A Study to Evaluate the add-on Efficacy and Safety of Opicapone 50 mg or an Extra Dose of L-DOPA 100 mg for the Treatment of Wearing-off in Patients With PD

Inclusion criteria

• Diagnosed with idiopathic PD according to the UK Parkinson's Disease Society Brain Bank Clinical Diagnostic Criteria (2006) or according to the Movement Disorder Society (MDS) Clinical Diagnostic Criteria (2015).
• Disease severity Stage III (H&Y staging) at ON.
• Treated on a stable regimen for at least four weeks before screening with immediate-release L-DOPA/DDCI, three to four intakes per day, and up to maximum daily dose of 600mg L-DOPA.
• Signs of wearing-off phenomenon with average total daily OFF-time while awake of at least 1 hour, including the early morning pre-first dose OFF (i.e. the time between wake-up and response to the first L-DOPA/DDCI dosage), despite optimal anti-PD therapy (based on Investigator's assessment).

Exclusion criteria

• Non-idiopathic PD (atypical Parkinsonism, secondary [acquired or symptomatic] parkinsonism, Parkinson-plus syndrome.
• Severe and/or unpredictable OFF periods, according to Investigator judgment.
• Average total daily OFF-time while awake of >5 hours, including the early morning pre-first dose OFF, despite optimal anti-PD therapy (based on Investigator's assessment).
• Treatment with prohibited medication: entacapone, tolcapone, monoamine oxidase (MAO) inhibitors (except selegiline up to 10 mg/day in oral formulation or 1.25 mg/day in buccal absorption formulation, rasagiline up to 1 mg/day or safinamide up to 100 mg/day), apomorphine or antiemetics with antidopaminergic action (except domperidone) within the last four weeks before screening.
• Previous or planned (during the entire study duration) deep brain stimulation or stereotactic surgery (e.g. pallidotomy, thalamotomy).