ACE Inhibitors

What are ACE inhibitors and how do they work?

The class of drugs called angiotensin converting enzyme (ACE) inhibitors, as the class name suggests, reduces the activity of angiotensin converting enzyme. ACE converts angiotensin I produced by the body to angiotensin II in the blood. Angiotensin II is a very potent chemical that causes the muscles surrounding blood vessels to contract and narrow the blood vessels. Narrowing of blood vessels increases the pressure within the blood vessels and may lead to high blood pressure (hypertension).

By reducing the activity of ACE, ACE inhibitors decrease the formation of angiotensin II which leads to widening (dilation) of blood vessels, and thereby reduces blood pressure. By lowering blood pressure against which the heart must pump, the amount of work that the heart must do is reduced. ACE inhibitors also reduce blood pressure in the kidneys, slowing the progression of kidney disease due to high blood pressure or diabetes.

For what conditions are ACE inhibitors used?

ACE inhibitors are effective for

ACE inhibitors are especially important because they have been shown to prevent

  • early death resulting from hypertension,
  • heart failure, or heart attacks; in studies of patients with hypertension, heart failure, or prior heart attacks, patients who received an ACE inhibitor survived longer than patients who did not receive an ACE inhibitor.
  • ACE inhibitors may be combined with other drugs to achieve optimal blood pressure control.

Are there any differences among the different types of ACE inhibitors?

  • ACE inhibitors are very similar, and all are effective for treating hypertension.
  • Some are eliminated primarily by the kidneys while others are also eliminated in bile and feces.
  • This difference in elimination may be important in choosing among ACE inhibitors in patients with reduced kidney or liver function, who may accumulate drugs that are excreted via the kidneys or liver.
  • Except for captopril (Capoten) and lisinopril (Prinivil, Zestril), ACE inhibitors are inactive until they are converted to an active form in the body.

What are the side effects of ACE inhibitors?

Common side effects are:

  • dizziness,
  • headache,
  • drowsiness,
  • diarrhea,
  • low blood pressure,
  • weakness,
  • cough, and
  • rash.

Rare side effects of ACE inhibitors include

  • An abnormal taste (metallic or salty), elevated blood potassium levels, and sexual dysfunction may also occur.
  • A nonproductive and persistent cough may occur in 5%-25% of individuals. It may take up to 2 weeks or longer for coughing to subside after the ACE inhibitor is discontinued. If one ACE inhibitor causes cough, it is likely that the others will also.
  • ACE inhibitors may cause birth defects and, therefore, should not be used during pregnancy.
  • Individuals with stenosis (narrowing) of both arteries supplying the kidneys may experience worsening of kidney function.

Other side effects of ACE inhibitors include

  • kidney failure,
  • allergic reactions,
  • a decrease in white blood cells, and
  • swelling of tissues (angioedema).

With which drugs do ACE inhibitors interact?

ACE inhibitors have few important interactions with other drugs.

  • Quinapril (Accupril) may reduce the absorption of tetracycline because quinapril (Accupril) contains magnesium which binds to tetracycline in the intestine and prevents its absorption.

  • Combining potassium supplements, salt substitutes (which often contain potassium), or other drugs that increase potassium levels with ACE inhibitors may result in excessive blood potassium levels because ACE inhibitors can further increase potassium to toxic levels.

  • ACE inhibitors may increase blood concentrations of lithium (Eskalith) and possibly increase side effects of lithium.

  • Nonsteroidal antiinflammatory drugs [NSAIDs, for example, aspirin, ibuprofen, indomethacin (Indocin, Indocin IV), and naproxen (Naprosyn, Naprelan)] may reduce the blood pressure-lowering effects of ACE inhibitors.

What are some examples of ACE inhibitors available?

The following is a list of the ACE inhibitors that are available in the United States:

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Robert J. Bryg, MD
Board Certified Internal Medicine with subspecialty in Cardiovascular Disease

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