Sensitive MS/MS–liquid chromatography assay for simultaneous determination of tegafur, 5-fluorouracil and 5-fluorodihydrouracil in plasma

Ftorafur (FT), an oral prodrug of 5-FU, is part of UFT and S1, two oral prodrugs widely used in digestive tract cancer. We set up a liquid chromatography tandem mass spectrometry (LC/MS–MS) method, chosen for its specificity of detection, for simultaneously measuring in human plasma FT, 5-FU and 5-FUH2. Separation was performed on a Hypercarb column. Linearity, precision and accuracy were validated in the concentration range studied for each compound. This simple and reliable LC/MS–MS method allows specific, sensitive and reproducible quantification of FT, 5-FU and FUH2 in human plasma and can be applied to further pharmacokinetic studies in patients treated with FT-based prodrugs.