MAO-B Inhibitors

Selegiline (also called deprenyl, with trade names Eldepryl®and Zelapar®) and rasagiline (Azilect®) block an enzyme in the brain that breaks down levodopa.

Monoamine Oxidase Type B (MAO-B) is an enzyme in our body that breaks down several chemicals in the brain, including dopamine. By giving a medication that blocks the effect of MAO-B, an MAO-B inhibitor), more dopamine is available to be used by the brain. This can modestly improve many motor symptoms of PD.

MAO-B inhibitors also provide some benefit for the motor symptoms of PD and are useful as early monotherapy or as an add-on to other medications, including levodopa. When used with other medications, MAO-B inhibitors may reduce “off” time and extend “on” time.

Forms of MAO-B Inhibitors

Selegiline (l-deprenyl, Eldepryl)

Available Doses: 5mg
Typical Treatment Regimen: 5 mg Twice/day with breakfast and lunch
Side Effects:  Nausea, dry mouth, light-headedness, constipation; may worsen dyskinesia; insomnia
Indications:Monotherapy for slowness, stiffness and tremor; adjunct therapy formotor fluctuations

Selegiline HCL orally disintegrating (Zelapar)

Available Doses: 1.25 mg, 2.5 mg
Typical Treatment Regimen: 1.25–2.5 mg once/day
Side Effects: Nausea, dry mouth, light-headedness, constipation; may worsen dyskinesia; insomnia
Indications: Adjunctive therapy for motor fluctuation, plus need for dissolvable medication in mouth especially if swallowing is impaired

Rasagiline (Azilect®) 

Available Doses: 0.5 mg, 1 mg doses
Typical Treatment Regimen: 1 mg once/day
Side Effects: Nausea, dry mouth, light-headedness, constipation; may worsen dyskinesia
Indications: Monotherapy for slowness, stiffness and tremor; adjunct therapy for motor fluctuations

Safinamide (Xadago)

Available Doses: 200 mg
Typical Treatment Regimen: 4–8 times/day (with each levodopa dose)
Side Effects: Nausea, dry mouth, light-headedness, constipation; may worsen dyskinesia; insomnia
Indications: Adjunctive therapy to carbidopa/levodopa for “off” episodes

Common Side Effects of MAO-B Inhibitors

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

Taking some MAO-B inhibitors with the heavy consumption (greater than 150 mg/day) of foods high in tyramine carries a risk of raising blood pressure to dangerous levels. These foods are typically aged or fermented, and can include things like cheeses, dried or cured meats, fava beans, beer, sauerkraut, and soybeans. This is more of a risk with non-selective MAO-B inhibitors not used to treat Parkinson’s disease.

Potential for Neuroprotection

In addition, it was suggested in animal studies that MAO-B inhibitors might slow the progression of PD, offering neuroprotection. When tested in humans in the 1980s, Selegiline was shown to delay the need for levodopa by nine months, suggesting neuroprotection. However, this benefit may simply have been from the antiparkinson symptom effect of selegiline.

A worldwide study of rasagiline’s potential for neuroprotection was published in 2008, and follow-up data from the original study. These results suggest that the use of rasagiline earlier in PD may offer the greatest long-term advantage and potentially manage symptoms over time, although true disease modification remains unproven.

Based on these results, we cannot say conclusively that any MAO-B inhibitors slow the progression of the disease.

Quick Facts

  • MAO-B enzymes naturally break down and block several chemicals in the brain, including dopamine
  • MAO-B inhibitors prevent the break down of dopamine, making dopamine more available
  • Provide modest benefit for the motor features of PD 
  • Usually used early in the disease as monotherapy 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

Disclaimers:

* Please note that the side effects listed in the tables that accompany each class of medication are the most commonly experienced. Not all individuals will experience such side effects. For many people who do experience side effects, they can often be effectively limited or eliminated with careful adjustments to dosage or the timing of the individual doses.

Speak to the treating physician immediately if any side effects are experienced. For a complete description of each drug and its possible side effects, please request a “package insert” from your pharmacist for each drug used. It is recommended that all prescriptions be filled at the same pharmacy to avoid interactions between medications. Interactions can be dangerous and even life-threatening, so make sure the pharmacist knows of all medications and supplements being taken, including over-the-counter medications and supplements.

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 their doctor and pharmacist about potential drug interactions.

 

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