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BETA BLOCKERS

What are the types of Beta Blocker?

They are broadly divided into two types. Cardioselective beta-blockers work only or mainly on the heart and to some extent on the lungs. They include atenolol, bisoprolol, acebutolol and metoprolol. Non-cardioselective ones work more generally on the body. The main ones are propranolol, oxprenolol, pindolol, celiprolol, labetalol, nadolol, sotalol, carvedilol and timolol.

What are Beta Blockers for ?

They are firstly used to treat angina (pain from the heart muscle). They are also used to treat high blood pressure (hypertension) and irregular, fast heartbeats. After a heart attack they are often used to prevent an irregular heartbeat from developing and more damage to the heart. For most heart and blood pressure problems, cardioselective beta-blockers are likely to be used. Carvedilol and bisoprolol are used in low doses for the treatment of heart failure. Non-cardioselective blockers are used to treat migraine and to offset the symptoms of an overactive thyroid gland. In people who are anxious, these beta-blockers reduce the physical symptoms of trembling and sweating.

How do Beta Blockers work ?

Beta-blockers work by interfering with the action of adrenaline and its related chemicals. These chemicals are made by the adrenal glands and by the nerves themselves. Adrenaline is an important hormone, but it can also produce harmful effects if too much is allowed to get into the tissues. This is why beta-blockers are used. As a result the heart beats more slowly and less strongly, and blood pressure falls. There is less work for the heart to do, so angina gets better. They stop blood-vessels around the brain from widening so easily which helps to prevent migraine. Blocking the nerve stimulation of adrenaline cuts back the sweating and trembling of people with anxiety or an overactive thyroid gland.

How should Beta Blockers be used ?

They should be taken regularly, according to your doctor's advice. Some beta-blockers need only be taken once daily; others more often. Only for the symptoms of anxiety is it reasonable to take beta-blockers for very short courses. Even then, talk with your doctor about the recommended way to take them.

During Treatment with Beta Blockers

If you are taking them for angina, your chest pain should become less frequent and less severe. If not, you may need a bigger dose, a different type of tablet or a combination of tablets. If you are taking them for high blood pressure, you are not likely to notice any benefit: high blood pressure gives very little, if any, symptoms, anyhow. However, you will be helping reduce the longer-term risk of heart attack or stroke. Some of the most dramatic benefit is seen if you have an overactive thyroid gland. Trembling, sweating and palpitations all get better within a day of starting treatment. Because beta-blockers have effects all over the body, they quite commonly cause side-effects. Many people find cold hands and feet a problem due to reduced blood circulation: this may be reason to stop the drug. Impotence may be a problem in men. If you are a diabetic, you may lose some of the warning symptoms of a low blood sugar level (such as palpitations and trembling). You may need to take special care to avoid your blood sugar falling too low. Asthma can be triggered by beta-blockers of both types: these drugs should not be used if you have asthma or bronchitis. Some people have disturbed sleep and nightmares. Changing to a different beta-blocker sometimes helps.

Drug Interference

If taken with any other drug which lowers blood pressure, it could fall too low, making you feel dizzy and faint. However, many people with high blood pressure actually need two or even three different drugs to keep their blood pressure under control. Using beta-blockers with certain other heart drugs, including amiodarone, nifedipine, diltiazem and verapamil, can cause an abnormally slow heartbeat or very low blood pressure. One particular beta-blocker, sotalol, can cause an irregular heartbeat if taken with mefloquine (Lariam), a malaria-preventing drug. Cough and cold medicines and some appetite suppressants contain a drug which can cause an alarming rise of blood pressure in people on beta-blockers. It is a good idea to check with your pharmacist before you use any of these medicines. The effect of beta-blockers is reduced by several groups of drugs: anti-inflammation tablets, the combined oral contraceptive pill and some forms of hormone replacement therapy (HRT) for the menopause. You may therefore need to take a higher dose of beta-blockers.

What if Beta Blockers are not taken ?

Suddenly stopping a beta-blocker can be very dangerous: the problem for which it was being given can come back more seriously than before. If it does need to be stopped, your doctor will advise how to do it safely. If you forget a dose, take it when you remember. If your next dose is due within 6 hours (for once a day tablets), 12 hours (for slow release tablets) or 2 hours for short-acting tablets, take one dose now, miss your next dose, and then continue as usual.

General advice on the use of Beta Blockers

If you need an operation or dental treatment under general anaesthetic, you may need to stop your beta-blocker temporarily, since some anaesthetics react badly. Check with your doctor. Some beta-blockers are probably safe in pregnancy, but check with your doctor if you are or want to become pregnant: other drugs known to be safe are available as alternatives. If you have any questions not dealt with in this leaflet, please ask your pharmacist or doctor: Keep this leaflet handy in case you need to refer to it at a later date.