J. Macwan, I. Ionita, M. Dostálek
Feb 26, 2011
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Influential Citations
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Journal
Analytical and Bioanalytical Chemistry
Abstract
AbstractThe aim of the proposed work was to develop and validate a simple and sensitive assay for the analysis of atorvastatin (ATV) acid, ortho- and para-hydroxy-ATV, ATV lactone, and ortho- and para-hydroxy-ATV lactone in human plasma using liquid chromatography-tandem mass spectrometry. All six analytes and corresponding deuterium (d5)-labeled internal standards were extracted from 50 μL of human plasma by protein precipitation. The chromatographic separation of analytes was achieved using a Zorbax-SB Phenyl column (2.1 mm × 100 mm, 3.5 μm). The mobile phase consisted of a gradient mixture of 0.1% v/v glacial acetic acid in 10% v/v methanol in water (solvent A) and 40% v/v methanol in acetonitrile (solvent B). All analytes including ortho- and para-hydroxy metabolites were baseline-separated within 7.0 min using a flow rate of 0.35 mL/min. Mass spectrometry detection was carried out in positive electrospray ionization mode, with multiple-reaction monitoring scan. The calibration curves for all analytes were linear (R2 ≥ 0.9975, n = 3) over the concentration range of 0.05–100 ng/mL and with lower limit of quantitation of 0.05 ng/mL. Mean extraction recoveries ranged between 88.6–111%. Intra- and inter-run mean percent accuracy were between 85–115% and percent imprecision was ≤ 15%. Stability studies revealed that ATV acid and lactone forms were stable in plasma during bench top (6 h on ice-water slurry), at the end of three successive freeze and thaw cycles and at −80 °C for 3 months. The method was successfully applied in a clinical study to determine concentrations of ATV and its metabolites over 12 h post-dose in patients receiving atorvastatin. FigureChromatogram of atorvastatin and metabolites obtained with postcolumn infusion shows no matrix effect at the retention times of analytes and IS. Arrow indicates region where the signal of compounds infused post-column is suppressed during the elution of endogenous matrix components