Mechanism of Action of Acetylcysteine NAC vs Glutathione: Comparing Antioxidant Powerhouses for Your Health IVDrips L Glutathione VS NAC: Differences, Similarities, and Uses What is NAC (N Acetyl L Cysteine)?, NAC is a derivative of the amino acid L Cysteine, designed to be more stable and bioavailable than regular cysteine on its own., Lets break it down:, Cysteine N Acetyl Cysteine (Glutathione Precursor)