Plemstop Mechanism of Action

Pharmacotherapeutic group: Mucolytics.
Pharmacology: Pharmacodynamics: Acetylcysteine exerts its mucolytic action through its free sulfhydryl group, which opens the disulfide bonds and lowers mucus viscosity. This action increases with increasing pH and is most significant at pH 7 to 9. The mucolytic action of acetylcysteine is not affected by the presence of DNA. N-acetylcysteine has been demonstrated to cause a decrease in sputum consistency, to facilitate easier expectoration, and to increase sputum volume. Bronchial mucus is composed of over 95% water; however, the physical characteristics of the mucus are due to glycoproteins. These glycoproteins bind to each other by way of disulfide bonds and give the mucus viscosity. N-acetylcysteine ruptures these disulfide bonds causing depolymerization and a rapid decrease in mucus viscosity. It also produces an irritative bronchorrheic effect on the mucosa, stimulating mucociliary clearance; this irritative effect may cause bronchospasm, thus acetylcysteine is not recommended in asthmatics.
Pharmacokinetics: Absorption: Absorption of acetylcysteine is rapid following oral administration, but the bioavailability is only 6-10% due to extensive first past metabolism. Oral bioavailability is similar for a single 600-mg dose and three 200-mg doses.
Peak plasma levels of acetylcysteine occur approximately one hour following oral administration.
Distribution: Acetylcysteine may be present in plasma as the parent compound or as various oxidised metabolites such as N-acetylcysteine, N,N-diacetylcysteine, and cysteine either free or bound to plasma proteins by labile disulfide bonds or as a fraction incorporated into protein peptide chains.
Following a 100-mg oral dose, 48% was present in lung tissue.
Metabolism: Acetylcysteine undergoes extensive metabolism in the liver and intestinal wall.
Acetylcysteine undergoes rapid deacetylation in vivo to yield cysteine or oxidation to yield diacetylcysteine. Following deacetylation in the liver, it enters the normal metabolic pathway of the amino acid cysteine. An appreciable elevation in total serum sulfhydryl concentration occurs.
Elimination: Renal Excretion: 22% to 30% Feces: 3% Total Body Clearance: 6.5 L/hr (healthy subjects). The mean terminal half-life is approximately 6 hours.