Single-centre, open-label, randomised, three-part, two-way crossover study in 84 healthy volunteers. In each part, the study consisted of two consecutive single-dose treatment periods separated by a washout period of at least 14 days.

Inclusion Criteria:

• A signed and dated informed consent form before any study-specific screening procedure was performed;
• Male or female subjects aged 18 to 45 years, inclusive;
• Body mass index (BMI) between 18 and 30 kg/m2 inclusive;
• Healthy as determined by pre-study medical history, physical examination, vital signs, complete neurological examination and 12-lead electrocardiogram (ECG);
• Negative tests for hepatitis B surface antigen (HBsAg), anti- hepatitis C virus antibodies (HCV Ab) and anti-human immunodeficiency virus antibodies (HIV-1 and HIV-2 Ab) at screening;
• Clinical laboratory test results clinically acceptable at screening and admission to each treatment period;
• Negative screen for alcohol and drugs of abuse at screening and admission to each treatment period;
• Non-smokers or ex-smokers for at least 3 months;
• Able to participate, and willing to give written informed consent and comply with the study restrictions.
• If female:
• She was not of childbearing potential by reason of surgery or, if of childbearing potential, she used an effective non-hormonal method of contraception [intrauterine device or intrauterine system; condom or occlusive cap (diaphragm or cervical or vault caps) with spermicidal foam or gel or film or cream or suppository; true abstinence; or vasectomized male partner, provided that he was the sole partner of that subject] for all the duration of the study;
• She had a negative serum pregnancy test at screening and a negative urine pregnancy test at admission to each treatment period.

Exclusion Criteria:

• Subjects who had a clinically relevant history or presence of respiratory, gastrointestinal, renal, hepatic, haematological, lymphatic, neurological, cardiovascular, psychiatric, musculoskeletal, genitourinary, immunological, dermatological, endocrine, connective tissue diseases or disorders, or had a clinically relevant surgical history;
• Had clinically relevant findings in laboratory tests, particularly any abnormality in the coagulation tests, or any abnormality in the liver function tests;
• Had a history of relevant atopy or drug hypersensitivity;
• Had a history of alcoholism and/or drug abuse;
• Consumed more than 14 units of alcohol per week [1 unit of alcohol = 280 mL beer (3-4°) = 100 mL wine (10-12°) = 30 mL spirits (40°)];
• Had a significant infection or known inflammatory process on screening or admission to each treatment period;
• Had acute gastrointestinal symptoms (e.g., nausea, vomiting, diarrhoea, heartburn) at the time of screening or admission to each treatment period;
• Had used medicines within 2 weeks of admission to first period that could affect the safety or other study assessments, in the Investigator's opinion;
• Had previously received opicapone;
• Had used any investigational drug or participated in any clinical trial within 90 days prior to screening;
• Had participated in more than 2 clinical trials within the 12 months prior to screening;
• Had donated or received any blood or blood products within the 3 months prior to screening;
• Were vegetarians, vegans or had medical dietary restrictions;
• Could not communicate reliably with the Investigator;
• Were unlikely to co-operate with the requirements of the study;
• Were unwilling or unable to give written informed consent;

If female:

• She was pregnant or breast-feeding.