Quantification of tiazofurin in plasma by high-performance liquid chromatography

A simple and sensitive method was developed for the separation and quantification of tiazofurin ( TCAR ) in plasma using 2-beta-D- ribofuranosylthiazole -5-carboxamide (iso- TCAR ) or [5-3H] TCAR as an internal standard. The procedure uses C18 extraction columns to clean-up the plasma samples for measurement by high-performance liquid chromatography. A sensitivity of 0.33 microM (0.08 microgram/ml) was easily achieved for 0.5-ml plasma samples. When human whole blood was incubated in vitro with TCAR for 2 h, the plasma concentrations were decreased by 10% (4 degrees C) and 25% (23 degrees C). TCAR could still be measured 22 h after injection of 220 mg/kg into mice. For a two-compartment pharmacokinetic model, the half-lives of TCAR were 18.8 and 412 min.