The metabolism of S-carboxymethylcysteine in rodents, marmosets and humans.

1. The metabolism of S-carboxymethylcysteine (Mucodyne) has been studied in the rat, rabbit, guinea-pig, marmoset and human. All species studied, except the rabbit, excrete large amounts of the parent compound. 2. Rabbits and humans give S-carboxymethylcysteine sulphoxide, rats form N-acetyl-S-carboxymethylcysteine while marmosets excrete methylmercapturic acid as other major metabolites. Traces of methylmercapturic acid sulphoxide, methylcysteine, methylcysteine sulphoxide and 3-(S-carboxymethylthio)lactic acid were also found.