Pharmacokinetics and metabolism of [35S]-Thiazolidine carboxylic acid in the rat. I. Elimination and distribution.

The localization and elimination of 35S-Thiazolidine carboxylic acid has been studied in rats following a single oral dose (100 mg/kg) and multiple oral doses (100 mg/kg/day) over 15 days. The compound was rapidly and completely absorbed as evaluated by the time of the maximum plasma 35S-concentration (140 micrograms eq/ml at 30 min) and the amount of radioactivity in the feces (less than 1% of the dose over 48 h). Urinary excretion seems to be the unique route of elimination. There was specific tissue accumulation of drug or metabolite, particularly in liver (29% of the dose at 3 h), pancreas (7% of the dose at 3 h), adrenals (320 micrograms eq/g at 3 h), pituitary and thyroid (230 micrograms eq/g at 3h). Fixation of radioactivity appears significantly higher after chronic treatment than after acute treatment.