title: Determination of L-753,037 in human plasma by liquid chromatography/turbo ionspray tandem mass spectrometry.
abstract: A liquid chromatographic/turbo ionspray tandem mass spectrometric (LC/MS/MS) method was developed and validated for the determination of L-753,037, a potent endothelin receptor antagonist currently under development for the treatment of cardiovascular diseases, in human plasma. L-753,037 is extracted from 0.5 ml of human plasma using liquid-liquid extraction and analyzed by LC/MS/MS with a turbo ionspray interface. Method validation results showed that this method is very sensitive, reliable, selective and reproducible. L-753,048, an ethoxy analogue of L-753,037, was used as the internal standard. The method has a lower limit of quantitation (LOQ) of 50 pg ml(-1) with a linear calibration range of 0.05-50 ng ml(-1). The intra-day precision and accuracy (n = 5) were measured to be below 10% relative standard deviation (RSD) and between 97.4 and 102.8% of the nominal values, respectively, for all calibration standard concentrations within the calibration curve range. The inter-day precision and accuracy (n = 3 days, 5 replicates per day) were measured to be below 6.5% RSD and between 99.3 and 102.0% of the nominal values, respectively, for all quality control concentrations. The extraction recovery was determined to be approximately 99% on average. The analyte was found to be stable in plasma through three freeze-thaw cycles, for at least 4 h at ambient temperature and for up to 40 days under -20 degrees C freezer storage conditions. The analyte was also shown to be stable for at least 24 h in the reconstitution solution at room temperature and for up to 3 days as a dried extract at 4 degrees C. Additional variations in plasma concentration of the analyte due to the use of different sources of plasma were also evaluated.
authors.affiliation: Department of Drug Metabolism, Merck Research Laboratories, West Point, Pennsylvania 19486, USA. jamie_zhao@merck.com
authors.forename: J J
authors.initials: JJ
authors.lastname: Zhao
authors.forename: I
authors.initials: I
authors.lastname: Xie
authors.forename: J D
authors.initials: JD
authors.lastname: Rogers
mesh_terms: D002138:Calibration; D002853:Chromatography, Liquid; D065128:Endothelin Receptor Antagonists; D006801:Humans; D007202:Indicators and Reagents; D013058:Mass Spectrometry; D011725:Pyridines / Q000097:blood*; D015203:Reproducibility of Results
chemical_list: D065128:Endothelin Receptor Antagonists; D007202:Indicators and Reagents; D011725:Pyridines; C119319:J 104132