These drugs are offsprings of adrenelin, the major hormone produced by the adrenal gland, and act directly on particular sites called receptors or nerve cells of sympathetic nervous system. There are three main types of receptor sites called alpha, beta-1 and beta-2. These receptor sites are located in the airways, but they are also found in other parts of the body such as the inside of heart muscles, and muscles in the arms and legs. Some of these drugs act on all three types of receptor sites, but others are more selective.
The most effective adrenergic bronchodilator drugs are called beta-2 agonists, or simply beta agonists. They primarily influence the beta-2 receptors which are present only in the bronchial airways. These drugs are preferred because of their property to selectively relax bronchial muscles only, without stimulating muscles in the heart or other body areas.
They cause fewer side effects. Examples of these drugs are salbutamol and terbutaline. They are available in tablet form as well as in aerosols in metered-dose inhalers and nebulizers. However care should be taken not to overuse these drugs during an attack. If their use does not provide adequate relief, it is an indication that some other group of drugs should also be added.
Beta-2 agonists also provide more rapid action with inhalers rather than with oral intake. While salbutamol or terbutaline may provide more or less immediate relief through inhalation, it may take upto three hours to obtain similar relief through the oral route.
The most effective adrenergic bronchodilator drugs are called beta-2 agonists, or simply beta agonists. They primarily influence the beta-2 receptors which are present only in the bronchial airways. These drugs are preferred because of their property to selectively relax bronchial muscles only, without stimulating muscles in the heart or other body areas.They cause fewer side effects. Examples of these drugs are salbutamol and terbutaline. They are available in tablet form as well as in aerosols in metered-dose inhalers and nebulizers. However care should be taken not to overuse these drugs during an attack. If their use does not provide adequate relief, it is an indication that some other group of drugs should also be added.
Beta-2 agonists also provide more rapid action with inhalers rather than with oral intake. While salbutamol or terbutaline may provide more or less immediate relief through inhalation, it may take upto three hours to obtain similar relief through the oral route.
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