Long-acting beta-agonist treatment in patients with persistent asthma already receiving inhaled corticosteroids

International guidelines recommend that long-acting beta -agonists should b e considered in patients who are symptomatic despite moderate doses of inha led corticosteroids. When combined with inhaled corticosteroids they improv e asthma symptoms and lung function and reduce exacerbations. The evidence suggests that they are well tolerated. However, they are less effective tha n inhaled corticosteroids as monotherapy and should not be used alone, alth ough the addition of long-acting beta -agonist may permit a small reduction in the corticosteroid dose. Both salmeterol and formoterol appear equally effective in improving asthma control. Formoterol, however, has a rapid ons et of action and is now being promoted for the relief of acute asthma sympt oms. Both drugs provide prolonged protection against exercise-induced bronc hospasm. However, this effect rapidly diminishes with continuous therapy an d if this is the main aim of treatment, intermittent use may be preferable. When compared with alternative treatments, inhaled long-acting beta -agonis ts are more effective in controlling asthma symptoms than either theophylli ne or antileukotriene agents. Bambuterol, an oral prodrug of terbutaline, a ppears to he as effective as the inhaled long-acting beta -agonists and has the advantage of once daily oral administration. However, the inhaled long -acting beta -agonists are less likely to have systemic adverse effects. There are theoretical concerns that regular beta -agonist treatment may lea d to tolerance and a failure to respond to emergency asthma treatment. Whil e there is no doubt that tolerance occurs, there is currently little eviden ce that this is a clinical problem. Insights into pharmacological as well as therapeutic interactions between i nhaled corticosteroids and beta -agonists are providing justification for t heir use in combination. Guidelines for the management of patients with chr onic persistent asthma are likely to require modification to reflect these developments.