AE=any untoward medical occurrence (UMO), temporally associated with the use of a medicinal product (MP), whether or not considered related to the MP. SAE=any UMO that, at any dose, results in death, is life threatening, requires hospitalization/prolongation of existing hospitalization, results in disability/incapacity, or is a congenital anomoly/birth defect. The Investigator determined if an AE/SAE was related to investigational product. Medical/scientific judgment was used to determine whether SAE reporting was appropriate in situations in which an event may not have met the SAE definition.

An adverse event is defined as any untoward medical occurrence in a participant, temporally associated with the use of a medicinal product, whether or not considered related to the medicinal product. The Investigator determined if an AE/SAE was related to investigational product. The On-Treatment Phase is comprised of the Open-label Treatment Phase and the Down-titration Phase.

AE=any untoward medical occurrence (UMO), temporally associated with the use of a medicinal product (MP), whether or not considered related to the MP. SAE=any UMO that, at any dose, results in death, is life threatening, requires hospitalization/prolongation of existing hospitalization, results in disability/incapacity, or is a congenital anomoly/birth defect. The Investigator determined if an AE/SAE was related to investigational product. Medical/scientific judgment was used to determine whether SAE reporting was appropriate in situations in which an event may not have met the SAE definition.

An adverse event is defined as any untoward medical occurrence in a participant, temporally associated with the use of a medicinal product, whether or not considered related to the medicinal product. In addition to the data recorded at the follow-up visit, SAEs occurring up to and including 2 days after the last dose of down-titration medication are included in the Follow-up Phase.

An adverse event is defined as any untoward medical occurrence in a participant, temporally associated with the use of a medicinal product, whether or not considered related to the medicinal product. The Investigator determined if an AE/SAE was related to investigational product. In addition to the data recorded at the follow-up visit, SAEs occurring up to and including 2 days after the last dose of down-titration medication are included in the Follow-up Phase.

The "off" state is defined as the state in which Parkinson's Disease (PD) symptoms (lack of mobility, tremor, or rigidity) are not adequately controlled by the drug. Participants were asked to record the duration of their "off " periods in 24-hour diary cards prior to each visit on two days of each relevant week. The total number of awake hours spent "off" per 24-hour period was the sum of the hours recorded on the two 24-hour diary cards. Change from Baseline is calculated as the value at Week 24 minus the Baseline value.