Is extended-release guaifenesin no better than a placebo?

In this issue of RESPIRATORY CARE, Hoffer-Schaefer et al1 report the results of a double-blind randomized placebocontrolled trial examining the effects of guaifenesin on both the volume and physical properties of sputum in patients with acute respiratory tract infections (RTIs). Guaifenesin has been marketed as an FDA-approved over-thecounter (OTC) expectorant medication with annual sales of approximately $135 million in the United States. There is currently a paucity of data suggesting that guaifenesin is an effective expectorant, mucolytic, or cough suppressant. Hoffer-Schaefer et al1 report the effects of two 600-mg extended-release guaifenesin tablets taken twice daily on sputum volume and sputum properties in adolescents and adults with acute RTIs. In its natural healthy state, the lung produces mucus on a continuous basis to clear airways, to entrap bacteria and viruses, and to maintain airway hydration. Sputum refers to the expectorated sample of retained mucus in combination with bacteria and inflammatory cells from within the lung and is a manifestation of underlying lung inflammation and infection. There is an increasing understanding of the complexity of the physics of mucus production, transport, and clearance from within the bronchial tree.2 This clearance of mucus from the lung is dependent on a number of factors, including the rheological properties of the mucus, airway wall factors, and the physical interactions between the mucus and the airway wall.