WHAT IS THEOPHYLLINE (AMINOPHYLLINE) TEST?
Theophylline is a methylxanthine drug that decreases the breakdown of intracellular cyclic adenosine monophosphate (cAMP), which in turn stimulates dilation of the smooth muscles of the bronchial airways and relaxation of the pulmonary blood vessels. However, this therapeutic effect does not occur until levels are at or near the top of the therapeutic range. At lower levels, theophylline exhibits anti–inflammatory properties, enabling the sparing of steroid medication. It is for the latter reason that there has been a return to use of intravenous theophylline for acute exacerbation of the obstructive pulmonary disease. Theophylline is 60% plasma protein bound, with a half-life of 6-10 hours in adults and 2-5 hours in children (half-life is reduced 40% in cigarette smokers); 90% of theophylline is metabolized in the liver. Steady-state levels occur in 15-20 hours in adults and in 5-40 hours in children.