Prazosin, used in the treatment of benign prostatic hyperplasia, relieves urinary outflow obstruction through which mechanism?
- A Beta-3 receptor stimulation causing detrusor relaxation
- B Muscarinic M3 blockade reducing detrusor contraction
- C Alpha-1A receptor blockade relaxing smooth muscle of the prostate and bladder neck ✓
- D Alpha-2 receptor blockade increasing urethral sphincter tone
Correct answer: C. Alpha-1A receptor blockade relaxing smooth muscle of the prostate and bladder neck
Explanation
The prostate smooth muscle, bladder neck, and urethra are richly supplied with alpha-1A adrenergic receptors. Prazosin blocks these receptors, reducing smooth muscle tone in the prostatic capsule and bladder neck, thereby decreasing urethral resistance and improving urine flow. Tamsulosin is more alpha-1A subtype-selective and therefore causes less orthostatic hypotension than prazosin in BPH management.
Reference: KD Tripathi, Essentials of Medical Pharmacology, 8th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.