BackgroundTherapeutic intervention in the pathophysiology of airway mucus hypersecretion is clinically important. Several types of drugs are available with different possible modes of action. We examined the effects of guaifenesin (GGE), N-acetylcysteine (NAC) and ambroxol (Amb) on differentiated human airway epithelial cells stimulated with IL-13 to produce additional MUC5AC.MethodsAfter IL-13 pre-treatment (3 days), the cultures were treated with GGE, NAC or Amb (10–300 μM) in the continued presence of IL-13. Cellular and secreted MUC5AC, mucociliary transport rates (MTR), mucus rheology at several time points, and the antioxidant capacity of the drugs were assessed.ResultsIL-13 increased MUC5AC content (~25%) and secretion (~2-fold) and decreased MTR, but only slightly affected the G’ (elastic) or G” (viscous) moduli of the secretions. GGE significantly inhibited MUC5AC secretion and content in the IL-13-treated cells in a concentration-dependent manner (IC50s at 24 hr ~100 and 150 μM, respectively). NAC or Amb were less effective. All drugs increased MTR and decreased G’ and G” relative to IL-13 alone. Cell viability was not affected and only NAC exhibited antioxidant capacity.ConclusionsThus, GGE effectively reduces cellular content and secretion of MUC5AC, increases MTR, and alters mucus rheology, and may therefore be useful in treating airway mucus hypersecretion and mucostasis in airway diseases.

Hydroxypropylmethylcellulose (HPMC) is a food gum that shares certain characteristics, such as high viscosity, with soluble fibers. In this trial, the safety and cholesterol-lowering efficacy of HPMC consumed with and between meals was evaluated in free-living male volunteers with mild-to-moderate hypercholesterolemia. After a 14-d baseline period, men (n = 51) with LDL cholesterol between 3.36 and 4.91 mmol/L and triglycerides <3.95 mmol/L were randomly assigned to consume 5.0 g/d HPMC in 240 mL of orange drink, taken either with or between meals, for a 2-wk treatment period. In the Between Meals group, total cholesterol was reduced by 8.0% vs. baseline in wk 1 of treatment (P < 0.05) and 5.1% in wk 2 (P < 0.01). LDL cholesterol concentrations fell by 12.0 and 7.7% (P < 0.01). In the With Meals group, reductions were 9.5 and 8.3% for total cholesterol, and 12.5 and 12.8% for LDL cholesterol (wk 1 and 2, respectively, P < 0.01). In both groups, HDL cholesterol decreased by approximately 5% during wk 1 of treatment (P < 0.01), but the wk 2 concentrations were not significantly different from baseline. There were no significant differences between groups in lipid responses, although there was a trend for a smaller LDL cholesterol-lowering effect during wk 2 of treatment in the Between Meals group (P < 0.06). Gastrointestinal-related adverse experiences (mostly mild) were twice as common among participants who ingested HPMC with meals (P < 0.05). These results suggest that HPMC has a lipid-lowering effect, which may be more consistent when taken with meals.

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Guaifenesin is widely used to alleviate symptoms of excessive mucus accumulation in the respiratory tract. However, its mechanism of action is poorly understood. The authors hypothesized that guaifenesin improves mucociliary clearance in humans by reducing mucin release, by decreasing mucus viscoelasticity, and by increasing mucociliary transport. To test these hypotheses, human differentiated airway epithelial cells, cultured at an air-liquid interface, were treated with clinically relevant concentrations of guaifenesin by addition to the basolateral medium. To evaluate the effect on mucin secretion, the authors used an anzyme-linked immunosorbent assay (ELISA) to measure the amounts of MUC5AC protein in apical surface fluid and cell lysates. To measure mucociliary transportability, additional cultures were treated for 1 or 6 hours with guaifenesin, and the movement of cell debris was measured from video data. Further, the authors measured mucus dynamic viscoelasticity using a micro cone and plate rheometer with nondestructive creep transformation. Guaifenesin suppressed mucin production in a dose-dependent manner at clinically relevant concentrations. The reduced mucin production was associated with increased mucociliary transport and decreased viscoelasticity of the mucus. Viability of the cultures was not significantly affected. These results suggest that guaifenesin could improve mucociliary clearance in humans by reducing the release and/or production of mucins, thereby altering mucus rheology.

BackgroundGuaifenesin is a component of medicines used to improve symptoms associated with upper respiratory tract infections. Patient-reported outcome instruments are valuable for evaluating symptom improvements; however, a validated tool to assess efficacy of mucoactive drugs does not exist. We compared the efficacy of extended-release guaifenesin with placebo for treatment of symptoms of upper respiratory tract infection using subjective efficacy assessments in a pilot study and confirmed precision of assessments in a validation study.MethodsThe pilot study was a randomized, double-blind study where patients were dosed with either 1200 mg extended-release guaifenesin (n = 188) or placebo (n = 190), every 12 hours for 7 days. Efficacy was assessed using subjective measures including the Daily Cough and Phlegm Diary, the Spontaneous Symptom Severity Assessment and the Wisconsin Upper Respiratory Symptom Survey. End-of-study assessments were completed by patients and investigator. The validation study consisted of two phases. In Phase I, subjects completed interviews to gather evidence to support the content validity of the Daily Cough and Phlegm Diary, the Spontaneous Symptom Severity Assessment and Patient’s End-of-Treatment Assessment. Phase II examined the psychometric properties of assessments evaluated in Phase I of the validation study using data from the pilot study.ResultsSubjective measures of efficacy at Day 4 showed the most prominent difference between treatment groups, in favor of guaifenesin. The 8-symptom related questions (SUM8) in the Daily Cough and Phlegm Diary, analyzed as a composite score appeared to be the strongest candidate endpoint for further evaluation. Results from the interviews in Phase I supported the content of the assessments which were validated during Phase II. Treatments were well tolerated.ConclusionsResults from the clinical pilot and validation studies showed that the SUM8 diary scores were robust and reliable for use as efficacy endpoints in studies of mucoactive drugs.Trial registrationThe study was registered with clinicaltrials.gov (NCT01046136).