Simultaneous determination of calycosin‐7‐O‐β‐d‐glucoside,calycosin, formononetin,astragaloside IV and schisandrin in rat plasma by LC‐MS/MS: application to a pharmacokinetic study after oral administration of Shenqi Wuwei chewable tablets

A rapid, sensitive and reliable high‐performance liquid chromatography–mass spectrometry (LC‐MS/MS) method was developed and validated for simultaneous quantification of the five main bioactive components, calycosin, calycosin‐7‐O‐β‐d ‐glucoside, formononetin, astragaloside IV and schisandrin in rat plasma after oral administration of Shenqi Wuwei chewable tablets. Plasma samples were extracted using solid‐phase extraction separated on a CEC₁₈ column and detected by MS with an electrospray ionization interface in multiple‐reaction monitoring mode. Calibration curves offered linear ranges of two orders of magnitude with r > 0.995. The method had a lower limit of quantitation of 0.1, 0.02, 0.1, 1 and 0.1 ng/mL for calycosin, calycosin‐7‐O‐β‐d ‐glucoside, formononetin, astragaloside IV and schisandrin, respectively. Intra‐ and inter‐day precisions (relative standard deviation) for all analytes ranged from 0.97 to 7.63% and from 3.45 to 10.89%, respectively. This method was successfully applied to the pharmacokinetic study of the five compounds in rats after oral administration of Shenqi Wuwei chewable tablets. Copyright © 2014 John Wiley & Sons, Ltd.     

Liquid chromatography–mass spectrometry for the simultaneous determination of the catalpol‐related iridoid glucosides,verproside, isovanilloylcatalpol,catalposide and 6‐O‐veratroyl catalpol in rat plasma

Verproside, isovanilloylcatalpol, catalposide and 6‐O‐veratroyl catalpol are bioactive iridoid glucosides isolated from in a number of folk medicinal plants. A rapid, sensitive and selective liquid chromatography/mass spectrometric (LC/MS) method for the simultaneous determination of verproside, isovanilloylcatalpol, catalposide and 6‐O‐veratroyl catalpol in rat plasma was developed. The analytes were extracted from 50 µL of rat plasma with ethyl acetate using 7‐carboxymethyloxy‐3',4',5‐trimethoxyflavone as internal standard and analyzed on an X‐Bridge C₁₈ column within 6.5 min with 40% methanol in 10 mm ammonium formate (pH 3.0). The analytes were quantified using an electrospray ionization mass spectrometry in the selected ion monitoring mode. The standard curves were linear over the concentration ranges of 10–2000 ng/mL for verproside, isovanilloylcatalpol and catalposide and 20–2000 ng/mL for 6‐O‐veratroyl catalpol. The coefficients of variation and relative errors of verproside, isovanilloylcatalpol, catalposide and 6‐O‐veratroyl catalpol for intra‐ and inter‐assay at four quality control levels were 2.5–8.0 and–4.0–6.6%, respectively. This method was successfully applied to the pharmacokinetic study of verproside and its possible metabolite isovanilloylcatalpol after intravenous administration of verproside, a candidate anti‐asthma drug, in male Sprague–Dawley rats. Copyright © 2009 John Wiley & Sons, Ltd.     

Simultaneous determination of aurantio‐obtusin,chrysoobtusin, obtusin and 1‐desmethylobtusin in rat plasma by UHPLC‐MS/MS

A sensitive and reliable ultra‐high‐performance liquid chromatography–electrospray ionization–tandem mass spectrometry (UHPLC‐MS/MS) method was developed and validated for the simultaneous determination of four active components of Semen Cassiae extract (aurantio‐obtusin, chrysoobtusin, obtusin and 1‐desmethylobtusin) in rat plasma after oral administration. Chromatographic separation was achieved on an Agilent Poroshell 120 C₁₈ column with gradient elution using a mobile phase that consisted of acetonitrile‐ammonium acetate in water (30 mm ) at a flow rate of 0.4 mL/min. Detection was performed by a triple‐quadrupole tandem mass spectrometer in multiple reaction monitoring mode. The calibration curve was linear over a range of 3.24–1296 ng/mL for aurantio‐obtusin, 0.77–618 ng/mL for chrysoobtusin, 34.55–1818 ng/mL for obtusin and 1.86–1485 ng/mL for 1‐desmethylobtusin. Inter‐ and intra‐day assay variation was <15%. All analytes were shown to be stable during all sample storage and analysis procedures. Copyright © 2013 John Wiley & Sons, Ltd.     

