N-acetyl-cysteine is an antidote for:-

Paracetamol (Acetaminophen) It is metabolized to N-acetyl paraaminobenzo quinoneimine (NAPQ) by microsomal enzymes. When a very large dose of paracetamol is taken, glucuronidation capacity is saturated; more of the minor metabolite is formed, leading to depletion of glutathione stores. This metabolite has high affinity for sulfhydryl groups and can combine with the enzymes and other biomolecules resulting in hepatotoxicity characterized by hepatic necrosis. Acetaminophen toxicity can be decreased by providing sulfhydryl donors like N-acetylcysteine (antidote of choice). Note : Chronic alcoholism induces CYP enzymes, especially CYP2E1, which is involved in the conversion of acetaminophen to the toxic metabolite NAPQI.