Muclear Mechanism of Action

Pharmacology: Pharmacodynamics: The viscosity of pulmonary mucus secretions depends on the concentration of mucoprotein in the secretory fluid, the presence of disulfide bonds between the macromolecules and, to a lesser extent deoxyribonucleic acid (DNA). The mucolytic action of acetylcysteine is related to the sulfhydryl group in the molecule, which acts directly to split disulfide linkages between mucoprotein molecular complexes, resulting in depolymerization and a decrease in mucus viscosity. Its action is unaffected by the presence of DNA. The mucolytic activity of acetylcysteine increases with increasing pH. Significant mucolysis occurs between pH 7 and 9.
Acetylcysteine also reduces the extent of liver injury following acetaminophen overdosage. It is thought that acetylcysteine protects the liver by maintaining or restoring glutathione levels, or by acting as an alternate substrate for conjugation with and thus, detoxification of the reactive metabolite of acetaminophen.
Pharmacokinetics: Acetylcysteine is rapidly absorbed from the gastrointestinal tract and peak plasma concentrations (C_max) occur about 0.5-1 hr after oral dosed of 200-600 mg. About 50% was in a covalently protein-bound from 4 hrs after a dose. Volume of distribution is 0.33-0.47 L/kg. The terminal half-life (t_½) of reduced acetylcysteine is 6.25 hrs. Approximately 70% of total body clearance is nonrenal.