Pharmacokinetics of oral acetylcysteine: absorption, binding and metabolism in patients with respiratory disorders.
The fate of an oral 100 mg dose of 35S-acetylcysteine, a mucolytic agent, was studied in 10 patients with respiratory disorders, 5 of whom underwent pneumonectomy or lobectomy a few hours after administration of the drug. In the 5 nonoperated patients, plasma radioactivity concentrations were maximal after 2 to 3 hours and remained high after 24 hours; about 22% of radioactivity was excreted in urine after 24 hours. In the 5 operated patients, plasma radioactivity concentrations were comparable with those in the nonoperated patients. Lung tissue radioactivity concentrations after 5 hours were comparable with those in plasma, while the presence of small amounts of radioactivity in the bronchial secretions indicates that acetylcysteine passes into the mucus. Total radioactivity after 5 hours consisted of free, unchanged drug and metabolites (about 22% of total in plasma, 48% in lung tissue), unchanged drug bound to protein by means of labile disulphide bridges (about 14% in plasma, 47% in lung tissue), and drug firmly bound to protein (about 64% in plasma, 5% in lung tissue). Oral acetylcysteine is rapidly absorbed and slowly excreted and is available in the lung in an active form for at least 5 hours at high concentrations.
D000111:Acetylcysteine / Q000008:administration & dosage / Q000097:blood / Q000378:metabolism*; D000284:Administration, Oral; D000328:Adult; D001980:Bronchi / Q000378:metabolism; D006801:Humans; D007408:Intestinal Absorption; D007700:Kinetics; D008168:Lung / Q000378:metabolism; D008297:Male; D008875:Middle Aged; D011485:Protein Binding; D012140:Respiratory Tract Diseases / Q000378:metabolism*
D000111:Acetylcysteine