Understanding Monoamine Oxidase Inhibitors

Efficacy, Side Effects and Interactions of MAOI Antidepressants

Jul 3, 2008

MAIOs are effective for treatment-refractory depression, increasing levels of certain neurotransmitters. However, people on MAOIs must follow a restricted diet.

Monoamine oxidase inhibitors (MAOIs) belong to an older class of antidepressants used to treat depression, bipolar disorder and anxiety disorders. MAOIs aren’t prescribed often, partly due to the potential dangers of interactions with certain foods and drugs. It has been suggested that the benefits of MAOIs are sometimes overlooked by clinicians.

There is evidence to support MAOIs for use in depression that has previously been resistant to treatment. Some studies suggest they are particularly helpful to people with atypical depression, a subtype of depression with symptoms such as:

However, there is no evidence to suggest that a newer class of antidepressants, selective serotonin reuptake inhibitors, are any less effective in treating this type of depression.

Types of MAOIs

There is also a newer group of antidepressants called reversible inhibitors of monoamine oxidase (RIMAs). These drugs work slightly differently, and have fewer interactions than MAIOs. However, research into RIMAs is limited and so they should be used with caution.

It is important for doctors to take a full history of the patient before prescribing MAOIs, as some conditions may affect their suitability for treatment. It is also important that patients are fully informed on both the benefits and the risks associated with these medications.

How MAOIs Work

Monoamine neurotransmitters are chemical messengers in the brain, including those that have been linked to low mood. These include:

Monoamine oxidase is the enzyme responsible for breaking down monoamines. By inhibiting this enzyme, the result is more active monoamines in the brain, therefore improving mood.

People taking MAOIs for depression may not notice any difference in their mood for several weeks. They may need to continue taking them for several months after they start feeling better, as this reduces the possibility of relapse.

Interactions of MAOIs

MAOIs also prevent the breakdown of an amino acid called tyranine, which can be found in certain food and drink. Tyranine can be dangerous when not broken down, and so diet must be restricted. Here are some examples of foods that must be avoided:

Clinicians prescribing MAOIs should provide patients with a full list of both foods to avoid and foods that can be eaten in small amounts. It is important that this list is up to date as recent investigation has shown that previously advised dietary restrictions are unnecessary.

There are several medications that dangerously interact with MAOIs, including some antidepressant drugs, recreational drugs and cough medicines. A list of these interactions can be found in the patient information leaflet provided with the medication.

Side Effect of MAOIs

Adjusting dosage may help in managing side-effects, however, any dosage changes must be overseen by a doctor. Medical attention should be sought for diet-related side-effects, including:

The patient information leaflet provided with the medication includes a comprehensive list of side-effects.

Discontinuing MAOIs

Stopping MAOIs can cause withdrawal symptoms, however, these symptoms are not an indication of addiction. Withdrawal symptoms may be less severe or avoided completely by gradually reducing the dose over several weeks. A washout period, usually of a couple of weeks, is necessary if another antidepressant is to be commenced.

Read How Depression Medication Works for more information on the different classes of antidepressant medication. People with queries or concerns about MAOIs should contact a qualified health practitioner for advice.

Sources

The copyright of the article Understanding Monoamine Oxidase Inhibitors in Depression is owned by Barbara Melville. Permission to republish Understanding Monoamine Oxidase Inhibitors in print or online must be granted by the author in writing.