Pharmacology Drug Classifications Practice Test

The main concept is how blocking ACE dampens the vasoconstrictor arm of the renin-angiotensin system. ACE inhibitors prevent conversion of angiotensin I to angiotensin II, the peptide that causes blood vessels to constrict and that promotes aldosterone release. With less angiotensin II, blood vessels relax, aldosterone-mediated salt and water retention decreases, and blood pressure falls. ACE inhibition also increases bradykinin levels (since ACE helps break it down), which further promotes vasodilation but can lead to a cough or, less commonly, angioedema. Other drug classes lower blood pressure through different mechanisms—ARBs block the angiotensin II receptor, beta-blockers reduce sympathetic activity, and calcium channel blockers decrease calcium entry into vascular smooth muscle—so they don’t inhibit ACE itself.