Effects of Monoamine Reuptake Inhibitor NS2330 in Parkinson's Disease

This study will evaluate the effects of an experimental drug called NS2330 on Parkinson's disease symptoms and on dyskinesias (involuntary movements) that develop as a result of long-term treatment with levodopa. This drug prevents the neurotransmitter dopamine from entering nerve cells.

Patients between 18 and 75 years old who have moderately advanced Parkinson's disease and motor problems resulting from levodopa therapy may be eligible for this 5-week study. Candidates will have a complete medical history and physical examination with a detailed neurological evaluation. If needed, some patients will undergo a magnetic resonance imaging (MRI) or computerized tomography (CT) scan of the brain and a chest X-ray. All patients will have blood and urine tests and an electrocardiogram (EKG) and will take a written test for evaluation of depression.

Patients enrolled in the study will, if possible, stop taking all antiparkinson medications except levodopa (Sinemet) for one month before the study begins and through its duration. For the first 1 to 3 days, patients will undergo a levodopa "dose-finding" procedure. For this study, patients will stop taking their usual oral levodopa medicine and instead will have levodopa infused through a vein for up to 12 hours. During the infusions, the drug dose will be increased slowly until either 1) parkinsonism symptoms improve, 2) dyskinesias appear, 3) unacceptable side effects occur, or 4) the maximum study dose is reached.

When the patient's optimal dose is determined, treatment will begin. Patients will take three pills containing NS2330 or placebo (a look-alike pill with no active ingredient) 3 days a week for up to 5 weeks, in addition to their regular levodopa medication. All participants will receive placebo at some point in the study; some patients will receive only placebo throughout the entire 5 weeks.

On treatment days, patients will have a brief medical examination before receiving the drug and will then be monitored for side effects for about 6 to 8 hours after taking the drug. At the beginning of weeks 2 and 5, the levodopa infusions will be repeated at the previously determined optimum rate. Throughout the study, parkinsonism symptoms, dyskinesias and depression will be evaluated. Blood and urine samples will be collected each week for standard safety tests, and blood will also be drawn periodically to measure NS2330 levels.