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MAO-B Inhibitors

What Are the Facts?

  • MAO-B is an enzyme that naturally breaks down several chemicals in our brain, including dopamine.
  • MAO-B inhibitors help to block the breakdown of dopamine in the brain. This makes more dopamine available and reduces some of the motor symptoms of PD.
  • MAO-B inhibitors provide modest benefit for the motor features of PD. They are usually used early in the disease as monotherapy (meaning it is the only drug you take) or as an adjunct (add-on) to other medications.
  • When used together with other medications, MAO-B inhibitors may reduce “off” time and extend “on” time.

The MAO-B inhibitors selegiline and rasagaline enhance the effect of levodopa:

Selegiline is available in two formulations:

  • Standard oral (Eldepryl®) – This form gets converted by the body into an amphetamine-like by-product, which may contribute to side effects of jitteriness and confusion.
  • Orally-disintegrating (Zelpar®) – This is the preferred form for people with PD who have difficulty swallowing.

Rasagiline is available in 0.5 mg and 1 mg doses:

  • Rasagiline (Azilect®) is generally given in 1 mg doses once per day. Two studies (LARGO and TEMPO) have shown that it can reduce wearing off in people treated with levodopa.
  • It is structurally different than selegiline and does not have the amphetamine-like byproduct that can cause jitteriness. 
  • Recently, the FDA expanded the indication for rasagiline from monotherapy and adjunct to levodopa to include adjunct to dopamine agonists. This means that rasagiline can be used alone or in combination with other PD medications. However, there may be contraindications with other prescription medications, vitamins, over-the-counter cold pills or homeopathic remedies. Talk to your doctor and pharmacist about potential drug interactions.
Recent studies have led to the reclassification of these medications as highly selective MAO-B inhibitors.  

What Are the Side Effects?

The most common side effects of MAO-B inhibitors include the following:

  • Mild nausea
  • Dry mouth
  • Lightheadedness
  • Constipation
  • Confusion (can occur in the elderly person with PD)
  • Hallucinations (can occur in the elderly person with PD)

Taking some MAO-B inhibitors with the heavy consumption of aged cheeses or wines high in tyramine carries a risk of raising blood pressure to dangerous levels, but this "cheese effect" has not been found in selegiline and rasagiline. The FDA has relaxed food restrictions related to MAO-B inhibitors. 

Caution: PD medications may have interactions with certain foods, other medications, vitamins, herbal supplements, over-the-counter cold pills and other remedies. Anyone taking a PD medication should talk to his or her doctor and pharmacist about potential drug interactions.

Page reviewed by Dr. Joash Lazarus, NPF Movement Disorders Fellow, Department of Neurology at Emory University School of Medicine.

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