**Question:** Angiotensin II level decreased by which antihypertensive -

A. ACE inhibitor
B. Angiotensin II antagonist
C. Calcium channel blocker
D. Beta-blocker

**Core Concept:** Angiotensin II is a potent vasoconstrictor peptide that plays a crucial role in regulating blood pressure through the renin-angiotensin-aldosterone system (RAAS). ACE inhibitors and angiotensin II antagonists work by blocking the action of angiotensin II, while calcium channel blockers and beta-blockers are not primarily targeting angiotensin II but have a secondary effect on blood pressure control.

**Why the Correct Answer is Right:** Angiotensin II antagonists (like ACE inhibitors) and angiotensin II receptor blockers (ARBs) directly target the RAAS by inhibiting the effects of angiotensin II. By doing so, they reduce blood pressure by counteracting the vasoconstrictor properties of angiotensin II.

**Why Each Wrong Option is Incorrect:**

**Option A (ACE inhibitor):** ACE inhibitors indirectly block angiotensin II by inhibiting the conversion of angiotensin I to angiotensin II by angiotensin-converting enzyme (ACE). Although ACE inhibitors do decrease angiotensin II levels, they are not as direct and specific as angiotensin II antagonists (ARBs) in blocking the action of angiotensin II.

**Option B (Angiotensin II antagonist):** Angiotensin II antagonists (like ARBs) directly block the action of angiotensin II without affecting its levels. This makes them more effective in reducing blood pressure by blocking the vasoconstrictor action of angiotensin II.

**Option C (Calcium channel blocker):** Calcium channel blockers are primarily used to reduce heart rate and myocardial contractility. Although they indirectly affect blood pressure by reducing myocardial workload, they do not directly target angiotensin II and its vasoconstrictor action.

**Option D (Beta-blocker):** Beta-blockers are primarily used to reduce myocardial oxygen demand by blocking beta-adrenergic receptors. While they indirectly affect blood pressure by reducing heart rate and cardiac output, they do not directly target angiotensin II and its vasoconstrictor action.

**Clinical Pearl:** ACE inhibitors are often preferred over ARBs in patients with severe renal impairment due to their lower risk of acute kidney injury. This is because ARBs can cause acute kidney injury in some patients with impaired renal function due to the activation of the renin-angiotensin system, which is already stimulated in these patients.

**Why the Correct Answer is Right:** Angiotensin II antagonists (ARBs) directly block the action of angiotensin II, which is a potent vasoconstrictor and plays a crucial role in the renin-angiotensin system. By blocking angiotensin II, ARBs reduce blood pressure directly by counteracting its vasoconstrictor effect. This makes them more effective in reducing blood pressure