Clinical Research Directory

Inclusion Criteria: * Patients diagnosed with PD according to the Parkinson's disease society brain bank clinical diagnostic criteria of the UK Parkinson's Disease Society * Patients who are being treated with levodopa or levodopa combination drugs and have any of the following troublesome symptoms or conditions: * Patients with wearing-off phenomenon * Patients with ON-/OFF-phenomenon * Patients with no-on/delayed on phenomenon * Patients with inadequate response to levodopa Exclusion Criteria: * Patients suspected of having parkinsonism other than PD based on medical history, physical findings, laboratory test values, dopamine transporter-single photon emission computed tomography (DAT-SPECT), etc. * Patients who have undergone neurosurgical therapy for PD (e.g., stereotactic thalamotomy and pallidotomy and deep brain stimulation) or who are scheduled to undergo surgical therapy during the trial period * Patients complicated with overt dementia or a Mini-Mental State Examination (MMSE) score of \< 24 at the start of the screening period