Determination of piracetam in rat plasma by LC–MS/MS and its application to pharmacokinetics

A sensitive and selective liquid chromatography–tandem mass spectrometry method for the determination of piracetam in rat plasma was developed and validated over the concentration range of 0.1–20 µg/mL. After addition of oxiracetam as internal standard, a simplified protein precipitation with trichloroacetic acid (5%) was employed for the sample preparation. Chromatographic separation was performed by a Zorbax SB‐Aq column (150 × 2.1 mm, 3.5 µm). The mobile phase was acetonitrile–1% formic acid in water (10:90 v/v) delivered at a flow rate of 0.3 mL/min. The MS data acquisition was accomplished in multiple reaction monitoring mode with a positive electrospray ionization interface. The lower limit of quantification was 0.1 µg/mL. For inter‐day and intra‐day tests, the precision (RSD) for the entire validation was less than 9%, and the accuracy was within the 94.6–103.2% range. The developed method was successfully applied to pharmacokinetic studies of piracetam in rats following single oral administration dose of 50 mg/kg. Copyright © 2010 John Wiley & Sons, Ltd.     

LC–MS/MS method for the simultaneous determination of ethyl gallate and its major metabolite in rat plasma

A simple, rapid and sensitive liquid chromatography–tandem mass spectroscopy (LC–MS/MS) method was developed and validated for the determination of ethyl gallate, a pharmacologically active constituent isolated from Lagerstroemia speciosa (Linn.) Pers. This method was used to examine the pharmacokinetics of ethyl gallate and its major metabolite gallic acid in rat plasma using propyl gallate as an internal standard. After precipitation of the plasma proteins with acetonitrile, the analytes were separated on a Zorbax SB‐C₁₈ column (3.5 μm, 2.1 × 50 mm) with an isocratic mobile phase consisted of methanol–acetonitrile–10 mM ammonium acetate (10 : 25 : 65, v/v/v) containing 0.1% formic acid at a flow rate of 0.25 mL/min. The Agilent G6410A triple quadrupole LC/MS system was operated under the multiple‐reaction monitoring mode using the electrospray ionization technique in negative mode. The lower limits of quantification of gallic acid and ethyl gallate of the method were 0.5 and 1.0 ng/mL. The intra‐day and inter‐day accuracy and precision of the assay were less than 8.0%. This method has been applied successfully to a pharmacokinetic study involving the intragastric administration of ethyl gallate to rats. Copyright © 2009 John Wiley & Sons, Ltd.     

A rapid and sensitive LC‐MS/MS method for the determination of linarin in small‐volume rat plasma and tissue samples and its application to pharmacokinetic and tissue distribution study

A rapid and sensitive LC‐MS/MS method was developed for the determination of linarin in small‐volume rat plasma and tissue sample. Sample preparation was employed by the combination of protein precipitation (PPT) and liquid–liquid extraction (LLE) to allow measurement over a 5‐order‐of‐magnitude concentration range. Fast chromatographic separation was achieved on a Hypersil Gold column (100 × 2.1 mm i.d., 5 µm). Mass spectrometric detection was achieved using a triple‐quadrupole mass spectrometer equipped with an electrospray ionization interface operating in positive ionization mode. Quantification was performed using selected reaction monitoring of precursor‐product ion transitions at m/z 593 → 285 for linarin and m/z 447 → 271 for baicalin (internal standard). The total run time was only 2.8 min per sample. The calibration curves were linear over the concentration range of 0.4–200 µg/mL for PPT and 0.001–1.0 µg/mL for LLE. A lower limit of quantification of 1.0 ng/mL was achieved using only 20 μL of plasma or tissue homogenate. The intra‐ and inter‐day precisions in all samples were ≤14.7%, while the accuracy was within ±5.2% of nominal values. The validated method has been successfully applied to pharmacokinetic and tissue distribution study of linarin. Copyright © 2015 John Wiley & Sons, Ltd.     

Quantification of henatinib maleate,a novel potent inhibitor of VEGF receptors,in rat plasma by LC‐MS/MS

Henatinib maleate (R,Z)‐2‐[(5‐fluoro‐1,2‐dihydro‐2‐oxo‐3H‐indol‐3‐ylidene) methyl]‐5‐(2‐hydroxy‐3‐morpholinopropyl)‐3‐methyl‐5,6,7,8‐tetrahydro‐1H‐pyrrolo[3,2‐c] azepin‐4‐ketone maleate is a potent inhibitor of vascular endothelial growth factor receptors, and is currently under preclinical evaluation as an anticancer drug. A novel method for the quantification of henatinib maleate in rat plasma using high performance liquid chromatography–tandem mass spectrometry has been developed. The analyte (henatinib maleate) and internal standard (papaverine hydrochloride) were extracted from 50 μL of rat plasma by protein precipitation and separated on a C₁₈ column using a mixture of 25 mm ammonium acetate buffer : methanol : acetonitrile (35 : 50 : 15, v/v/v) as mobile phase with a run time of 4.5 min. The detection was performed by means of triple quadrupole mass spectrometer equipped with an ESI interface operating in the multiple‐reaction monitoring mode. A linear response was observed over the concentration range 5.0–1000 ng/mL. The limit of quantification was 5.0 ng/mL. Both intra‐ and inter‐day precision, defined as relative standard deviation, were within 9.7%. Accuracy, defined as relative error, was within ± 3.1%. The developed method was successfully applied to preclinical pharmacokinetic studies of henatinib maleate in rat after a single oral administration of the drug. Copyright © 2009 John Wiley & Sons, Ltd.