Study objective: To assess the effects of tiotropium on lung mucociliary clearance in COPD.
Design: Randomized, double-blind, placebo-controlled, parallel-group study.
Setting: Outpatients of an urban-area university teaching hospital.
Patients: Thirty-four patients with COPD aged 40 to 75 years classified equally into two groups.
Intervention: Single (18 microg) daily dose of tiotropium inhalation capsules or of placebo for 21 days.
Methods: Six-hour tracheobronchial clearance of inhaled 99mTc-labeled polystyrene particles using a 48-h retention measurement to determine the "nontracheobronchial" deposition fraction.
Results: Test radioaerosol penetration into the lungs increased significantly (p < 0.003) as did FEV1 (p < 0.006) in the tiotropium-treated patients, but measured mucociliary clearance was not significantly changed despite the increased pathway length for clearance (mean +/- SE area under the tracheobronchial retention curve changed from 442 +/- 22 to 453 +/- 20%/h). Smaller (nonsignificant) decreases of radioaerosol penetration and FEV1 occurred in the placebo group together with a small (nonsignificant) decrease in the area under the retention curve.
Conclusion: Twenty-one days of inhaled tiotropium, 18 microg/d, as a dry powder does not retard mucus clearance from the lungs.