The effect of inhaled beta2-agonists on clinical outcomes in chronic obstructive pulmonary disease

The major clinical outcomes measured in evaluating the responses to pharmacotherapy in patients with chronic obstructive pulmonary disease (COPD) include the severity of dyspnea, exercise capacity, exacerbations, and health status. Various studies have demonstrated that testing for acute bronchodilator reversibility in the pulmonary function laboratory does not predict the clinical responses to a trial of bronchodilator therapy in patients with COPD. Separate studies have shown that inhaled albuterol, both a single dose (300 microg) and 2 weeks of therapy (200 microg/4x/day), reduces dyspnea. There is more published information available about the effects of long-acting (>/=12 hours' duration of action) inhaled beta(2)-agonists because of greater interest in considering clinical outcomes at the time of drug testing. In one randomized clinical trial, formoterol reduced symptoms (as recorded in a home diary) and improved health status. Nine clinical studies have examined the effects of salmeterol on clinical outcomes. Salmeterol reduced the perception of breathlessness (in 6 of 9 studies) and improved health status (in 3 of 4 studies). These results collectively demonstrate that long-acting inhaled beta(2)-agonists not only relax bronchial smooth muscle but also provide important clinical benefits in symptomatic patients with COPD.