N-Acetyl-L-Cysteine
Compiled from published pharmacological and botanical literature. Not independently verified by Herbuno. Spotted an error or have a correction? Flag it below →
| Compound Class | N-acetylated derivative of L-cysteine; cysteine prodrug and glutathione precursor |
| Molecular Formula / CAS | C5H9NO3S · CAS 616-91-1 |
| Production Route | Acetylation of L-cysteine, itself produced by fermentation or hydrolysis |
| Grades Available | EP (European Pharmacopoeia) and USP (United States Pharmacopeia) grades |
| Comparator Forms | L-cysteine; glutathione (oral); S-adenosylmethionine; L-cysteine-glutathione mixed disulfide |
| Solubility / Format | Water-soluble crystalline powder; distinctly sulphurous odour and taste |
| Regulatory Note | Regulatory status varies by market — classified as a medicine in some jurisdictions and a supplement ingredient in others |
| Buy from Herbuno | N-Acetyl-L-Cysteine EP, USP |
| Origin | Processed / Sourced from India |
| MOQ | R&D 100 g / 250 g (subject to stock) · Pilot batch 1–5 kg · Bulk 10 kg, 25 kg and above |
| Lead Time | Dispatch within 72 hrs from stock · fresh-batch production (typically 50 kg+): 10 working days |
| Documentation | CoA & MSDS standard with every lot |
Name origin: The name is purely descriptive chemistry — N-acetylated L-cysteine, with cysteine itself named from cystine, the disulphide dimer first isolated from a urinary calculus in 1810 and named for the Greek kystis, bladder. The acetyl group is the entire functional point of the molecule: it protects the reactive thiol and markedly improves stability and oral handling relative to free cysteine.
Traditional use: NAC is a synthetic pharmaceutical and has no traditional record; presenting one would be fabrication. What it does have is an unusually well-defined clinical lineage. It entered practice in the 1960s as an inhaled mucolytic, cleaving the disulphide bonds that give mucus its viscosity, and became the standard antidote for paracetamol poisoning — a role in which it remains on the WHO Model List of Essential Medicines. Its supplement use descends from that clinical position rather than from any folk tradition.
Research trajectory: NAC research has broadened well beyond its two established clinical indications, driven by the observation that cysteine availability limits glutathione synthesis. Trials have investigated it across respiratory, psychiatric, addiction, fertility and metabolic settings. That breadth is best read with some caution: it reflects a cheap, safe, mechanistically plausible molecule being tested widely, and the resulting literature is uneven, with a number of individually promising results that have not consistently replicated.
Commercial source: NAC is manufactured by acetylation of L-cysteine, which is itself now produced predominantly by microbial fermentation rather than by the older route of hydrolysing keratin from hair or feathers. Buyers requiring vegan or non-animal-origin declarations should confirm the cysteine route explicitly, since both remain in commercial use and the distinction is invisible in the finished molecule.
Evidence for N-Acetyl-L-Cysteine Applications
The mechanism is well established and unusually direct: NAC is deacetylated to L-cysteine, which is the rate-limiting substrate for glutathione synthesis. Because glutathione is the principal intracellular antioxidant and the conjugating agent for the reactive paracetamol metabolite NAPQI, this single mechanism accounts for both its antidotal use and its wider investigational applications. Its mucolytic action is separate, arising from direct reduction of disulphide bonds in mucin polymers. Claim strength: High.
The pharmacokinetics carry an important limitation that supplement material rarely mentions. Oral NAC undergoes extensive first-pass metabolism and oral bioavailability is low, which constrains what oral dosing can achieve relative to intravenous administration. Single and multiple oral dose pharmacokinetics have been characterised in healthy volunteers in a phase I study across two ethnic groups. [Phase I PK study] For an ingredient whose entire proposition is raising intracellular glutathione, low oral bioavailability is not a footnote — it is the central formulation and dosing question. Claim strength: High.
The consequences of that limitation are visible in outcome data. In a repeated-dose oral NAC study in Parkinson's disease, peripheral antioxidant measures including catalase and the reduced-to-oxidised glutathione ratio increased significantly relative to baseline, but there were no significant increases in brain glutathione, and markers of lipid peroxidation were unchanged. The authors attributed the absence of a central effect partly to low oral NAC bioavailability. [Coles 2018] Intravenous NAC does raise brain glutathione; oral NAC, in that study, did not. Claim strength: Moderate.
Clinical results in other indications are genuinely mixed and should be represented as such. A 24-week randomised multicentre double-blind placebo-controlled trial evaluated oral NAC at 1 g twice daily as an add-on to maintenance antipsychotic medication in 140 people with chronic schizophrenia, with 84 completing treatment. [Berk 2008] Studies of this kind have generated continuing interest in NAC for psychiatric applications without establishing it as standard care, and a supplier should not present investigational findings as settled. Claim strength: Emerging.
