Simultaneous Analysis Of Plasma Capecitabine And Its Metabolites By HPLC-MS / MS

AIM:To develop a sensitive, specific and validated rapid method for simultaneous quantification of capecitabine and its metabolites in human and SD rat plasma by liquid chromatography-tandem mass spectrometry and apply it to preclinical pharmacokinetic studies.METHODS:After a simple protein precipitation using ice methanol and acetonitrile, the supernatant was dried under N2at40℃and reconsititued with H2O-0.1%FA. All the analytes and the internal standard5-CU were chromatographed on a Phenomenex Luna PFP(50×4.6mm,3μm) column. The mobile phase consisted of water-0.1%formic acid and methanol-0.1%formic acid at a flow rate of0.8mL/min. An API-4000triple quadrupole mass spectrometer, equipped with an electrospray ionization interface was operated in the negative ion mode. Selected reaction monitoring (SRM) using the precursor→product ion combination of m/z129.1→m/z42.1, m/z261.1→m/z171.1, m/z245.3→m/z155.1, m/z325.1→m/z129.1, m/z358.2→m/z153.9, m/z244.1→m/z128.1, m/z245.1→m/z129.0and m/z145.1→m/z42.1was used to quantify5-FU,5-FUrd,5-FdUrd,5-FdUMP, capecitabine,5’-DFCR,5’-DFUR and internal standard5-CU respectively.RESULTS:The linear calibration curve was obtained in the concentration range from10.0-1000ng/mL for5-FU;5.00-1000ng/mL for5-FUrd,5-FdUrd,5-FdUMP, Capecitabine,5’-DFUR; and20.0-1000ng/mL for5’-DFCR. The intra-and inter-run precisions, expressed as the relative standard deviation (RSD) were less than9.3%,5.7%,7.4%,6.9%,8.2%,11.3%,10.8%for5-FU,5-FUrd,5-FdUrd,5-FdUMP, Capecitabine,5’-DFCR and5’-DFUR respectively in human plasma, and the accuracy was within-4.2%～4.8%,-0.6%～5.9%,0.5%～5.5%,-1.3%～8.O%,-3.8%～6.7%,0.8%～5.4%,-3.2%～4.1%in terms of relative error. The intra-and inter-run precisions, expressed as the relative standard deviation (RSD) were less than11.6%,10.7%,10.2%,10.6%,7.9%,8.8%,9.8%for5-FU,5-FUrd,5-FdUrd,5-FdUMP, Capecitabine,5’-DFCR and5’-DFUR respectively in SD rat plasma, and the accuracy was within-3.2%～-2.1%,1.6%～4.3%,-3.1%～2.8%,-2.1%～5.2%,-2.7%～5.7%,1.8%～1.9%,4.9%～7.5%in terms of relative error.CONCLUSION:The methods were sensitive, specific and validate rapid for simultaneous quantification of capecitabine and its metabolites in SD rat and human plasma by liquid chromatography-tandem mass spectrometry, and were successfully applied for the determination and evaluation of the preclinical pharmacokinetic studies of capecitabine, as a reference for clinical pharmacokinetic studies.