A 65-year-old man is started on tamsulosin for benign prostatic hyperplasia. Which receptor subtype does tamsulosin preferentially block to achieve its therapeutic effect with minimal cardiovascular side effects?

• A Alpha-1B
• B Alpha-2A
• C Beta-1
• D Alpha-1A ✓

Explanation

Tamsulosin is a selective alpha-1A adrenoceptor antagonist; the alpha-1A subtype predominates in the smooth muscle of the prostate and urethra, mediating urethral tone. The alpha-1B subtype mediates vascular smooth muscle contraction, so selective alpha-1A blockade produces urodynamic relief without significant orthostatic hypotension, unlike non-selective agents such as prazosin. Beta-1 receptors are cardiac and are unrelated to prostatic tone.

Reference: KD Tripathi, Essentials of Medical Pharmacology, 8th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

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