Long Term Study of Istradefylline in Subjects With Moderate to Severe Parkinson's Disease

You may be eligible if

• 1. Written informed consent;
• 2. Subjects who completed Study No. 6002-014 inclusive of the 30-day follow-up period;
• 3. Currently taking levodopa combination (carbidopa/levodopa or benserazide/levodopa) therapy plus at least one adjunctive PD medication;
• 4. Women of child-bearing potential (WOCBP) must use a reliable method of contraception and have a negative serum pregnancy test at Screening;
• 2. Subjects on apomorphine and/or dopamine receptor antagonists or direct gastrointestinal levodopa infusion;
• 3. Subject who have had neurosurgical operation for PD;
• 4. Subjects taking A2a antagonist, potent CYP3A4 inhibitors, potent CYP34A inducers;
• 5. Subjects who have had a diagnosis of cancer or evidence of continued malignancy within the past three years (with the exception of adequately treated basal cell or squamous cell skin cancer, in situ cervical cancer, or in situ prostate cancer with normal prostate-specific antigens post resection).