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Beta2 agonistsThis is the second of the medicine of the week features looking at asthma drugs. The first article looked at inhaled steroids and this article looks at the medicines used to relieve an asthma attack - the blue-coloured inhalers containing medicines known as beta2 agonists. Selective beta2-adrenoreceptor agonists, or beta2 agonists for short, are more commonly known as asthma 'relievers' or bronchodilators. They are drugs that relax and open up the airways (bronchi) in the lungs, which become narrowed during an asthma attack. The most widely known of these drugs are salbutamol (e.g. Ventolin, Volmax) and terbutaline (Bricanyl).
What are beta2 agonists for? Side effects When to avoid beta2 agonists Use beta2 agonists with care if ... Interactions with other medicines How to use beta2 agonists Common beta2 agonists How do beta2 agonists work?Beta2 agonists work by copying certain effects of natural chemicals - adrenaline and noradrenaline - produced in the body. These chemicals prepare the body for action, such as exercise or a stressful situation (they are also released as part of the 'fight or flight' reaction). One of the effects of these chemicals is to open up the airways so that more air can reach the lungs.  What are beta2 agonists for?Relievers are used to relieve the symptoms of asthma, such as chest tightness, coughing, wheezing and breathlessness. If you have mild asthma, you may be given a reliever to use just when you have symptoms. Or, if you get asthma only when you exercise, your doctor might suggest you use a reliever about 20 minutes beforehand, to prevent any symptoms from developing. If your asthma is more severe, and you find yourself needing to use a reliever more than once a day, you may have to use it regularly, along with another drug (such as an inhaled steroid) to prevent symptoms. Sometimes beta2 agonists are also used to relieve symptoms of other lung conditions such as chronic bronchitis and emphysema. Side effectsThe most common Side effects with beta2 agonists are fine tremor of the hands, restlessness, nervousness and headache. They can also cause flushing and palpitations. Rare, but more serious, Side effects include abnormal heart rhythms, sleep and behaviour disturbances in children, low blood potassium levels, muscle cramps and allergic reactions. When to avoid beta2 agonistsYou should avoid using certain beta2 agonists if you have severe kidney or liver disease. Your doctor or pharmacist can tell you which ones to avoid. Use beta2 agonists with care if ...You should use beta2 agonists with care if you have:
If you are pregnant or breast feeding, you should use beta2 agonists with care, and some should be avoided. Interactions with other medicinesDo not take any other medicines or herbal remedies with a beta2 agonist, including those you have bought without a prescription, before talking to your doctor or pharmacist. For example beta2 agonists can increase the blood pressure-lowering effects of the medicine methyldopa. How to use beta2 agonistsBeta2 agonists are most commonly taken via an inhaler. There are several different types of inhaler available, such as aerosol inhalers, dry powder inhalers and breath-controlled inhalers. Sometimes, particularly for children, a spacer device can be used with an inhaler to make it easier to inhale the drug. Some beta2 agonists are also available as injections, nebuliser solutions or oral preparations (e.g. as tablets or syrup). Common beta2 agonists
July 2001 Back to Medicines index.
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