A standard 12-lead ECG will be performed. A central facility will be used for interpretation and analysis of the ECGs. If a patient discontinues in between these visits, this will be assessed at the time of discontinuation.

Part III of the UPDRS (items 18-31; total score 0-56), has been proven to be a reliable instrument in assessing the anti-parkinsonian effect in PD patients. This scale measures 14 items such as speech, facial expression, tremor, action or postural tremor, rigidity, finger taps, hand movement, alternating movement, leg agility, arising from a chair, posture, gait, postural stability, and bradykinesia. A higher score is indicative of worsening of symptoms. If a patient discontinues in between these visits, this will be assessed at the time of discontinuation.

The occurrence of adverse events relating to the underlying movement disorder Parkinson's disease would be sought by non-directive questioning of the patient at each visit. Adverse events may also be detected when they are volunteered by the patient during or between visits or through physical examination, laboratory test, or other assessment.

The LFADLDS is a questionnaire asking the patient about the degree to which dyskinesia interferes with activities of daily living. The LFADLDS is modified from the ADL section of the UPRDS (part II). Specific definitions for severity rating codes (range, 0-4 for each task) will be provided for reproducibility of results. A higher score indicates more severe impairment. Two versions of the revised LFADLDS will be used in this study: a patient version and a caregiver version. If a patient discontinues in between these visits, this will be assessed at the time of discontinuation.

The UPDRS is a standardized instrument for measuring the disease state of PD patients.

Question 32 assesses duration of dyskinesias expressed in percentage of the day . Question 33 makes a historical assessment of disability due to dyskinesia during the previous week (not disabling, mildly disabling, moderately disabling, severely disabling, completely disabling).

Question 34 of part IV assesses how painful the dyskinesias are from 0 (no painful dyskinesias) to 4 (marked). If a patient discontinues in between these visits, this will be assessed at the time of discontinuation.

The MMSE is a brief test of cognitive dysfunction consisting of five sections (orientation, registration, attention-calculation, recall, and language) administered by a health care professional. The MMSE results in total possible score of 30, with higher scores indicating better function. If a patient discontinues in between these visits, this will be assessed at the time of discontinuation.

The SCOPA-PC is an easily administered semi-structured, questionnaire developed for the assessment of psychiatric symptoms, including compulsive behavior, in Parkinson's disease patients administered by a clinician with input provided by patient and caregiver. The total SCOPA score ranges from 0-21, with higher scores reflecting more psychiatric complications. If a patient discontinues in between these visits, this will be assessed at the time of discontinuation.

The C-SSRS assesses suicidal ideation/behavior using a patient interview. The data is mapped to Columbia Classification Algorithm for Suicide assessment. The code and categories are: completed suicide, suicide attempt, preparatory actions toward imminent suicide behavior, suicidal ideation, self-injurious behavior without suicidal intent.

The proportion of patients who are coded in the categories above, the proportion of patients with any suicidal behavior engaged in during the study, and the proportion of patients with suicidality will be summarized.