The mucolytic effect is apparently due to the cleavage of disulfide bridges present in mucopolysaccharides (a component of mucus). This makes the mucus thinner and easier to cough up. The effect as a paracetamol antidote comes from the metabolization of acetylcysteine to cysteine. Cysteine is required for the formation of glutathione, which plays a major role in the degradation of paracetamol into non-toxic metabolites.
The bioavailability of acetylcysteine is only 5-10%. This is due to its rapid metabolism to cysteine in the liver. Plasma protein binding is about 83%. The resulting cysteine is absorbed into the body's natural amino acid metabolism and thus metabolized. The half-life is about 5-6 hours.
Acetylcysteine should not be taken together with cough suppressants as this inhibits coughing up. Acetylcysteine inactivates some antibiotics (penicillins, aminoglycosides, tetracycline). For this reason, they should be taken 2 hours apart from each other. Acetylcysteine can increase the effect of glycerol trinitrate, which can possibly lead to life-threatening side effects.