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Pharmacology: Pharmacodynamics and Pharmacokinetics: The viscosity of pulmonary mucus secretions depends on the concentration of mucoprotein in the secretory fluid, the presence of disulfide bonds between these macromolecules and, to a lesser extent, DNA. The mucolytic action of Acetylcysteine is related to the sulfhydryl group in the molecule, which acts directly to split disulfide linkages between mucoprotein molecule complexes, resulting in the polymerization and decrease in mucus viscosity. Its action is unaffected by the presence of DNA. The mucolytic activity of Acetylcysteine increase with increasing pH. Significant mucolysis occurs between 7 and 9.
Acetylcysteine also reduces the extent of liver injury following Paracetamol overdose. 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 Paracetamol.
Acetylcysteine is rapidly absorbed from the gastrointestinal tract and peak plasma concentrations occur about 0.5 to 1 hour after oral dose of 200 to 600 mg. About 50% was in a covalently protein-bound from 4 hours after a dose. Volume of distribution is 0.33 to 0.47 L/kg. The terminal half-life of reduced Acetylcysteine is 6.25 hours. Approximately 70% of total body clearance is nonrenal.
