Acetylcysteine (or N-acetylcysteine or N-acetyl-L-cysteine), with its CAS registry number , has its IUPAC name of (2R)-2-acetamido-3-sulfanylpropanoic acid. This chemical belongs to the classes of Amino Acids, and it is applied as a pharmaceutical drug and nutritional supplement which is used primarily as a mucolytic agent and in the management of paracetamol (acetaminophen) overdose.

Following are the detailed information of Acetylcysteine:
1). Indication of Acetylcysteine: Acetylcysteine is used mainly as a mucolytic and in the management of paracetamol (acetaminophen) overdose.
2). Pharmacodynamics of Acetylcysteine: Acetylcysteine has been shown to reduce the extent of liver injury following acetaminophen overdose. It is most effective when given early, with benefit seen principally in patients treated within 8-10 hours of the overdose. Acetylcysteine likely protects the liver by maintaining or restoring the levels, or by acting as an alternate substrate for conjugation with, and thus detoxification of, the reactive metabolite. 
3). Mechanism of action: Acetylcysteine may protect against acetaminophen overdose-induced hepatotoxicity by maintaining or restoring hepatic concentrations of glutathione. It does this by producing the glutathione precursor cysteine. Glutathione is required to inactivate an intermediate metabolite (N-acetyl-imine) of acetaminophen that is thought to be hepatotoxic. In acetaminophen overdose, excessive quantities of this metabolite are formed because the primary metabolic (glucuronide and sulfate conjugation) pathways become saturated. Acetylcysteine may act by reducing the metabolite to the parent compound and/or by providing sulfhydryl for conjugation of the metabolite. Experimental evidence also suggests that a sulfhydryl-containing compound such as acetylcysteine may also directly inactivate the metabolite. When inhaled, cetylcysteine exerts its mucolytic action through its free sulfhydryl group, which opens the disulfide bonds and lowers mucus viscosity. This action increases with increasing pH and is most significant at pH 7 to 9. The mucolytic action of acetylcysteine is not affected by the presence of DNA. Acetylcysteine is also and reduces oxidative stress.
4). Absorption of Acetylcysteine: Bioavailability is 6–10% following oral administration and less than 3% following topical administration.