In healthy lungs, inhaled insoluble material such as bacteria, viruses, antigens, and toxins deposit in the tracheobronchial airway mucus and are removed from the lung in a matter of hours by mucociliary clearance (MCC). When MCC is overwhelmed or impaired, some mucus can be removed by mechanical or cough clearance (CC). Impairment of MCC typically leads to the accumulation of mucus in the airways, and this in turn is associated with acute infections, chronic bacterial colonization, and chronic inflammation.
Racemic albuterol has been shown to stimulate MCC in various patient populations. Inhaled and subcutaneous terbutaline has also been shown to stimulate MCC in healthy subjects. We hypothesize that levalbuterol will be more potent than racemic albuterol in enhancing MCC and CC in healthy subjects.
