Medications

Selegiline (Eldepryl, Movergan, Zelepar), also known as deprenyl, is an antioxidant drug that blocks monoamine oxidase B (MAO-B), an enzyme that degrades dopamine. (Rasagiline, another MAO-B inhibitor, is under investigation.) Until recently, selegiline was the drug most commonly used in early-onset disease and in combination with levodopa for maintenance. A major 2002 study reported, however, that although selegiline delayed the need for L-dopa by a few months, it has no effect on long-term progression.

Other Adverse Effects. Selegiline has important side effects:

• One of the most important side effects is orthostatic hypertension, particularly in people taking Sinemet plus selegiline. (Orthostatic hypotension can occur with other Parkinson's drugs and the condition by itself indicates a more serious condition, regardless of the drug taken.)
• Can cause hypertension if combined with agents that increase serotonin levels--such agents include nearly every major antidepressant. Patients suffering from depression and taking selegiline should discuss all treatment options with their physician.

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Debate over Mortality Rates. Some major studies, including one in 2002, have reported a higher mortality rates in patients with advanced PD. Such findings may be due to adverse effects on the heart and blood vessels. Although other studies have not reported lower survival rates, some experts believe that, given its modest effects, selegiline may be a poorer drug choice than others, particularly in patients with risk factors for heart disease.

Dopamine Agonists

Dopamine agonists stimulate dopamine receptors in the substantia nigra, the part of the brain in which Parkinson's is thought to originate. Dopamine agonists are effective in delaying motor complications during the first one or two years of treatment. Studies also report that they improve impaired movements and disability compared to placebo.