Comparison of the rapid effects of single inhalations of formoterol and tiotropium bromide on respiratory function and COPD symptoms in a randomized crossover study.

Background: This study aimed to compare rapid improvements in respiratory function and symptoms following single inhalation of formoterol (FOM) dry power inhaler (DPI) or tiotropium bromide (TIO) DPI in patients with chronic obstructive pulmonary disease (COPD).

Methods: Fifty-two outpatients with COPD (GOLD stage 2 or 3) received either a single inhalation of FOM DPI (9 μg via a Turbuhaler) or TIO DPI (18μg via a HandiHaler) in a randomized crossover manner. Respiratory function testing was performed before, and 15, 60, and 120min after drug administration. Indices of respiratory resistance (assessed with a Mostgraph) were measured before, and 3, 7, 10, 15, 30, 60, and 120min after treatment.Visual analogue scale (VAS) (range 0-10cm) and modified Borg scale scores (CR10) were compared before and after treatment.

Results: Forced expiratory volume in 1 second (FEV1) significantly improved 15min after both FOM (p=0.002) and TIO (p=0.026). Respiratory resistance at 5Hz (R5) and resonant frequency indices significantly decreased 10min (p=0.007) and 3min (p=0.034) after inhaling FOM and remained reduced at 120min. Low frequency reactant indices at 5Hz (X5) significantly increased at 30min (p=0.012) VAS significantly correlated with FEV1 (r=-0.371, p=0.007), X5 (r=-0.304, p=0.029), and low-frequency reactance area (AX; r=0.305, p=0.028) in FOM, but not in TIO. Borg scale scores significantly correlated with FEV1% (r=-0.398, p=0.004), R5 (r=-0.379, p=0.006), respiratory resistance at 20Hz (R20; r=0.321, p=0.020), and R5-R20 (r=0.377, p=0.006) in FOM, but not in TIO.

Conclusions: FOM is more effective than TIO at rapidly improving pulmonary function and symptoms in patients with COPD.