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A monoamine oxidase inhibitor (MAOI) is a medicine that blocks one or both monoamine oxidase enzymes. These enzymes normally break down neurotransmitters such as serotonin, norepinephrine, and dopamine. Blocking them increases the availability of these chemical messengers in the brain. MAOIs are used mainly for certain depressive disorders and, in selected forms, for Parkinson's disease.
read more about mao inhibitor ...Traditional MAOIs such as phenelzine, tranylcypromine, and isocarboxazid can be prescribed for depression that has not improved with other treatments. They can be particularly useful for selected patients with atypical or treatment-resistant depression. Selegiline is available in forms used for depression or Parkinson's disease, depending on the dose and product. MAOIs are not commonly chosen first because they require careful management of interactions and diet.
Monoamine oxidase A and monoamine oxidase B break down different combinations of neurotransmitters and dietary amines. MAOIs reduce this breakdown, which raises levels of serotonin, norepinephrine, dopamine, or related chemicals. Some medicines block both enzyme types, while others are more selective at certain doses. Their clinical benefit develops gradually even though enzyme inhibition begins earlier.
MAOIs must be taken according to a strict medication plan because they interact with many prescription, over-the-counter, and recreational drugs. A washout period is commonly required before starting or stopping medicines that affect serotonin, blood pressure, or the central nervous system. Traditional MAOIs also require limits on high-tyramine foods, including certain aged, fermented, cured, or spoiled products. Patients should check with a prescriber or pharmacist before using decongestants, stimulants, other antidepressants, or new supplements.
Possible side effects include dizziness, orthostatic hypotension, dry mouth, constipation, sleep changes, weight gain, and sexual problems. Combining an MAOI with high levels of tyramine or certain sympathomimetic medicines can cause a dangerous rise in blood pressure. Combining one with serotonergic drugs can cause serotonin syndrome, which can involve agitation, fever, sweating, muscle rigidity, diarrhea, or confusion. Severe headache, chest pain, fainting, very high fever, seizures, or marked confusion requires emergency medical care.
Other antidepressants are usually tried first because they have fewer food restrictions and drug interactions. MAOIs can still be effective when earlier treatments have not worked or have caused unacceptable effects.
Traditional MAOIs can require avoidance of foods high in tyramine, such as certain aged cheeses, cured meats, fermented products, and improperly stored foods. The exact restrictions depend on the medicine and dose, so patients should follow their prescribed food list.
A washout period allows the previous medicine's effects to decline before another interacting drug is started. This reduces the risk of serotonin syndrome, hypertensive reactions, and other serious complications.
MAOIs should not be stopped or switched without prescriber guidance. Abrupt changes can cause withdrawal symptoms, a return of depression, or dangerous interactions when another medicine is started too soon.
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