Drug Therapies that Augment Airway Surface Liquid

This chapter briefly describes the airway surface liquid (ASL) and the critical role of its hydration status and reviews the pathophysiology initiated by insufficient hydration of ASL. It then presents detailed evidence about medications intended to restore ASL and their effectiveness in people with CF. Inhaled osmotic agents are one class of ASL-augmenting medications. Nebulized hypertonic saline significantly improves lung function, reduces exacerbations, and improves the quality of life of people with CF. Dry powder mannitol also significantly improves lung function and reduces the incidence of exacerbations in this population, but it does not significantly improve quality of life. Ion transport modifiers are another class of inhaled medications that augment the ASL. These medications address the underlying ion transport defects by either inhibiting sodium absorption (e.g., amiloride) or by stimulating chloride secretion (e.g., denufosol). Despite promising preliminary research, ion transport modifiers have not demonstrated clinical benefits to date. In summary, osmotic agents, such as hypertonic saline and dry powder mannitol, have clinical worthwhile benefits in people with CF and are currently used in clinical practice.