Conditions: Idiopathic Parkinson's Disease
Keywords: Parkinson's disease Moderate to Severe Parkinson's Disease
Allocation: RANDOMIZED | Intervention model: PARALLEL
Enrollment: 613
Healthy volunteers: no

Brief summary:
This is a study to assess the efficacy and safety of oral Istradefylline (KW-6002) in patients with moderate to severe Parkinson's Disease. While on this study, participants will continue to take their usual, prescribed, stable regimen of Levodopa/Carbidopa or Levodopa/Benserazide therapy plus adjunct Parkinson's medications. Patients will be randomized 1:1:1 to receive either Istradefylline 20 mg per day, or Istradefylline 40 mg per day or an equivalent placebo. Patients will be treated for a 12 week period to demonstrate the effectiveness of Istradefylline in improving Parkinson's disease symptoms (referred to as improvement in patient OFF time) and that Istradefylline has an acceptable safety profile in this group.

Detailed description:

Arms:
arm 1: Istradefylline 20 mg and placebo to match istradefylline 40 mg:

A daily, oral, double-blind treatment dose of both tablets will be taken in the morning for 12 weeks. arm 2: Istradefylline 40 mg and placebo to match istradefylline 20 mg:

A daily, oral, double-blind treatment dose of both tablets will be taken in the morning for 12 weeks. arm 3: Placebo to match istradefylline 20 mg and placebo to match istradefylline 40 mg:

A daily, oral, double-blind treatment dose of both tablets will be taken in the morning for 12 weeks.

Interventions: intervention 1: Istradefylline 40 mg intervention 2: Istradefylline 20 mg intervention 3: Placebo
Intervention descriptions: intervention 1: Istradefylline 40 mg and placebo intervention 2: Istradefylline 20 mg and placebo intervention 3: Placebo

Protocol document: