Parkinson's Disease - Medications

(Page 2)

• Confusion.
• Extreme emotional states, particularly anxiety.
• Vivid dreams.
• Visual and possibly auditory hallucinations. The drug may even unmask dementia that had not been previously noticed.
• Effects on learning. L-dopa appears to have mixed effects on learning. It may improve working memory. However, some evidence suggests that it impairs areas of the brain related to other learning functions and social behavior.
• Sleepiness and sleep attacks.

Levodopa causes fewer psychiatric side effects than other drugs used for Parkinson's disease, including anticholinergics, selegiline, amantadine, and dopamine agonists. Because psychiatric side effects often occur at night, if they are severe some doctors recommend reducing or stopping the evening dose.

---

---

The Wearing-Off Effect and Dyskinesia (Inability to Control Muscles)

Within 4 - 6 years of treatment with levodopa, the effects of the drug in many patients begin to last for shorter periods of time after a dose (called the wearing-off effect) and the following pattern may occur:

• Patients may first notice slowness (bradykinesia) or tremor in the morning before the next dose is due.
• Less commonly, some experience painful dystonia, muscle spasms that can cause sustained contortions of various parts of the body, particularly the neck, jaw, trunk, and eyes and possibly the feet.
• Patients must increase the frequency or the dose of levodopa. This puts them at risk for dyskinesia (the inability to control muscles), which usually occurs when the drug level peaks.
• In some people, L-dopa eventually becomes effective only for 1 - 2 hours, and patients start to have motor fluctuations. In about 15 - 20% of patients, such fluctuations become extreme, a phenomenon known as the on-off effect, which consists of unpredictable, alternating periods of dyskinesia and immobility. Sometimes the symptoms switch back in forth within minutes or even seconds. (The transition may follow such symptoms as intense anxiety, sweating, and rapid heartbeats.)

Preventing the Wearing-Off Effect. To reduce the effects of fluctuation and the wearing-off effect, it is important to maintain as consistent a level of dopamine as possible. Unfortunately, levodopa is poorly absorbed and may remain in the stomach a long time. A number of strategies are used to take care of these problems:

• Some patients take multiple small doses on an empty stomach, crushing the pills and mixing them with a lot of liquid.
• A liquid form of Sinemet may produce fewer fluctuations and a prolonged "on" time compared with the tablet.
• A prolonged release version of levodopa and carbidopa (Sinemet CR) may control fluctuations for some patients.

Review Date: 06/18/2010
Reviewed By: Harvey Simon, MD, Editor-in-Chief, Associate Professor of Medicine, Harvard Medical School; Physician, Massachusetts General Hospital. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.

A.D.A.M., Inc. is accredited by URAC, also known as the American Accreditation HealthCare Commission (www.urac.org).