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.