On‐line 2D‐LC‐ESI/MS/MS determination of rifaximin in rat serum

A highly sensitive and selective on‐line two‐dimensional reversed‐phase liquid chromatography/electrospray ionization–tandem mass spectrometry (2D‐LC‐ESI/MS/MS) method was developed and validated to determine rifaximin in rat serum by direct injection. The 2D‐LC‐ESI/MS/MS system consisted of a restricted access media column for trapping proteins as the first dimension and a Waters C₁₈ column as second dimension using 0.1% aqueous acetic acid:acetonitrile as mobile phase in a gradient elution mode. Rifampacin was used as an internal standard. The linear dynamic range was 0.5–10 ng/mL (r² > 0.998). Acceptable precision and accuracy were obtained over the calibration range. The assay was successfully used in analysis of rat serum to support pharmacokinetic studies. Copyright © 2009 John Wiley & Sons, Ltd.     

A sensitive and specific liquid chromatography/tandem mass spectrometry method for determination of echinacoside and its pharmacokinetic application in rats

A rapid and sensitive method based on liquid chromatography/tandem mass spectrometry (LC/MS/MS) for the determination of echinacoside in rat plasma was established and fully validated. A single step of liquid–liquid extraction with n‐butanol was utilized. Chromatographic separation of the analyte and the internal standard (IS), chlorogenic acid, from the sample matrix was performed using a Capcell‐MG C₁₈ analytical column (100 2.0 mm × 5 µm), with a gradient of acetonitrile and water containing 0.1% acetic acid as the mobile phase. Detection was performed on a triple quadrupole tandem mass spectrometer equipped with electrospray ionization source operated in negative ion selected reaction monitoring mode. The method was linear in the concentration range 10–2500 ng/mL. The deviations of both intra‐ and inter‐day precisions (RSD) were 7.1% and the assay accuracies were within 99.2–106.5%. Echinacoside proved to be stable during sample storage, preparation and analysis when an antioxidant solution was used. The method was successfully applied to a pharmacokinetic study in rats after an intragastric administration of echinacoside (100 mg/kg). With the lower limit of quantification at 10 ng/mL, this method proved to have sufficient selectivity, sensitivity and reproducibility for the pharmacokinetic study of echinacoside. Copyright © 2009 John Wiley & Sons, Ltd.     

Quantification of montelukast,a selective cysteinyl leukotriene receptor (CysLT1) antagonist in human plasma by liquid chromatography–mass spectrometry: validation and its application to a human pharmacokinetic study

A highly sensitive, rapid assay method has been developed and validated for the estimation of montelukast (MTK) in human plasma with liquid chromatography coupled to tandem mass spectrometry with electro spray ionization in the positive‐ion mode. Liquid–liquid extraction was used to extract MTK and amlodipine (internal standard, IS) from human plasma. Chromatographic separation was achieved with 10 mm ammonium acetate (pH 6.4): acetonitrile (15:85, v/v) at a flow rate of 0.50 mL/min on a Discovery HS C₁₈ column with a total run time of 3.5 min. The MS/MS ion transitions monitored were 586.10 → 422.10 for MTK and 409.20 → 238.30 for IS. Method validation and clinical sample analysis were performed as per FDA guidelines and the results met the acceptance criteria. The lower limit of quantitation achieved was 0.25 ng/mL and linearity was observed from 0.25 to 800 ng/mL. The intra‐day and inter‐day precisions were 5.97–8.33 and 7.09–10.13%, respectively. This novel method has been applied to a pharmacokinetic study of MTK in humans. Copyright © 2009 John Wiley & Sons, Ltd.     

