N-acetyl cysteine

Acetylcysteine

Clinical data
Pronunciation	/əˌsɛtəlˈsɪstiːn/
Trade names	Acetadote, Fluimucil, Mucomyst, others
AHFS/Drugs.com	Monograph
License data	US DailyMed: 5558a5f5-e821-473b-7d8a-5d33d09f0586 US FDA: Acetylcysteine
Pregnancy category	AU: B2 US: B (No risk in non-human studies)
Routes of administration	By mouth, injection, inhalation
ATC code	R05CB01 (WHO) S01XA08 (WHO) V03AB23 (WHO)
Legal status
Legal status	AU: S2 (Pharmacy only) US: OTC (by mouth), Rx-only (IV, inhalation)
Pharmacokinetic data
Bioavailability	10% (Oral)
Protein binding	50 to 83%
Metabolism	Liver
Biological half-life	5.6 hours
Excretion	Renal (30%), faecal (3%)
Identifiers
IUPAC name (2R)-2-acetamido-3-sulfanylpropanoic acid
CAS Number	616-91-1 Y
PubChem CID	12035
DrugBank	DB06151 Y
ChemSpider	11540 Y
UNII	WYQ7N0BPYC
KEGG	D00221 Y
ChEBI	CHEBI:28939 Y
ChEMBL	CHEMBL600 Y
ECHA InfoCard	100.009.545
Chemical and physical data
Formula	C5H9NO3S
Molar mass	163.195
3D model (Jmol)	Interactive image
Specific rotation	+5° (c = 3% in water)
Melting point	109 to 110 °C (228 to 230 °F)
SMILES C/C(=N/[C@@H](CS)C(=O)O)/O
InChI InChI=1S/C5H9NO3S/c1-3(7)6-4(2-10)5(8)9/h4,10H,2H2,1H3,(H,6,7)(H,8,9)/t4-/m0/s1 Y Key:PWKSKIMOESPYIA-BYPYZUCNSA-N Y

Acetylcysteine, also known as N-acetylcysteine or N-acetyl-L-cysteine (NAC), is a medication used to treat paracetamol (acetaminophen) overdose and to loosen thick mucus such as in cystic fibrosis or chronic obstructive pulmonary disease. It can be taken intravenously, by mouth, or inhaled as a mist.

Common side effects include nausea and vomiting when taken by mouth. The skin may occasionally become red and itchy with either form. A non immune type of anaphylaxis may also occur. It appears to be safe in pregnancy. It works by increasing glutathione levels and binding with the toxic breakdown products of paracetamol.

Acetylcysteine was initially patented in 1960 and licensed for use in 1968. It is on the World Health Organization's List of Essential Medicines, the most effective and safe medicines needed in a health system. It is available as a generic medication and is not very expensive.

Intravenous and oral formulations of acetylcysteine are available for the treatment of paracetamol (acetaminophen) overdose. When paracetamol is taken in large quantities, a minor metabolite called N-acetyl-p-benzoquinone imine (NAPQI) accumulates within the body. It is normally conjugated by glutathione, but when taken in excess, the body's glutathione reserves are not sufficient to inactivate the toxic NAPQI. This metabolite is then free to react with key hepatic enzymes, thereby damaging . This may lead to severe liver damage and even death by acute liver failure.