Angiotensin Converting Enzyme (ACE) Inhibitors
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ACE inhibitors or angiotensin-converting enzyme inhibitors are a group of drugs that relax blood vessels and therefore lower blood pressure. They are primarily prescribed to treat hypertension (high blood pressure) and congestive heart failure. They can also be used to treat scleroderma and migraines.
General pharmacology
Angiotensin II is a protein naturally found in the human body. It is formed from angiotensin I and the action of the angiotensin-converting enzyme (ACE). Angiotensin II is a natural vasoconstrictor, which means that it narrows and constricts blood vessels, increasing blood pressure.
An ACE inhibitor drug reduces the action of the angiotensin-converting enzyme (ACE), which means that less angiotensin II is produced in the body. This has an overall vasodilator effect, which means that blood vessels relax and widen, decreasing blood pressure.
In summary, angiotensin II is normally responsible of the following actions:
- Generalized vasoconstriction, which increases blood pressure.
- Thirst is generated, and therefore by drinking water there is an increase of blood volume.
- Cardiac and vascular hypertrophy, which means an increase of the volume of heart muscles and smooth muscles around blood vessels.
- An increase of sympathetic activity (part of the nervous system that becomes active during stress) on the heart and blood vessels because angiotensin II facilitates the release of norepinephrine, a precursor of adrenaline, which increases blood pressure.
ACE inhibitors counteract the effects of angiotensin II:
- They cause generalized vasodilatation, by relaxing blood vessels which therefore decreases blood pressure.
- They reduce blood volume because less thirst is induced.
- They inhibit cardiac and vascular hypertrophy which is associated with hypertension (high blood pressure), heart failure, and myocardial infarction (heart attack).
- They decrease adrenaline sympathetic activity (nervous system reaction during stress) by blocking the angiotensin II effects on nerves.
Examples of ACE inhibitors
ACE inhibitors are divided into three classes based on molecular structure:
- Sulfhydryl-containing agents.
- Dicarboxylate-containing agents.
- Phosphonate-containing agents.
Examples of sulfhydryl-containing agents include:
- Captopril (Capoten).
- Zofenopril.
Examples of dicarboxylate-containing agents:
- Enalapril (Vasotec/Renitec).
- Ramipril (Altace/Tritace/Ramace/Ramiwin).
- Quinapril (Accupril).
- Perindopril (Coversyl/Aceon).
- Lisinopril (Lisodur/Lopril/Novatec/Prinivil/Zestril).
- Benazepril (Lotensin).
Examples of phosphonate-containing agents:
- Fosinopril (Monopril).
Therapeutic indications
ACE inhibitors are usually prescribed to treat hypertension, congestive heart failure and post-myocardial infarction (heart attack). Other conditions can also be treated with these drugs.
Doctors recommend ACE inhibitors to treat:
- Hypertension (high blood pressure).
- Congestive heart failure.
- Post-myocardial infarction (heart attack).
- Coronary artery disease.
- Diabetes.
- Certain chronic kidney diseases.
- Scleroderma.
- Migraines.
Side effects
Most people who use ACE inhibitors have little side effects. The most common side effect is a dry cough.
Possible, although rare, side effects of ACE inhibitors include:
- Dry cough.
- Hypotension (low blood pressure).
- Hyperkalemia (increased blood-potassium level).
- Rash.
- Dizziness.
- Fatigue.
- Nausea.
- Changes in taste.
- Reduced appetite over long intervals.
- Angiooedema (swelling of the internal layer of the skin) which happens rarely, but is more common for smokers. If it occurs in the throat area, it can be life-threatening.
Cautions
Non-steroidal anti-inflammatory drugs (NSAIDs), such as ibuprofen (Advil and Motrin) and naproxen (Aleve) decrease the effectiveness of ACE inhibitors if taken on a regular basis.
ACE inhibitors can cause birth defects. It is therefore important for a pregnant woman or a woman planning to become pregnant not to use these drugs.
Major drug groups
Cardiovascular system
References
Sélection Reader's Digest, Le Guide canadien des médicaments, 2002.
Wikipedia, the free encyclopedia (www.wikipedia.org).
Mayo Clinic, medical information and tools for better living (www.mayoclinic.com).
CV Pharmacology, cardiovascular pharmacology concepts (www.cvpharmacology.com).
The information above should be used as a reference only. Any medical decision should not be done before consulting a health care professional.
Last update: 29th of July 2009.