About Theophylline Bronchodilator, a methylxanthine derivative, Anti asthma, in COPD. Mechanism of Action of Theophylline It inhibit phosphodiesterase enzyme which degrades cyclic nucleotides intracellularly and it results the cyclic AMP accumulation in the cell. This cause bronchodialatation, cardiac stimulation and vasodilatation. This drug release calcium from sarcoplasmic reticulam, especially in cardiac muscles and results increased cardiac muscle contraction. This drug also blocks adenosine receptors (adenosine acts as a local mediator in CNS & CVS and other organs- which contracts smooth muscles, especially in bronchi, blood vessels etc). This results bronchodialatation and vasodialatation. Indications for Theophylline 1. Asthma 2. Chronic obstructive pulmonary disease 3. Chronic bronchitis 4. Emphysema 5. It can be used in premature infants who stop breathing