OpiCapone Effect on Motor Fluctuations and pAiN

Inclusion Criteria

• Able to comprehend and willing to sign an informed consent form and to comply with all aspects of the study.
• Male or female patients aged 30 years or older.
• Experiencing PD associated pain for at least 4 weeks prior to V1.
• Diagnosed with idiopathic PD according to the UK Parkinson's Disease Society Brain Bank Clinical Diagnostic Criteria (2006) or according to MDS Clinical Diagnostic Criteria (2015).
• Disease severity Stages I-III (modified Hoehn & Yahr staging) at ON.
• Treated with 3 to 8 intakes per day of L-dopa/DDCI (which may include a slow-release formulation), on a stable regimen for at least 4 weeks before V1.
• In case of any other anti-PD-treatment, it should be on a stable regimen for at least 4 weeks before V1, and not likely to need any adjustment until V6.
• No changes in chronic treatment regimen for pain within the last 4 weeks before V1. This includes medication (including but not limited to paracetamol, opioids, nonsteroidal anti-inflammatory drugs [NSAIDS], antidepressants, anticonvulsants and corticosteroids) and non-medication therapies (including but not limited to transcutaneous electrical nerve stimulation and bioelectrical therapy).
• Signs of "wearing-off" phenomenon (end-of-dose motor fluctuations) with average total daily OFF time while awake of at least 1.5 hours, excluding the early morning pre-first dose OFF, despite optimal anti-PD therapy (based on investigator's assessment).
• Domain 3 of KPPS ≥ 12.
• For females: Postmenopausal for at least 2 years before V1, surgically sterile for at least 6 months before V1, or practicing effective contraception until V6. Female patients who request to continue with oral contraceptives must be willing to use non-hormonal methods of contraception in addition during the course of this study.

For males: Male patients who are sexually active with a partner of childbearing potential must use, with their partner, a condom plus an approved method of highly effective contraception during the treatment period until V6.

• Have filled-in self-rating diary in accordance with the diary instructions and with ≤ 3 missing entries per day, in the 3 days preceding V2a/V2b.
• With at least 1.5 OFF hours per day, excluding the early morning pre-first dose OFF period (i.e. the time between wake-up and response to the first L dopa/DDCI dosage), as recorded in at least 2 of the 3 days in the self-rating diary for the 3 days preceding V2a/V2b.
• Results of the screening laboratory tests are considered acceptable by the investigator (i.e. not clinically relevant for the well-being of the patient or for the purpose of the study).
• Domain 3 of KPPS ≥ 12.
• Adequate compliance to relevant (PD and pain related) concomitant medication during the screening period (based on the investigator's judgment).

Exclusion Criteria

• Non-idiopathic PD (atypical parkinsonism, secondary [acquired or symptomatic] parkinsonism, Parkinson-plus syndrome).
• Severe and/or unpredictable OFF periods, according to investigator judgement.
• Major/prominent non-PD-related pain (e.g. due to malignant disease).
• 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), or antiemetics with antidopaminergic action (except domperidone) within the last 4 weeks before V1.
• Previous or planned (during the entire study duration) L-dopa/carbidopa intestinal gel infusion, deep brain stimulation or stereotactic surgery (e.g. pallidotomy, thalamotomy).
• Treatment with apomorphine within the last 4 weeks before V1 or likely to be needed at any time until V6.
• Previous or current use of opicapone.
• Use of any other IP, currently or within the 3 months (or within 5 half-lives of the IP, whichever is longer) before V1.
• Past (within the past year) or presen