Angiotensin II Receptor Blockers (ARBs)

Angiotensin II is a very potent chemical formed in the blood that causes muscles surrounding blood vessels to contract, thereby narrowing the vessels. This narrowing increases the pressure within the vessels and can cause high blood pressure (hypertension).

Angiotensin II receptor blockers (ARBs) are medications that block the action of angiotensin II by preventing angiotensin II from binding to angiotensin II receptors on the muscles surrounding blood vessels. As a result, blood vessels enlarge (dilate), and blood pressure is reduced. Reduced blood pressure makes it easier for the heart to pump blood and can improve heart failure.

In addition, the progression of kidney disease caused by high blood pressure or diabetes is slowed. ARBs have effects that are similar to angiotensin-converting enzyme (ACE) inhibitors, but ACE inhibitors act by preventing the formation of angiotensin II rather than by blocking the binding of angiotensin II to muscles on blood vessels.

• ARBs are used for controlling high blood pressure, treating heart failure, and preventing kidney failure in people with diabetes or high blood pressure.
• ARBs also may prevent diabetes and reduce the risk of stroke in patients with high blood pressure and an enlarged heart.
• ARBs also may prevent the recurrence of atrial fibrillation.

Since ARB medications have effects that are similar to those of ACE inhibitors, they often are used when ACE inhibitors are not tolerated by patients (for example, due to excessive coughing).

ARBs are well tolerated by most people. The most common side effects are:

• cough,
• elevated potassium levels in the blood (hyperkalemia),
• low blood pressure,
• dizziness,
• headache,
• drowsiness,
• diarrhea,
• abnormal taste sensation (metallic or salty taste),
• rash,
• orthostatic hypotension (low blood pressure upon standing),
• fatigue,
• indigestion,
• increased blood glucose levels,
• flu-like symptoms,
• sinusitis (sinus infection),
• bronchitis, and
• upper respiratory tract infections.

Compared to ACE inhibitors, cough occurs less often with ARBs.

Serious side effects of ARBs

• The most serious, but rare, side effects are
  • kidney failure,
  • liver failure (hepatitis),
  • serious allergic reactions,
  • a decrease in white blood cells,
  • a decrease in blood platelets, and
  • swelling of tissues (angioedema).
• There have been reports of rhabdomyolysis (destruction of skeletal muscle) in patients receiving ARBs.
• Individuals who have a narrowing of both arteries that supply the kidneys or have had a severe reaction to ARBs should avoid them.
• Like other antihypertensives, ARBs have been associated with sexual dysfunction.

The ARBs that are currently available are:

• azilsartan (Edarbi)
• candesartan (Atacand)
• eprosartan (Teveten)
• irbesartan (Avapro)
• telmisartan (Micardis)
• valsartan (Diovan, Prexxartan)
• losartan (Cozaar)
• olmesartan (Benicar)
• entresto (sacubitril/valsartan)
• byvalson (nebivolol/valsartan)

ARBs are similar in actions 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 some studies, irbesartan (Avapro) and candesartan (Atacand) reduced blood pressure better than losartan (Cozaar).

• 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 and cardiac arrhythmias.
• ARBs may also increase the blood concentration of lithium (Eskalith, Lithobid) and lead to an increase in side effects from lithium.
• Rifampin (Rifadin) 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.
• ARBs should not be combined with ACE inhibitors because such combinations increase the risk of hypotension, hyperkalemia, and renal impairment.
• ARBs should not be combined with aliskiren (Tekturna) because such combinations increase the risk of kidney failure, excessive low blood pressure, and hyperkalemia.

ARBs are not prescribed for women during pregnancy because they may cause a serious condition called oligohydramnios, which may result in injury and even death of the fetus.