Conditions: Parkinson Disease Movement Disorders Central Nervous System Diseases Neurodegenerative Diseases Brain Diseases
Allocation: RANDOMIZED | Intervention model: PARALLEL
Enrollment: 253
Healthy volunteers: no

Brief summary:
The purpose of the study is to assess the efficacy and safety of a range of doses of SCH 420814 (preladenant) when used together with a stable dose of L-dopa/dopa decarboxylase inhibitor to treat Parkinson's disease. In this study, we will be comparing 3 doses (1 mg, 2 mg, and 5 mg taken twice a day) of preladenant with placebo (sugar pill). Following an Interim Analysis (temporary hold for new enrollment-ongoing subjects will continue on treatment) to review drug safety, a new dose group of 10 mg (taken twice a day) may be added.

Approximately 160 participants will be randomized in this study in approximately 22 study centers worldwide for the first part of this study. Following the Interim Analysis, 40 new participants may be added, for a total of 200 participants. The study is double blind, which means neither you nor your study doctor will know whether you are receiving the study medication or placebo.

Detailed description:

Arms:
arm 1: Participants received preladenant 1 mg twice daily (BID) during the 12-week treatment period. arm 2: Participants received preladenant 2 mg BID during the 12-week treatment period. arm 3: Participants received preladenant 5 mg BID during the 12-week treatment period. arm 4: Participants received preladenant 10 mg BID during the 12-week treatment period. arm 5: Participants received preladenant matching placebo BID during the 12-week treatment period.

Interventions: intervention 1: Preladenant intervention 2: Preladenant intervention 3: Preladenant intervention 4: Preladenant intervention 5: Placebo intervention 6: L-dopa intervention 7: Other Parkinson's Disease treatments
Intervention descriptions: intervention 1: 1 mg BID capsules intervention 2: 2 mg BID capsules intervention 3: 5 mg BID capsules intervention 4: 10 mg BID capsules intervention 5: BID capsules intervention 6: Participants must receive L-dopa as part of their usual ongoing treatment for Parkinson's Disease. L-dopa is often administered concomitantly with a dopa decarboxylase inhibitor (e.g., carbidopa). intervention 7: Participants may also receive other drugs as part of their usual ongoing treatment for Parkinson's Disease, such as dopamine agonists (e.g., pramipexole) and/or the catechol-O-methyl transferase (COMT) inhibitor entacapone.

Protocol document: