title: Guaifenesin has no effect on sputum volume or sputum properties in adolescents and adults with acute respiratory tract infections.
abstract: BACKGROUND
  Guaifenesin (glyceryl guaiacolate ether [GGE]) has been studied as a cough suppressant and as an expectorant; however, published studies to date have failed to find a consistent benefit.
  
  
  METHODS
  An 8-day multi-center clinical trial was conducted to study the effect of two 600-mg extended-release GGE tablets twice daily for 1 week on cold symptoms, sputum volume, and properties in adolescents and adults with productive cough from an acute respiratory tract infection (RTI). The study enrolled 378 subjects (GGE, n = 188; and placebo, n = 190) who were otherwise healthy and had an RTI for up to 5 days before enrollment. Subjects suffered from at least 2 of 3 symptoms of cough, thickened mucus, and chest congestion. A total of 151 GGE and 144 control subjects completed the full protocol. Single-sputum samples were collected from each subject on days 1, 3, 4, and 8 of the study. The rheology and interfacial tension of sputum were measured, and 24-h collected samples from days 1 and 4 were analyzed for total volume and hydration.
  
  
  RESULTS
  Symptoms in both the GGE and placebo groups improved to a similar degree over time. There were no significant differences between the GGE and placebo groups for sputum volume (P = .41), percent solids (P = .69), interfacial tension (P = .88), elasticity (P = .71), viscosity (P = .45), or mechanical impedance (P = .75).
  
  
  CONCLUSIONS
  The recommended dose of GGE had no measurable effect on sputum volume or properties and is unlikely to be an expectorant or mucolytic when used to treat acute RTI. (ClinicalTrials.gov registration NCT01046136.).
authors.affiliation: Department of Pediatrics, Virginia Commonwealth University, Richmond, Virginia.
authors.forename: Agathe
authors.initials: A
authors.lastname: Hoffer-Schaefer
authors.forename: Henry J
authors.initials: HJ
authors.lastname: Rozycki
authors.forename: Melissa A
authors.initials: MA
authors.lastname: Yopp
authors.forename: Bruce K
authors.initials: BK
authors.lastname: Rubin
mesh_terms: D000293:Adolescent; D000328:Adult; D004311:Double-Blind Method; D004548:Elasticity / Q000187:drug effects; D005100:Expectorants / Q000494:pharmacology*; D005260:Female; D006140:Guaifenesin / Q000494:pharmacology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D009093:Mucus / Q000737:chemistry / Q000187:drug effects; D012141:Respiratory Tract Infections / Q000150:complications / Q000188:drug therapy*; D012212:Rheology / Q000187:drug effects; D013183:Sputum / Q000187:drug effects*; D013500:Surface Tension / Q000187:drug effects; D014783:Viscosity / Q000187:drug effects; D014867:Water / Q000032:analysis; D055815:Young Adult
chemical_list: D005100:Expectorants; D014867:Water; D006140:Guaifenesin
keywords: cough therapy; expectorant; guaifenesin; mucus; upper respiratory infection