Determination of the novel antiarrhythmic drug sulcardine sulfate in human plasma by liquid chromatography tandem mass spectrometry and its application in a clinical pharmacokinetic study

Sulcardine sulfate (Sul), a novel antiarrhythmic agent, is currently in phase I and phase II clinical trials. To elucidate its clinical pharmacokinetic characteristics, a rapid and accurate liquid chromatography–tandem mass spectrometry (LC–MS/MS) method has been developed and validated for the quantification of Sul in human plasma. Plasma samples were precipitated by acetonitrile and isotope‐labeled sulcardine was added as internal standard. The analysis was carried out on a Capcell Pak C₁₈ MG III column (100 × 2.0 mm, 5 μm) with 0.1% formic acid in acetonitrile solution and water (17:83, v/v) as mobile phase. The linear range was 5.0–1000 ng/mL for Sul, with a lower limit of quantification of 5.0 ng/mL. The intra‐ and inter‐batch CVs were within ±11.0% and the accuracies were 4.9–107.3%. Our method, for the first time, allows the rapid (only 3.0 min) and accurate quantification of Sul in human plasma. The method has been successfully applied in the pharmacokinetic study of Sul in a clinical trial following oral administration of Sul to healthy volunteers. Copyright © 2016 John Wiley & Sons, Ltd.     

Development and validation of a quantification method for oleanolic acid and hederagenin in rat plasma: application to the pharmacokinetic study

A rapid and sensitive liquid chromatography tandem mass spectrometry (LC–MS/MS) was developed and validated for simultaneous quantification of oleanolic acid and hederagenin in rat plasma. After the two analytes were extracted with liquid–liquid extraction, chromatographic separation was performed on a C₁₈ column with acetonitrile and water (85:15, v /v) as mobile phase at a flow rate of 0.4 mL/min. Calibration curves exhibited good linearity (r > 0.995) over the ranges of 0.41–82.0 ng/mL for oleanolic acid and 0.32–64.0 ng/mL for hederagenin, respectively. The lower limit of quantifications (LLOQs) in plasma were 0.41 ng/mL for oleanolic acid and 0.32 ng/mL for hederagenin. The established LLOQs were within the concentration needed for the assay in plasma, which met the requirements to evaluate their pharmacokinetics of oleanolic acid and hederagenin. This developed assay was successfully applied in the pharmacokinetic study of oleanolic acid and hederagenin in rats after oral administration of Rhizoma Clematidis extract.     

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.     

Development and validation of a liquid chromatography–tandem mass spectrometry method for quantitation of indomethacin in rat plasma and its application to a pharmacokinetic study in rats

A highly sensitive and rapid bioanalytical method has been developed and validated for the estimation of indomethacin in rat plasma with liquid chromatography coupled to tandem mass spectrometry with electrospray ionization in the positive‐ion mode. The assay procedure involves a simple liquid–liquid extraction of indomethacin and phenacetin (internal standard, IS) from rat plasma with acetonitrile. Chromatographic separation was achieved with 0.2% formic acid–acetonitrile (25:75, v/v) at a flow rate of 0.60 mL/min on an Atlantis dC₁₈ column with a total run time 3.0 min. The MS/MS ion transitions monitored were 357.7 → 139.1 for indomethacin and 180.20 → 110.10 for IS. Method validation and pharmacokinetic study plasma analysis were performed as per FDA guidelines and the results met the acceptance criteria. The lower limit of quantitation achieved was 0.51 ng/mL and the linearity was observed from 0.51 to 25.5 ng/mL. The intra‐ and inter‐day precisions were in the range of 1.00–10.2 and 5.88–9.80%, respectively. This novel method has been applied to an oral pharmacokinetic study in rats. Copyright © 2012 John Wiley & Sons, Ltd.     

