N-acetyl-L-cysteine (NAC)

N-acetyl-L-cysteine (NAC) is a thiol-containing derivative of the amino acid L-cysteine and a crucial precursor for the intracellular synthesis of glutathione (GSH), the primary endogenous antioxidant in human cells [2, 8]. It is clinically recognized as the essential antidote for acetaminophen (paracetamol) poisoning, where it prevents lethal hepatotoxicity by replenishing GSH stores and detoxifying the reactive metabolite N-acetyl-p-benzoquinone imine (NAPQI) [3, 7, 12]. In the context of respiratory medicine, NAC serves as a mucolytic agent by reducing disulfide bonds within mucoprotein complexes, effectively thinning thickened mucus in conditions like chronic obstructive pulmonary disease (COPD) and cystic fibrosis [3, 17]. Beyond its antioxidant and mucolytic properties, NAC exhibits significant anti-inflammatory and cytoprotective effects by directly scavenging free radicals and inhibiting redox-sensitive transcription factors such as NF-κB [6, 15]. Furthermore, NAC is increasingly investigated for its potential neuroprotective and psychotropic effects, largely due to its ability to modulate glutamate homeostasis and improve mitochondrial health in various psychiatric and neurodegenerative conditions [4, 13, 14]. As a safe and versatile pharmacological tool, NAC remains a cornerstone of clinical toxicology and a promising adjunctive therapy for chronic inflammatory and oxidative stress-related diseases [12, 14].

Other names

AcetylcysteineN-acetylcysteineNALCMucomystAcetadoteN-acetyl-3-mercapto-L-alanineParvolex

N-acetyl-L-cysteine (NAC) primarily acts as a precursor for the de novo synthesis of glutathione (GSH), restoring antioxidant capacity and detoxifying reactive metabolites like NAPQI [2, 8, 12]. It also functions as a mucolytic by reducing disulfide bonds in mucoproteins, thereby decreasing mucus viscosity [3, 17]. Additionally, it provides direct antioxidant activity by scavenging free radicals and modulates redox-sensitive signaling pathways such as the inhibition of NF-kappaB and regulation of glutamate homeostasis via the cystine/glutamate antiporter [6, 12, 17].