Simultaneous quantification and rat pharmacokinetics of formononetin‐7‐O‐β‐d‐glucoside and its metabolite formononetin by high‐performance liquid chromatography–tandem mass spectrometry

Formononetin‐7‐O‐β‐d ‐glucoside has been proved to have significant anti‐inflammatory effect. To evaluate its rat pharmacokinetics, a rapid, sensitive, and specific liquid chromatography–tandem mass spectrometry method has been developed and validated for the quantification of formononetin‐7‐O‐β‐d ‐glucoside and its main metabolite formononetin in rat plasma. Samples were pretreated using a simple protein precipitation and the chromatographic separation was performed on a C₁₈ column by a gradient elution using a mobile phase consisting of water and acetonitrile both containing 0.1% formic acid. Both analytes were detected using a tandem mass spectrometer in positive multiple reaction monitoring mode. The assay showed wide linear dynamic ranges of both 0.10–100 ng/mL, with acceptable intra‐ and inter‐batch accuracy and precision. The lower limits of quantification were both 0.10 ng/mL using 50 μL of rat plasma for two analytes. The method has been successfully used to investigate the oral pharmacokinetic profiles of both analytes in rats. After oral administration of formononetin‐7‐O‐β‐d ‐glucoside at the dose of 50 mg/kg, it was rapidly absorbed in vivo and metabolized to its metabolite formononetin. The plasma concentration‐time profiles both showed double‐peak phenomena, which would be attributed to the strong enterohepatic circulation of formononetin‐7‐O‐β‐d ‐glucoside.     

Development and validation of a UPLC‐MS/MS method for the determination of 7‐hydroxymitragynine,a μ‐opioid agonist,in rat plasma and its application to a pharmacokinetic study

A simple, sensitive and specific ultra‐performance liquid chromatography–tandem mass spectrometry (UPLC‐MS/MS) method was developed and validated to determine the concentrations of 7‐hydroxymitragynine in rat plasma. Following a single‐step liquid–liquid extraction of plasma samples using chloroform, 7‐hydroxymitragynine and the internal standard (tryptoline) were separated on an Acquity UPLC^TM BEH C₁₈ (1.7 µm, 2.1 × 50 mm) column using an isocratic elution at a flow rate of 0.2 mL/min. The mobile phase consisted of 0.1% acetic acid in water and 0.1% acetic acid in acetonitrile (10:90, v/v). The run time was 2.5 min. The analysis was carried out under the multiple reaction‐monitoring mode using positive electrospray ionization. Protonated ions [M + H]⁺ and their respective product ions were monitored at the following transitions: 415 → 190 for 7‐hydroxymitragynine and 173 → 144 for the internal standard. The calibration curve was linear over the range of 10–4000 ng/mL (r² = 0.999) with a lower limit of quantification of 10 ng/mL. The extraction recoveries ranged from 62.0 to 67.3% at concentrations of 20, 600 and 3200 ng/mL). Intra‐ and inter‐day assay precisions (relative standard deviation) were <15% and the accuracy was within 96.5–104.0%. This validated method was successfully applied to quantify 7‐hydroxymitragynine in rat plasma following intravenous administration. Copyright © 2013 John Wiley & Sons, Ltd.     

