ACE Inhibitors

What conditions are ACE inhibitors used to treat?

Angiotensin-converting enzyme (ACE) inhibitors are used to treat a number of different conditions:

• High blood pressure (hypertension) - ACE inhibitors usually work well to lower blood pressure.
• Heart failure - ACE inhibitors reduce the strain on the heart by decreasing the amount of fluid pumped around the body. They also help the heart by relaxing blood vessels. This reduces the amount of force needed to eject blood from the heart.
• Diabetic kidney disease (diabetic nephropathy) - these medicines can help to maintain good kidney function.
• Chronic kidney disease - ACE inhibitors may help to slow the progress of kidney disease.
• After a heart attack (myocardial infarction).

For more information on the conditions see the separate leaflets called High Blood Pressure (Hypertension), Congestive Heart Failure, Diabetic Kidney Disease, Heart Attack (Myocardial Infarction), and Chronic Kidney Disease.

List of ACE inhibitors

They include:

• Captopril
• Enalapril
• Fosinopril
• Imidapril
• Lisinopril
• Perindopril
• Quinapril
• Ramipril
• Trandolapril

Each of these medicines also has various different brand names. Some ACE inhibitor medicines are also part of a combined tablet with a calcium-channel blocker medicine or 'water tablet' (diuretic) medicine.

How do ACE inhibitors work?

ACE inhibitors prevent the body from creating a hormone known as angiotensin II. They do this by blocking (inhibiting) a chemical called angiotensin-converting enzyme.

Angiotensin II has three main effects:

• Constriction of blood vessels.
• Re-absorption of water by the kidneys.
• Release of the hormone aldosterone which also causes water re-absorption by the kidneys.

Increasing the volume of the blood by adding more water and constricting your blood vessels increases blood pressure.

ACE inhibitors reduce the amount of angiotensin II which causes blood vessels to dilate. The amount of water put back into the blood by the kidneys decreases. These actions reduce blood pressure.

• In high blood pressure (hypertension), ACE inhibitors should help to reduce the blood pressure.
• In heart failure, there may be too much circulating fluid in the blood vessels. ACE inhibitors help to reduce this. They appear to have a protective effect on the heart and slow the progression of the heart failure.

Who cannot take ACE inhibitors?

A full list of people who should not take ACE inhibitors is included with the leaflet that comes with your medicine. If you are prescribed ACE inhibitors, read this to be sure you are safe to take it. For example, people who should not take ACE inhibitors include:

• Pregnant and breastfeeding women.
• Those with a known sensitivity to ACE inhibitors.
• Those who have had a severe allergic response to ACE inhibitors in the past - eg, swelling of the lips, eyes or tongue (angio-oedema).
• People with certain types of kidney disease - for example, renal artery stenosis.

Side-effects

A common side-effect associated with an ACE inhibitor is low blood pressure (hypotension). You may have no symptoms of this, or it may make you feel dizzy. If you experience this you should report it to your doctor. Around one in ten people who take an ACE inhibitor have a persistent dry cough. Less common side-effects include swelling of the lips, eyes or tongue (angio-oedema) and a decline in kidney function.

A number of medicines may interact with ACE inhibitors. In particular, non-steroidal anti-inflammatory drugs (NSAIDs), 'water tablets' (diuretics) and lithium. Your doctor will normally check what other medicines you take and give further advice about this.

So, make sure your doctor knows of any other medicines that you are taking, including ones that you have bought rather than been prescribed.