Test Details: Theophylline, also known as 1,3-dimethylxanthine, is a phosphodiesterase inhibiting drug used in therapy for respiratory diseases such as chronic obstructive pulmonary disease (COPD) and asthma As a member of the xanthine family, and is readily found in nature, being present in tea, caffeine and and cocoa. A small amount of theophylline is one of the products of caffeine metabolic processing in the liver. Theophylline is a bronchodilator, a type of medication that makes it easier to breathe. Theophylline comes as an extended-release (long-acting) tablet, extended-release capsule, and a solution (liquid) to take by mouth. Theophylline is used to prevent and treat wheezing, shortness of breath, and chest tightness caused by asthma, chronic bronchitis, emphysema, and other lung diseases. It relaxes and opens air passages in the lungs, making it easier to breathe. Theophylline is sometimes used to treat breathing problems in premature infants.