Acetylcysteine, the active substance of the drug Fluimucil, exhibits an intense mucolytic-fluidizing effect on mucous and mucopurulent secretions. This mucolytic effect of acetylcysteine is based on the depolymerization (opening of disulfide bonds) of mucoprotein complexes and nucleic acids that provide viscosity to the glassy and purulent component of sputum and other secretions.
In addition, acetylcysteine exhibits a direct antioxidant effect, given that it has a free thiol/sulfhydryl group (-SH) that can directly interact with electrophilic groups of oxidative radicals. Recent findings are of particular importance, as acetylcysteine prevents the inactivation of alpha-antitrypsin, an enzyme that inhibits elastase. This effect occurs via hypochlorous acid (HOCl), which is a strong oxidative agent, and is produced by the enzyme myeloperoxidase in activated phagocytes.
Thanks to its molecular structure, N-acetylcysteine easily passes through cell membranes. Inside the cell, N-acetylcysteine is deacetylated to L-cysteine, an amino acid necessary for the synthesis of glutathione (GSH). GSH is a highly reactive tripeptide, which is very widespread in various tissues of animal organisms, and is necessary for maintaining both the functional capacity and the morphological integrity of cells. In fact, GSH represents the most important mechanism of intracellular defense against oxidative radicals, whether exogenous or endogenous, as well as numerous cytotoxic substances.
