Synatura® is a drug commonly used to suppress cough and sputum in patients with acute upper respiratory tract infection and chronic inflammatory bronchitis. According to the Phase III studies conducted in Korea, the safety and efficacy of Synatura® on antitussive and expectorant effects were confirmed in patients with acute upper respiratory infection and chronic inflammatory bronchitis. However, no studies have been conducted for the effects of Synatura® in patients with COPD. COPD is divided into emphysema type and chronic bronchitis type, while typical clinical symptoms of chronic bronchitis are cough and sputum. Therefore, Synatura®, which is effective for chronic bronchitis, is expected to be effective in patients with chronic bronchitis accompanied by COPD.