What is the mechanism of action of albuterol?

• A. Vasoconstriction and decreased airway flow
• B. Bronchodilation and relaxes smooth muscle airways
• C. Decreases heart rate
• D. Sedation and CNS depression

Answer: (B)

Albuterol works by stimulating beta-2 receptors in the bronchial smooth muscle. This activates a signaling pathway that increases cyclic AMP, which leads to relaxation of the smooth muscles and dilation of the airways. The result is reduced airway resistance and easier breathing during bronchospasm. The other options describe effects that don’t occur with albuterol’s primary action—vasoconstriction would narrow airways, decreased heart rate isn’t how this drug works, and sedation/CNS depression is not its mechanism. Note that at higher doses, some beta-1 effects can cause a faster heart rate, but the main therapeutic action is bronchodilation.