Guaifenesin

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1 : 1 mixture (racemate)
Guaifenesin

Systematic (IUPAC) name
(RS)-3-(2-methoxyphenoxy)propane-1,2-diol
Identifiers
CAS number	93-14-1
ATC code	R05CA03 QM03BX90
PubChem	3516
DrugBank	APRD01005
ChemSpider	3396
Chemical data
Formula	C10H14O4
Mol. mass	198.216 g/mol
Pharmacokinetic data
Bioavailability	?
Metabolism	?
Half life	1 hour
Excretion	?
Therapeutic considerations
Licence data	US FDA:link
Pregnancy cat.	C (US)
Legal status	OTC (US, CA)
Routes	Oral (PO)

Guaifenesin (pronounced /ɡwaɪˈfɛnɨsɪn/) (INN) or guaiphenesin (former BAN), also glyceryl guaiacolate,^[1] is an expectorant drug sold over the counter and usually taken by mouth to assist the bringing up ("expectoration") of phlegm from the airways in acute respiratory tract infections.

History

Similar medicines derived from the guaiac tree were in use as a generic remedy by Native Americans when explorers reached North America in the 1500s. Guaifenesin was first approved by the Food and Drug Administration (FDA) in 1952.

Availability

Guaifenesin is sold as pills or syrups under many brand names. It is also included in many other over-the-counter cough and cold remedy combinations (usually in conjunction with dextromethorphan and/or pseudoephedrine or phenylephrine and/or acetaminophen). In certain jurisdictions, guaifenesin is available over-the-counter in combination with codeine to be sold at the pharmacist's discretion, though many pharmacists decline to do so. Guaifenesin is a component of Robitussin DAC, Mucinex and Robitussin AC. Single ingredient formulations of guaifenesin are also available.

Uses

The principal use of guaifenesin is in the treatment of coughing, but the drug has numerous other uses, including medical, veterinary, and personal.

Mechanism of action/Effect

Guaifenesin is thought to act as an expectorant by increasing the volume and reducing the viscosity of secretions in the trachea and bronchi. Thus, it may increase the efficiency of the cough reflex and facilitate removal of the secretions; however, objective evidence for this is limited and conflicting.

Treatment of coughing

Guaifenesin is frequently combined with dextromethorphan, an antitussive. In normal use this combination is believed to produce fewer, but more productive coughs. However, a Cochrane Collaboration meta-analysis of over the counter medicines for acute cough in children and adults found no evidence for the effectiveness of any examined drug other than guaifenesin; evidence for guaifenesin was ambiguous.^[2]

Treatment of asthma

Guaifenesin is effective in the treatment of the thickened bronchial mucosa characteristic of asthma.^{[citation needed]} It works by drawing water into the bronchi. The water both thins mucus and lubricates the airway, facilitating the removal of mucus by coughing. One may notice a sense of dry mouth when taking this medication. Water consumption is important, not only to help with dry mouth, but also to improve the effectiveness of the drug.

Treatment of gout

Guaifenesin is a uricosuric, increasing excretion of uric acid from the blood serum into the urine.^[3] This fact was discovered by chance, during a survey of hypouricemia in hospital inpatients.^[4] Compared to other uricosuric drugs used to treat gout, guaifenesin is relatively mild.^{[citation needed]}

Treatment of fibromyalgia

Because of its uricosuric effect, guaifenesin was chosen in the 1990s for the experimental guaifenesin protocol – a treatment for fibromyalgia. Proponents^[who?] of the guaifenesin protocol believe that it cures fibromyalgia by removing excess phosphate from the body. However, a consumer alert on the Fibromyalgia Network's website (http://www.fmnetnews.com/resources-alert-product6.php) states that Dr. St. Amand's claims of guaifenesin's effects on fibromyalgia are groundless, and cites double blind research by Robert Bennett, M.D. which found no significant differences between guaifenesin and a placebo in terms of any effect on fibromyalgia or its markers.

Use to facilitate conception

Guaifenesin is widely used by women to facilitiate conception by thinning and increasing the amount of cervical mucus.^[5] Evidence concerning the effectiveness of this use is almost entirely anecdotal; the exception^[6] is a very small study without controls. One investigator^[7] regards guaifenesin as the simplest but least effective method of improving cervical mucus.

Following a medical article in Czech about guaifenesin in the treatment of primary dysmenorrhea,^[8] another very small but double-blind and placebo-controlled experiment^[9] found that guaifenesin reduced primary dysmenorrhea, but the effect was not significant.

Use by singers

Opera singers sometimes refer to guaifenesin as the "wonder drug" for its ability to promote secondary mucosal secretion in the respiratory system. Secondary mucous is the thinner, lubricating mucus that occurs on the vocal folds naturally when they are healthy and well hydrated. Singers use guaifenesin to improve the state of their vocal folds in extremes of humidity (very humid or very dry), after flying long distances, and during mild allergies.^[10]

Other uses

Guaifenesin also has other known neurological effects, including an analgesic effect that is related to its action as a skeletal muscle relaxant, and possible inhibition of platelet aggregation.^{[citation needed]}

Side effects

Consumption of guaifenesin in above-normal quantities has the potential to cause side effects. Known side effects include nausea, vomiting, and (rarely) the formation of kidney stones of uric acid (uric acid nephrolithiasis).^[11] Nausea and vomiting can be reduced by taking guaifenesin with meals.^[1] The risk of forming kidney stones can be reduced by maintaining good hydration and increasing the pH of urine (see Uric acid nephrolithiasis).

Veterinary use

Guaifenesin's neurological properties first became known in the late 1940s, and it is widely used in veterinary medicine to induce and maintain anesthesia in horses^[12][13] and llamas.^[14] In contrast to other propanediol drugs used for this purpose, guaifenesin has less hemolytic activity (i.e., less destruction of red blood cells) and is more soluble in water.^{[citation needed]}

See also

• Guaiacol
• pseudovent

References

External links

• MedlinePlus DrugInfo meds-a682494
• RxList site giving some properties
• Information from MedicineNet.com