Angiotensin receptor blockers (ARBs)

Angiotensin receptor blockers or ARBs are used to treat many conditions such as high blood pressure, heart failure and kidney disease caused by diabetes.

Examples of ARBs

Most ARBs have names that end in 'sartan'. The following ARBs are available in New Zealand:

When are ARBs used?

ARBs have many different effects on your body and are used to treat many 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
  • after a heart attack (myocardial infarction) to protect your heart.

ARBs have a similar effect to another group of medicines called ACE inhibitors – they are usually used when taking ACE inhibitors is not suitable. Once you have started taking an ARB you will generally keep taking it for life unless you have a side effect.

Who can't take ARBs?

ARBs are not recommended if you:

  • are pregnant or planning a pregnancy – they should be avoided at all stages of pregnancy
  • are breastfeeding – your doctor may recommend another medicine
  • 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 ARB and about 1–2 weeks after the first dose, and every few months while you are taking it. You may need to have more blood tests if your dose increases. These tests check how well your kidneys are working and check your sodium and potassium levels. The kidneys are affected in a small number of people who take an ARB.

Cautions while you are taking ARBs

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 stop taking your ARB for a few days and restart when you feel better. The reason for this is that ARBs can increase the amount of potassium salts in your blood, particularly if you are dehydrated.

Be careful when taking some pain relief medicines

ARBs help to protect your kidneys from damage if you have diabetes. In most cases ARBs are protective but if you are taking an ARB and 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 ARB 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
  • Bendroflumethiazide (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)

Possible side effects

Like all medicines, ARBs 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 and allergic reaction. 

Dizziness

Dizziness is quite common when you first start taking an ARB, 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 ARB, 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.

Allergic reaction

Some people taking ARBs may develop an allergic reaction, which causes swollen lips and breathing difficulties. This can happen any time from 2 weeks to 2 years after starting an ARB. If this happens, seek medical attention immediately.

References

  1. Angiotensin-II receptor antagonists New Zealand Formulary
  2. Prescribing ACE inhibitors: time to reconsider old habits BPAC NZ, 2018
Credits: Sandra Ponen, Pharmacist. Reviewed By: Angela Lambie, Pharmacist, Auckland Last reviewed: 13 Dec 2018