Here’s a pharmacology MCQ question along with the answer and explanation:
Question
A 45-year-old patient with hypertension is prescribed a medication that inhibits the angiotensin-converting enzyme (ACE). Which of the following is the most likely mechanism of action of this drug?
A. Blocks angiotensin II receptors
B. Inhibits the conversion of angiotensin I to angiotensin II
C. Increases the production of bradykinin
D. Promotes the excretion of sodium and water
Answer
B. Inhibits the conversion of angiotensin I to angiotensin II
Explanation
- ACE inhibitors (e.g., lisinopril, enalapril) work by blocking the angiotensin-converting enzyme, which is responsible for converting angiotensin I to angiotensin II.
- Angiotensin II is a potent vasoconstrictor, and its inhibition leads to vasodilation, reduced blood pressure, and decreased aldosterone secretion.
- Option A describes the mechanism of angiotensin II receptor blockers (ARBs).
- Option C is partially correct, as ACE inhibitors do increase bradykinin levels (leading to side effects like cough), but this is not their primary mechanism of action.
- Option D describes the mechanism of diuretics, not ACE inhibitors.
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