Theophylline

Not A/B H target. Theophylline is a natural alkaloid dimethylxanthine derivative of xanthine isolated from the plants Camellia sinensis and Coffea arabica, green and black tea. Theophylline appears to inhibit phosphodiesterase and prostaglandin production, regulate calcium flux and intracellular calcium distribution, and antagonize adenosine. Physiologically, this agent relaxes bronchial smooth muscle, produces vasodilation (except in cerebral vessels), stimulates the CNS, stimulates cardiac muscle, induces diuresis, and increases gastric acid secretion; it may also suppress inflammation and improve contractility of the diaphragm. Theophylline played an important role in the management of both acute and chronic reversible airway obstruction, in particular asthma and chronic bronchitis. However, it has a narrow safety window, which, along with its variability in disposition, makes dosing difficult to predict and toxicity difficult to prevent. Symptoms of toxicity include tachycardia, severe restlessness, agitation, nausea and vomiting, particularly at high blood concentrations