N-acetyl-cysteine (NAC) have received attention as a potential treatment for lung symptoms and mucus thickening due to cytokine-induced cascade due to its known efficacy as a mucolytic, anti-inflammatory, antioxidant and its ability to reduce the microbial flora in the lungs (14; 2; 3; 15), moreover, it seems that NAC is able to activate chloride movement in epithelial cells expressing the mutant protein (16; 17) and it has also been used for the treatment of gastrointestinal problems in CF patients (6; 5; 4).

The best studied North American NAC product is PharmaNAC. Thiolex, the form of N-acetylcysteine used in PharmaNAC, is compliant to the European pharmacopeia and the USP.

PharmaNAC acts as a cysteine pro-drug, a human amino acid that is necessary for the body to make glutathione, but it is less reactive than L-cysteine, then much less toxic and also less susceptible to oxidation and more soluble in water (18). NAC can be orally delivered and it is readily taken up in the stomach and gut. It is subsequently sent to the liver through the portal vein where it is converted in cysteine (19) and then in GSH, which is largely secreted into circulation. The oral administration of NAC at doses up to 8,000 mg/day in adults is not known to cause adverse effects (20).