Pharmacy PEBC Practice Exam

What is the main action of ACE inhibitors in treating hypertension?

1. Increasing heart rate

2. Blocking calcium channels

3. Inhibiting the angiotensin-converting enzyme

4. Promoting aldosterone secretion

The correct answer is: Inhibiting the angiotensin-converting enzyme

Angiotensin-converting enzyme (ACE) inhibitors primarily function by inhibiting the angiotensin-converting enzyme, which plays a crucial role in the renin-angiotensin-aldosterone system (RAAS). By blocking this enzyme, the production of angiotensin II is reduced. Angiotensin II is a potent vasoconstrictor that raises blood pressure by narrowing blood vessels and stimulating the release of aldosterone, which promotes sodium and water retention. By inhibiting the enzyme, ACE inhibitors lead to vasodilation and a decrease in blood volume, ultimately lowering blood pressure. This mechanism is particularly beneficial in treating hypertension and provides additional benefits, such as reduced cardiovascular risks. The other options involve actions that are not characteristic of ACE inhibitors. For instance, increasing heart rate is not a direct effect of ACE inhibitors; instead, they typically help in reducing heart workload. Blocking calcium channels is associated with a different class of antihypertensive drugs called calcium channel blockers, which act on vascular smooth muscle. Promoting aldosterone secretion contradicts the action of ACE inhibitors, as these medications actually decrease aldosterone levels through their inhibition of angiotensin II production.