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 been diagnosed 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 been receiving levodopa treatment for at least one year, may be taking other antiparkinsonian drugs, will have an average of at least three hours OFF time as recorded in two 24-hour ON/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 the protocol, have been treated with any investigational drug within 30 days prior to randomisation (or five half-lives if longer), have ever received istradefylline or been treated with a COMT inhibitor, are psychotic, have clinically significant illness or laboratory values at screening, have insufficient mental capacity to comply with protocol requirements or certain psychiatric or neurological conditions. \-