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.