Which of the following drug is used in BHP and has negligible risk of causing postural hypotension?
## **Core Concept**
Benign Prostatic Hyperplasia (BHP) is a common condition in aging men characterized by the enlargement of the prostate gland, leading to urinary obstruction. Pharmacological management of BHP often involves drugs that relax smooth muscles in the prostate and bladder neck or reduce the size of the prostate. Postural hypotension is a concern with some treatments due to their effect on blood pressure.
## **Why the Correct Answer is Right**
The correct answer, , is a selective α1-adrenergic receptor antagonist. Drugs in this class, such as tamsulosin, alfuzosin, and silodosin, are specifically used to treat BHP. They work by relaxing the smooth muscles in the prostate and bladder neck, improving urine flow. These drugs have a lower risk of causing postural hypotension compared to non-selective alpha blockers because they have a higher affinity for the α1A receptor subtype, which is predominantly found in the prostate, rather than the α1B subtype, which is more associated with vascular smooth muscle and blood pressure regulation.
## **Why Each Wrong Option is Incorrect**
* **Option A:** - This option would likely represent a non-selective alpha blocker or a different class of drug not primarily used for BHP or known to cause significant postural hypotension.
* **Option B:** - This could be a 5-alpha-reductase inhibitor (like finasteride), which does treat BHP but by reducing prostate size over time, not by immediate relaxation of smooth muscles. It doesn't directly relate to the risk of postural hypotension but works through a different mechanism.
* **Option D:** - This might represent another class of drug, such as a muscarinic receptor antagonist or a phosphodiesterase inhibitor, used for overactive bladder or erectile dysfunction, not primarily for BHP.
## **Clinical Pearl / High-Yield Fact**
A key point to remember is that α1-adrenergic receptor antagonists, particularly the uroselective ones like tamsulosin, are preferred in BHP treatment because they have a lower risk of causing postural hypotension. This is due to their selectivity for the α1A receptor subtype in the prostate.
## **Correct Answer:** .