Which of the following is a class of drugs that stimulate beta-adrenergic receptors to improve airflow in asthma?

• A. Beta-agonists
• B. Bronchodilation
• C. Asthma
• D. Bronchoconstriction

Answer: (A)

Activating receptors that respond to adrenaline in the airways relaxes the smooth muscle and widens the bronchi, which is why this drug class is used to improve airflow in asthma. These medications are beta-agonists, and they mainly target beta-2 receptors on airway smooth muscle. When a beta-2 receptor is stimulated, it triggers a signaling cascade (via Gs protein and increased cAMP) that reduces intracellular calcium, causing the muscle to relax. The result is bronchodilation, making it easier to breathe and relieving the wheeze and shortness of breath.

Understanding the context helps: such drugs come in fast-acting forms for immediate relief and longer-acting forms for ongoing control, often used alongside other therapies like corticosteroids for comprehensive asthma management. It’s important to note that the goal of beta-agonists is bronchodilation, not bronchoconstriction, and the other options listed are not drug classes that produce this effect.