Havodil-M Tablet SR is a combination medication containing Doxofylline 400 mg and Montelukast 10 mg, formulated for sustained release to provide prolonged therapeutic effects. Doxofylline, a xanthine derivative, acts as a bronchodilator by inhibiting phosphodiesterase enzymes, leading to relaxation of bronchial smooth muscles and improved airflow in obstructive airway diseases. Montelukast, a leukotriene receptor antagonist, selectively blocks cysteinyl leukotriene receptors, thereby reducing inflammation, bronchoconstriction, and mucus secretion associated with asthma and allergic rhinitis. This combination is indicated for the management and prevention of chronic respiratory conditions such as asthma and chronic obstructive pulmonary disease (COPD), where both bronchospasm and inflammatory pathways contribute to symptomatology. Havodil-M Tablet SR is designed to improve pulmonary function, reduce the frequency and severity of exacerbations, and enhance patient quality of life. The sustained-release formulation ensures steady plasma concentration, minimizing dosing frequency and improving compliance. It is generally well tolerated; however, clinicians should monitor for potential side effects including headache, gastrointestinal disturbances, and hypersensitivity reactions. Caution is advised in patients with hepatic or renal impairment, and concurrent use with other xanthines or leukotriene modifiers should be carefully evaluated. Havodil-M Tablet SR should be used under medical supervision with appropriate monitoring.