Mucoactive agents are a class of chemical agents that aid in the clearance of

mucus Mucus ( ) is a slippery aqueous secretion produced by, and covering, mucous membranes. It is typically produced from cells found in mucous glands, although it may also originate from mixed glands, which contain both serous and mucous cells. It is ...

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 cytological investigation ...

from the upper and lower airways, including the

lungs The lungs are the primary organs of the respiratory system in humans and most other animals, including some snails and a small number of fish. In mammals and most other vertebrates, two lungs are located near the backbone on either side of ...

, bronchi, and

trachea The trachea, 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 air-breathing animals with lungs. The trachea extends from the la ...

. Mucoactive drugs include expectorants, mucolytics, mucoregulators, and mucokinetics. These medications are used in the treatment of respiratory diseases that are complicated by the oversecretion or

inspissation Inspissation is the process of thickening by dehydration. Intentional use Inspissation is the process used when heating high-protein containing media; for example to enable recovery of bacteria for testing. Once inspissation has occurred, any stain ...

of mucus. These drugs can be further categorized by their

mechanism of action In pharmacology, the term mechanism of action (MOA) refers to the specific biochemical interaction through which a drug substance produces its pharmacological effect. A mechanism of action usually includes mention of the specific molecular targ ...

Mechanism of action

Mucoactive agents - expectorants – include mucolytics, secretolytics and mucokinetics (also called secretomotorics) * Mucolytics – thin (reduce the viscosity of) mucus * Secretolytics – increase airway water or the volume of airway secretions * Mucokinetics – increase mucociliary transport (clearance) and transportability of mucus by cough * Mucoregulators – suppress underlying mechanisms of mucus hypersecretion Alternatively, attacking the affinity between secretions and the biological surfaces is another avenue, which is used by abhesives and

surfactants Surfactants are chemical compounds that decrease the surface tension between two liquids, between a gas and a liquid, or interfacial tension between a liquid and a solid. Surfactants may act as detergents, wetting agents, emulsifiers, foaming ...

. Any of these effects could improve airway clearance during coughing. In general, clearance ability is hampered by the bonding to surfaces (stickiness) and by the

viscosity The viscosity of a fluid is a measure of its resistance to deformation at a given rate. For liquids, it corresponds to the informal concept of "thickness": for example, syrup has a higher viscosity than water. Viscosity quantifies the inter ...

of mucous secretions in the lungs. In turn, the viscosity is dependent upon the concentration of

mucoprotein A mucoprotein is a glycoprotein composed primarily of mucopolysaccharides. Mucoproteins can be found throughout the body, including the gastrointestinal tract, reproductive organs, airways, and the synovial fluid of the knees. They are called muco ...

in the secretions. Mucolytics, secretolytics and secretomotorics are different types of medication, yet they are intended to promote drainage of mucus from the lungs. An expectorant (from the Latin ''expectorare'', to expel or banish) works by signaling the body to increase the amount or hydration of secretions, resulting in more, yet clearer, secretions and lubricating the irritated respiratory tract. One mucoactive agent, guaifenesin, has anxiolytic and muscle-relaxing properties. It is commonly available in cough syrups and also as sustained-release tablets. Mucolytics can dissolve thick mucus and are usually used to help relieve respiratory difficulties. They do this by breaking down the chemical bonds between molecules in the mucus. This in turn can lower the viscosity by altering the

mucin Mucins () are a family of high molecular weight, heavily glycosylated proteins (glycoconjugates) produced by epithelial tissues in most animals. Mucins' key characteristic is their ability to form gels; therefore they are a key component in most ...

-containing components.

Mucoactive drugs

Many mucoactive drugs are available, including

sodium citrate Sodium citrate may refer to any of the sodium salts of citric acid (though most commonly the third): * Monosodium citrate * Disodium citrate * Trisodium citrate The three forms of salt are collectively known by the E number E331. Applications ...

potassium citrate Potassium citrate (also known as tripotassium citrate) is a potassium salt of citric acid with the molecular formula K3C6H5O7. It is a white, hygroscopic crystalline powder. It is odorless with a saline taste. It contains 38.28% potassium by ma ...

potassium iodide Potassium iodide is a chemical compound, medication, and dietary supplement. It is a medication used for treating hyperthyroidism, in radiation emergencies, and for protecting the thyroid gland when certain types of radiopharmaceuticals are us ...

, guaifenesin,

tolu balsam Tolu balsam or balsam of Tolu is a balsam that originates from South America ( Colombia, Peru, Venezuela). It is similar to (and frequently confounded with) the balsam of Peru. It is tapped from the living trunks of '' Myroxylon balsamum var. ba ...

vasaka ''Justicia adhatoda'' commonly known in English as Malabar nut, adulsa, adhatoda, vasa, vasaka, is native to Asia. The plant's native range is Afghanistan, the Indian subcontinent (Bangladesh, India, Pakistan, Nepal and Sri Lanka), Laos, My ...

, ammonium chloride, acetylcysteine,

ambroxol Ambroxol is a drug that breaks up phlegm, used in the treatment of respiratory diseases associated with viscid or excessive mucus. Ambroxol is often administered as an active ingredient in cough syrup. It was patented in 1966 and came into med ...

bromhexine Bromhexine is a mucolytic drug used in the treatment of respiratory disorders associated with viscid or excessive mucus. It was developed in the research laboratory of Boehringer Ingelheim in the late 1950s as an active ingredient for pharma ...

carbocisteine Carbocisteine, also called carbocysteine, is a mucolytic that reduces the viscosity of sputum and so can be used to help relieve the symptoms of chronic obstructive pulmonary disorder (COPD) and bronchiectasis by allowing the sufferer to bring up ...

erdosteine Erdosteine is a molecule with mucolytic activity. Structurally it is a thiol derivative characterized by the presence of two thiol groups. These two functional sulfhydryl groups contained in the molecule are released following first-pass metaboli ...

mecysteine Cysteine methyl ester is the organic compound with the formula HSCH2CH(NH2)CO2CH3. A white solid, it is the methyl ester of the amino acid cysteine. Uses Under the brand name Mecysteine, cysteine methyl ester is a commercial drug with mucolytic ...

, and

dornase alfa Dornase alfa (proprietary name Pulmozyme from Genentech) is a highly purified solution of recombinant human deoxyribonuclease I (rhDNase), an enzyme which selectively cleaves DNA. Dornase alfa hydrolyzes the DNA present in sputum/mucus of c ...

References

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External links

National Center for Biotechnology Information
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