Which of the following drugs is primarily used to lower blood pressure by relaxing blood vessels?

• A. Beta-blockers
• B. Angiotensin II receptor blockers (ARBs)
• C. Calcium channel blockers
• D. Diuretics

Answer: (B)

Angiotensin II receptor blockers (ARBs) are primarily utilized to lower blood pressure by relaxing blood vessels. These medications work by blocking the action of angiotensin II, a hormone that typically causes blood vessels to constrict. When ARBs inhibit this action, the result is vasodilation, which effectively reduces vascular resistance and lowers blood pressure.

The fundamental mechanism behind ARBs is their selective inhibition of the receptor that angiotensin II binds to, leading to a decrease in the hormones that induce vasoconstriction. This not only helps in managing hypertension but also provides benefits in conditions like heart failure or to protect the kidneys in diabetic patients.

In contrast, the other classes of drugs mentioned serve different primary functions: Beta-blockers mainly reduce heart rate and cardiac output, calcium channel blockers can also induce vasodilation but do so by a different mechanism involving calcium channel blockade, and diuretics primarily work by reducing blood volume through increased urinary output rather than directly relaxing blood vessels. Therefore, ARBs are particularly effective in their role of directly targeting and relaxing blood vessels to manage high blood pressure.