FY363 is a new chemical entity of gemcitabine analog, which has been shown to have a significant inhibitory effect on cell proliferation in a variety of tumor cell lines in vitro. As a carbamate derivative, FY363 would be converted to the active metabolite gemcitabine through enzyme action in vivo. In order to clarify the exposure of FY363 prototype and its metabolite gemcitabine in vivo after administration of FY363, a sensitive and specific liquid chromatography tandem mass spectrometry (LC-MS/MS) was developed and validated to simultaneously determine FY363 and gemcitabine in rat plasma after liquid-liquid extraction with ethyl acetate. Chromatographic separation was achieved on a highly stable polar column of Synergi 4u Polar-RP 80A (4 μm, 4.6 × 250 mm) which has a unique ether - phenyl bonded phase. Gradient elution was accomplished with mobile phase system consisting of 5 mM ammonium formate buffer containing 0.1% formic acid and mixed organic solvents containing methanol-acetonitrile (3:2, v/v). Multiple reaction monitoring transitions were performed on triple quadrupole mass spectrometric detection in positive-ion mode with an electrospray ionization source. The calibration curves showed good linearity (r > 0.99) over the established concentration range of 1.0–1000 ng/mL both for FY363 and gemcitabine. The assay was validated to be selective, robust and reproducible. This well validated method was successfully applied to demonstrate the pharmacokinetic behavior and the metabolic transformation of FY363 in rats. Results revealed that about 20% of FY363 were converted into its active metabolite gemcitabine in rats by comparing the exposure of gemcitabine after the FY363 administration with that after direct gemcitabine administration at equimolar dose.

FY363是吉西他滨类似物的新化学实体，已显示出对多种肿瘤细胞系体外细胞增殖具有显着抑制作用。作为氨基甲酸酯衍生物，FY363将通过体内酶作用转化为活性代谢物吉西他滨。为了阐明FY363原型及其代谢产物吉西他滨在给药后在体内的暴露情况，开发了灵敏而特异的液相色谱串联质谱法（LC-MS / MS），并进行了验证，可同时测定大鼠血浆中的FY363和吉西他滨用乙酸乙酯液-液萃取。色谱分离是在Synergi 4u Polar-RP 80A的高度稳定的极性色谱柱（4μm，4.6×250 mm）上完成的，该色谱柱具有独特的醚-苯基键合相。用流动相系统完成梯度洗脱，该系统由含0.1％甲酸的5 mM甲酸铵缓冲液和含甲醇-乙腈（3：2，v / v）的混合有机溶剂组成。使用电喷雾电离源，在正离子模式下的三重四极杆质谱检测中执行多个反应监测转换。校准曲线显示出良好的线性（r  > 0.99）在FY363和吉西他滨的既定​​浓度范围内（1.0-1000 ng / mL）。该测定方法经验证具有选择性，稳健性和可重复性。这种经过充分验证的方法已成功应用于证明FY363在大鼠中的药代动力学行为和代谢转化。结果显示，通过比较FY363给药后与等摩尔剂量吉西他滨直接给药后的暴露量，大鼠中约有20％的FY363转化为其活性代谢物吉西他滨。