What is the mechanism of action of theophylline in asthma treatment?

Theophylline is primarily known for its role as a bronchodilator in the treatment of asthma, and its mechanism of action involves the inhibition of phosphodiesterase. By inhibiting this enzyme, theophylline prevents the breakdown of cyclic adenosine monophosphate (cAMP), leading to increased levels of cAMP within bronchial smooth muscle cells. The elevated cAMP results in relaxation of these muscles, which helps to dilate the airways, thereby alleviating symptoms of asthma and improving airflow.

This mechanism also has anti-inflammatory effects, contributing to the reduction of airway hyperreactivity and improving lung function over time. Theophylline may not be as commonly used today, given the availability of newer therapies with better therapeutic profiles, but understanding its action remains crucial for a comprehensive grasp of asthma treatment modalities.

Other mechanisms listed, such as inhibition of leukotriene synthesis, activation of adrenergic receptors, or blockade of histamine receptors, represent different pathways or classes of medications that are not the primary action of theophylline. These mechanisms exist in relevant therapies but do not describe the action of theophylline itself.