• Diagnosis of PD consistent with United Kingdom (UK) Brain Bank criteria and MDS Research Criteria for the Diagnosis of PD; must include bradykinesia with sequence effect and motor asymmetry if no rest tremor, and a prominent response to levodopa.

• Body Mass Index (BMI) \> 18.0 and \< 35.0 Kilograms per meter square (kg/m\^2), inclusive at Screening.

• Modified Hoehn and Yahr Stage ≤ 3 in the ON state.

• Freely ambulatory at the time of Screening (with/without assistive device).

• Montreal Cognitive Assessment (MoCA) Score of at least 24.

• PD medications must be stable for at least 4 weeks prior to Screening; monoamine oxidase B (MAO-B) inhibitors must be stable for at least 12 weeks prior to Screening.

• Levodopa administration at least 4 times daily (immediate or extended release) or three times daily (Rytary or Crexont).

• Stable use of oral anti-sialorrhea medications for 30 days before Screening, without anticipated need for change during the study.

• Average of ≥ 3 h total OFF time/day on Screening home diaries, with at least 2.5 hours OFF on each diary day.

• During Screening, capable of adequately identifying ON, OFF, and dyskinetic states (\>80% concordance) through properly completed ON/OFF diaries.

• Female participants of childbearing potential and male participants with female partners of childbearing potential must agree to either remain abstinent or use adequate and reliable contraception throughout the study and for at least 12 weeks after the last dose of study drug has been taken.

• Able and willing to give written informed consent approved by an institutional review board, and to comply with scheduled visits, treatment plan, laboratory tests, and other study-related procedures.

• Approved as an appropriate and suitable candidate by the Enrollment Authorization Committee (EAC)