Which alpha-1 antagonist is most uroselective for BPH?

Which alpha-1 antagonist is most uroselective for BPH?

• A. Tamsulosin
• B. Alfuzosin
• C. Doxazosin
• D. Terazosin

Answer: (A)

The key idea is selectivity for receptors in the urinary tract versus blood vessels. The prostate and bladder neck mainly use the alpha-1A (and to some extent alpha-1D) receptors, while vascular smooth muscle relies on alpha-1B. A drug with high affinity for alpha-1A/1D will relieve BPH symptoms with less impact on blood pressure. Tamsulosin fits this pattern, being highly selective for alpha-1A (and some alpha-1D) and showing minimal blockade of alpha-1B, so it improves urinary flow without causing significant orthostatic hypotension. Alfuzosin is uroselective but not as specific as tamsulosin; doxazosin and terazosin block broader vascular receptors and tend to lower blood pressure more, leading to more orthostatic effects. Thus, the most uroselective option is tamsulosin.

The key idea is selectivity for receptors in the urinary tract versus blood vessels. The prostate and bladder neck mainly use the alpha-1A (and to some extent alpha-1D) receptors, while vascular smooth muscle relies on alpha-1B. A drug with high affinity for alpha-1A/1D will relieve BPH symptoms with less impact on blood pressure. Tamsulosin fits this pattern, being highly selective for alpha-1A (and some alpha-1D) and showing minimal blockade of alpha-1B, so it improves urinary flow without causing significant orthostatic hypotension. Alfuzosin is uroselective but not as specific as tamsulosin; doxazosin and terazosin block broader vascular receptors and tend to lower blood pressure more, leading to more orthostatic effects. Thus, the most uroselective option is tamsulosin.