Background: Evidence has been provided that high-dose indacaterol (300 μg) can reduce lung hyperinflation in moderate-to-severe chronic obstructive pulmonary disease (COPD).
Aim: To study whether low-dose indacaterol (150 μg) also reduces lung hyperinflation in comparison with the recommended dose of tiotropium (18 μg) in moderate COPD.
Methods: This was a multicenter, randomized, blinded, 3-period cross-over, placebo-controlled study. Spirometry and lung volumes were measured before and 30, 60, 120, 180 and 240 min after the administration of single-doses of indacaterol, tiotropium, or placebo. The primary end-point was the change in peak inspiratory capacity (IC). The area under the 4-h curve (AUC(0-4)) for IC, 1-s forced expiratory volume (FEV(1)) and forced vital capacity (FVC) were secondary variables.
Results: 49 patients completed the study. On average, peak IC and AUC(0-4) for IC were significantly greater after indacaterol than placebo by 177 mL (p = 0.007) and 142 mL (p = 0.001), respectively. Differences in peak IC and AUC(0-4) for IC between tiotropium and placebo were 120 mL (p = 0.07) and 85 mL (p = 0.052), respectively. Differences between indacaterol and tiotropium were statistically insignificant. Peak IC increased by >20% in 12 patients with indacaterol and 9 with tiotropium (p = 0.001), and by >30% in 8 patients with indacaterol and 3 with tiotropium (p = 0.001). The effects of indacaterol and tiotropium on FEV(1) and FVC were statistically significant vs placebo.
Conclusions: Low-dose indacaterol has a bronchodilator effect that is similar to the recommended dose of tiotropium, but it is slightly superior in reducing lung hyperinflation.
Trial registration: ClinicalTrials.gov number: NCT00999908.
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