Development of a LC‐MS/MS method for simultaneous determination of metoprolol and its metabolites, α‐hydroxymetoprolol and O‐desmethylmetoprolol,in rat plasma: application to the herb–drug interaction study of metoprolol and breviscapine

A simple, specific and sensitive LC‐MS/MS method was developed and validated for the simultaneous determination of metoprolol (MET), α‐hydroxymetoprolol (HMT) and O‐desmethylmetoprolol (DMT) in rat plasma. The plasma samples were prepared by protein precipitation, then the separation of the analytes was performed on an Agilent HC‐C₁₈ column (4.6 × 250 mm, 5 µm) at a flow rate of 1.0 mL/min, and post‐column splitting (1:4) was used to give optimal interface flow rates (0.2 mL/min) for MS detection; the total run time was 8.5 min. Mass spectrometric detection was achieved using a triple‐quadrupole mass spectrometer equipped with an electrospray source interface in positive ionization mode. The method was fully validated in terms of selectivity, linearity, accuracy, precision, stability, matrix effect and recovery over a concentration range of 3.42–7000 ng/mL for MET, 2.05‐4200 ng/mL for HMT and 1.95‐4000 ng/mL for DMT. The analytical method was successfully applied to herb–drug interaction study of MET and breviscapine after administration of breviscapine (12.5 mg/kg) and MET (40 mg/kg). The results suggested that breviscapine have negligible effect on pharmacokinetics of MET in rats; the information may be beneficial for the application of breviscapine in combination with MET in clinical therapy. Copyright © 2015 John Wiley & Sons, Ltd.     

Development and validation of LC‐MS/MS method for the estimation of β‐hydroxy‐β‐methylbutyrate in rat plasma and its application to pharmacokinetic studies

A simple, sensitive and specific high‐performance liquid chromatography mass spectrometry (LC‐MS/MS) method was developed and validated for the quantification of β‐hydroxy‐β‐methyl butyrate (HMB) in small volumes of rat plasma using warfarin as an internal standard (IS). The API‐4000 LC‐MS/MS was operated under the multiple reaction‐monitoring mode using the electrospray ionization technique. A simple liquid–liquid extraction process was used to extract HMB and IS from rat plasma. The total run time was 3 min and the elution of HMB and IS occurred at 1.48 and 1.75 min respectively; this was achieved with a mobile phase consisting of 0.1% formic acid in a water–acetonitrile mixture (15:85, v/v) at a flow rate of 1.0 mL/min on a Agilent Eclipse XDB C₈ (150 × 4.6, 5 µm) column. The developed method was validated in rat plasma with a lower limit of quantitation of 30.0 ng/mL for HMB. A linear response function was established for the range of concentrations 30–4600 ng/mL (r > 0.998) for HMB. The intra‐ and inter‐day precision values for HMB were acceptable as per Food and Drug Administration guidelines. HMB was stable in the battery of stability studies, viz. bench‐top, autosampler freeze–thaw cycles and long‐term stability for 30 days in plasma. The developed assay method was applied to a bioavailability study in rats. Copyright © 2012 John Wiley & Sons, Ltd.     

Simultaneous determination of trifolirhizin, (–)‐maackiain, (–)‐sophoranone,and 2‐(2,4‐dihydroxyphenyl)‐5,6‐methylenedioxybenzofuran from Sophora tonkinensis in rat plasma by liquid chromatography with tandem mass spectrometry and its application to a pharmacokinetic study

A new liquid chromatography with tandem mass spectrometry method was developed and validated for the simultaneous determination of trifolirhizin, (–)‐maackiain, (–)‐sophoranone, and 2‐(2,4‐dihydroxyphenyl)‐5,6‐methylenedioxybenzofuran from Sophora tonkinensis in rat plasma using chlorpropamide as an internal standard. Plasma samples (50 μL) were prepared using a simple deproteinization procedure with 150 μL of acetonitrile containing 100 ng/mL of chlorpropamide. Chromatographic separation was carried out on an Acclaim RSLC120 C₁₈ column (2.1 × 100 mm, 2.2 μm) using a gradient elution consisting of 7.5 mM ammonium acetate and acetonitrile containing 0.1% formic acid (0.4 mL/min flow rate, 7.0 min total run time). The detection and quantitation of all analytes were performed in selected reaction monitoring mode under both positive and negative electrospray ionization. This assay was linear over concentration ranges of 50–5000 ng/mL (trifolirhizin), 25–2500 ng/mL ((–)‐maackiain), 5–250 ng/mL ((–)‐sophoranone), and 1–250 ng/mL 2‐(2,4‐dihydroxyphenyl)‐5,6‐methylenedioxybenzofuran) with a lower limit of quantification of 50, 25, 5, and 1 ng/mL for trifolirhizin, (–)‐maackiain, (–)‐sophoranone, and 2‐(2,4‐dihydroxyphenyl)‐5,6‐methylenedioxybenzofuran, respectively. All the validation data, including the specificity, precision, accuracy, recovery, and stability conformed to the acceptance requirements. The results indicated that the developed method is sufficiently reliable for the pharmacokinetic study of the analytes following oral administration of Sophora tonkinensis extract in rats.     

