Theophylline, also known as dimethylxanthine. It is a methylxanthine drug used in therapy for respiratory diseases such as COPD or asthma under a variety of brand names. As a member of the xanthine family it bears structural and pharmacological similarity to caffeine. It is naturally found in tea, although in trace quantities (~1mg/l), significantly less than therapeutic doses. The main actions of theophylline are relaxing of bronchial smooth muscle, positive inotropic (increasing heart muscle contractility and efficiency), positive chronotropic (increasing heart rate)increase of blood pressure, increase of renal blood flow, some anti-inflammatory effects.