Study of BIA 9-1067 to Investigate Its Effect on Levodopa Pharmacokinetic

Inclusion Criteria: * Able and willing to give written informed consent. * Male or female subjects aged between 18 and 45 years, inclusive. * Subjects of body mass index (BMI) between 19 and 30 kg/m2, inclusive. * Healthy as determined by pre-study medical history, physical examination, vital signs, complete neurological examination and 12-lead ECG. * Negative tests for HBsAg, anti-HCVAb and HIV-1 and HIV-2 Ab at screening. * Clinical laboratory test results clinically acceptable at screening and admission to the treatment period. * Negative screen for alcohol and drugs of abuse at screening and admission to the treatment period. * Non-smokers or ex-smokers for at least 3 months. * (If female) She was not of childbearing potential by reason of surgery or, if of childbearing potential, she used one of the following methods of contraception: intrauterine device (by the subject) and condoms (by the partner) or diaphragm (by the subject) and condoms (by the partner) or spermicide (by the subject) and condoms (by the partner). * (If female) She had a negative urine pregnancy test at screening and admission to the treatment period. Exclusion Criteria: * 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. * Clinically relevant surgical history. * Any abnormality in the coagulation tests. * Any abnormality in the liver function tests. * A history of relevant atopy or drug hypersensitivity. * A history or presence of narrow-angle glaucoma. * A suspicious undiagnosed skin lesions or a history of melanoma. * History of alcoholism or drug abuse. * Consumed more than 14 units of alcohol a week. * Significant infection or known inflammatory process at screening or admission to the treatment period. * Acute gastrointestinal symptoms (e.g., nausea, vomiting, diarrhoea, heartburn) at the time of screening or admission to the treatment period. * Had used non-selective monoamine oxidase (MAO) inhibitors within 2 weeks of admission to the treatment period. * Had used medicines within 2 weeks of admission to the treatment period that may have affected the safety or other study assessments, in the investigator's opinion. * Had previously received BIA 9-1067. * Had used any investigational drug or participated in any clinical trial within 6 months 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. * Vegetarians, vegans or had medical dietary restrictions. * Cannot communicate reliably with the investigator. * Unlikely to co-operate with the requirements of the study. * Unwilling or unable to gave written informed consent. * (If female) She was pregnant or breast-feeding. * (If female) She was of childbearing potential and she did not use an approved effective contraceptive method or she used oral contraceptives.