Which beta-adrenergic antagonist is nonselective for both beta1 and beta2 receptors?

Which beta-adrenergic antagonist is nonselective for both beta1 and beta2 receptors?

• A. Atenolol
• B. Betaxolol
• C. Esmolol
• D. Nadolol

Answer: (D)

The main idea here is receptor selectivity of beta-adrenergic blockers. Nonselective blockers inhibit both beta-1 receptors (primarily in the heart) and beta-2 receptors (in the lungs and other tissues). This means they slow the heart and reduce contractility like others, but they can also cause bronchoconstriction and affect glucose homeostasis because of beta-2 blockade. Nadolol is nonselective for both beta-1 and beta-2 receptors, so it fits the definition of a nonselective beta-blocker. The other agents listed are beta-1 selective, meaning they mainly affect the heart with less impact on the airways, which is why they’re less likely to provoke bronchospasm in susceptible individuals.

The main idea here is receptor selectivity of beta-adrenergic blockers. Nonselective blockers inhibit both beta-1 receptors (primarily in the heart) and beta-2 receptors (in the lungs and other tissues). This means they slow the heart and reduce contractility like others, but they can also cause bronchoconstriction and affect glucose homeostasis because of beta-2 blockade. Nadolol is nonselective for both beta-1 and beta-2 receptors, so it fits the definition of a nonselective beta-blocker. The other agents listed are beta-1 selective, meaning they mainly affect the heart with less impact on the airways, which is why they’re less likely to provoke bronchospasm in susceptible individuals.