MedifocusHealth

There are two MAO-B inhibitors that are used in the treatment of Parkinson's disease, selegiline and rasagiline.

Selegiline

The most widely used MAO-B inhibitor is selegiline (e.g., Eldepryl, Deprenyl). Selegiline is used as an adjunct to levodopa since it increases the half-life of dopamine in the brain. There has been considerable debate as to whether selegiline is neuroprotective and possibly delays the progression of Parkinson's disease.

When given to patients in early stage of Parkinson's disease as a monotherapy, some studies suggest that selegiline delays the need for Sinemet possibly by as long as 9 months. Other studies have shown that there is no support for giving selegiline as an initial monotherapy. When given later in disease progression, selegiline boosts the effect of levodopa and improves the problem of fluctuations of motor response in about one half to two thirds of patients. The drug is easily tolerated. In general, selegiline is considered to be only moderately effective resulting in its being prescribed more as an adjunct medication rather than as a monotherapy.

Side effects of selegiline include:

• Nausea
• Orthostatic hypotension (low blood pressure when standing)
• Insomnia (difficulty sleeping)
• Confusion
• Abdominal pain

Rasagiline

On May 17, 2006, the U.S. Food and Drug Administration (FDA) approved a newer MAO-B drug called rasagiline (Azilect) for the treatment of Parkinson's disease. This drug was approved for use as an initial single drug therapy (monotherapy) for patients with early Parkinson's disease and in combination with levodopa in patients with more advanced Parkinson's disease. Various studies have indicated that rasagiline when used in levodopa-treated patients is effective for:

• Reducing motor fluctuations
• Reducing mean daily "off" time
• Improving UPDRS scores for activities of daily living

When rasagiline was studied as a monotherapy, total UPDRS scores improved by 30% or more. Studies are ongoing regarding the possibility of rasagiline slowing the rate of progression of Parkinson's disease.

Rasagiline is well tolerated and is not associated with side effects.

A study published in 2005 in the British Journal of Cancer (Volume 92, Issue 1; pp. 201-205) reported that Parkinson's disease patients may be at increased risk for developing a type of skin cancer known as malignant melanoma. During development, this type of skin cancer was also diagnosed in a small number of patients treated with rasagiline (Azilect). Since there is some evidence that patients with Parkinson's disease may be at increased risk for developing melanoma, currently there is no definitive proof that treatment with rasagiline (Azilect) is associated with an increased risk for developing melanoma. It is currently recommended that patients receiving treatment with rasagiline (Azilect) should undergo periodic check-ups from a dermatologist to monitor for signs of melanoma and other types of skin cancer.

While taking MAO-B inhibitors, caution must be taken regarding adverse drug interactions with other medications, including many nonprescription cold medications that contain pseudoephedrine, (a decongestant) and dextromethorphan (a cough suppressant).

Catechol-O-Methyltransferase (COMT) Inhibitors

• Entacapone (Comtan)