The Influence of Febuxostat on Coronary Artery Endothelial Dysfunction in Participants With Chronic Stable Angina

The drug being tested in this study is called febuxostat. Febuxostat is being tested to treat people who have angina. This study will look at the heart and blood flow of people who take febuxostat. The study will enroll approximately 30 patients. Participants will be randomly assigned (by chance, like flipping a coin) to one of the two treatment groups (or sequences)-which will remain undisclosed to the patient and study doctor during the study (unless there is an urgent medical need): * Sequence 1: 6 weeks febuxostat followed by 6 weeks of placebo. * Sequence 2: 6 week placebo followed by 6 weeks of febuxostat All participants will be asked to take one capsule at the same time each day throughout the study. All participants will be asked to record any time they have angina symptoms during the study. This single-center trial will be conducted in the United States. The overall time to participate in this study is 16 weeks. Participants will make 7 visits to the clinic including a final visit 4 weeks after last dose of study drug for a follow-up assessment.