Prescribing Safety Assessment (PSA) Practice Exam

What effect do ACE inhibitors have that can contribute to renal failure?

1. They increase renin production

2. They block the conversion of angiotensin I to angiotensin II

3. They enhance glomerular pressure

4. They promote renal blood flow

The correct answer is: They block the conversion of angiotensin I to angiotensin II

ACE inhibitors primarily function by blocking the conversion of angiotensin I to angiotensin II. Angiotensin II is a potent vasoconstrictor that plays a crucial role in regulating blood pressure and maintaining renal blood flow. By inhibiting this conversion, ACE inhibitors lead to reduced levels of angiotensin II, which can cause dilation of the efferent arterioles of the glomeruli in the kidneys. In certain scenarios, particularly when renal perfusion is already compromised—such as in conditions of renal artery stenosis or in patients who are volume-depleted—the reduction of angiotensin II levels can result in decreased glomerular pressure. This decrease can impair the filtration rate in the kidneys and potentially lead to acute renal failure. It is crucial to monitor kidney function when initiating or adjusting therapy with ACE inhibitors, especially in susceptible patients. The other choices do not accurately reflect the mechanism relevant to renal failure in the context of ACE inhibitor use. For instance, increasing renin production is not a direct effect of ACE inhibitors; instead, they can decrease renin levels due to the negative feedback mechanism. Additionally, ACE inhibitors do not enhance glomerular pressure or promote renal blood flow; rather, their action effectively lowers pressures that can lead