Pharmacology: Acetylcysteine is a natural amino acid derivative of cysteine. N-acetylcysteine has fluidification activity through free sulfhydryl groups on mucoid or mucopurulent secretions by cutting intra-molecular and inter-molecular disulfide bridges in glycoprotein aggregates. N-acetylcysteine has good intestinal tolerance, is quickly absorbed after oral administration and distributed throughout the body including the lungs.