Angiotensin II Receptor Blockers (ARB)

Pharmacy Author: Omudhome Ogbru, Pharm.D.
Medical Editor: Jay W. Marks, M.D.

What are angiotensin receptor blockers and how do they work?

Angiotensin II is a very potent chemical that causes the muscles surrounding the blood vessels to contract, which thereby narrows the blood vessels. This narrowing increases the pressure within the vessels and can cause high blood pressure (hypertension). Angiotensin receptor blockers (ARBs) are medications that block the action of angiotensin II. As a result, the blood vessels dilate and the blood pressure is reduced. The lower blood pressure makes it easier for the heart to pump blood and can improve heart failure. In addition, the progression of kidney disease due to high blood pressure or diabetes is slowed.

For what conditions are ARBs used?

ARBs are used for controlling high blood pressure, treating heart failure, and preventing kidney failure in people with diabetes or high blood pressure. Since these medications have effects that are similar to those of ACE inhibitors, they are often used when an ACE inhibitor can not be tolerated by patients.

Are there any differences among the different types of ARBs?

ARBs are similar in action and side effects. They differ in how they are eliminated from the body and the extent to which they are distributed throughout the body. Some ARBs need to be converted to an active form in the body before they can lower blood pressure. In addition, some ARBs are better at lowering blood pressure. In head to head comparisons, irbesartan (AVAPRO) and candesartan (ATACAND) have demonstrated superior blood pressure lowering as compared with losartan (COZAAR). Irbesartan also has shown better blood pressure reduction than valsartan (DIOVAN).

What are the side effects of ARBs?

ARBs are well-tolerated by most individuals. The most common side effects are cough, elevated potassium levels, low blood pressure, dizziness, headache, drowsiness, diarrhea, abnormal taste sensation (metallic or salty taste), and rash. Compared to ACE inhibitors, cough occurs less often with ARBs. The most serious, but rare, side effects are kidney failure, liver failure, allergic reactions, a decrease in white blood cells, and swelling of tissues (angioedema). ARBs usually are not prescribed for pregnant patients because they may cause birth defects. Individuals with severe kidney problems and those who have had a severe reaction to ARBs probably should avoid them.

With which drugs do ARBs interact?

ARBs have few interactions with other drugs. Since ARBs may increase blood levels of potassium, the use of potassium supplements, salt substitutes (which often contain potassium), or other drugs that increase potassium may result in excessive blood potassium levels. ARBs may also increase the blood concentration of lithium (ESKALITH) and lead to an increase in side effects from lithium. Rifampin reduces the blood levels of losartan, and fluconazole (DIFLUCAN) reduces the conversion of losartan to its active form. These effects could decrease the effects of losartan.

What are the available ARBs?

The following is a list of currently available ARBs: candesartan (ATACAND), eprosartan (TEVETAN), irbesartan (AVAPRO), telmisartan (MYCARDIS), valsartan (DIOVAN), and losartan (COZAAR).

Last Editorial Review: 4/19/2001

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