To Evaluate Whether Naproxen and Darexaban (YM150) Interact in Their Effects

Inclusion Criteria: * Body mass index (BMI) between 18.5-30.0 kg/m2 * Male subjects must be non-fertile, i.e. surgically sterilized or must practice an adequate contraceptive method to prevent pregnancies Exclusion Criteria: * Known or suspected hypersensitivity to darexaban or naproxen or any components of the formulation used * A contra-indication for the use of naproxen * Any of the liver function tests (i.e. ALT, AST and bilirubin) above the upper limit of normal at repeated measures * Any clinically significant history of any other disease or disorder - gastrointestinal, cardiovascular, respiratory, renal, hepatic, neurological, dermatological, psychiatric or metabolic as judged by the medical investigator. * Any clinically significant abnormality following the investigator's review of the pre-study physical examination, ECG and clinical laboratory tests * Use of any prescribed or OTC (over-the-counter) drugs (including vitamins, natural and herbal remedies, e.g. St. John's wort) in the 2 weeks prior to admission to the Clinical Unit, except for occasional use of paracetamol (up to 3 g/day) * Regular use of any inducer of liver metabolism (e.g. barbiturates, rifampicin) in the 3 months prior to admission to the Clinical Unit * Donation of blood or blood products within 3 months prior to admission to the Clinical Unit * Any use of drugs of abuse, or smoking of more than 10 cigarettes (or equivalent) or more than 21 units (210 g) of alcohol per week within the 3 months prior to study * Participation in any clinical study within 3 months or participation in more than 3 clinical studies within 12 months, prior to the expected date of enrolment into the study, provided that the clinical study did not entail a biological compound with a long terminal half life