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Theophylline is a methylxanthine used in the treatment of obstructive pulmonary diseases such as asthma and emphysema. Its use has largely fallen by the wayside as alternative, less toxic medications have been developed. However, patients with refractory pulmonary disease may still be prescribed this drug.
Toxicity is classified as acute or chronic. The management strategy is different depending on whether the drug is an immediate- or sustained-release preparation.
Theophylline exerts its therapeutic effects by promoting catecholamine release, which results in enhanced β-agonism.1 Additionally, at high doses, theophylline is a phosphodiesterase inhibitor, which prolongs the effects of β-agonism by preventing the breakdown of cyclic adenosine monophosphate. Theophylline is also an adenosine antagonist, which in therapeutic doses enhances bronchodilatation. However, in toxic doses, adenosine antagonism is associated with the development of tachydysrhythmias and seizures.