ACE Inhibitors for the Treatment of High Blood Pressure

These are angiotensin II converting enzyme (ACE) inhibitors. List of ACE inhibitors.

How ACE Inhibitors work

See an explanation of the renin-angiotensin system. Briefly, angiotensin II is a protein made by the body that causes blood vessels to narrow. This narrowing increases blood pressure. Additionally, another function of angiotensin II is to increase the volume of the blood, which also elevates blood pressure.

Angiotensin II is made from the protein angiotensin I. Unlike angiotensin II, angiotensin I does not cause narrowing of blood vessels. The body converts angiotensin I to angiotensin II using the enzyme called angiotensin II converting enzyme (ACE). If this enzyme is inhibited, then less of the angiotensin I is converted to angiotensin II. With less angiotensin II in the blood, the blood vessels do not narrow as much. Wider vessels result in lower blood pressure.

Use of ACE inhibitors

ACE inhibitors usually slowly reduce blood pressure over a number of weeks. Studies indicate that after a couple of weeks, up to 50% of people with mild to moderate high blood pressure will have their blood pressure return to normal.

It is usually recommended that potassium in the diet be restricted, since ACE inhibitors can cause an increase of potassium in the blood. This includes not using salt substitutes that contain potassium, and restricting intake of raisins, prunes, bananas and other foods high in potassium.

ACE inhibitors are often prescribed to patients who have diabetes as well as high blood pressure. This class of drugs has been shown to slow the rate of damage that diabetes causes in the kidney (diabetic glomerulopathy).

ACE inhibitors tend to increase the effectiveness of diuretics (particularly thiazide diuretics), and so are a good choice for a combination therapy, when diuretics alone do not cause a large enough reduction in blood pressure.

ACE inhibitors are often prescribed to those who have high blood pressure and atherosclerosis of the coronary arteries (also called coronary artery disease - coronary arteries are the arteries that take blood away from the heart).

Potential Side Effects of ACE inhibitors

ACE inhibitors have a low incidence of side effects and are generally well tolerated by most patients.

Initial therapy with ACE inhibitors may cause a temporary, very large, drop in blood pressure. This only occurs when first taking the medication, so usually a patient will start out at a low dose and then the dosage will be increased. Too low blood pressure (hypotension) can cause dizziness and lightheadedness, and if very severe can cause fainting.

There is a risk for fetal damage, so ACE inhibitors should not be taken by women who are pregnant, or are likely to be pregnant in the near future.

- Angioedema is a rare but serious side effect. Angioedema is a sudden swelling of the skin and mucous membranes, usually on the face and sometimes the hands. Frequently, it is accompanied by itchy skin. Swelling of the tongue and throat can cause difficulty breathing. If any signs of angioedema occur, no more tablets of the ACE inhibitor should be taken and a physician consulted to see if angioedema has occurred. A different blood pressure lowering drug will be prescribed to replace the ACE inhibitor, if angioedema has occurred.

A persistent dry cough, particularly in women, is a common side effect.

Other side effects may include diarrhea, headache, and a salty or metallic taste in the mouth.

As with all drugs, there may be side effects when this class of drugs is taken in combination with certain other drugs. Make sure that your health care provider is aware of any, and all, prescription drugs, non-prescription drugs, herbal supplements, nutritional supplements and vitamins that are being taken.