Which medication provides bronchodilation primarily through beta-2 receptor stimulation?

• A. Albuterol
• B. Ipratropium bromide
• C. Mannitol
• D. Furosemide

Answer: (A)

Bronchodilation achieved by beta-2 receptor stimulation comes from triggering beta-2 adrenergic receptors on bronchial smooth muscle, which sets off a cascade that relaxes the muscle and widens the airways. Albuterol is a classic example of this approach: it’s a beta-2 adrenergic agonist that selectively stimulates those receptors, increasing cAMP inside smooth muscle cells and causing rapid relaxation of the bronchial airways. That direct activation of beta-2 receptors is what makes albuterol effective for quick relief of bronchospasm.

The other options don’t work this way. Ipratropium bromide blocks muscarinic receptors, reducing acetylcholine-mediated bronchoconstriction rather than acting through beta-2 receptors. Mannitol is an osmotic agent used to aid mucus clearance, not to induce smooth muscle relaxation via beta-2 stimulation. Furosemide is a diuretic with no direct bronchodilatory effect.