Quantification of oltipraz using liquid chromatography-tandem mass spectrometry and its application to a pharmacokinetic study in rat plasma

An assay method for the determination of oltipraz, a candidate drug for the treatment of liver fibrosis and liver cirrhosis, was developed in rat plasma using a fast-flow protein precipitation (FF-PPT) method coupled with LC-MS/MS for quantification to reduce the labor and to improve the speed of analysis. The applicability of the assay to pharmacokinetic studies was also evaluated. Oltipraz and ethyl-oltipraz, an internal standard (IS), were analyzed by multiple reaction monitoring (MRM) at m/z transitions of 227 → 193 and 241 → 174, respectively. A lower limit of quantification (LLOQ) of 20 ng/mL was observed, with a linear dynamic range from 20 to 4000 ng/mL (R > 0.997). The accuracy, precision, dilution, recovery, and stability of the assay were deemed acceptable according to FDA guidelines. Oltipraz concentrations were measured successfully in plasma samples up to 12 h post-dose in rats that had received an oral dose of 60 mg/kg. The findings indicate that the assay method is rapid and sensitive to oltipraz, showing applicability for pharmacokinetics (PK) studies of oltipraz in other small animals, including rats.