N-acetylcysteine

N-acetylcysteine is a modified form of the amino acid cysteine used as a medicine and as a precursor for cellular glutathione synthesis.

Glutathione: A tripeptide antioxidant that helps cells control oxidative stress and detoxify reactive compounds. N-acetylcysteine supplies cysteine, often the limiting building block for glutathione synthesis.
Acetaminophen: A pain reliever and fever reducer that can cause severe liver injury in overdose. N-acetylcysteine is used to prevent or reduce liver injury after excessive ingestion.
Cysteine: A sulfur-containing amino acid used to build proteins and other cellular molecules. N-acetylcysteine is derived from cysteine and can be converted into it in the body.
Cysteamine: A small aminothiol medicine used to treat cystinosis and other conditions. Like N-acetylcysteine, it contains a reactive thiol, but its principal clinical uses differ.
Mucolytic: A substance that reduces the thickness or viscosity of mucus. N-acetylcysteine breaks disulfide bonds in mucus proteins, making secretions easier to clear.
Chronic obstructive pulmonary disease: A progressive lung disease characterized by persistent airflow limitation, commonly including emphysema or chronic bronchitis. Inhaled or oral N-acetylcysteine has been studied and used as a mucus-thinning adjunct.
Acetylation: The chemical addition of an acetyl group to a molecule. An acetyl group attached to cysteine gives N-acetylcysteine its name and altered properties.
Antioxidant: A substance that slows oxidation by reacting with oxidants or interrupting oxidative processes. N-acetylcysteine is often described as an antioxidant, but its effects depend on dose and biological context.
Disulfide bond: A covalent bond between two sulfur atoms, often linking parts of proteins. Breaking these bonds loosens the mucin network that gives mucus its viscosity.
Cystic fibrosis: An inherited disorder that causes thick secretions and progressive damage in several organs, especially the lungs. Mucus thinning motivated investigation of N-acetylcysteine, though clinical benefit is not established.

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