Assays - Acetylcysteine

Endogenous plasma N-Acetylcysteine and single dose oral bioavailability from two different formulations as determined by a new analytical method

Author: B. Gabard, H.J. Mascher
Publisher: Biopharm. Drug Disposit. 12 (1991) 343 - 353

A method to quantitate N-acetylcysteine in plasma using reductive cleavage with tributylphosphine and post-HPLC column derivatisation with o-phtalaldehyde is described. Using this method, endogenous average concentrations of 0.08 µM were measured in 10 volunteers participating in a crossover study to compare the bioavailability of two different formulations of N-acetylcysteine. The drug was detected in plasma for up to 12 h after administration of a single oral dose (200 mg); the Cmax values were up to 20 times the endogenous levels. The sensitivity and selectivity of the method should thus enable the behaviour of N-acetylcysteine after oral administration to be properly described and bioavailability studies to be performed.