Determination of angiotensin II receptor antagonist (E4177) in human plasma and urine by high-performance liquid chromatography

Abstract

A sensitive reversed-phase high-performance liquid chromatographic (HPLC) method with fluorescence detection was developed for the analysis of a new angiotensin II receptor antagonist, E4177, in human plasma and urine. The analyte and internal standard (I.S.) are extracted from acidified plasma and urine by liquid—liquid extraction and then refined by solid-phase extraction. The extraction recovery was greater than 90%. E4177 and I.S. were separated from endogenous components in plasma and urine on a C 18 column using a mobile phase of acetonitrile—water—85% phosphoric acid (27.3:72.0:0.7, v/v). The eluent was monitored by fluorescence with excitation and emission set at 280 and 380 nm, respectively. The assay was linear from 2.5 to 1000 ng/ml of plasma and from 5 to 1500 ng/ml of urine. The limit of quantification was 2.5 and 5 ng/ml for plasma and urine, respectively. Inter- and intra-day coefficients of variation for the plasma and urine ranged from 0.6 to 4.7%. E4177 was stable in plasma and urine for at least 9 months during storage at −20°C, respectively. The method was successfully applied to the determination of E4177 in plasma and urine for a pharmacokinetic study.