Ipratropium bromide: mucociliary clearance rate and airway resistance in normal subjects.

The effect of ipratropium bromide, a new anticholinergic drug, on the rate of clearance of secretions from the lung and on airways resistance was investigated in 12 healthy subjects in a double-blind cross-over trial with placebo and a control run without aerosol. Before taking the drug the subjects inhaled uniform 5 micrometer tracer particles of polystyrene in which 99mTc had been unleachably incorporated. The initial depth of deposition and the rate of clearance of the particles were obtained from serial gamma counts made externally to the chest over six hours. The difference between drug, placebo and control runs in the deposition patterns of the tracer particles and their subsequent rates of clearance were not significant. The drug treatment resulted in statistically significant falls in specific airway resistance at 1, 2, 3 and 6 hours (P less than 0.02). There was no objective or subjective evidence of side effects from the drug.