ACE inhibitors

ACE inhibitors are angiotensin converting enzyme inhibitors. They block a chemical in your body called angiotensin converting enzyme.

Examples of ACE inhibitors

Most ACE inhibitors have names that end in 'pril'. The following ACE inhibitors are available in New Zealand.

ACE inhibitors available in New Zealand

  • captopril (Capoten)
  • cilazapril (Zapril, Apo-Cilazapri)
  • enalapril (Enalapril Ethics, Renitec M)

ACE inhibitors are sometimes combined with a diuretic (water tablet), for example:

  • cilazapril + hydrochlorothiazide
  • quinapril + hydrochlorothiazide (Accuretic®).

When are ACE inhibitors used?

ACE inhibitors have many different effects on the body and are used to treat a variety of conditions. They may be used for:

  • high blood pressure by relaxing and widening your blood vessels and lowering your blood pressure
  • heart failure to help the heart pump blood more easily. This can help to relieve symptoms such as shortness of breath and swelling of feet, legs and abdomen
  • diabetic kidney disease (diabetic nephropathy) to protect your kidneys and help them to function
  • chronic kidney disease to slow the progress of kidney disease
  • after a heart attack (myocardial infarction) to protect your heart.

ACE inhibitors can work very quickly for high blood pressure (hypertension). If you have heart failure it may be a few weeks or months before you notice an improvement in your symptoms. Once you have started taking an ACE inhibitor you will generally keep taking it for life unless you have a side effect.
The following animation describes how ACE inhibitors work in the body (British Heart Foundation)

Who cannot take ACE inhibitors?

ACE inhibitors are not recommended if you:

  • are pregnant or planning a pregnancy – they should be avoided at all stages of pregnancy
  • are breastfeeding
  • have allergic reactions with swelling of your lips, eyes or tongue (called angioedema)
  • have low sodium, high potassium or low blood pressure
  • have certain types of kidney disease such as renal artery stenosis.

Blood tests and monitoring

A blood test is usually done before starting an ACE inhibitor, and about 1-2 weeks after the first dose. You may also require further blood tests as your dose increases. These tests check on how well your kidneys are working and to check your sodium and potassium levels. The kidneys are affected in a small number of people who take an ACE inhibitor. Thereafter you will have blood tests every few months.

Cautions while you are taking ACE inhibitors

Have a sick day plan

If you have diarrhoea or are vomiting from a stomach bug, or have dehydration from other causes, it’s important to let your GP know, as they may advise you to temporarily stop taking your ACE inhibitor for a few days and restart when you feel better. The reason for this is that ACE inhibitors can increase the amount of potassium salts in your blood, particularly if you are dehydrated.

Be careful when taking some pain relief medicines

ACE inhibitors help to protect your kidneys from damage if you have diabetes. In most cases taking ACE inhibitors are not only safe, but they are protective as well. However, if you are on an ACE inhibitor and take diuretics (water pills), the combination of these with NSAIDs (anti-inflammatory pain relief medication) can be very harmful to your kidneys. It can cause acute kidney injury. This combination is called the dangerous trio or triple whammy. You have a higher risk of harm to your kidneys if you are also elderly or are dehydrated. 

If you are taking an ACE inhibitor with a diuretic, do not use NSAIDs for pain relief. Ask your doctor or pharmacist for a safer option. Read more about NSAIDs and protecting your kidneys.

Examples of diuretics Examples of NSAIDs
  • bendrofluazide (Arrow-Bendrofluazide)
  • chlorthalidone (Hygroton)
  • indapamide (Dapa-Tabs, Napamide)
  • metolazone (Zaroxolyn)
  • furosemide (Diurin)
  • ibuprofen (Ibugesic, I-Profen, Nurofen)
  • diclofenac (Voltaren)
  • naproxen (Noflam, Naprosyn)
  • mefenamic acid (Ponstan)
  • celecoxib (Celebrex)

Other medicines

Let your doctor and pharmacist know about all the other medicines you are taking. Some medicines should not be taken together with ACE inhibitors or the dose needs to be adjusted. These medicines include lithium, some types of diuretics and some medicines used for diabetes.

Possible side effects

Like all medicines, ACE inhibitors can cause side effects, although not everyone gets them. Often side effects improve as your body gets used to the new medicine. Common side effects include headache and nausea (feeling sick) or vomiting (being sick). Some people may get a change in their taste, but this is rare. Other side effects to be aware of are dizziness, dry cough and allergic reaction. 

Dizziness

Dizziness is quite common when you first start taking an ACE inhibitor, especially after the first or second dose. During this time, you are at increased risk of falls, especially when you stand up from sitting or lying down. Your doctor will start you on a low dose and slowly increase how much you take. When starting an ACE inhibitor, get up slowly out of bed or stand up slowly; take a few minutes to sit on your bed or on a chair first. The dizziness goes away after a while. If the dizziness is severe or ongoing, tell your doctor.

Dry cough

This is quite common with people taking an ACE inhibitor – it happens in about 1 in 10 people. Sometimes this even happens after you have been taking the medicine for months. If you have a dry cough and is uncomfortable, talk to your doctor. You might be able to try another kind of ACE inhibitor. 

Allergic reaction

About 1 in 100 people taking ACE inhibitors develop an allergic reaction, which causes swollen lips and breathing difficulties. This can happen any time from 2 weeks to 2 years after starting to take ACE inhibitors. If this happens, seek medical attention immediately.

References

  1. Angiotensin-converting enzyme inhibitors New Zealand Formulary
  2. Safe and effective use of ACE inhibitors in primary care BPAC, NZ, 2012
  3. Guide for initiation and up-titration of ACE inhibitors for patients with heart failure SafeRx, 2017
Credits: Sandra Ponen, Pharmacist. Reviewed By: Angela Lambie, Pharmacist, Auckland Last reviewed: 21 Aug 2018