Doxofylline 400mg is a bronchodilator medication commonly used to treat respiratory conditions like asthma and chronic obstructive pulmonary disease (COPD). It works by relaxing the muscles of the airways, helping to widen them and make breathing easier. Doxofylline is a xanthine derivative, similar to theophylline, but with a lower risk of side effects such as tremors and tachycardia. It helps to improve airflow, reduce symptoms like wheezing and shortness of breath, and prevent asthma attacks. The 400mg dosage is typically used for sustained therapeutic effect, providing relief for patients suffering from chronic respiratory conditions.