MAO-B inhibitors for Parkinson's disease

Examples

Generic Name	Brand Name
rasagiline mesylate	Azilect
selegiline hydrochloride

How It Works

Monoamine oxidase inhibitors (MAOIs) prolong the effects of dopamine in the brain by preventing its breakdown. They also may prevent the removal of dopamine between nerve endings and enhance release of dopamine from nerve cells. Rasagiline and selegiline are selective monoamine oxidase (MAO-B) inhibitors.

Why It Is Used

MAO-B inhibitors may be used in the early stages of Parkinson's disease to treat very mild symptoms (such as resting tremor) and delay the need for levodopa. However, they have minimal effects when used alone, and better medications are available for this purpose.

In people with advanced Parkinson's disease who are taking levodopa, rasagiline or selegiline may be added to levodopa treatment to reduce motor fluctuations, increase the time of effect of the levodopa, and decrease the amount of levodopa needed to control symptoms.¹

How Well It Works

In the early stages of Parkinson's disease MAO-B inhibitors may improve symptoms and can delay the need for levodopa. However, the benefits are considered modest.²

When used with levodopa in people with advanced disease, rasagiline or selegiline may reduce motor fluctuations and increase the length of “on” periods (times when medication is able to control symptoms).¹

Side Effects

When rasagiline or selegiline is used alone, it causes few side effects in the doses that are used to treat Parkinson's disease. These medicines can cause nausea, insomnia, and occasionally confusion and hallucinations (seeing or hearing things that aren't really there). Insomnia can be avoided by taking the last dose by midday so that its stimulant effect will have declined before bedtime. Most people tolerate MAO-B inhibitors fairly well.

Increased confusion and other cognitive side effects are more likely to occur when MAO-B inhibitors are used in combination with levodopa, especially in older people. Rasagiline and selegiline also can cause frequent falls and should not be given to older people who have orthostatic hypotension (low blood pressure when a person stands up).

Certain risk-taking behaviour, like uncontrollable gambling and shopping, has been linked to medicines used to treat Parkinson's disease. It seems that these behaviours may occur more often in patients taking MAO-B inhibitors in addition to levodopa.

It may be dangerous to take MAO-B inhibitors with antidepressants, including both selective serotonin reuptake inhibitors (SSRIs, such as fluoxetine [Prozac] or sertraline [Zoloft]) and tricyclic antidepressants (such as amitriptyline [for example, Elavil]).

Unlike other drugs in the monoamine oxidase inhibitor (MAOI) class, rasagiline and selegiline are not thought to cause high blood pressure when taken in combination with alcohol (wine, beer, or sherry) or certain foods, including cheddar and aged cheeses, avocados, bananas, liver, miso, pickled herring, and yeast extract. However, if you experience a severe headache or chest pain while taking rasagiline or selegiline, you should seek medical care immediately.

See Drug Reference for a full list of side effects. (Drug Reference is not available in all systems.)

What To Think About

MAO-B inhibitors have a mild effect on the relief of Parkinson's disease symptoms when used alone. A greater effect is seen when they are used in combination with levodopa.

Experts continue to debate whether rasagiline and selegiline may protect dopamine-producing nerves in the brain and slow the progression of the disease. Although some studies suggest that rasagiline and selegiline may help to slow the progression of Parkinson's disease, they are currently being used only to treat symptoms of the disease.

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Author:	Douglas Dana Monica Rhodes	Last Updated: February 12, 2007
Medical Review:	Anne C. Poinier, MD - Internal Medicine E. Gregory Thompson, MD - Internal Medicine Colin Chalk, MD, CM, FRCPC - Neurology
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