The Role of Guaifenesin in the Management of Chronic Mucus Hypersecretion Associated with Stable Chronic Bronchitis: A Comprehensive Review.

Chronic obstructive pulmonary disease is the third leading cause of death and disease burden worldwide. It includes a spectrum of diseases including chronic bronchitis which is characterized by overproduction, hypersecretion and decreased elimination of mucus. Chronic bronchitis has numerous clinical consequences, including predisposition to lower respiratory tract infections, accelerated decline in lung function, increased exacerbation rate and decreased health-related quality of life. Although the inflammatory mechanisms responsible for mucus cell metaplasia in chronic obstructive pulmonary disease and stable chronic bronchitis are poorly understood, the main goals of therapy are to decrease mucus hypersecretion by controlling inflammation and to increase mucus clearance. Non-pharmacological measures include smoking cessation and chest physiotherapy. Pharmacological interventions include expectorants and mucolytics together with long-acting beta2-adrenergic receptor agonists, anticholinergics, glucocorticoids, phosphodiesterase-4 inhibitors, antioxidants, and antibiotics. Guaifenesin is an expectorant that is thought to increase hydration and decrease viscosity of mucus leading to improved clearance of accumulated secretions from the upper and lower airway. Although guaifenesin has a Food and Drug Administration Over-the-Counter (OFC) Monograph indication to "help loosen phlegm (mucus) and thin bronchial secretions in patients with stable chronic bronchitis," there is limited published evidence of either mechanism of action or clinical efficacy in this disease state. Here we review the pathophysiology and consequences of chronic mucus hypersecretion and examine the evidence for the use of guaifenesin in patients with stable chronic bronchitis.