Which of the following medications is an example of a xanthine bronchodilator?

• A. Aspirin
• B. Theophylline
• C. Epinephrine
• D. Prednisone

Answer: (B)

Theophylline is an example of a xanthine bronchodilator because it acts primarily through the relaxation of bronchial smooth muscle, which leads to bronchodilation. Theophylline works by inhibiting phosphodiesterase, the enzyme that breaks down cyclic AMP. This action increases the levels of cAMP within the cells, which promotes relaxation of the respiratory muscles and improves airflow in the lungs.

Additionally, theophylline is categorized as a methylxanthine, a class of compounds that includes other similar agents. Xanthine bronchodilators are often used in the management of asthma and chronic obstructive pulmonary disease (COPD) because of their ability to alleviate symptoms of bronchoconstriction.

In contrast, the other medications listed serve different therapeutic purposes. Aspirin is primarily an anti-inflammatory and analgesic medication but does not have bronchodilatory effects. Epinephrine, while a bronchodilator, is classified as a catecholamine and functions differently than xanthine derivatives. Prednisone is a corticosteroid, used primarily for its anti-inflammatory properties, rather than for direct bronchodilation. Thus, theophylline is the correct answer as it specifically belongs to the class of xanthine bronchodilators.