A Study of MK0657 in Parkinson's Disease Patients (0657-006)

Inclusion Criteria: * Parkinson's Disease patients between the ages of 40 and 80 inclusive * Patient is in general good health based on screening assessments * Patient is willing to discontinue anti-parkinson's medications at least 8 hours prior to dosing * Patient is levodopa responsive with levodopa-induced peak-dose dyskinesias * Patient taking selective serotonin inhibitors (SSRIs), sleep medications and neuroleptics, have been on a stable dose for at least 30 days and has not experienced any CNS-related side effects * Patient is not a heavy smoker or drinker Exclusion Criteria: * Patient has atypical Parkinson's syndrome due to drugs, identified metabolic and/or neurologic disorders, encephalitis, or other degenerative syndrome * Patient has known intolerance or hypersensitivity to levodopa or carbidopa * Patient has been on anticholinergics or memantine within 30 days prior to dosing * Patients have a history of the following: seizure disorder, stroke or head trauma, pronounced cognitive impairment, psychiatric disorder, cardiovascular disease, cancer, diabetes as defined by HbA1c of greater than 8% * Patient has a systolic BP or less than 80 mm Hg or greater than 150 mm Hg