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Chapter 52. Benign Prostatic Hypertrophy

Student Questions

Which one of these agents is a pharmacologically uroselective α1A-adrenergic antagonist?

A. Doxazosin

B. Alfuzosin

C. Silodosin

D. Darifenacin

Answer: C

Option A: Incorrect. Doxazosin is a non-uroselective α1-adrenergic antagonist.

Option B: Incorrect. Alfuzosin is a non-uroselective α1-adrenergic antagonist. It has been proposed that its greater propensity to concentrate in the prostate (as opposed to vascular tissues) and its fixed dosing schedule allows it to behave as a clinically uroselective α1A-adrenergic antagonist.

Option C: Correct. Silodosin and tamsulosin are uroselective α1A-adrenergic antagonists. Between these 2, silodosin exhibits greater inhibition of the α1A receptor than tamsulosin.

Option D: Incorrect. Darifenacin is a uroselective anticholinergic agent.

What is a clinical advantage of using an α1A-adrenergic antagonist as opposed to an α1-adrenergic antagonist for management of BPH?

A. An α1A-adrenergic antagonist is more effective in reducing LUTS when compared to other α1-adrenergic antagonists.

B. The peak clinical effect of an α1A-adrenergic antagonist occurs 1 month after the start of treatment as opposed to 3 months after the start of an α1-adrenergic antagonist.

C. Floppy Iris Syndrome has not been reported with any α1A-adrenergic antagonist.

D. Hypotension is less likely to occur with an α1A-adrenergic antagonist as compared to an α1-adrenergic antagonist.

Answer: D

Option A: Incorrect. α1A-Adrenergic antagonist and α1-adrenergic antagonists are equally effective in reducing LUTS secondary to BPH.

Option B: Incorrect. The onset of tamsulosin or silodosin is typically with 1 week after the start of treatment. This is because the initial dose is therapeutic and up-titration is not necessary or is not recommended (tamsulosin). For other α1-adrenergic antagonists, which require slow up-titration to a therapeutic dose, the peak onset takes about 1 month.

Option C: Incorrect. Floppy iris syndrome (FIS) has been reported with the highest frequency with tamsulosin, an α1A-adrenergic antagonist. However, FIS has also been reported with other α1-adrenergic antagonists.

Option D: Correct. α1A-Adrenergic antagonist selectively block α1A-adrenergic receptors, which predominate in the prostate and bladder neck, as compared to α1B receptors, which are embedded in the vasculature. As a result, hypotension is ...

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