Heart Attacks are a major cause of death in this country. When patients have a heart attack, they are treated with anti-clotting drugs, one of which is a drug called Prasugrel. It is important that Prasugrel starts to work as quickly as possible following a heart attack. As many patients who have a heart attack experience excruciating pain, they are often given morphine (a strong painkiller) by the Ambulance crew. We think that morphine may affect how Prasugrel is absorbed from the stomach and may delay how quickly it starts to work. We intend to study the effect of morphine on the absorption of Prasugrel.