MAO-B inhibitors are molecules that modify the metabolic pathways that lead to the breakdown of dopamine, a neurotransmitter, or chemical messenger, required to relay electric signals between two nerve cells and between the brain and muscles.
In Parkinson’s disease, the dopamine-producing nerve cells progressively deteriorate in specific parts of the brain, leading to a range of symptoms.
How MAO-B inhibitors work
Although restoring dopamine levels cannot cure Parkinson’s disease, it can alleviate many of the symptoms brought about because of a decrease in this neurotransmitter.
Monoamine oxidase-B (MAO-B) is an enzyme responsible for the chemical breakdown of dopamine in the brain. MAO-B inhibitors act by inhibiting the activity of this enzyme and therefore slowing the breakdown of dopamine.
MAO-B inhibitors can be given either as a monotherapy or they can be combined with carbidopa-levodopa therapy.
Although MAO-B inhibitors have been shown to bring about only a modest decrease in the severity of Parkinson’s symptoms, the use of these medications can delay the reliance on levodopa.
Examples of MAO-B inhibitors used in Parkinson’s disease
Selegiline
Selegiline is one of the most commonly used MAO-B inhibitors and is the active ingredient in medications such as Eldepryl, Carbex and Zelapar.
Rasagiline
Rasagiline is as an irreversible MAO-B inhibitor and the active agent of Azilect. It is frequently prescribed to manage symptoms of Parkinson’s disease.
Safinamide
Safinamide is the active agent of Xadago. Although it has other modes of action, it also acts as an MAO-B inhibitor. In many cases, the effects of levodopa can wear off for some time. This is referred to as an off episode. Safinamide is used as an add-on treatment during such episodes.
Additional information
Some common side effects of MAO-B inhibitors include dizziness, headache, confusion, nausea, insomnia, and dyskinesia.
Interactions of MAO-B inhibitors with certain foods and medications are also fairly common. For example, MAO-B inhibitors may interact with antidepressants, selective serotonin reuptake inhibitors (SSRIs), and serotonin-norepinephrine reuptake inhibitors (SNRIs). It is therefore very important to consult a medical professional before using MAO-B inhibitors in order to determine the right dose and frequency of treatment.
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