Angiotensin II receptor antagonists or Angiotensin II receptor blockers are a group of medicines used in the treatment of high blood pressure. They can also help to prevent some kidney problems (nephropathy) that can occur in people with diabetes, and can help to relieve the symptoms of heart failure, such as shortness of breath, which some people with diabetes experience.
Angiotensin II receptor antagonists work by blocking the action of a hormone called Angiotensin II which occurs naturally in the body. Angiotensin II causes blood vessels to constrict (tighten). This makes it harder for blood to flow through them and so the blood pressure goes up. By blocking the action of this hormone the blood vessels relax, the blood pressure comes down and the heart muscle doesn’t have to work as hard to pump blood round the body. Because there is more blood flowing to the kidneys it is easier for the body to get rid of excess salt and fluid.
High blood pressure is often associated with diabetes and can lead to kidney disease (nephropathy), heart attack or stroke. Controlling blood pressure is, therefore, very important for people with diabetes. The aim is to keep the blood pressure at 130/80 mmHg or below.
The first choice of treatment would usually be an ACE Inhibitor (see our separate information sheet on ACE Inhibitors) but a common side effect of ACE Inhibitors is a dry cough, indicating that that particular medicine is not suiting the person. Angiotensin II receptor antagonists give doctors an alternative choice in the treatment of high blood pressure and prevention of nephropathy in people with diabetes.
Angiotensin II receptor antagonists include Losartan, Valsartan, Irbesartan, Candesartan, Telmisartan and Eprosartan.
It is important to take these tablets at approximately the same time each day. They can usually be taken with or without meals, although food decreases the absorption of Valsartan so this particular tablet must be taken on an empty stomach.
Small doses may be prescribed at first to prevent a sudden drop in blood pressure, which could cause dizziness or fainting. The dose may then gradually be increased as required. Standing up too quickly from a sitting or lying position, hot weather, drinking alcohol or exercise may cause dizziness. Driving or operating machinery should be avoided until any dizziness is over.
This type of medication must not be taken during pregnancy.
Angiotensin II receptor antagonists may increase potassium levels in the body so potassium supplements or salt substitutes should be avoided unless specifically recommended by a doctor.