Addition of an extra dose of salmeterol Diskus® to conventional dose of salmeterol Diskus® in patients with COPD

Patients experiencing dyspnoea can request an additional dose of salmeterol during the dose interval for the control of their symptoms, although under treatment with salmeterol. In this study we have explored the effects on respiratory function of an additive dose of salmeterol Diskus® in 15 chronic obstructive pulmonary disease (COPD) patients in regular treatment with a conventional dose of 50 μg salmeterol. On two different days, patients inhaled 50 μg Diskus®. After 240 min, they inhaled additional 50 μg salmeterol Diskus® (salmeterol arm) or placebo Diskus® (placebo arm). Lung function was controlled before first drug administration and 0.5, 1, 2, 3, 4, 4.5, 6, 8, 10, and 12 h thereafter. The mean (95% CI) peak increase in FEV₁ from baseline was reached after 4 h in the salmeterol arm (0.174 L; 0.144-0204) and after 5 h (0.141 L; 0.115-0.168) in the placebo arm; after 12 h, the mean (95% CI) increase in FEV₁ from basal values was still 0.149 L (0.119-0.179) in salmeterol arm, but only 0.041 L (0.017-0.064) in placebo arm. The mean (95% CI) FEV₁ AUC_0-12h for all patients were 2.01 (1.72-2.30) L when salmeterol was added and 1.30 (1.03-1.58) L when placebo was inhaled. The difference (mean; 95% CI) between the FEV₁ AUC₀-12h of the two arms (0.71 L; 0.47-0.95) was statistically significant (P <0.0001), although the difference (mean; 95% CI) between the FEV₁ AUC_0-4h of the two treatments (0.08 L; -0.02-0.18) was not statistically significant (P=0.126). The addition of an extra dose of salmeterol did not significantly increase the heart rate or decrease the SpO₂. This study suggests that the addition of an extra dose of salmeterol does not give room for further increase in peak FEV₁, but the effect of adding salmeterol to salmeterol is largely additive when considering the duration of action and safe.