A Study of Istradefylline (KW-6002) for the Treatment of Parkinson's Disease

Inclusion Criteria: Patients selected for this study will be at least 30 years of age and will have beendiagnosed with advanced Parkinson's disease as determined by UK Parkinson's Disease Society (UKPDS) criteria and the Modified Hoehn and Yahr Scale. The patients will have beenreceiving levodopa treatment for at least one year, may be taking other antiparkinsoniandrugs, will have an average of at least three hours OFF time as recorded in two 24-hourON/OFF diaries, and if female, must be non-pregnant and non-nursing.

Exclusion Criteria: Patients may not be enrolled if they are taking certain medications excluded by theprotocol, have been treated with any investigational drug within 30 days prior torandomisation (or five half-lives if longer), have ever received istradefylline or beentreated with a COMT inhibitor, are psychotic, have clinically significant illness orlaboratory values at screening, have insufficient mental capacity to comply with protocolrequirements or certain psychiatric or neurological conditions.