Harvard Heart Letter

Going after angiotensin

An ACE inhibitor or an ARB, not both, best protects the heart.

Deep inside the body, a protein known as angiotensin-converting enzyme creates angiotensin II, a small molecule that signals the muscles in arteries and veins to contract. By narrowing blood vessels, angiotensin II increases blood pressure. ACE inhibitors, which first hit the market in 1981, keep angiotensin-converting enzyme from making angiotensin II. This helps blood vessels relax, which lowers blood pressure. ACE inhibitors do more than just lower blood pressure. They also help prevent heart attacks and strokes, protect the kidneys in people with diabetes and kidney trouble, and slow potentially damaging changes in the size and shape of the heart that often occur with heart failure. Ten ACE inhibitors are on the market; their generic names all end in "pril," like quinapril.

A newer class of drugs, the angiotensin-receptor blockers (ARBs), lowers blood pressure in a slightly different way. Instead of turning off the production of angiotensin II, these drugs block its entry into cells. The first ARB, losartan, was introduced in 1995. There are now seven on the market; their generic names end in "sartan," like candesartan.

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