The commercially decisive point for this material is not efficacy but regulatory classification, and it is where buyers most often come unstuck. NAC is a licensed medicine in a number of jurisdictions, and its permissibility as a food supplement ingredient differs markedly between markets and has been the subject of regulatory reversals. This is not a claims question that can be managed with careful wording — it determines whether the product is lawfully a supplement at all in a given territory. Confirm the current position in each target market before committing to a formulation. Claim strength: High.
Sourcing NAC: N-Acetyl-L-Cysteine in EP and USP pharmacopoeial grades is available from Herbuno, with CoA and MSDS on every lot. View NAC EP grade → · USP grade →
Dosage & Formulator Specification
Production route. NAC is produced by acetylation of L-cysteine followed by crystallisation and purification. The upstream cysteine is now predominantly fermentation-derived, though keratin hydrolysis from hair or feathers remains in commercial use in some supply chains. That distinction is invisible in the finished molecule and matters only for vegan, halal, kosher and non-animal-origin declarations — so it must be established through supplier documentation rather than inferred from the specification, and we provide route documentation on request.
Analytical standardisation. This material is supplied to pharmacopoeial monograph rather than to a percentage assay, and that is the substantive difference from a food-grade amino acid. EP and USP monographs specify identity, assay limits, related substances, heavy metals, residual solvents and microbiological limits. Specify which monograph you require, since EP and USP differ in some test methods and acceptance criteria and are not automatically interchangeable for a regulated dossier. Where the finished product is a medicine, monograph compliance is a dossier requirement rather than a quality preference.
Regulatory and handling context. This is the parameter that most affects commercial feasibility. NAC holds marketing authorisation as a medicine in numerous jurisdictions and is on the WHO Model List of Essential Medicines for paracetamol poisoning; its status as a permissible food supplement ingredient varies by market and has changed within recent years in at least one major territory. Establish the current classification in every target market before formulating. Store cool, dry and sealed; the free thiol oxidises on exposure to air and moisture, and the material is hygroscopic.
Formulation behaviour. Two practical problems dominate. First, organoleptics: NAC has a pronounced sulphurous odour and taste that is difficult to mask and will carry through into any open-format product, which is why capsules and coated tablets are the standard formats and why powder and beverage applications need serious flavour work. Second, oxidation: the free thiol is reactive, so avoid co-formulating with strong oxidisers and with certain metal ions that catalyse thiol oxidation, and specify packaging with adequate moisture and oxygen barrier. Effervescent and fast-dissolving formats exist in pharmaceutical practice and are viable but require formulation expertise to manage both issues at once.
Frequently Asked Questions — N-Acetyl-L-Cysteine
Because the entire proposition of the ingredient is raising intracellular glutathione, and oral NAC undergoes extensive first-pass metabolism with correspondingly low bioavailability. This is visible in outcome data: a repeated-dose oral NAC study in Parkinson's disease found increases in peripheral antioxidant measures but no significant increase in brain glutathione, which the authors attributed partly to low oral bioavailability. Intravenous NAC does raise brain glutathione. Dose and format should be designed with this limitation in view.
That depends entirely on the market, and it is the first question to resolve rather than the last. NAC holds marketing authorisation as a medicine in a number of jurisdictions and appears on the WHO Model List of Essential Medicines for paracetamol poisoning. Its permissibility as a supplement ingredient varies by territory and has been subject to regulatory change in recent years. Confirm the current classification in each target market before committing to a formulation.
They are different pharmacopoeial monographs with differing test methods and acceptance criteria for identity, assay, related substances, heavy metals, residual solvents and microbiological limits. They are not automatically interchangeable for a regulated dossier, so specify which you require rather than treating pharmacopoeial grade as a single category. Where your finished product is a medicine, compliance with the correct monograph is a dossier requirement.
It depends on the upstream cysteine route, which is invisible in the finished molecule. Cysteine is now produced predominantly by microbial fermentation, but hydrolysis of keratin from hair or feathers remains in commercial use in some supply chains. If you require vegan, halal, kosher or non-animal-origin declarations, obtain explicit route documentation rather than inferring it from the specification. We provide this on request.
NAC has a pronounced sulphurous character that is difficult to mask, which is why capsules and coated tablets are the standard formats. Powder, stick and beverage applications are possible but require substantial flavour development and should not be assumed straightforward. Packaging also matters, since the odour will transfer to a poorly sealed format over shelf life.
Every lot ships with a Certificate of Analysis and MSDS as standard. R&D quantities are available at 100 g and 250 g subject to stock, pilot batches at 1–5 kg, and bulk at 10 kg, 25 kg and above. Stock orders dispatch within 72 hours; fresh-batch production, typically 50 kg and above, runs to about 10 working days. Material is processed and sourced in India, providing a documented alternative origin for pharmacopoeial-grade supply.
Related compounds: L-Glutamine · Betaine · Choline
Claim strength scale: High — consistent human data or established biochemistry. Moderate — supportive human data with limitations. Emerging — mechanistic or preliminary evidence only.