Determination of a hydrophilic paclitaxel derivative, 7‐xylosyl‐10‐deacetylpaclitaxel in rat plasma by LC–MS/MS

A LC‐MS/MS method for the determination of a hydrophilic paclitaxel derivative 7‐xylosyl‐10‐deacetylpaclitaxel in rat plasma was developed to evaluate the pharmacokinetics of 7‐xylosyl‐10‐deacetylpaclitaxel in the rats. 7‐Xylosyl‐10‐deacetylpaclitaxel and docetaxel (IS for 7‐xylosyl‐10‐deacetylpaclitaxel) were extracted from rat plasma with acetic ether and analyzed on a Hypersil C₁₈ column (4.6 × 150 mm i.d., particle size 5 µm) with the mobile phase of ACN/0.05% formic acid (50:50, v/v). The analytes were detected using an ESI MS/MS in the multiple reaction monitoring mode. The standard curves for 7‐xylosyl‐10‐deacetylpaclitaxel in plasma were linear (r >0.999) over the concentration range of 2.0–1000 ng/mL with a weighting of 1/concentration². The method showed a satisfactory sensitivity (2.0 ng/mL using 50 µL plasma), precision (CV ≤ 10.1%), accuracy (relative error ?12.4 to 12.0%), and selectivity. This method was successfully applied to the pharmacokinetic study of 7‐xylosyl‐10‐deacetylpaclitaxel in rat plasma after intravenous administration of 7‐xylosyl‐10‐deacetylpaclitaxel to female Wistar rats. Copyright © 2008 John Wiley & Sons, Ltd.     

Simultaneous determination of β‐sitosterol,campesterol, and stigmasterol in rat plasma by using LC–APCI‐MS/MS: Application in a pharmacokinetic study of a titrated extract of the unsaponifiable fraction of Zea mays L.

A liquid chromatography with atmospheric pressure chemical ionization tandem mass spectrometry method was developed and validated to investigate the pharmacokinetic properties of β‐sitosterol, campesterol, and stigmasterol in rat plasma. Cholesterol‐d₆ was used as an internal standard. To avoid interference of the three phytosterols in rat plasma and minimize matrix effects, a small volume (10 μL) of 4% bovine serum albumin was used as a surrogate matrix for making calibrators and quality control samples. Rat plasma (10 μL) samples were extracted by liquid–liquid extraction with methyl tert‐butyl ether and separated on a Kinetex C₁₈ column. The detection was performed on a triple quadrupole tandem mass spectrometer in selected reaction monitoring mode using positive atmospheric pressure chemical ionization. This assay was linear over concentration ranges of 250–5000 ng/mL (β‐sitosterol), 250–5000 ng/mL (campesterol), and 50–2000 ng/mL (stigmasterol). Additionally, a second set of quality controls made in rat plasma was also evaluated against calibration curves made using the surrogate matrix. All the validation data, including the specificity, precision, accuracy, recovery, matrix effect, stability, and incurred sample reanalysis conformed to the acceptance requirements. Our method was successfully applied to study the pharmacokinetics of three phytosterols in rats.     

