| Indication | Used to assist the expectoration of phlegm from the airways in acute respiratory tract infections. |
| Pharmacodynamics | Guaifenesin is an expectorant which increases the output of phlegm (sputum) and bronchial secretions by reducing adhesiveness and surface tension. The increased flow of less viscous secretions promotes ciliary action and changes a dry, unproductive cough to one that is more productive and less frequent. By reducing the viscosity and adhesiveness of secretions, guaifenesin increases the efficacy of the mucociliary mechanism in removing accumulated secretions from the upper and lower airway. |
| Mechanism of action | Guaifenesin may act as an irritant to gastric vagal receptors, and recruit efferent parasympathetic reflexes that cause glandular exocytosis of a less viscous mucus mixture. Cough may be provoked. This combination may flush tenacious, congealed mucopurulent material from obstructed small airways and lead to a temporary improvement in dyspnea or the work of breathing. |
| Absorption | Rapidly absorbed from the GI tract |
| Volume of distribution | Not Available |
| Protein binding | Not Available |
| Metabolism | Rapidly hydrolyzed (60% within seven hours) and then excreted in the urine, with beta-(2-methoxyphenoxy)-lactic acid as its major urinary metabolite. |
| Route of elimination | Not Available |
| Half life | 1 hour |
| Clearance | Not Available |
| Toxicity | LD50 1510 mg/kg (rat, oral) |
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