Chronic inhalation of nebulized levalbuterol does not increase mucociliary clearance in healthy subjects

Acute inhalations of β2-adrenergic receptor agonists increase mucociliary clearance (MCC). Less is known about the effect of long-term inhalations of these agents on MCC, or cough clearance (CC). We hypothesized that chronic inhalations of nebulized levalbuterol, the R-isomer of albuterol, would enhance MCC and/or CC in healthy subjects, compared to albuterol or placebo. This was a randomized, double-blind, placebo-controlled trial in ten healthy, adult subjects who inhaled nebulized levalbuterol (1.25 mg), albuterol (2.5 mg), or placebo for 7 days, three times daily. MCC and CC were measured 6-7 h after the last dose of drug on the 7th day of treatment. These were quantified from gamma camera images of the lungs following inhalation of an aerosol containing the isotope 99mtechnetium. Levalbuterol did not improve MCC or CC. MCC averaged (±SD) 12.3±8.3%, 9.2±4.7% and 10.0±9.6% with placebo, albuterol and levalbuterol, respectively. CC averaged 3.9±6.8%, 4.9±4.3% and 3.8±6.4% with placebo, albuterol and levalbuterol, respectively. These results indicate that chronic inhalations of nebulized levalbuterol for 1 week do not increase MCC or CC in healthy subjects, compared to albuterol or placebo.