Deriphyllin Retard 300Tablet belongs to the class of drugs called bronchodilators used to prevent and treat symptoms of asthma and chronic obstructive pulmonary disease (COPD). Asthma is a chronic (long-term) respiratory condition in which airways narrow, swell, and produce extra mucus, leading to difficulty breathing. COPD is a group of lung diseases with emphysema (shortness of breath) and chronic bronchitis (inflammation of the lining of bronchial tubes).