ABSTRACT
OBJECTIVE: To develop a sensitive and rapid HPLC-MS/MS method for the determination of losartan potassium and E-3174 in human plasma. METHODS: The plasma samples were extracted with methyl tert-butyl ether (MTBE) after addition of internal standard and acetic acid, and then analyzed with API 3000 LC-MS/MS system. The analytical column was SHISEIDO, CAP-CELL PAK C18 MG II (2.0 mm × 50 mm, 5 μm) and the column temperature was room temperature. The mobile phase was composed of 0.1% formic acid in water (containing 5 mmol·L-1 ammonium acetate) -0.1% formic acid in acetonitrile (20:80) and the flow rate was 0.85 mL·min-1. Detection was performed with multiple reactions monitoring (MRM) using positive electrospray ionization (ESI). RESULTS: The calibration curves were linear over the concentration ranges of 10.10-2525 ng·mL-1 for losartan potassium and 9.820-2455 ng·mL-1 for E-3174, respectively. The lower-limit-of-quantifications were 10.10 ng·mL-1 for losartan potassium and 9.820 ng·mL-1 for E-3174, respectively. Inter-and intra-day precisions were less than 9.22% and accuracy was within 93.56%-102.88%. Extraction recoveries were around 70% and the analytes were proved to be stable. Total run time of an analyte was only 2.5 min. The relative bioavailabilities of the two preparations were 96.5% for losartan potassium and 110.0% for E-3174. These two losartan potassium preparations were bioequivalent. CONCLUSION: This method is rapid, sensitive, specific and applicable to the pharmacokinetic study in human and bioequivalence study of losartan potassium.
ABSTRACT
OBJECTIVE:To develop an HPLC-fluorescence method for simultaneous determination of losartan and its major metabolite(E-3174) in human plasma.METHODS:Plasma sample was pretreated by liquid-liquid extraction with aether then determined with valsartan served as internal standard.The determination was performed on Diamonsil C18 with column temperature set at room temperature.The mobile phase consisted of 0.02 mol?L-1 sodium dihydrogen phosphate buffer (adjusted to pH=2.35 with phosphoric acid)-acetonitrile (57∶43) at a flowrate of 0.5 mL?min-1.The excitation wavelength was set at 250 nm and the emission wavelength was set at 370 nm.RESULTS:The linear range of losartan was 10～1 000 ng?mL-1(r=0.999 0) with a lowest limiest of quantification(LLOQ) of 10 ng?mL-1;the linear range of E-3174 was 5～1 000 ng?mL-1(r=0.999 0) with a LLOQ of 5 ng?mL-1.The methodological recoveries of losartan and E-3174 were 94.05%～110.09% and 107.7%～110.94%,respectively,with both intra-day RSD and inter-day RSD at less than 10.0%;the extraction recoveries of losartan and E-3174 were 69.16%～70.85% and 67.50%～70.77%,respectively.CONCLUSION:The developed method is simple,accurate and reproducible,and it is applicable for the concentration determination and pharmacokinetic studies of losartan and its major metabolite (E-3174) in human plasma.