Determination of urinary androgen glucuronides by capillary electrophoresis with electrospray tandem mass spectrometry

Capillary electrophoresis–electrospray tandem mass spectrometry (CE‐ESI/MS/MS) is a simple and highly sensitive method for quantifying seven urinary androgen glucuronides. The urine samples were diluted and filtered through a membrane filter, and the filtrate was injected into a CE‐MS/MS system without further sample preparation steps such as extraction and derivatization. The calibration ranges were 0.01–5 µg/mL for glucuronides of androsterone and 11β‐OHAn‐3G, and 5–500 ng/mL for glucuronides of 11‐ketoAn, DHEA, testosterone, epitestosterone and DHT. The linearity of the method was 0.992–0.998, and the limits‐of‐detection at a signal‐to‐noise ratio of 3 were 5–10 ng/mL. The coefficients of variation were in the range of 4.0–9.0% for intra‐day assay and 4.1–9.8% for inter‐day assay. The proposed method may be applicable to metabolic profiling in both quantitative and qualitative analysis. Copyright © 2008 John Wiley & Sons, Ltd.     

Determination of teniposide in rat plasma by ultra performance liquid chromatography electrospray ionization tandem mass spectrometry after intravenous administration

A novel, specific and rapid ultra performance liquid chromatography electrospray ionization tandem mass spectrometry method has been developed and validated for determination of teniposide in rat plasma. A one‐step liquid–liquid extraction method was used and the separation was carried out on an Acquity UPLC^TM BEH C₁₈ column with gradient elution using a mobile phase composed of acetonitrile and water (containing 0.1% formic acid) at a flow rate of 0.20 mL/min. A triple quadrupole tandem mass spectrometer in multiple‐reaction monitoring mode via an electrospray ionization interface was used for the detection of teniposide. The detection was complete within 3.0 min. A linear calibration curve was obtained over the concentration range 10–10,000 ng/mL for teniposide, with a lower limit of quantification of 10 ng/mL. The intra‐day precision and inter‐day precision (relative standard deviation) were less than 10.23 and 13.09%, respectively. The developed method was applied for the first time to the pharmacokinetic study of teniposide in rats following a single intravenous administration of 4.5 mg/kg teniposide. Copyright © 2009 John Wiley & Sons, Ltd.     

An LC‐MS/MS method for determination of calceorioside B with cardiomyocyte protective activity in rat plasma and application to a pharmacokinetic study

A simple, sensitive and rapid liquid chromatography–tandem mass spectrometry (LC‐MS/MS) method was developed and validated for the determination of calceorioside B (CLB) in rat plasma. Detection was performed on a Thermo Scientific Hypersil Gold chromatography column using isocratic elution with a mobile phase of methanol–5 m m ammonium acetate–formic acid (70:30:0.1, v/v/v). Mass spectrometry was performed in selection reaction monitoring mode using a positive electrospray ionization interface. Good linearity was found for CLB in plasma in the linear range of 1.00–500 ng/mL (r > 0.9960). The validated method was successfully applied to the pharmacokinetic study of CLB in rats. Copyright © 2015 John Wiley & Sons, Ltd.     

Noninvasive determination of human cortisol and dehydroepiandrosterone sulfate using liquid chromatography-tandem mass spectrometry

Liquid chromatography-tandem mass spectrometry (LC-MS/MS) for measurements of steroids in human saliva has garnered increased interest in the area of clinical psychoneuroendocrinological research. However, performance characteristics of LC-MS/MS methods for the analysis of steroids in saliva are limited. Human saliva samples were collected via passive drool. Cortisol and dehydroepiandrosterone sulfate (DHEA-S) in the samples were extracted together, resolved on a C18-A column, and analyzed using tandem mass spectrometry. The LC-MS/MS method had limits of quantitation of 0.03 and 0.06 ng/mL for DHEA-S and cortisol, respectively. Method evaluations showed coefficient variation (%CV) of inter-assay ranging 4.6–17.9% for DHEA-S and cortisol, recoveries of 102.4–109.5% for DHEA-S and 94.6–98.3% for cortisol, and assay linearity with R² = 0.9964 for DHEA-S (1.0–25.0 ng/mL) and R² = 0.997 (1.0–25.0 ng/mL) for cortisol. No cross contamination among samples was observed. Human saliva showed 20% and 18% ion enhancement effect for DHEA-S and cortisol assay, respectively. No interference by ten common steroids was detected. Regression analysis of method comparisons with laboratory-developed test (LDT) method revealed R² = 0.9688 (LC-MS/MS = 0.9665 LDT-LC-MS/MS − 0.7355) for cortisol, and R² = 0.9039 (LC-MS/MS = 1.0173 LDT-LC-MS/MS + 3.6797) for DHEA-S. Reference ranges for young adults were determined to be 0.3–5.9 ng/mL for females and 0.1–5.6 ng/mL for males for salivary cortisol, and 0.6–7.4 ng/mL for females and 0.6–10.1 ng/mL for males for salivary DHEA-S. An LC-MS/MS method for quantifying cortisol and DHEA-S in human saliva was developed and validated for clinical and psychoneuroendocrinological research that require noninvasive means of measuring these hormones.

