This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: ACE Inhibitors, Subject name: Pharmacology
Bilateral renal artery stenosis is a contraindication for which Antihypertansive drug- 
Select and explain. 
A. Beta - blockers, B. Calcium channel blockers, C. ACE inhibitors, D. Diuretics
C: ACE inhibitors
Answer: C: ACE inhibitors 
Explanation: Ans. is 'c' i.e., ACE inhibitors o Patients with renal artery stenosis are dependent on efferent arteriolar vasoconstiction for maintenance of glomerular filtration pressure. Angiotensin II is responsible for vasoconstriction of efferent arteriole.o ACE inhibitors prevent the generation of Angiotensin II. This causes dilatation of efferent arterioles and fall in glomerular filtration pressure. This can ppt renal failure.o Therefore ACE inhibition are C/I in patients with bilateral renal artery stenosis.