Simultaneous quantification of multiple active components from Xiexin decoction in rat plasma by LC‐ESI‐MS/MS: application in pharmacokinetics

A sensitive and specific liquid chromatography–electrospray ionization–tandem mass spectrometric (LC‐ESI‐MS/MS) method was developed and validated to simultaneously quantify 11 active compounds (coptisine, jatrorrhizine, berberine, palmatine, baicalin, baicalein, wogonoside, wogonin, rhein, emodin and aloeemodin) from Xiexin decoction (XXD) in rat plasma. Plasma samples extracted by a single‐step protein precipitation procedure were separated using the gradient mode on a Dikma ODS‐C₁₈ column. Selected reaction monitoring scanning was employed for quantification with switching electrospray ion source polarity between positive and negative modes in a single run. Calibration curves offered satisfactory linearity (r > 0.995) at linear range of 0.47–60 ng/mL for coptisine, jatrorrhizine, berberine and palmatine, 15–1930 ng/mL for baicalin, 20–2560 ng/mL for baicalein, 14–1790 ng/mL for wogonoside, 0.57–72.8 ng/mL for wogonin, 10–1280 ng/mL for rhein, 0.6–76.8 ng/mL for emodin and 3.0–384 ng/mL for aloeemodin. The intra‐ and interday precisions were less than 10.2% in terms of relative standard deviation (RSD), and the accuracies were within ±10.84% in terms of relative error (RE). It was successfully applied to the evaluation of pharmacokinetics after single oral doses of XXD were administered to rats. Copyright © 2010 John Wiley & Sons, Ltd.     

Simultaneous determination of baicalin,oroxylin A‐7‐O‐glucuronide and wogonoside in rat plasma by UPLC‐DAD and its application in pharmacokinetics of pure baicalin,Radix Scutellariae and Yinhuang granule

A novel UPLC‐DAD method was developed and validated for the simultaneous determination of baicalin (baicalein‐7‐glucuronide, BG), oroxylin A‐7‐O‐glucuronide (OAG) and wogonoside (WG) in rat plasma using rutin as the internal standard. Plasma samples were precipitated using acetonitrile containing 0.1% formic acid. Separation was performed on an Agilent Eclipse Plus C₁₈ column (2.1 × 50 mm, 1.8 µm) using gradient acetonitrile and 0.2% formic acid water solution as mobile phase. The flow‐rate was set at 0.4 mL/min and the eluate was detected at 275 nm. The method was linear over the ranges of 0.075–17.50, 0.050–12.60 and 0.056–14.10 µg/mL for BG, OAG and WG, respectively. The intra‐ and inter‐day precisions were respectively <4.8% and 6.4%. All of the limits of detection of three analytes in rat plasma were 0.01 µg/mL, whereas the limits of quantification were, respectively, 0.035, 0.025 and, 0.025 µg/mL. This assay has been successfully applied to pharmacokinetics of BG, OAG and WG in rats after oral administration of Yinhuang granule (YHG) and comparative pharmacokinetics of BG in rats following oral administration of the pure BG, Radix Scutellariae (RS) or YHG. We speculate that some co‐existing ingredients in RS or YHG may increase the absorption and elimination of BG in rat. This work may be helpful for the quality control of Yinhuang granule. Copyright © 2015 John Wiley & Sons, Ltd.     

Quantitative determination of paclitaxel and its metabolites, 6α‐hydroxypaclitaxel and p‐3′‐hydroxypaclitaxel,in human plasma using column‐switching liquid chromatography/tandem mass spectrometry

A column‐switching liquid chromatography/electrospray ionization tandem mass spectrometry to determine paclitaxel and its metabolites, 6α‐hydroxypaclitaxel and p‐3′‐hydroxypaclitaxel, in human plasma was developed. The analytical system had a Shim‐Pack MAYI‐ODS (10 × 4.6 mm i.d.) trapping column with deproteinization ability that concentrates analytes and removes water‐soluble components. This method covered a linearity range of 5–5000 ng/mL of concentrations in plasma for paclitaxel, a range of 0.87–870 ng/mL for 6α‐hydroxypaclitaxel and a range of 0.87–435 ng/mL for p‐3′‐hydroxypaclitaxel. The intra‐day precision and inter‐day precision of analysis were less than 11.1%, and the accuracy was within ±14.4% at concentrations of 5, 50, 500 and 5000 ng/mL for paclitaxel, 0.87, 8.7, 87 and 870 ng/mL for 6α‐hydroxypaclitaxel, and 0.87, 8.7, 87 and 435 ng/mL for p‐3′‐hydroxypaclitaxel. The total run time was 30 min. Our method was successfully applied to clinical pharmacokinetic investigation. Copyright © 2012 John Wiley & Sons, Ltd.     