     

Ultra‐performance liquid chromatography‐tandem mass spectrometry method for the determination of febuxostat in dog plasma and its application to a pharmacokinetic study

A rapid, sensitive and selective ultra‐performance liquid chromatography–tandem mass spectrometry (UPLC–MS/MS) method was developed and validated for the determination of febuxostat in dog plasma. Using paclitaxel as an internal standard (IS), a simple liquid–liquid extraction method with ethyl acetate was adopted for plasma sample pretreatment. Separation was carried out on an Acquity UPLC BEH C₁₈ column with a mobile phase consisting of acetonitrile and water (containing 0.2% formic acid). The assay was linear in the concentration ranged from 5 to 5000 ng/mL with a lower limit of quantification of 5 ng/mL for febuxostat. The single run analysis was as short as 2.0 min. Finally, the developed method was successfully applied to the pharmacokinetic study of febuxostat tablets following oral administration at a single dose of 40 mg in beagle dogs. Copyright © 2012 John Wiley & Sons, Ltd.     

Simultaneous determination of the bioactive components in rat plasma by UPLC‐MS/MS and application in pharmacokinetic studies after oral administration of radix Scutellariae extract

A highly sensitive and rapid ultraperformance liquid chromatography–tandem mass spectrometry (UPLC‐MS/MS) method has been developed and validated for simultaneous quantification of the four main bioactive compounds, i.e. baicalin, baicalein, wogonoside and wogonin, in rat plasma after oral administration of Radix Scutellariae extract. Clarithromycin was used as an internal standard (IS). Plasma samples were processed by protein precipitation with methanol. The separation was performed on an Acquity BEH C₁₈ column (100 × 2.1 mm, 1.7 μm) at a flow rate of 0.4 mL/min, using 0.1% formic acid–acetonitrile as mobile phase. The MS/MS ion transit ions monitored were 447.5 → 270.1 for baicalin, 270.1 → 168.1 for baicalein, 461.2 → 284.0 for wogonoside, 284.2 → 168.1 for wogonin and 748.5 → 158.1 for IS. Method validation was performed according to US Food and Drug Administration guidelines and the results met the acceptance criteria. The lower limit of quantification (LLOQ) achieved was 1.13 ng/mL for baicalin, 1.23 ng/mL for baicalein, 0.82 ng/mL for wogonoside and 0.36 ng/mL for wogonin. The calibration curves obtained were linear (r > 0.99) over the concentration range ~ 1–1000 ng/mL. The intra‐ and inter‐day precision was <15% and the accuracy was within ±14.7%. After validation, this method was successfully applied to a pharmacokinetic study of Radix Scutellariae extract.     

