Monoamine Oxidase B (MAO-B) Inhibitors


Selegiline is an inhibitor of the enzyme MAO-B (monoamine oxidase B). Since MAO-B breaks down dopamine, inhibiting it prolongs the action of dopamine in the brain, and improves the symptoms of Parkinson's disease. Selegiline also has a mild antidepressant effect. Early studies of selegiline initially led doctors to believe that it may delay the progression of Parkinson's disease, but currently there is no firm evidence that this is so.

Patients taking selegiline should avoid treatment with meperidine (Demerol), a pain medication.

Selegiline Preparations include:

  • Eldepryl®: 5 mg capsule
  • Atapryl®: 5 mg tablets
  • Carbex®: 5 mg tablets

Usually it is taken once in the morning and at midday.   Zelapar is an orally disintegrating form of selegiline which comes in 1.25 mg tablets; it is usually taken once daily.

Side Effects

Side effects may include heartburn, nausea, dry mouth, insomnia, and dizziness. Confusion, nightmares, hallucinations, and headache occur less frequently and should be reported to your doctor.


Rasagiline is a new MAO-B inhibitor which has been approved for use as a single medication to treat symptoms in early Parkinson’s disease or in addition to other agents such as dopamine agonists or levdopa when the symptoms of Parkinson’s disease are more prominent.  It is taken once daily and is less likely to cause insomnia than selegiline.

A recent study showed that treatment with 1 mg rasagiline provided benefits that were consistent with a possible disease-modifying effect (i.e., slowing the disease) whereas treatment with 2 mg daily did not.  Because the two doses were not associated with different outcomes, the study is difficult to interpret.


Rasagiline (Azilect®) is available as 0.5 and 1 mg tablets.

Side Effects

Side effects include abnormal movements, headache, and fatigue.

Precautions: Patients taking rasagiline should avoid meperidine (Demerol), dextromethorphan, and ephedrine, Treatment with ciprofloxacin may increase the blood level of rasagiline so it should be avoided or only be used with caution.

Copyright © 2010, The Regents of the University of California