Which of the following medications is NOT an ACE inhibitor?

Losartan is the correct answer as it is not an ACE inhibitor. Instead, it belongs to a class of medications known as angiotensin II receptor blockers (ARBs). ARBs work by blocking the action of angiotensin II, a hormone that causes blood vessels to constrict, leading to an increase in blood pressure. By preventing angiotensin II from binding to its receptors, Losartan and other ARBs help to lower blood pressure and provide benefits similar to those of ACE inhibitors, but they do so through a different mechanism.

In contrast, the other medications listed, including Lisinopril, Ramipril, and Enalapril, are all ACE inhibitors. These drugs work by inhibiting the angiotensin-converting enzyme (ACE), which prevents the conversion of angiotensin I to angiotensin II. This inhibition leads to vasodilation, decreased blood volume, and a reduction in blood pressure. Understanding the distinctions between ACE inhibitors and ARBs is crucial for proper management of conditions such as hypertension and heart failure, as each class has its unique benefits and side effect profiles.