A client is prescribed losartan (Cozaar). The nurse teaches the client that an angiotensin II receptor blocker (ARB) acts by doing what?

• A. Inhibiting angiotensin-converting enzyme
• B. Blocking angiotensin II from AT1 receptors
• C. Preventing the release of angiotensin I
• D. Promoting the release of aldosterone

Answer: (B)

Blocking angiotensin II from AT1 receptors is how this class works. An ARB like losartan binds to the AT1 receptor so angiotensin II cannot attach and activate it. Because the receptor is blocked, angiotensin II can’t trigger vasoconstriction or stimulate aldosterone release, which together lowers blood pressure and reduces fluid retention.

It helps to contrast with ACE inhibitors: those drugs prevent the formation of angiotensin II, rather than blocking its action at the receptor, and they can raise bradykinin levels (which is why a cough can occur). ARBs don’t increase bradykinin, and they don’t stop the release of angiotensin I or prevent its formation, they simply block the receptor Ang II would use.

The option about promoting aldosterone release is opposite to what actually happens with ARBs; their effect is to reduce aldosterone activity, contributing to their antihypertensive and volume-lowering actions.