Study of KW-6002 (Istradefylline) for the Treatment of Parkinson's Disease in Patients Taking Levodopa

Inclusion Criteria

• •1. Be willing and able to give written informed consent
• •2. UK Parkinson's Disease Society (UKPDS) brain bank criteria (Step 1 and 2) for PD
• •3. PD stages 2-4 in the OFF state for Modified Hoehn and Yahr Scale
• •4. On levodopa/dopa-decarboxylase inhibitor for at least one year
• •5. Taking at least three doses and \>=300 mg of levodopa/dopa-decarboxylase inhibitor per day for at least four weeks before randomization
• •6. Predictable end of dose wearing off
• •7. Able to satisfactorily complete Hauser based 24-hour patient Parkinson's diary
• •8. Have an average of two hours of OFF time on 24-hour diaries
• •9. On a stable regimen of any other anti-Parkinson's drugs for at least four weeks before randomization
• •10. On a stable dose of domperidone for at least 14 days before randomization