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Abstract: For the rapid, selective and sensitive analysis of metoclopramide in human plasma, hydrophilic interaction chromatography with electrospray ionization tandem mass spectrometric (HILIC/MS/MS) method was developed. This method involved liquid–liquid extraction with dichloromethane followed by separation on an Atlantis HILIC silica column using the mobile phase of acetonitrile–ammonium formate (100mM, pH 6.5) (85:15, v/v). Analytes were quantified using electrospray ionization mass spectrometry in the selected reaction monitoring mode. The standard curve was linear (r 2 =0.998) over the concentration range of 2.00–150ng/mL using 50μL of plasma sample. The coefficient of variation and relative error for intra- and inter-assay at four QC levels were 1.8–7.7% and −7.5 to 3.6%, respectively. The matrix effect for metoclopramide and levosulpiride (internal standard) was practically absent. The present method was successfully applied to the pharmacokinetic study of metoclopramide after oral dose of metoclopramide hydrochloride (10mg) to male healthy volunteers. [Copyright &y& Elsevier]

Abstract: A rapid, sensitive and selective liquid chromatography–tandem mass spectrometric (LC–MS/MS) method for the determination of baicalein, baicalin, oroxylin A and wogonin, Scutellaria baicalensis active components in rat plasma was developed. After liquid–liquid extraction with 2-(3,4-dimethoxy-phenyl)-5,7-dihydroxy-chromen-4-one as internal standard, baicalein, baicalin, oroxylin A and wogonin were eluted from an Atlantis C18 column within 7min with isocratic mobile phase consisting of methanol and 0.1% formic acid (60:40, v/v). The analytes were detected using an electrospray ionization tandem mass spectrometry in the multiple reaction monitoring (MRM) mode. The standard curves were linear (r =1.000) over the concentration ranges of 5–500ng/ml for baicalein, wogonin and oroxylin A and 5–5000ng/ml for baicalin. The coefficients of variation and relative errors of baicalein, wogonin, oroxylin A and baicalin for intra- and inter-assay at three or four quality control (QC) levels were 0.8–6.1% and −4.0 to 5.8%, respectively. The lower limits of quantification for baicalein, wogonin, oroxylin A and baicalin were 5ng/ml using 50μl of plasma sample. This method was successfully applied to the pharmacokinetic study of baicalein, baicalin, wogonin and oroxylin A after an intravenous administration of Scutellariae radix extract to male Sprague–Dawley rats. [Copyright &y& Elsevier]

Abstract: A rapid, sensitive and selective hydrophilic interaction liquid chromatography–tandem mass spectrometric (HILIC–MS/MS) method for the determination of levofloxacin in human plasma was developed. Levofloxacin and ciprofloxacin (internal standard) were extracted from human plasma with dichloromethane and analyzed on an Atlantis HILIC Silica column with the mobile phase of acetonitrile-ammonium formate (100mM, pH 6.5) (82:18v/v). The analytes were detected using an electrospray ionization tandem mass spectrometry in the multiple-reaction-monitoring mode. The standard curve was linear (r >0.999) over the concentration range of 10.0–5000ng/ml. The lower limit of quantification for levofloxacin was 10.0ng/ml using 20μl plasma sample. The coefficient of variation and relative error for intra- and inter-assay at four QC levels were 2.9–7.8% and −7.3% to −2.2%, respectively. The recoveries of levofloxacin and ciprofloxacin were 55.2% and 77.3%, respectively. This method was successfully applied to the pharmacokinetic study of levofloxacin in humans. [Copyright &y& Elsevier]

A rapid, sensitive and selective hydrophilic interaction liquid chromatography–tandem mass spectrometric (HILIC–MS/MS) method for the determination of levosulpiride in human plasma was developed. Levosulpiride and internal standard, tiapride were extracted from human plasma with ethyl acetate at pH 11 and analyzed on an Atlantis HILIC silica column with the mobile phase of acetonitrile–ammonium formate (190mM, pH 3.0) (94:6, v/v). The analytes were detected using an electrospray ionization tandem mass spectrometry in the multiple-reaction-monitoring mode. The standard curve was linear (r = 0.999) over the concentration range of 1.00–200ng/ml. The lower limit of quantification for levosulpiride was 1.00ng/ml using 100μl plasma sample. The coefficient of variation and relative error for intra- and inter-assay at three quality control (QC) levels were 3.8–9.1 and -2.9 to -0.1%, respectively. The recoveries of levosulpiride ranged from 80.5 to 87.4%, with that of tiapride (internal standard) being 84.6%. This method was successfully applied to the pharmacokinetic study of levosulpiride in humans. [Copyright &y& Elsevier]

A liquid chromatographic–mass spectrometric (LC/MS) method for the simultaneous determination of ginsenoside Rb1 and Rg1 in human plasma was developed. The method involved the protein precipitation followed by analysis of ginsenoside Rb1 and Rg1 in an Atlantis C18 column with the gradient elution of acetonitrile and ammonium formate (10 mM, pH 3.0) at a flow rate of 0.2 ml/min. The analytes were determined using electrospray negative ionization mass spectrometry in the selected ion monitoring mode. The standard curves for ginsenoside Rb1 and Rg1 were linear over the concentration range of 10.0–1000 ng/ml. The lower limit of quantification was 10.0 ng/ml using 100 μl plasma sample. The coefficient of variation of intra- and inter-day assays for ginsenoside Rb1 and Rg1 at three quality control levels ranged from 1.0 to 6.8% and 5.4 to 9.8%, respectively. Ginsenoside Rb1 and Rg1 were stable in blank human plasma at room temperature for 24 h and following three freeze–thaw cycles. [Copyright &y& Elsevier]

