目的 通过LC-MS/MS法测定大鼠血浆中依那普利活性代谢产物依那普利拉浓度,研究依那普利在大鼠体内的药动学。方法 Wistar大鼠ig依那普利15 mg/kg,采用固相萃取法对大鼠血浆样品预处理,洗脱液为甲醇、水。色谱与质谱条件为Diamond C₁₈色谱柱(150 mm×4.6 mm,5 μm);流动相:乙腈–5 mmol/L乙酸铵(45:55);体积流量:0.5 mL/min;柱温:30 ℃;进样量:5 μL。采用ESI(＋)离子源;干燥气(N₂)体积流量11.0 L/min,压力275.8 kPa,温度350 ℃;毛细管电压3 500 V;多级反应监测(MRM)模式,正离子模式;EMV为400 eV。结果 血浆中内源性物质对测定无干扰,依那普利拉的线性范围为20~1 500 ng/mL,最低定量限为20 ng/mL。准确度和精密度良好。血浆样本中依那普利拉的提取回收率大于85%,且无浓度相关性。经2次冻融以及冷冻14 d稳定良好。大鼠体内依那普利拉的主要药动学参数:AUC₀-_t为(8015±297.7)ng/mL·h,C_max为(1 405±269.10)ng/mL,t_max为(2.45±0.19)h,t_1/2为(4.82±0.32)h,Clz/F为(2.18±0.10)L/kg·h,Vz/F为(12.63±1.31)L/kg。结论 本方法专属性强、灵敏度高、准确性好。通过测定代谢产物依那普利拉经时血药浓度,可以考察依那普利的药动学特征。

Objective To investigate the pharmacokinetics of enalapril in rat by establishing LC-MS/MS method for determination of enalaprilat, active metabolite of enalapril in rat plasma. Methods Wistar rats were ig administered with a single dose 15 mg/kg of enalapril. Plasma samples were pretreated by solid-phase extraction, and elution solutions were methanol and water. The separation was performed on Diamonsil C₁₈ column (150 mm × 4.6mm, 5 μm) with mobile phase consisted of acetonitrile-5mmol/L ammonium (45:55) at 0.5 mL/min. The column temperature was set at 30 ℃, and the flow rate was 0.5 mL/min with injection volume of 5 μL. Enalaprilat was determined by LC-MS/MS in the positive ion multiple reaction monitoring (MRM) mode with EMV 400 eV. ESI (+) ion source was used, dry gas (N₂) had flow rate of 11.0 L/min, pressure was 275.8 kPa with temperature 350 ℃, and capillary voltage was 3 500 V. Results No endogenous interfering peak was observed in chromatograms. The calibration curve was linear over the concentration range of 20 - 1 500 ng/mL, and the lower limit of quantitation was 20 ng/mL. Accuracy and precision met the requirements. The recovery of enalaprilat was more than 85% with no concentration dependence. The plasma samples were stable after two freeze-thaw cycles and after being stored for 14 d. Main pharmacokinetic parameters of enalaprilat were as following: AUC_0-t (8 015 ± 297.7) ng/mL·h, C_max (1 405 ± 269.10) ng/mL, t_max (2.45 ± 0.19)h, t_1/2 (4.82 ± 0.32) h, Clz/F (2.18 ± 0.10) L/kg·h, Vz/F (12.63 ± 1.31) L/kg. Conclusions The method is excellent specificity, acceptable precision, and accuracy. The pharmacokinetics of enalaprilat, the active metabolite of enalapril in plasma could be investigated by determine the concentration-time, and pharmacokinetic characteristics of enalapril drug can also be investigated.