COPD is a disease in which the lung airways are partly damaged and obstructed, making it difficult to breathe. COPD is the fourth leading cause of death in the United States. Symptoms include coughing, excess mucus production, shortness of breath, wheezing, and chest tightness. Treatment usually includes inhaled bronchodilator or steroid medications that work by relaxing the muscles around the lung airways and reducing inflammation. Zileuton, a medication that is used to prevent asthma symptoms, may be beneficial in treating people who experience COPD exacerbations. Zileuton works by blocking the formation of substances that cause inflammation, fluid retention, and constriction in the lungs. The purpose of this study is to evaluate the effectiveness of zileuton at reducing the length of a hospital stay for adults who are hospitalized for a COPD exacerbation.