Which statement best describes the role of alpha-adrenergic antagonists in treating hypertension and benign prostatic hyperplasia, with doxazosin as an example?

Which statement best describes the role of alpha-adrenergic antagonists in treating hypertension and benign prostatic hyperplasia, with doxazosin as an example?

• A. They cause vasodilation and relaxation of bladder neck smooth muscle; doxazosin is an example.
• B. They decrease heart rate through beta blockade.
• C. They inhibit ACE.
• D. They cause tachycardia.

Answer: (D)

Blocking alpha-1 receptors produces two key therapeutic effects relevant to hypertension and BPH. First, it causes dilation of vascular smooth muscle, lowering peripheral resistance and blood pressure. Second, it relaxes smooth muscle in the bladder neck and prostate, improving urine flow and reducing obstruction in BPH. Doxazosin is a classic example of an alpha-1 antagonist that achieves both effects. The other descriptions don’t fit the mechanism. This class is not beta-blocking, so it doesn’t decrease heart rate through beta blockade. It doesn’t inhibit ACE. Tachycardia can occur as a reflex response to the blood pressure drop, but that is a side effect rather than the therapeutic role.

Blocking alpha-1 receptors produces two key therapeutic effects relevant to hypertension and BPH. First, it causes dilation of vascular smooth muscle, lowering peripheral resistance and blood pressure. Second, it relaxes smooth muscle in the bladder neck and prostate, improving urine flow and reducing obstruction in BPH. Doxazosin is a classic example of an alpha-1 antagonist that achieves both effects.

The other descriptions don’t fit the mechanism. This class is not beta-blocking, so it doesn’t decrease heart rate through beta blockade. It doesn’t inhibit ACE. Tachycardia can occur as a reflex response to the blood pressure drop, but that is a side effect rather than the therapeutic role.