Which antihypertensive drug class is the preferred agent in hypertensive patients with unilateral renal artery stenosis and is potentially harmful due to a specific haemodynamic mechanism?

• A ACE inhibitors — preferred because they lower efferent arteriolar tone maintaining GFR
• B Calcium channel blockers — preferred because they selectively dilate the afferent arteriole
• C Beta-blockers — preferred because they reduce renin secretion in the affected kidney
• D ACE inhibitors are relatively contraindicated because they reduce efferent arteriolar tone, causing acute GFR fall in the stenotic kidney ✓

Explanation

In significant renal artery stenosis, GFR in the affected kidney is maintained by angiotensin II-mediated constriction of the efferent arteriole, which sustains glomerular filtration pressure despite reduced perfusion. ACE inhibitors (and ARBs) lower angiotensin II, dilating the efferent arteriole and removing this compensatory mechanism, precipitating acute kidney injury in the stenosed kidney. Therefore, ACE inhibitors/ARBs are contraindicated in bilateral renal artery stenosis and used with caution in significant unilateral stenosis.

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

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.