Which medication is an example of a nonselective β-antagonist?

Propranolol is an example of a nonselective β-antagonist, which means that it inhibits both β1 and β2 adrenergic receptors throughout the body. This nonselectivity is significant because it means the medication can affect various physiological systems. For instance, by blocking β1 receptors in the heart, propranolol can reduce heart rate and contractility, making it useful for treating conditions such as hypertension and anxiety.

Additionally, the inhibition of β2 receptors, which are found in smooth muscles like those in the lungs and vasculature, can contribute to effects on bronchial tone and peripheral vasodilation. This broad efficacy makes propranolol valuable for a range of clinical applications, including migraine prophylaxis and treatment of certain types of tremors. This nonselectivity contrasts with other options listed, such as metoprolol and atenolol, which are selective β1 antagonists, focusing primarily on cardiovascular effects, and terbutaline, which is a selective β2 agonist used primarily for bronchial relaxation. Understanding these differences is crucial for selecting appropriate treatments based on the patient's condition and the desired pharmacological effect.