VA Class:RE516

ATC Class:R05CA03

AHFS Class:

• Expectorants 48:16

Generic Name(s):

• guaiFENesin

• Dyphylline and guaiFENesin

• guaiFENesin and Codeine Phosphate

• Theophylline and guaiFENesin

Guaifenesin is an expectorant.

Cough

Guaifenesin is used as an expectorant in the symptomatic management of coughs associated with the common cold, bronchitis, laryngitis, pharyngitis, pertussis, influenza, and measles, and coughs provoked by chronic paranasal sinusitis. While there is clinical evidence that guaifenesin is an effective expectorant (i.e., increasing expectorated sputum volume over the first 4-6 days of a productive cough, decreasing sputum viscosity and difficulty in expectoration, and improving associated symptoms), there currently is insufficient evidence to support efficacy of the drug as an antitussive (cough suppressant). Therefore, guaifenesin's principal benefit in the symptomatic treatment of coughs results from the drug's ability to loosen and thin sputum and bronchial secretions and ease expectoration. Although such facilitation of evacuation of secretions may indirectly diminish the tendency to cough, the mechanism of this effect differs from that of antitussives, which inhibit or suppress cough. In addition to usefulness in the management of productive cough, guaifenesin's effects on sputum production and viscosity and on ease of expectoration suggest that the drug may prove useful in the management of irritative nonproductive cough and coughs productive of scanty amounts of thick, viscous secretions.

Although cough and cold preparations that contain cough suppressants, nasal decongestants, antihistamines, and/or expectorants commonly are used in pediatric patients younger than 2 years of age, systematic reviews of controlled trials have concluded that over-the-counter cough and cold preparations are not more effective than placebo in reducing acute cough and other symptoms of upper respiratory tract infection in these patients. Furthermore, adverse events, including deaths, have been (and continue to be) reported in pediatric patients younger than 2 years of age receiving these preparations. (See Cautions: Pediatric Precautions.)

Guaifenesin is combined with bronchodilators, decongestants, antihistamines, or opiate antitussives in numerous commercial liquid cough preparations.

Administration

Guaifenesin is administered orally.

Mucinex^® 600-mg extended-release tablets should not be broken, crushed, or chewed and should not be used in children younger than 12 years of a the tablets should be kept out of reach of young children to avoid accidental swallowing and choking.

Dosage

Cough

The usual dosage of guaifenesin as an expectorant in adults and children 12 years of age and older is 200-400 mg as conventional preparations every 4 hours, not to exceed 2.4 g daily. The usual dosage of guaifenesin 600-mg extended-release tablets as an expectorant in adults and children 12 years of age and older is 600 mg or 1.2 g every 12 hours, not to exceed 2.4 g daily. The usual dosage of guaifenesin as an expectorant for children 6 to younger than 12 years of age is 100-200 mg as conventional preparations every 4 hours, not to exceed 1.2 g daily. Alternatively, children 6-12 years of age may receive 600 mg as an appropriate extended-release preparation every 12 hours, not to exceed 1.2 g daily. Children 2 to younger than 6 years of age may receive 50-100 mg as conventional preparations every 4 hours, not to exceed 600 mg daily. Alternatively, children 2-6 years of age may receive 300 mg as an appropriate extended-release preparation every 12 hours, not to exceed 600 mg daily. Dosage of guaifenesin in children younger than 2 years of age must be individualized. Suggested dosages for children younger than 2 years of age† for some cough and cold preparations have been published in various references for prescribing and parenting. Using recommended dosages for adults and older children, some clinicians have extrapolated dosages for these preparations based on the weight or age of children younger than 2 years of age. However, these extrapolations were based on assumptions that pathology of the disease and pharmacology of the drugs are similar in adults and pediatric patients. There currently are no specific dosage recommendations (i.e., approved by the US Food and Drug Administration [FDA]) for cough and cold preparations for this patient population. (See Cautions: Pediatric Precautions.)

Doses of guaifenesin larger than those required for expectorant action may produce emesis, but GI upset at ordinary dosage levels is rare.

For self-medication , unless directed by a physician, guaifenesin should not be used for persistent or chronic cough such as that occurring with smoking, asthma, chronic bronchitis, or emphysema, or for cough accompanied by excessive phlegm. A persistent cough may be indicative of a serious condition. If cough persists for more than one week, is recurrent, or is accompanied by fever, rash, or persistent headache, a physician should be consulted.

When preparations containing guaifenesin in fixed combination with other agents (e.g., acetaminophen, chlorpheniramine, codeine, dextromethorphan, ephedrine, phenylephrine, pseudoephedrine) are used, the cautions, precautions, and contraindications applicable to each ingredient should be considered.

Pediatric Precautions

Overdosage and toxicity (including death) have been reported in children younger than 2 years of age receiving nonprescription (over-the-counter, OTC) preparations containing antihistamines, cough suppressants, expectorants, and nasal decongestants alone or in combination for relief of symptoms of upper respiratory tract infection. There is limited evidence of efficacy for these preparations in this age group, and appropriate dosages (i.e., approved by the US Food and Drug Administration [FDA]) for the symptomatic treatment of cold and cough have not been established. Therefore, FDA stated that nonprescription cough and cold preparations should not be used in children younger than 2 years of a the agency continues to assess safety and efficacy of these preparations in older children. Meanwhile, because children 2-3 years of age also are at increased risk of overdosage and toxicity, some manufacturers of oral nonprescription cough and cold preparations agreed to voluntarily revise the product labeling to state that such preparations should not be used in children younger than 4 years of age. FDA recommends that parents and caregivers adhere to the dosage instructions and warnings on the product labeling that accompanies the preparation if administering to children and consult with their clinician about any concerns. Clinicians should ask caregivers about use of nonprescription cough and cold preparations to avoid overdosage. For additional information on precautions associated with the use of cough and cold preparations in pediatric patients, see Cautions: Pediatric Precautions in Dextromethorphan 48:08.

Pharmacology

By increasing respiratory tract fluid, guaifenesin reduces the viscosity of tenacious secretions and acts as an expectorant.

Chemistry and Stability

Chemistry

Guaifenesin is an expectorant. Guaifenesin occurs as a white to slightly gray, crystalline powder, having a bitter taste. Guaifenesin may have a slight characteristic odor. Guaifenesin is soluble in alcohol and in water.

Stability

Guaifenesin powder tends to become lumpy on storage. Guaifenesin preparations should be stored in tight containers.