High blood pressure

What are angiotensin II receptor blockers?

Angiotensin II receptor blockers (ARBs) are drugs that affect a chemical in your body called angiotensin. Your body makes angiotensin when it notices that less blood is being pumped around your blood vessels. Your blood carries the oxygen and food that all the cells in your body need.

Angiotensin has two forms, angiotensin I and angiotensin II.

Angiotensin I tries to control how much blood is circulating around your body. If less blood is circulating, angiotensin I makes your body save salt and water. It does this to try to increase the amount of fluid circulating in your blood vessels.
Angiotensin I also makes your blood vessels narrower and raises your blood pressure. Over a long time, this can make the chamber on the lower left side of your heart (called the left ventricle) flabby. This means that it doesn't pump as well as it should.
Angiotensin I can be changed into a more active chemical called angiotensin II. This chemical makes the heart use more oxygen than usual to pump, which in turn makes your blood pressure go up.
Angiotensin II receptor blockers stop angiotensin II from making your blood pressure go up.

Angiotensin II receptor blockers work in a slightly different way to ACE inhibitors. ARBs block the effect of angiotensin II. ACE inhibitors stop angiotensin I from being changed into angiotensin II.

This information was last updated on Jul 02, 2009

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