Guaifenesin, also known as glyceryl guaiacolate, sold under the brand name Mucinex, among others, is an expectorant medication taken by mouth and marketed as an aid to eliminate

sputum Sputum is mucus that is coughed up from the lower airways (the trachea and bronchi). In medicine, sputum samples are usually used for a naked-eye examination, microbiological investigation of respiratory infections, and Cytopathology, cytological ...

from the

respiratory tract The respiratory tract is the subdivision of the respiratory system involved with the process of conducting air to the alveoli for the purposes of gas exchange in mammals. The respiratory tract is lined with respiratory epithelium as respirato ...

. Chemically, it is an

ether In organic chemistry, ethers are a class of compounds that contain an ether group, a single oxygen atom bonded to two separate carbon atoms, each part of an organyl group (e.g., alkyl or aryl). They have the general formula , where R and R� ...

of guaiacol and glycerine. It may be used in combination with other medications. A 2014 study found that guaifenesin does not affect sputum volume in upper respiratory infections (the upper respiratory system includes most breathing parts ''above'' the lungs). It has been alleged to work in 2023 by making airway secretions more liquid. Side effects may include

dizziness Dizziness is an imprecise term that can refer to a sense of disorientation in space, vertigo, or lightheadedness. It can also refer to Balance disorder, disequilibrium or a non-specific feeling, such as giddiness or foolishness. Dizziness is a ...

, sleepiness,

skin rash A rash is a change of the skin that affects its color, appearance, or texture. A rash may be localized in one part of the body, or affect all the skin. Rashes may cause the skin to change color, itch, become warm, bumpy, chapped, dry, cracked ...

, and

nausea Nausea is a diffuse sensation of unease and discomfort, sometimes perceived as an urge to vomit. It can be a debilitating symptom if prolonged and has been described as placing discomfort on the chest, abdomen, or back of the throat. Over 30 d ...

. While it has not been properly studied in pregnancy, it appears to be safe. Guaifenesin has been used medically since at least 1933. It is available as a generic medication and over-the-counter (OTC). In 2022, it was the 295th most commonly prescribed medication in the United States, with more than 400,000 prescriptions. In 2022, the combination dextromethorphan/guaifenesin was the 290th most commonly prescribed medication in the United States, with more than 400,000 prescriptions.

Medical uses

Guaifenesin is used to try to help with coughing up thick mucus. It is sometimes combined with the antitussive (cough suppressant)

dextromethorphan Dextromethorphan, sold under the brand name Robitussin among others, is a cough suppressant used in many cough and Common cold, cold medicines. In 2022, the US Food and Drug Administration (FDA) approved the combination dextromethorphan/bupropi ...

, such as in Mucinex DM or Robitussin DM. It is also combined with

ephedrine Ephedrine is a central nervous system (CNS) stimulant and sympathomimetic agent that is often used to prevent hypotension, low blood pressure during anesthesia. It has also been used for asthma, narcolepsy, and obesity but is not the preferred ...

in Primatene and Bronkaid tablets for symptomatic relief of

asthma Asthma is a common long-term inflammatory disease of the airways of the lungs. It is characterized by variable and recurring symptoms, reversible airflow obstruction, and easily triggered bronchospasms. Symptoms include episodes of wh ...

. Guaifenesin is combined with phenylephrine and

paracetamol Paracetamol, or acetaminophen, is a non-opioid analgesic and antipyretic agent used to treat fever and mild to moderate pain. It is a widely available over-the-counter drug sold under various brand names, including Tylenol and Panadol. Parac ...

in certain Lemsip formulations. A Cochrane review identified three

clinical trial Clinical trials are prospective biomedical or behavioral research studies on human subject research, human participants designed to answer specific questions about biomedical or behavioral interventions, including new treatments (such as novel v ...

s assessing guaifenesin for the treatment of acute cough, with one finding significant benefit and the other two trials finding that it was not effective.

Side effects

Although generally well-tolerated, side effects of guaifenesin may include an

allergic reaction Allergies, also known as allergic diseases, are various conditions caused by hypersensitivity of the immune system to typically harmless substances in the environment. These diseases include Allergic rhinitis, hay fever, Food allergy, food al ...

(rare),

vomiting Vomiting (also known as emesis, puking and throwing up) is the forceful expulsion of the contents of one's stomach through the mouth and sometimes the nose. Vomiting can be the result of ailments like food poisoning, gastroenteritis, pre ...

, or

headache A headache, also known as cephalalgia, is the symptom of pain in the face, head, or neck. It can occur as a migraine, tension-type headache, or cluster headache. There is an increased risk of Depression (mood), depression in those with severe ...

