Drugs used to treat respiratory disorders

Often the same drugs are used to treat asthma and bronchitis, so they are considered here together. Guidelines on the management of chronic asthma and COPD are produced by the British Thoracic Society and published in the BNF and MIMS. 

Drugs used to treat other respiratory conditions are considered separately. 

Beta2 adrenoreceptor stimulants cause bronchodilation by acting on adrenoreceptors in bronchial smooth muscle. Although they are selective for 2 receptors these drugs do have some affect on cardiac Pi receptors. Cardiac side effects are not usually a problem at therapeutic doses, but could be if a patient decided to increase the dose above that recommended. 

P2 adrenoreceptor stimulants are used as first choice for the rapid relief of an acute asthmatic attack and maintenance treatment of chronic asthma. They are more effective in treatment of the immediate phase reaction than the late phase reaction. P2 adrenoreceptor stimulants are less effective in chronic bronchitis, possibly because in this disease bronchoconstriction is due to reflex stimulation of acetylcholine receptors following stimulation of local irritant receptors in lung tissue. 

There are many drugs in this group but little to choose between them. They are most often used as aerosol or dry powder inhalers, but are also available as nebulizer solutions, tablets, syrups, injections and intravenous infusions. 

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