Which medication has equal amounts of B1 and B2 activity?

• A. Atenolol
• B. Propranolol
• C. Metoprolol
• D. Carvedilol

Answer: (B)

Propranolol is the medication that has equal amounts of B1 and B2 activity. It is a non-selective beta-adrenergic antagonist, meaning it blocks both beta-1 and beta-2 receptors without preference. This dual action makes propranolol effective in treating a variety of conditions, such as hypertension, anxiety, and certain types of tremors, by impacting both the heart (beta-1 activity) and the lungs or peripheral vasculature (beta-2 activity).

In contrast, atenolol and metoprolol are both selective beta-1 antagonists, primarily affecting the heart with little to no effect on beta-2 receptors. This selectivity leads to a reduced risk of bronchoconstriction and is particularly important for patients with respiratory conditions. Carvedilol, while having some beta-1 blocking activity, also possesses alpha-1 blocking properties, which alters its profile compared to propranolol. Thus, propranolol stands out as the medication with balanced effects on both B1 and B2 receptors.