Sep 11th 2023
Monoamine oxidase inhibitors, or MAOIs, are a type of antidepressant medication used to treat mental health and neurological conditions. MAOIs are no longer a first choice in treating depression unless in specific and necessary circumstances due to their potential risks. Alternative medications and treatments are available if required.
Monoamine oxidase inhibitors (MAOIs) are a type of antidepressant medication. They were the first antidepressants developed in the 1950s and are still used today to treat depressive disorders and neurological conditions .
MAOIs can cause various side effects, dietary restrictions, and health risks, so they are not typically used as a first-line treatment but are still used in necessary circumstances, as they can be effective treatments .
The FDA has approved some MAOIs to treat major depressive disorder . It is advised not to use MAOIs as a first-line treatment for depression due to their potential risks. However, MAOIs may be the preferred treatment for treatment-resistant depression or atypical depression, with symptoms such as anxiety, increased sleep, or changes in appetite .
Other MAOIs have been FDA-approved for use in treating Parkinson’s disease. They may be used alone or alongside levodopa, a commonly used medication for Parkinson’s, and help to reduce motor symptoms .
Monoamine oxidase is an enzyme in the brain responsible for degrading and regulating several neurotransmitters, including serotonin, dopamine, and norepinephrine. These neurotransmitters are known as amine neurotransmitters and help regulate several functions, including mood, behavior, energy, cognition, and sleep .
MAO inhibitors prevent the monoamine oxidase enzyme from breaking down these neurotransmitters, thereby increasing their levels. Reduced levels of amine neurotransmitters, particularly serotonin, are known to be involved in the development of depression, so by increasing these levels, MAOIs cause an antidepressant effect .
There are two types of monoamine oxidase enzymes, called MAO-A and MAO-B. MAO-A impacts serotonin, dopamine, and norepinephrine. In contrast, MAO-B does not impact serotonin but also affects dopamine and norepinephrine .
There are three types of MAOIs: ones that selectively inhibit MAO-A, ones that selectively inhibit MAO-B, and ones that are not selective, thus inhibiting both MAO-A and MAO-B. As such, each of these MAOIs can cause different effects, with those that inhibit MAO-A having a more substantial antidepressant effect than those that only inhibit MAO-B .
However, as MAO-A also metabolizes dietary tyramine, MAO-A inhibitors prevent this from occurring, allowing tyramine to enter the bloodstream. This triggers the release of norepinephrine, which results in an increase in blood pressure and a hypertensive crisis, commonly referred to as the ‘cheese effect’ .
Most MAOIs are administered as an oral tablet, which enters the gastrointestinal tract. But a transdermal patch has been developed to provide the antidepressant effects of MAOIs while preventing the ‘cheese effect’, as the medication is absorbed directly into the bloodstream .
To prevent withdrawal, your doctor will likely reduce your dose gradually. It is important not to suddenly stop MAOI treatment, as this can increase the risk of withdrawal symptoms.
MAOIs can contribute to the onset of serotonin syndrome if used alongside other antidepressants or medications that increase serotonin. Dangerously high serotonin levels can cause serotonin syndrome and can, in some cases, be fatal. Symptoms of serotonin syndrome include :
It is advised not to use MAOIs while using SSRIs, SNRIs, TCAs, other MAOIs, bupropion, and amphetamines. When changing between one of these medications and an MAOI, it is advised to wait at least 14 days between the last dose of the previous medication and the first dose of the next. For medicines with longer half-lives, such as fluoxetine, it is necessary to wait longer .
The hypertensive crisis that MAOIs can cause is often called the ‘cheese effect’. It is caused by the impact MAOIs have on tyramine metabolization in the intestines. The ‘cheese effect’ can cause severe and potentially fatal issues, including :
As such, it is required to follow a restricted diet when taking an MAOI to help prevent this. Foods high in tyramine should be avoided or limited, such as :
Dietary restrictions are not necessary when taking MAO-B inhibitors or the MAOI transdermal patch in a low dose, as these types of MAOIs are not likely to cause this effect.
Always inform your doctor of all medications you take, whether prescribed or over the counter, before starting a new treatment.
People with heart, liver, or kidney conditions may not be able to take MAOIs safely. It is advised to inform your doctor of any existing conditions before starting MAOI treatment, as it may be unsafe to do so, or your doctor may wish to prescribe you a reduced dose and ensure careful monitoring of your physical health .
Before being prescribed MAOIs, your doctor will likely try an alternative medication that carries fewer risks.
Alongside antidepressant medication, utilizing therapy and self-help techniques is often very helpful. Available therapies that can be effective at managing symptoms of depression include :
Many alternative medications can be used to treat Parkinson’s disease, which can be used alongside or instead of MAOIs. This includes :
Additional treatments for Parkinson’s disease include :