Simultaneous determination of major components of Huangqi–Honghua extract in rat plasma using LC–MS/MS and application to a pharmacokinetic study

A sensitive and reliable LC–MS/MS method was developed and validated for simultaneous quantification of the major components of Huangqi–Honghua extact in rat plasma, including hydroxysafflor yellow A (HSYA), astragaloside IV (ASIV), calycosin‐7‐O‐β‐d ‐glucoside (CAG), calycosin, calycosin‐3′‐O‐glucuronide (C‐3′‐G) and calycosin‐3′‐O‐sulfate (C‐3′‐S). After extraction by protein precipitation with acetonitrile and methanol from plasma, the analytes were separated on a Hypersil BDS C₁₈ column by gradient elution with acetonitrile and 5 mM ammonium acetate. The detection was carried out on a triple quadrupole tandem mass spectrometer equipped with electrospray ionization source switched between negative and positive modes. HSYA was monitored in negative ionization mode from 0 to 4.9 min, and ASIV, CAG, calycosin, C‐3′‐G and C‐3′‐S were determined in positive ionization mode from 4.9 to 10 min. The lower limits of quantification of the analytes were 6.25 ng/mL for HSYA, 0.781 ng/mL for CAG and 1.56 ng/mL for ASIV and calycosin. The intra‐ and inter‐assay precision (RSD) values were within 13.43%, and accuracy (RE) ranged from ?8.75 to 9.92%. The validated method was then applied to the pharmacokinetic study of HSYA, ASIV, CAG, calycosin, C‐3′‐G and C‐3′‐S in rat after an oral administration of Huangqi–Honghua extract.     

A validated HPLC‐MS/MS method for determination of genipin‐1‐o‐glucuronic acid in rat plasma after administration of genipin and its application to a pharmacokinetic study

A sensitive and specific method was developed and validated for the quantitation of one major metabolite of genipin in rats plasma. The major metabolite was isolated from rat bile via semi‐preparative HPLC technology and its chemical structure was identified as genipin‐1‐o‐glucuronic acid (GNP‐GLU), which was for the first time used as a standard compound for quantitative analysis in rat plasma after administration of genipin. The application of high‐performance liquid chromatography–tandem mass spectrometry in negative mode in multiple reaction monitoring mode was investigated. Chromatographic separation was achieved on an Eclipse XDB‐C₁₈ column using a mobile phase consisting of water with 0.1% formic acid (A)–acetonitrile (B). The limit of detecation was 0.214 ng/mL and the lower limit of quantification was 0.706 ng/mL. The calibration curve was linear from 1.27 to 3810 ng/mL for plasma samples, with a correlation coefficient of 0.9924. The intra‐ and inter‐day precisions and accuracy were all within 15%. The recoveries of GNP‐GLU and puerarin were above 90.0 and 76.2%, respectively. The highly sensitive method was successfully applied to estimate pharmacokinetic parameters of GNP‐GLU following oral and intravenous administration of genipin to rats. Copyright © 2013 John Wiley & Sons, Ltd.     

Quantitative determination of β,β‐dimethylacrylshikonin (DASK) in rat whole blood by liquid chromatography–tandem mass spectrometry with pre‐column derivation and its pharmacokinetic application

A sensitive and selective liquid chromatography–tandem mass spectrometric (LC‐MS/MS) method was developed and validated for the determination of β,β‐dimethylacrylshikonin (DASK) in rat whole blood. DASK was pretreated using pre‐column derivatization with 2‐mercaptoethanol followed by liquid–liquid extraction with cyclohexane. Detection was performed on Thermo Finnigan TSQ Quantum triple quadrupole mass spectrometer by selected reaction monitoring mode via electrospray ionization source. The linear range for the determination of DASK spiked in rat whole blood (0.25 mL) was 3–3000 ng/mL. The accuracy was within 9%. Intra‐ and inter‐day precisions were no more than 16.1 and 13.3%, respectively. The validated LC‐MS/MS method was successfully applied to the preliminary pharmacokinetic study in rats. After DASK administration (60 mg/kg, p.o.) in rats, pharmacokinetic parameters were obtained, where the area under the drug concentration–time curve was 2393.7 ± 224.4 ng h/mL and the elimination half‐life was 27.6 ± 5.3 h. Copyright © 2008 John Wiley & Sons, Ltd.     

