• Introduction 

• Illustrated mechanism of action 

• Examples of Medication Brand Names (with Images)

• Indication

• Side Effects 

• Precautions & Contraindications 

• Monographs

• Reference 

Introduction to Monoamine Oxidase Inhibitors (MAOIs):

Monoamine oxidase inhibitors (MAOIs) are a class of medications primarily used to treat depression, particularly atypical or treatment-resistant forms. They work by inhibiting the activity of monoamine oxidase enzymes (MAO-A and MAO-B), which are responsible for breaking down neurotransmitters such as serotonin, dopamine, and norepinephrine in the brain. By preventing this breakdown, MAOIs increase the levels of these neurotransmitters, helping to improve mood and emotional stability.

Though effective, MAOIs are often prescribed less frequently than other antidepressants due to their potential for serious interactions with certain foods and medications, requiring dietary restrictions and careful monitoring. Despite these challenges, they remain a valuable option for individuals who have not responded well to other treatments.

The illustration shows the mechanism of action of monoamine oxidase inhibitors (MAOIs) at the synapse between two neurons:

 1. Top part: This is the end of the presynaptic neuron, containing vesicles filled with neurotransmitters like:

Serotonin (red circles) Dopamine (blue squares)

Norepinephrine (orange triangles)

2. When a nerve signal arrives, these neurotransmitters are released into the synaptic cleft (the space between two neurons).

3. Normally, the enzyme monoamine oxidase (MAO) breaks down excess neurotransmitters to regulate their levels.

4. MAOIs (shown as blocking the MAO enzyme with a red "T" symbol) inhibit this enzyme, preventing it from breaking down serotonin, dopamine, and norepinephrine.

5. As a result, more neurotransmitters remain active in the synaptic cleft, which enhances mood and helps relieve symptoms of depression.

Serious: effects 

Hypertensive crisis (after consuming tyramine-rich foods or certain drugs)

Serotonin syndrome (if combined with serotonergic medications)

Mania or hypomania (especially in bipolar patients)

Liver toxicity (rare)

Peripheral edema

Contraindications of MAOIs:

1. Concurrent use with other antidepressants

SSRIs, SNRIs, TCAs, atypical antidepressants, or other MAOIs

Risk of serotonin syndrome or hypertensive crisis

2. Use of sympathomimetic drugs

Includes decongestants (like pseudoephedrine), stimulants, and appetite suppressants 

Can cause severe hypertension

3. Use with meperidine or related opioids (e.g., tramadol, methadone)

May lead to serotonin syndrome or respiratory depression

4. PheochromocytomaTumor that secretes catecholamines; MAOIs can dangerously raise blood pressure

5. Cerebrovascular or cardiovascular disease

Risk of stroke or cardiac complications due to blood pressure effects

6. Severe renal impairment or liver disease

7. History of hypersensitivity to MAOIs

8. Patients undergoing surgery requiring general anesthesia

Risk of unpredictable blood pressure change

9. Children and adolescents

Safety and efficacy not well established

10. Tyramine intolerance or inability to follow dietary restrictions

https://www.mayoclinic.org/diseases-conditions/depression/expert-answers/maois/faq-20058035https://my.clevelandclinic.org/health/treatments/25220-maois-monoamine-oxidase-inhibitors

https://www.mayoclinic.org/diseases-conditions/depression/in-depth/maois/art-20043992