A Clinical Trial to Find Out V81444's Side Effects and Blood Levels in Healthy Men

Inclusion Criteria: * Healthy male volunteers: aged 18 to 45 years, in good general health as determined by medical history, physical examination and screening investigations, and taking no regular medication. Confirmation to be sought for all volunteers that their general practitioner has provided an acceptable medical history. Exclusion Criteria: * have a history or evidence of clinically significant gastrointestinal disease, including ulcers, gastro-oesophageal reflux disease or gastritis * any known malformations that would make OGD difficult or unsafe(Part B only) * have taken V81444 in any previous investigational study * have taken any restricted concomitant medication * have multiple drug allergies or be allergic to any of the components of V81444 study medication or its matching placebo or midazolam (Part B only) * in the 4 calendar months before study drug administration have smoked more than 5 cigarettes per day have consumed more than 28 units of alcohol per week have donated blood or plasma in excess of 500 mL been exposed to any new investigational agent or any other adenosine A2A receptor antagonist used non-steroidal anti-inflammatory drugs regularly had a new tattoo or body piercing * have any clinically relevant abnormal findings at screening and/or admission * intend to father a child with their female partner or through sperm donation within 4 months after the last dose of study medication