Evidence has been provided that high-dose indacaterol (300 μg) can reduce lung hyperinflation in moderate-to-severe chronic obstructive pulmonary disease (COPD).

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.

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 (FEV₁) and forced vital capacity (FVC) were secondary variables.

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 FEV₁ and FVC were statistically significant vs placebo.

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.

ClinicalTrials.gov number: NCT00999908.