Determination of ospemifene in human plasma by LC–MS/MS and its application to a human pharmacokinetic study

A highly sensitive, specific and rapid liquid chromatography–tandem mass spectrometry (LC–MS/MS) analytical method has been developed and validated for the determination of ospemifene in human plasma using ospemifene‐d₄ as an internal standard. Solid‐phase extraction technique with Phenomenex Strata X‐33 μm polymeric sorbent cartridges (30 mg/1 mL) was used to extract the analytes from the plasma. The chromatographic separation was achieved on Agilent Eclipse XDB‐Phenyl, 4.6 × 75 mm, 3.5 μm column using the mobile phase composition of methanol and 20 mm ammonium formate buffer (90:10, v/v) at a flow rate of 0.9 mL/min. A detailed method validation was performed as per the US Food and Drug Administration guidelines and the calibration curve obtained was linear (r² = 99) over the concentration range 5.02–3025 ng/mL. The API‐4500 MS/MS was operated under multiple reaction monitoring mode during the analysis. The proposed method was successfully applied to a pharmacokinetic study in healthy human volunteers after oral administration of an ospemifene 60 mg tablet under fed conditions.     

Pharmacokinetic studies of soyalkaloid A from Portulaca oleracea L. using ultra high‐performance liquid chromatography electrospray ionization quadrupole–time of flight mass spectrometry and its antioxidant activity

Soyalkaloid A was isolated from Portulaca oleracea L. for the first time in our laboratory and then a rapid and sensitive ultra‐high‐performance liquid chromatography electrospray ionization quadrupole–time of flight mass spectrometry (UHPLC–ESI–Q–TOF/MS) method with hesperidin as internal standard (IS) was developed and validated to investigate the pharmacokinetics of soyalkaloid A in rats after oral and intravenous administrations. The analysis was achieved on an Agilent Zorbax Eclipse Plus C₁₈ Column (2.1 × 50 mm, 1.8 μm) by elution with acetonitrile and water (containing 0.1% formic acid), at a flow rate of 0.3 mL/min. The MS analysis was performed in the positive ion mode with monitored ion m/z 227.0814 [M + H]⁺ and 611.1971 [M + H]⁺ for soyalkaloid A and IS, respectively. The linear range was established over the concentration range 7.5–6000 ng/mL (r = 0.9951). The intra‐ and inter‐assay accuracy and precision were between ?4.86‐4.49 and 1.93–9.66, respectively. The lower limits of detection and quantitation observed were 2.1 and 7.4 ng/mL, respectively. The rapid, sensitive and specific UHPLC–ESI–Q–TOF/MS method was successfully applied to a pharmacokinetic study of soyalkaloid A. Moreover, its antioxidant was studied via a 1,1‐diphenyl‐2‐picryl‐hydrazyl radical scavenging assay, the IC₅₀ value being 20.73 ± 0.51 μM.     

GC–MS/MS method for the determination and pharmacokinetic analysis of borneol and muscone in rat after the intravenous administration of Xingnaojing injection

A simple and sensitive gas chromatography with tandem mass spectrometry method was developed and validated for the simultaneous determination of borneol and muscone in rat plasma. The analytes and internal standard, naphthalene, were extracted using a convenient one‐step liquid–liquid extraction method with ethyl acetate. The chromatographic separation was realized on a HP‐5MS capillary column and detected in multiple reaction monitoring mode. Excellent linearity (R ² ≥ 0.996) was shown over 10.0–5000 ng/mL for borneol and 2.5–250 ng/mL for muscone. The lower limit of quantitation was 10 and 2.5 ng/mL for borneol and muscone, respectively. The intra‐ and interday precisions were less than 7.52%, and the accuracy values were between  −8.03 and 14.52%. The extraction recovery, matrix effect, and stability were sufficient to meet the Food and Drug Administration criteria. Meanwhile, the assay was successfully applied to the preclinical pharmacokinetic study of borneol and muscone following intravenous administration of Xingnaojing injection, a modern Chinese herbal medicine preparation.     

