RESEARCH MONOGRAPH · KDC-MN-369
N-Acetylcysteine (NAC)
N-acetylcysteine (NAC) is the acetylated form of the amino acid cysteine, the rate-limiting building block for glutathione, the body's principal intracellular antioxidant. It has been FDA-approved since 1963 as a mucolytic (it breaks disulfide bonds in mucus) and as the standard antidote for acetaminophen overdose, where it replenishes the glutathione that overdose depletes. Beyond those approved uses, NAC has accumulated sizable trial literature in psychiatric conditions (OCD, trichotillomania, schizophrenia adjunct), substance use disorders, and PCOS. Effect sizes are generally modest but consistent enough that NAC has become a quietly important supplement and adjunct. Not stocked by Kodiac. This monograph is provided for research and educational reference.
Intrigue 0–100 blends mechanism novelty, evidence strength, and translational potential. Kodiac editorial, not peer-reviewed.
Glutathione precursor / mucolytic / antioxidant
N-acetyl-L-cysteine; a glutathione precursor used as a mucolytic, the antidote for acetaminophen overdose, and a candidate for neuropsychiatric and metabolic conditions.
Abstract
N-acetylcysteine (NAC; CAS 616-91-1; molecular formula C5H9NO3S; molecular weight 163.20) is the N-acetylated derivative of L-cysteine, approved by the FDA in 1963 as a mucolytic and acetaminophen overdose antidote. Mechanism: NAC is hydrolyzed to L-cysteine, the rate-limiting precursor for glutathione (GSH) biosynthesis; NAC administration rapidly replenishes intracellular GSH. The acetyl group also has direct mucolytic activity through disulfide bond reduction in mucus glycoproteins (the original FDA indication, Mucomyst). In acetaminophen overdose, replenished GSH conjugates the toxic NAPQI metabolite, preventing hepatocellular necrosis. Plasma half-life is approximately 6 hours. Off-label and research uses are extensive: OCD, trichotillomania, gambling disorder, addiction (cocaine, alcohol, cannabis), bipolar disorder, schizophrenia, and as a chemoprotective antioxidant. The clinical evidence is mixed; meta-analyses generally support modest effects in OCD and addictive behaviors. The compound is sold as both a prescription drug (oral, IV, inhaled) and as an OTC supplement. Used as the canonical glutathione precursor in research.
Mechanism of action
Glutathione precursor; rapidly hydrolyzed to L-cysteine, the rate-limiting amino acid for GSH synthesis. Direct mucolytic activity via disulfide bond reduction.
Reported research dose ranges
Clinical 600 to 2400 mg in the published literature; acetaminophen overdose IV protocol per body weight.
References
- Berk M, et al. The promise of N-acetylcysteine in neuropsychiatry. Trends Pharmacol Sci 2013.
- Atkuri KR, et al. N-Acetylcysteine - a safe antidote for cysteine/glutathione deficiency. Curr Opin Pharmacol 2007.
- Smilkstein MJ, et al. Efficacy of oral N-acetylcysteine in the treatment of acetaminophen overdose. N Engl J Med 1988.
Read the full monograph
The full reference document is available as a research-use-only PDF download. Note: PDFs for newly added compounds may take a few hours to propagate after this article was published.
The full reference document is provided strictly for research use only. It reports research dose ranges from the published literature, not instructions for use in humans or animals.
FOR RESEARCH USE ONLY. Not for medical, diagnostic, or therapeutic purposes. Not for human consumption. All information is provided for research and educational purposes only.