The metabolism of S-carboxymethyl-L-cysteine in man: isolation of an ester glucuronic acid conjugate from urine

Abstract

1. A conjugate isolated from urine of human volunteers after an oral dose of S-carboxymethyl-L-cysteine was characterized as a carboxylic acid ester glucuronide.

2. Of the 166 volunteers investigated, 61 gave no detectable drug glucuronide (<0.5% administered dose); the remaining 105 showed a unimodal distribution of drug glucuronide excretion accounting for 0.5–11.5% (mean 4.1%, median 3.4%) of the total dose recovered in the 0–8h urine.

3. No significant variation in subject age, sex or urinary pH was observed between the two groups, but those not excreting urinary glucuronide had significantly higher 0–8h urine volumes (P<0.001), although notable exceptions occurred.