What are MAO-B inhibitors?

MAO-B (monoamine oxidase-B) inhibitors are a class of drugs used to treat the symptoms of Parkinson’s disease (PD). Carbidopa-levodopa therapy is the most effective drug available to treat the motor symptoms of PD. However, other drugs like MAO-B inhibitors may also be used to manage symptoms.1,2

MAO-B inhibitors may be used alone in early stages of PD. Or, they may be used along with other treatments, like carbidopa-levodopa therapy. MAO-B inhibitors have been shown to have a modest effect on relieving the symptoms of PD.1,2

MAO-B inhibitors may reduce the motor fluctuations seen in many people with PD. People treated with carbidopa-levodopa often have fluctuating symptoms of PD described as "on" and "off" episodes. "On" episodes are when the medicine is working and symptoms are minimal. "Off" episodes are when the medicine has not yet taken effect or is wearing off and symptoms are worsened. "Off" episodes can interfere with daily activities and may be experienced multiple times a day. They may last a few minutes or as long as a few hours.1,2

How do MAO-B inhibitors work?

MAO is an enzyme found in cells. There are 2 types of MAOs: type A and type B.3

MAOs in the intestines are mostly type A. Most of the MAOs in the brain are type B. In the brain, MAO-B plays an important role in the breakdown of neurotransmitters (chemical messengers) like dopamine. MAO inhibitors (MAOI) block the action of the enzyme.3

The motor symptoms of Parkinson’s are caused by the reduction in dopamine, which sends signals in the brain to produce smooth, purposeful movement. As PD damages and destroys neurons (nerve cells) that make dopamine, the motor symptoms of PD appear.1

Levodopa therapy provides the precursor to dopamine. It is the substance used to make dopamine. Adding an MAO-B inhibitor slows the breakdown of levodopa and dopamine in the brain. This may boost the effect of levodopa.1

Examples of MAO-B inhibitors

Several different MAO-B inhibitors are used to treat PD, including:1

  • Eldepryl® (selegiline hydrochloride)
  • Carbex® (selegiline)
  • Zelapar® (selegiline hydrochloride, orally disintegrating tablet)
  • Azilect® (rasagiline)
  • Xadago® (safinamide, tablets)
  • Emsam® (selegiline patch)

What are the possible side effects of MAO-B inhibitors?

Side effects can vary depending on the specific drug you are taking.

The most common side effects of selegiline (found in Eldepryl, Carbex, and Zelapar) include:1,2

  • Dizziness
  • Headache
  • Confusion
  • Nausea
  • Insomnia
  • Dyskinesia (uncontrolled, abnormal movements)
  • Agitation

The most common side effects of rasagiline (found in Azilect) include:1,2

These are not all the possible side effects of MAO-B inhibitors. Talk to your doctor about what to expect or if you experience any changes that concern you during treatment with MAO-B inhibitors.

Things to know about MAO-B inhibitors

It is important that people with PD see a movement disorder specialist who is trained in the use of these drugs for PD. They understand drug interactions and how some medicines may make symptoms worse.1

MAO-B inhibitors may cause serious side effects when taken with other drugs, such as:4

  • Antidepressants
  • Selective serotonin reuptake inhibitors (SSRIs)
  • Serotonin-norepinephrine reuptake inhibitors (SNRIs)
  • Tricyclic antidepressants

Certain foods may also interact with MAO-B inhibitors. Before beginning treatment for Parkinson's disease, tell your doctor about all your health conditions and any other drugs, vitamins, or supplements you are taking. This includes over-the-counter drugs.4

Additional therapy

Besides MAO-B inhibitors, there are several different types of treatment for the symptoms of PD, including:

Each person with PD experiences a unique set of symptoms and progression of the disease. Treatments are based on the person's symptoms and how they respond to different drugs.

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Written by: Emily Downward | Last reviewed: May 2021