Determination of penciclovir in human plasma by liquid chromatography-electrospray ionization tandem mass spectrometry: application to a clinical pharmacokinetic study

A rapid, specific and sensitive liquid chromatography tandem mass spectrometry (LC–MS/MS) method was developed for the determination of penciclovir in human plasma. The method involved simple, one‐step SPE procedure coupled with a C₁₈, 75 × 4.mm, 3µm column with a flow‐rate of 0.5 mL/min, and acyclovir was used as the internal standard. The Quattro Micro mass spectrometry was operated under the multiple reaction‐monitoring mode using the electrospray ionization technique. Using 250 µL plasma, the methods were validated over the concentration range 52.555–6626.181 ng/mL, with a lower limit of quantification of 52.55 ng/mL. The intra‐ and inter‐day precision and accuracy values were found to be within the assay variability limits as per the FDA guidelines. The developed assay method was applied to a clinical pharmacokinetic study in human volunteers. Copyright © 2010 John Wiley & Sons, Ltd.     

An LC-MS/MS method for simultaneous determination of vincristine and verapamil in rat plasma after oral administration of a dual agent formulation

A rapid and sensitive method for simultaneous determination of vincristine and verapamil in rat plasma was first developed and validated, using high‐performance liquid chromatography–tandem mass spectrometry (LC‐MS/MS) in multiple reaction monitoring (MRM) mode via electrospray ionization (ESI). The method, which required a small sample volume (25 µL) of plasma, was linear in the concentration range of 0.5–500 ng/mL for vincristine and 0.1–100.0 ng/mL for verapamil. Finally, the method was successfully employed in a pharmacokinetic study of vincristine and verapamil in rats after an oral administration of a dual‐agent formulation containing vincristine and verapamil. Copyright © 2010 John Wiley & Sons, Ltd.     

Development and validation of novel LC–MS/MS method for determination of Lusutrombopag in rat plasma and its application to pharmacokinetic studies

A novel, simple and sensitive method for the determination of Lusutrombopag in rat plasma using liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS) was developed and validated. The determination was performed on an API4000 triple quadrupole mass spectrometry in the multiple reaction monitoring mode using the respective [M+H]⁺ ions m/z 593.1 → 272.3 for Lusutrombopag. The limit of detection was 0.5 ng/mL, and the lower limit of quantification was 2.0 ng/mL in rat plasma. Good linearity was obtained over the range of 2.0–150.0 ng/mL and the correlation coefficient was found to be 0.9998. The intra and inter-day precisions were found to be 3.8–6.9% and 6.8–10.5%, respectively. The intra and inter-day accuracy derived from QC samples was found to be 2.5–4.9% and 5.5–7.2%, respectively. The analyte was stable under various conditions (at room temperature, during freeze-thaw, in the autosampler and under deep-freeze conditions). The F-test and t-test at 95% confidence level were subjected on data for statistical analysis. The developed method was successfully applied to the pharmacokinetic study in rats.     

Quantification of sofosbuvir in human serum by liquid chromatography with negative ionization mass spectrometry using the parent peak and its source‐induced fragment: Application to a bioequivalence study

In the mass spectrometry of sofosbuvir, a new orally administered antihepatitis C drug, a weak peak is detected at the m/z value of the parent ion (m/z 530) as a result of in‐source dissociation and current methods to its quantification, is based on monitoring of the parent peak using ultra high‐performance liquid chromatography with tandem mass spectrometry. With these methods serum concentration of the drug is quantifiable only up to 4–5 h postdose. However, the fragmentation of the molecule generates a more stable ion at m/z 287 (base peak) with a signal intensity of about tenfold compared to the parent ion. Our study was aimed to improve sensitivity of analysis by acquisition of the m/z value of the daughter ion from which it originated instead of the parent molecule. This novelty allows us to measure serum concentrations of the drug for a longer time postdose and provides more opportunity for pharmacokinetic studies of sofosbuvir. Our method was linear over the concentration range of 2–2560 ng/mL of sofosbuvir in human serum with a limit of quantification of 2 ng/mL compared to 10 ng/mL reported previously. The coefficient variation values of both inter and intraday analysis were less than 13.8%, and the percentage error was less than 6.3.