Follow Up Safety Study of SCH 420814 in Subjects With Parkinson's Disease (P05175)

A Phase 2, 36-Week, Open-Label, Uncontrolled Safety Follow-up Study Assessing SCH 420814 (Preladenant) 5 mg BID (P05175)

The purpose of this study is to assess the long term safety of SCH 420814 (preladenant) in participants with moderate to severe Parkinson's Disease who are taking an L-Dopa/dopa decarboxylase inhibitor and/or dopamine agonist. All participants must have participated in the main study (P04501; NCT00406029) entitled "A Phase 2, 12 Week, Double Blind, Dose Finding, Placebo Controlled Study to Assess the Efficacy and Safety of a Range of SCH 420814 Doses in Subjects With Moderate to Severe Parkinson's Disease Experiencing Motor Fluctuations and Dyskinesias."

Inclusion Criteria:

• Participants must have participated in P04501.
• Participants must be >=30 years of age, with a diagnosis of moderate to severe idiopathic Parkinson's disease.
• Participants must have been on a regimen of L-Dopa and/or a dopamine agonist.

Exclusion Criteria:

• Participants who discontinued from Study P04501 because they experienced a serious adverse event (SAE)
• Participants with any form of drug-induced or atypical parkinsonism, cognitive impairment, or psychosis
• Participants taking tolcapone
• Participants who are participating in any other clinical study