Prescribing inhaled bronchodilators and inhaler devices

Inhaled bronchodilators act on the airways, including the trachea, the bronchi and bronchioles. They work by relaxing airway smooth muscle and are central to the treatment of airway disorders, such as asthma¹ and chronic obstructive pulmonary disease (COPD)². There are two major classes of inhaled bronchodilators, beta₂-adrenoceptor agonists and muscarinic receptor antagonists.³

Beta₂-adrenoceptor agonists

Short-acting beta₂-adrenoceptor agonists
Beta₂-adrenoceptor agonists, also referred to as beta₂-agonists can be classified as short- or long-acting agents according to their duration of action.³ Beta₂-agonists act mainly on beta₂-receptors, which are located on bronchial smooth muscle. When the beta₂-agonist attaches to the receptor, a substance called cyclic adenosine monophosphate (cAMP) is produced. This results in the relaxation of the smooth muscle in the walls of the airways, leading to bronchodilation.⁴ Short-acting beta₂-agonists also inhibit the release of inflammatory chemical signals from cells in the walls of the airways and improve the clearance of mucus.⁴ Short-acting beta₂-agonists include the drugs salbutamol and terbutaline; these are used to provide fast-acting symptomatic relief of bronchoconstriction in mild intermittent asthma.¹ They can also be used as a first-choice alternative to the short-acting muscarinic receptor antagonist ipratropium bromide to relieve breathlessness and/or exercise limitation in COPD.² The effects of the short-acting beta₂-agonists last for 4-6 hours.⁴