EFFECTS OF REGULAR SALMETEROL ON LUNG-FUNCTION AND EXERCISE CAPACITY IN PATIENTS WITH CHRONIC OBSTRUCTIVE AIRWAYS DISEASE

Background - The aim of this study was to evaluate the effects of sing le and chronic dosing with salmeterol on exercise capacity and lung fu nction in patients with chronic obstructive pulmonary disease. Methods - Twenty nine patients of mean (SE) age 64 (1.5) years, forced expira tory volume in one second (FEV(1)) 42(3)% of predicted, and 5-15% reve rsibility to salbutamol 200 mu g were randomised to receive four weeks treatment with salmeterol 50 mu g twice daily or placebo in a double blind crossover fashion with a one week washout period in between. Mea surements of spirometric parameters, static lung volumes, and exercise capacity were made one and six hours after a single dose, and six hou rs after the final dose of salmeterol or placebo.Results - Salmeterol produced a small increase in FEV(1) at one and six hours after a singl e dose, and this was maintained after chronic dosing (mean difference and 95% CI versus placebo): single dosing at one hour 0.07(95% CI 0.02 to 0.11) 1, single dosing at six hours 0.16 (95% CI 0.09 to 0.22) 1, chronic dosing at six hours 0.11(95% CI 0.03 to 0.19) 1. The increase in forced vital capacity (FVC) was greater with salmeterol than with p lacebo six hours after single but not chronic dosing: single dosing at six hours 0.17 (95% CI 0.04 to 0.29) 1, chronic dosing at six hours 0 .02 (95% CI -0.18 to 0.22) 1. Slow vital capacity was increased after treatment with salmeterol compared with placebo one and six hours afte r single but not after chronic dosing. There were no significant diffe rences in static lung volumes or exercise capacity after single or chr onic dosing with salmeterol compared with placebo. Patients reported a significantly lower Borg score for perceived exertion following the s ix minute walk after chronic treatment with salmeterol compared with p lacebo. Conclusions - Salmeterol produced a small improvement in spiro metric values compared with placebo consistent with the degree of reve rsibility originally shown by the subjects to salbutamol 200 mu g. Thi s was not associated with improvements in static lung volumes or exerc ise capacity, but there was some symptomatic benefit in that patients were able to walk the same distance in six minutes with less perceived exertion.