It should not be used in patients who have heart failure, an ‘ acute coronary syndrome’ such as unstable angina (a severe type of chest pain that changes in intensity) or certain types of heart attack, diseases that could affect the oxygen supply to the tissues (such as lung or heart problems, recent heart attack or shock), problems with their liver or kidneys, acute alcohol intoxication (excessive alcohol consumption), alcoholism, or complications of diabetes (diabetic ketoacidosis or diabetic coma).