A Study of the Pharmacokinetics, Pharmacodynamics, and Safety of Opicapone in Subjects With Parkinson's Disease Taking Levodopa.

Inclusion Criteria:

1. Have a clinical diagnosis of idiopathic Parkinson's Disease (PD) for at least 3 years
with clear improvement with levodopa treatment

2. Be at a stable dose of maintenance medication(s) for PD, including stable doses of
CD/LD

3. Subjects of childbearing potential who do not practice total abstinence must agree to
use hormonal or two forms of nonhormonal contraception (dual contraception)
consistently during the screening, treatment and follow-up periods of the study

4. Have a body mass index (BMI) of 18 to 40 kg/m2

5. Have a modified Hoehn and Yahr stage of ≤4 in the OFF state

6. Be able to tolerate an overnight period of 12 hours without CD/LD

7. Be in good general health and expected to complete the clinical study as designed

Exclusion Criteria:

1. Are currently pregnant or breastfeeding

2. More than 2 alcoholic beverages daily or more than 14 alcoholic beverages weekly
within 7 days of Day -1 or consume any alcohol within 48 hours of Day -1.

3. Have motor fluctuations during the day (ie, effect of levodopa "wearing off" or having
unpredictable "off" periods), or severe or intolerable levodopa-induced dyskinesia

4. Have had previous exposure to opicapone, or have an allergy, hypersensitivity, or
intolerance to opicapone or other COMT inhibitor.

5. Have a history of a medical condition or surgical procedure that might interfere with
absorption or metabolism.

6. Have a known history of neuroleptic malignant syndrome

7. Have an unstable medical condition or chronic disease

8. Have taken certain prohibited medications within 28 days of Day -1.

9. Have a known or suspected diagnosis of AIDS, or have tested seropositive for HIV

10. Have hepatitis A or B

11. Have a significant risk of suicidal or violent behavior