disorders
• Rare cases of bipolar disorder under close supervision

Because MAOIs affect dopamine, they are especially useful in movement disorders and some forms of depression that involve low energy, excessive sleep, or increased appetite.

Common side effects of MAOIs include:

• Weight gain
• Dizziness
• Dry mouth
• Constipation
• Drowsiness or insomnia
• Sexual side effects

Serious side effects include:

• Serotonin syndrome
• Hypertensive crisis with symptoms such as severe headache, chest pain, nausea, and high blood pressure (if MAOIs are taken with foods high in tyramine, such as aged cheese, cured meats, or certain fermented foods)

These are not all of the possible side effects of Monoamine Oxidase Inhibitors. You should always seek medical advice from your healthcare provider for any questions or concerns about your medical condition or treatment. Read all patient information, medication guides, or drug information sheets that come with this medication. You can also report adverse effects to the U.S. Food and Drug Administration at www.fda.gov/medwatch or 1-800-FDA-1088.

Although these medications are generally well-tolerated and safe, there are certain warnings, precautions, and drug interactions you should be aware of.

Warnings

Before starting monoamine oxidase inhibitors, it is crucial to discuss any existing health conditions with your healthcare provider. You should be sure that your healthcare provider is aware of all your medical conditions, including if you have:

• High blood pressure or heart disease
• A history of stroke
• Liver disease
• Bipolar disorder

-Parkinson’s disease

• Frequent headaches or migraines

Dietary restrictions are very important with MAOIs. Avoiding tyramine-containing foods is essential to prevent a hypertensive crisis. Pharmacists play a key role in educating patients on safe food choices.

Boxed Warning

The use of MAOIs carries warnings related to severe drug interactions and the risk of hypertensive crisis and serotonin syndrome. Combining MAOIs with certain antidepressants, opioids, or antibiotics like linezolid or methylene blue can be life-threatening. A washout period is required when switching to or from MAOIs.

They also have a boxed warning for an increased risk of suicidal thoughts and behaviors in children, adolescents, and young adults. This requires close monitoring, especially when first starting the medication or with dose changes.

Contraindications

MAOIs should not be used in people taking SSRIs, SNRIs, other antidepressants, or certain migraine medications. They are also contraindicated in patients with pheochromocytoma, severe cardiovascular disease, or known hypersensitivity. Use in children and adolescents is limited and closely monitored due to the risk of suicidal thoughts.

Drug interactions

When monoamine oxidase inhibitors are taken with other prescription drugs, over-the-counter medications, vitamins, and supplements, it may change how they work or increase the frequency or severity of side effects. Make sure that you tell your healthcare professional about anything that you are taking to avoid any negative drug interactions, including:

• Selective serotonin reuptake inhibitors and other antidepressants
• Certain opioids
• Decongestants and cold medicines
• Linezolid and methylene blue
• Stimulants and some herbal supplements

Always check with a healthcare professional before starting or stopping any medication.