Rapid and sensitive LC‐MS method for pharmacokinetic study of vinorelbine in rats

A rapid and sensitive LC‐electrospray ionization‐MS method was developed for determining vinorelbine in rat plasma. A 100 µL plasma sample was treated using a protein precipitation procedure and was chromatographed within 4 min using an Inertsil ODS‐3 C₁₈ (2.1 × 50 mm, 5 µm) column. The selected ion monitoring ions [M + H]⁺ were m/z 779 and m/z 811 for vinorelbine and vinblastine (internal standard), respectively. The method validation showed that the calibration curve for vinorelbine was linear over a concentration range of 1–1000 ng/mL with lower limit of quantification at 1 ng/mL. The method has been successfully applied to pharmacokinetics in rat plasma. Copyright © 2009 John Wiley & Sons, Ltd.     

Comparative pharmacokinetics study of a kaurane diterpenoid after oral administration of monomer and Siegesbeckiae pubescens Makino extract to rats

In this paper, a sensitive, rapid and reproducible high‐performance liquid chromatography–tandem mass spectrometry method was developed to analyze 16α‐hydro‐ent‐kauran‐17,19‐dioic acid in rat plasma. First, this study compared the pharmacokinetics of 16α‐hydro‐ent‐kauran‐17,19‐dioic acid after oral administration of monomer and Siegesbeckiae pubescens Makino extract in rat plasma with approximately the same dosage of 6.0 mg/kg. Second, chromatographic separation was performed on a Waters Symmetry C₁₈ column (2.1 × 100 mm, 3.5 µm) with isocratic elution using methanol–water containing 5 mmol/L ammonium acetate (70:30, v/v) as mobile phase at a flow rate of 0.2 mL/min. The calibration curves were linear over the range of 30–12000 ng/mL for monomer. At different time points (0, 0.083, 0.25, 0.75, 1, 2, 4, 6, 8, 12, 18, 24, 36, 48, 60 and 72 h) after administration, the concentrations of monomer in rat plasma were determined and main pharmacokinetic parameters were estimated. The double absorption presented in this study indicates that the pharmacokinetics of monomer in rat plasma have significant differences between different groups. Copyright © 2013 John Wiley & Sons, Ltd.     

Ultra‐high performance liquid chromatography with tandem mass spectrometry method for the simultaneous quantitation of five phthalides in rat plasma: Application to a comparative pharmacokinetic study of Huo Luo Xiao Ling Dan and herb‐pair extract

A fast, sensitive, and reliable ultra‐high performance liquid chromatography with tandem mass spectrometry method has been developed and validated for the simultaneous quantitation and pharmacokinetic study of five phthalides (senkyunolide A, ligustilide, butylidenephthalide, 3‐butylphthalide, and levistilide A) in rat plasma after oral administration of Huo Luo Xiao Ling Dan (HLXLD) or Angelica sinensis‐‐Ligusticum chuanxiong herb pair (DG‐CX) between normal and arthritis rats. After extraction from blood, the analytes and internal standard were subjected to ultra‐high performance liquid chromatography with a Shim‐pack XR‐ODS column (75 × 3.0 mm², 2.2 μm particles) and mobile phase was composed of methanol and water (containing 0.05% formic acid) under gradient elution conditions, with an electrospray ionization source in the positive ionization and multiple reaction monitoring mode. The lower limits of quantification were 0.192–0.800 ng/mL for all the analytes. Satisfactory linearity, precision, accuracy, mean extraction recovery, and acceptable matrix effect have been achieved. The validated method was successfully applied to a comparative pharmacokinetic study of five bioactive components in rat plasma after oral administration of HLXLD or DG‐CX alone, respectively, between normal and arthritic rats. The results showed that there were unlike characters of pharmacokinetics among different groups.