• Lung mucociliary clearance
• Lung cough clearance

• Forced expiratory volume in 1 second
• Forced vital capacity

The purpose of this study is to determine whether lung mucociliary clearance (MCC) can be significantly enhanced in healthy subjects by one week of inhalation of nebulized levalbuterol aerosol, as compared to racemic albuterol or placebo. Subjects will inhale one week of levalbuterol, one week of racemic albuterol, and one week of placebo, in a randomized order.

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.

• Drug: nebulized albuterol (2.5 mg/3ml/dose)
• Drug: nebulized levalbuterol (1.25 mg/3ml/dose)
• Drug: nebulized placebo (3ml/dose)

Inclusion Criteria:

• non-smoking males and non-pregnant females greater than or equal to 18 years of age
• forced expiratory volume in one second (FEV1) and forced vital capacity (FVC) greater than or equal to 80% of predicted values
• normal systolic and diastolic blood pressures

Exclusion Criteria:

• history of heart disease, irregular heartbeat, hypertension
• history of diabetes, hyperthyroid
• history of pneumonia, tuberculosis
• history of seizure disorder, depression, hospitalization in the last month for non-elective purposes, cold or flu in the previous three months