This phase 2b study is designed as multicentre, multinational, randomized, double blind, parallel group and placebo controlled with three doses of Bavisant (0.5, 1, and 3 mg/d) in subjects with excessive daytime sleepiness with Parkinson's disease.

Phase 2b study will be conducted with the aim of investigating the efficacy and safety of three fixed doses of Bavisant (0.5, 1 and 3 mg/d) compared to placebo for the treatment of excessive daytime sleepiness (EDS) in subjects with Parkinson's disease.

Inclusion Criteria:

• Subjects of either sex aged 50 to 80 years *Subjects with previous diagnosis of Parkinson's disease (following the UK Parkinson's disease society brain bank clinical diagnostic criteria)*
• Subjects capable of understanding and complying with protocol requirements
• Subjects with medical history of excessive daytime sleepiness

Exclusion Criteria:

• Subjects with excessive daytime sleepiness due to conditions other than Parkinson's disease (including narcolepsy)
• Subjects with clinical evidence of depression with significant psychiatric comorbidities (Hamilton Rating Scale for Depression - HAM-D score greater than or equal to 17; with or without treatment)
• Subjects with evidence of significant fatigue (Fatigue Severity Scale - FSS greater than or equal to 36
• Subjects with known history of abuse of alcohol or other addictive substances in the 6 months prior to inclusion.
• Subjects with known allergies or hypersensitivity to Bavisant or any of its excipients.
• Subjects who are pregnant or lactating.

ITT

70 days