A simple high performance liquid chromatography (HPLC) method was developed for the determination of butein in rat serum. The method involved the deproteinization followed by injection into a Luna C8 column. Butein was eluted at 3.8 min at a flow rate of 0.2 ml/min with the mobile phase of acetonitrile–ammonium formate (10 mM, pH 3.0) (35:65, v/v). The standard curve was linear (r2=0.995) over the concentration range of 0.1–10 μg/ml. The coefficient of variation (CV) of intra- and inter-assay ranged from 2.7 to 7.5% and 6.0 to 7.5%, respectively. The limit of quantification was 0.1 μg/ml using a serum sample of 50 μl. This method was applied to a pharmacokinetic study after intravenous injection of butein (5 mg/kg) to rats. [Copyright &y& Elsevier]

A liquid chromatography-mass spectrometric method was developed for the quantitative determination of catalposide in rat plasma. The method involved the deproteinization followed by injection onto an XTerra C18 column. Catalposide was eluted at 3.8 min at a flow rate of 0.4 mL/min with the mobile phase of methanol-acetonitrile-ammonium formate (10 mM, pH 4.5) (30:5: 65, v/v). The standard curve was linear (r2 = 0.997) over the concentration range of 0.05–10 µg/mL with the coefficient of variation of intra- and inter-assay ranged from 1.5–4.8% and 3.4–5.6%, respectively. The limit of quantification was 0.05 µg/mL using a plasma sample of 100 µL. Catalposide was stable in various pH solutions ranging from 2 to 13 for up to 24 h incubation at 37°C. Catalposide was relatively stable in rat whole blood and plasma, human plasma, and rat or human liver microsomes for up to 3 h incubation at 37°C. This method was applied to a pharmacokinetic study after intravenous injection of catalposide (10 mg/kg) to rats. [ABSTRACT FROM AUTHOR]

A rapid, sensitive and selective liquid chromatography–tandem mass spectrometric (LC/MS/MS) method for the determination of tiropramide in human plasma was developed. Tiropramide and internal standard, cisapride were extracted from human plasma by liquid–liquid extraction and analyzed on a Luna C8 column with the mobile phase of acetonitrile-ammonium formate (10 mM, pH 4.5) (50:50, v/v). The analytes was detected using an electrospray ionization tandem mass spectrometry in the multiple-reaction-monitoring mode. The standard curve was linear (r=0.998) over the concentration range of 2.0–200 ng/ml. The intra- and inter-assay coefficients of variation ranged from 2.8 to 7.8 and 6.7 to 8.9%, respectively. The recoveries of tiropramide ranged from 50.2 to 53.1%, with that of cisapride (internal standard) being 60.9±5.3%. The lower limit of quantification for tiropramide was 2.0 ng/ml using 100 μl plasma sample. This method was applied to the pharmacokinetic study of tiropramide in human. [Copyright &y& Elsevier]

A rapid and sensitive column-switching semi-micro high-performance liquid chromatography method was developed for the direct analysis of tiropramide in human plasma. The plasma sample (100 μl) was directly injected onto Capcell Pak MF Ph-1 precolumn where deproteinization and analyte fractionation occurred. Tiropramide was then eluted into an enrichment column (Capcell Pak UG C18) using acetonitrile–potassium phosphate (pH 7.0, 50 mM) (12:88, v/v) and was analyzed on a semi-micro C18 analytical column using acetonitrile–potassium phosphate (pH 7.0, 10 mM) (50:50, v/v). The method showed excellent sensitivity (limit of quantification 5 ng/ml), and good precision (C.V.⩽5.9%), and speed (total analysis time 20 min). The calibration curve was linear in the concentration range 5–200 ng/ml (coefficient of determination equal to 0.998). This method was successfully applied to the pharmacokinetic study of tiropramide in volunteers. [Copyright &y& Elsevier]

Stauntonia hexaphylla leaf extract (YRA-1909), which is widely used for the antirheumatic properties, has been under phase 2 clinical trials in patients with rheumatoid arthritis since April 2017. Liquid chromatography-tandem mass spectrometric method while using liquid–liquid extraction with ethyl acetate was validated for the simultaneous determination of the major active components of YRA-1909, including chlorogenic acid (CGA), neochlorogenic acid (NCGA), cryptochlorogenic acid (CCGA), and their metabolites (i.e., caffeic acid (CA), caffeic acid 3-O-glucuronide (CA-3-G), caffeic acid 4-O-glucuronide (CA-4-G), and ferulic acid (FA)) in rat plasma and applied to a pharmacokinetic study of YRA-1909 in rats. Seven analytes were separated on Halo C18 while using gradient elution of formic acid and methanol, and then quantified in selected reaction monitoring mode whle using negative electrospray ionization. Following oral administration of YRA-1909 at doses of 25, 50, and 100 mg/kg to male Sprague-Dawley rats, CGA, NCGA, and CCGA were rapidly absorbed and metabolized to CA, CA-3-G, and CA-4-G. The area under the plasma concentration-time curve (AUClast) of CGA, NCGA, CCGA, and three metabolites linearly increased as the YRA-1909 dose increased. Other pharmacokinetic parameters were comparable among three doses studied. AUClast values for CA, CA-3-G, and CA-4-G exceeded those for CGA, NCGA, and CCGA. [ABSTRACT FROM AUTHOR]