Guaifenesin

Guaifenesin (INN) or guaiphenesin (former BAN) is an expectorant drug usually taken orally to assist the expectoration ("bringing up") of phlegm from the airways in acute respiratory tract infections. 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, but guaifenesin was first approved by the Food and Drug Administration (FDA) in 1952. It is sold as pills or syrups under several brand names such as Guai-Aid, GuaiLife, Ethex 208, Humibid, Mucinex, and Robitussin. It is also included in many over-the-counter cough and cold remedies.

Treatment of asthma
Guaifenesin is effective in the treatment of the thickened bronchial mucosa characteristic of asthma. 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 coughing
Guaifenesin is frequently combined with dextromethorphan, an antitussive. Under normal circumstances this combination leads to fewer, but more productive coughs. However, in the quantities consumed by recreational users of dextromethorphan, it may cause nausea and vomiting, as well as the formation of stones in the urinary tract (urolithiasis). Moreover, because of concerns about illegal recreational drugs, the American FDA has forced manufacturers of ephedrine to add guaifenesin to over the counter weight loss medications.

Treatment of fibromyalgia
Because of its uricosuric effect, guaifenesin was chosen for the experimental guaifenesin protocol in the 1990s as a treatment for fibromyalgia, and proponents of the guaifenesin protocol believe that it cures fibromyalgia by removing excess phosphate from the body. A lesser publicized and thus lesser known fact among fibromyalgia sufferers is that guaifenesin has a skeletal muscle relaxant property, and a form of guaifenesin known as guafenesin carbomate is used for this purpose[Citation needed]. This may explain some of the symptomatic relief experienced by fibromyalgia sufferers who take guaifenesin.

Muscle relaxant and inhibition of platelet aggregation
Guaifenesin also has other known neurological effects, including an analgesic effect that is related to its action as a skeletal muscle relaxant, and it may inhibit platelet aggregation. Guaifenesin's neurological properties first became known in the late 1940s, and it is still used in veterinary medicine to anesthetize horses being prepared for surgery. When contrasted with 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.

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 your vocal chords 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.