Pharmacology

Mechanism of action

Guaifenesin might act as an expectorant by increasing the volume and reducing the viscosity of secretions in the

trachea The trachea (: tracheae or tracheas), also known as the windpipe, is a cartilaginous tube that connects the larynx to the bronchi of the lungs, allowing the passage of air, and so is present in almost all animals' lungs. The trachea extends from ...

and bronchi via stimulation of the gastric mucosa. This stimulation leads to an increased parasympathetic activity in the respiratory tract via the so-called gastro-pulmonary reflex, although some in vitro studies suggested that it might also act directly on the respiratory epithelium. This increase in volume and reduction in viscosity aids in the flow of respiratory tract secretions, allowing ciliary movement to carry the loosened secretions upward toward the

pharynx The pharynx (: pharynges) is the part of the throat behind the human mouth, mouth and nasal cavity, and above the esophagus and trachea (the tubes going down to the stomach and the lungs respectively). It is found in vertebrates and invertebrates ...

. Thus, guaifenesin may increase the efficiency of the cough reflex and facilitate the removal of the secretions. Additionally, guaifenesin has a demonstrated central antitussive effect.

History

Similar medicines derived from the guaiac tree were used as a generic remedy by American indigenous peoples when explorers reached

North America North America is a continent in the Northern Hemisphere, Northern and Western Hemisphere, Western hemispheres. North America is bordered to the north by the Arctic Ocean, to the east by the Atlantic Ocean, to the southeast by South Ameri ...

in the 16th century. The Spanish encountered guaiacum wood "when they conquered

Santo Domingo Santo Domingo, formerly known as Santo Domingo de Guzmán, is the capital and largest city of the Dominican Republic and the List of metropolitan areas in the Caribbean, largest metropolitan area in the Caribbean by population. the Distrito Na ...

; it was soon brought back to Europe, where it acquired an immense reputation in the sixteenth century as a cure for syphilis and certain other diseases..." The 1955 edition of the ''Textbook of Pharmacognosy'' states: "Guaiacum has a local stimulant action which is sometimes useful in sore throat. The resin is used in chronic gout and rheumatism, whilst the wood is an ingredient in the compound concentrated solution of sarsaparilla, which was formerly much used as an alternative in syphilis." In the US, guaifenesin was first approved by the

Food and Drug Administration The United States Food and Drug Administration (FDA or US FDA) is a List of United States federal agencies, federal agency of the United States Department of Health and Human Services, Department of Health and Human Services. The FDA is respo ...

(FDA) in 1952. Although previously deemed " Generally Regarded as Safe" in its original approval, the drug received a New Drug Application for the extended-release version, which received approval on 12 July 2002. Because of this, the FDA then issued letters to other manufacturers of ''timed-release'' guaifenesin to stop marketing their unapproved versions, leaving Adams Respiratory Therapeutics in control of the market. In 2007, Adams was acquired by Reckitt Benckiser. The drug is now sold over-the-counter by many companies, alone and in combination.

Veterinary use

Guaifenesin's neurological properties first became known in the late 1940s. Guaifenesin is a centrally acting

muscle relaxant A muscle relaxant is a drug that affects skeletal muscle function and decreases the muscle tone. It may be used to alleviate symptoms such as muscle spasms, pain, and hyperreflexia. The term "muscle relaxant" is used to refer to two major therapeu ...

used routinely in large-animal veterinary surgery. Guaifenesin is used in combination with, for example,

ketamine Ketamine is a cyclohexanone-derived general anesthetic and NMDA receptor antagonist with analgesic and hallucinogenic properties, used medically for anesthesia, depression, and pain management. Ketamine exists as its S- (esketamine) a ...

, since guaifenesin does not provide analgesia or produce unconsciousness. In horses, the drug's biological half-life is 77 minutes. Premedication with

xylazine Xylazine is a structural analog of clonidine and an α2-adrenergic receptor, α2-adrenergic receptor agonist, sold under many trade names worldwide, most notably the Bayer brand name Rompun, as well as Anased, Sedazine and Chanazine. Xylazine ...

(1.1 mg/kg) can reduce the dose required from 163 mg/kg (in geldings) to just 88 mg/kg.

Society and culture

Brand names

Guaifenesin is taken by mouth, and is supplied as a tablet, a capsule, an extended-release (long-acting) tablet, dissolving granules, and a syrup. It is available under many

brand name A brand is a name, term, design, symbol or any other feature that distinguishes one seller's goods or service from those of other sellers. Brands are used in business, marketing, and advertising for recognition and, importantly, to create and ...

s, as either the sole active ingredient or part of a

combination drug A combination drug is a combination of two or more pharmaceutical drugs as active ingredients combined into a single dosage form, typically as a ''fixed-dose combination'', with each constituent standardized to specifications of a fixed dose. Fix ...

. Drugs combined with guaifenesin in over-the-counter preparations include the cough-suppressant

, analgesics such as

/acetaminophen, and decongestants such as

, pseudoephedrine, or phenylephrine.

Economics

In 2014, sales of guaifenesin were estimated to be approximately $135 million per year in the United States.

References

External links

* {{Portal bar , Medicine Drugs with unknown mechanisms of action Expectorants Catechol ethers Wikipedia medicine articles ready to translate Glycerol ethers 2-Methoxyphenyl compounds