LC‐MS/MS determination of pogostone in rat plasma and its application in pharmacokinetic studies

Pogostone is an important constituent of Pogostemon cablin (Blanco) Benth., and possesses various known bioactivities. A rapid, simple and sensitive liquid chromatography tandem mass spectrometry (LC‐MS/MS) method was developed for the analysis of pogostone in rat plasma using chrysophanol as internal standard (IS). The analytes were extracted with methanol and separated using a reversed‐phase YMC‐UltraHT Pro C₁₈ column. Elution was achieved with a mobile phase consisting of methanol–water (75:25, v/v) for 5 min at a flow rate of 400 μL/min. The precursor/product transitions (m/z) under MS/MS detection with negative electrospray ionization (ESI) were 223.0 → 139.0 and 253.1 → 224.9 for pogostone and IS, respectively. The calibration curve was linear over the concentration range 0.05–160 µg/mL (r = 0.9996). The intra‐ and inter‐day accuracy and precision were within ±10%. The validated method was successfully applied to the preclinical pharmacokinetic investigation of pogostone in rats after intravenous (5, 10 and 20 mg/kg) and oral administration (5, 10 and 20 mg/kg). Finally, the oral absolute bioavailability of pogostone in rats was calculated to be 70.39, 78.18 and 83.99% for 5, 10 and 20 mg/kg, respectively. Copyright © 2013 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.     

Determination of Cefalothin and Cefazolin in Human Plasma,Urine and Peritoneal Dialysate by UHPLC‐MS/MS: application to a pilot pharmacokinetic study in humans

An ultra‐high‐performance liquid chromatography–tandem mass spectrometry (UHPLC‐MS/MS) method for the analysis of cefazolin and cefalothin in human plasma (total and unbound), urine and peritoneal dialysate has been developed and validated. Total plasma concentrations are measured following protein precipitation and are suitable for the concentration range of 1–500 µg/mL. Unbound concentrations are measured from ultra‐filtered plasma acquired using Centrifree^® devices and are suitable for the concentration range of 0.1–500 µg/mL for cefazolin and 1–500 µg/mL for cefalothin. The urine method is suitable for a concentration range of 0.1–20 mg/mL for cefazolin and 0.2–20 mg/mL for cefalothin. Peritoneal dialysate concentrations are measured using direct injection, and are suitable for the concentration range of 0.2–100 µg/mL for both cefazolin and cefalothin. The cefazolin and cefalothin plasma (total and unbound), urine and peritoneal dialysate results are reported for recovery, inter‐assay precision and accuracy, and the lower limit of quantification, linearity, stability and matrix effects, with all results meeting acceptance criteria. The method was used successfully in a pilot pharmacokinetic study with patients with peritoneal dialysis‐associated peritonitis, receiving either intraperitoneal cefazolin or cefalothin. Copyright © 2015 John Wiley & Sons, Ltd.     

An LC‐MS/MS method for determination of 3,6′‐disinapoylsucrose in rat plasma and its application to a pharmacokinetic study

3,6′‐Disinapoylsucrose (DSS), a major active component of traditional Chinese medicine Yuan‐Zhi (the roots of Polygala tenuifolia), has significant effects for neuroprotection and improving learning memory. In order to explore the pharmacokinetic properties of DSS so as to further understand its in vivo activities, a sensitive LC‐MS/MS method was developed for determination of DSS in rat plasma and applied to a pharmacokinetic study in the present study. After treatment by protein precipitation, the plasma sample was separated on a C₁₈ HPLC column and analyzed by a mass spectrometry under positive electrospray ionization. Multiple‐reaction monitoring was employed to measure the ion transition at m/z 777.4 → 409.2 for DSS and m/z 557.2 → 309.1 for forsythin as internal standard. The method was linear over the studied concentration range of 0.5–1000.0 ng/mL. The precision and accuracy ranged from 1.4 to 18.4%, and from ?3.7 to ?9.5%, respectively, for within‐day and between‐day assay. Extraction recovery was higher than 86.6%. The limits of detection and quantification were 0.3 and 0.5 ng/mL, respectively. The present method was successfully applied to a pharmacokinetic study. DSS was found to have poor oral absorption with only about 0.5% bioavailability. Copyright © 2009 John Wiley & Sons, Ltd.     

Determination and validation of hupehenine in rat plasma by UPLC‐MS/MS and its application to pharmacokinetic study

In this work, a sensitive and selective ultra‐performance liquid chromatography–tandem mass spectrometry (UPLC‐MS/MS) method for determination of hupehenine in rat plasma was developed and validated. After addition of imperialine as an internal standard (IS), protein precipitation by acetonitrile–methanol (9:1, v/v) was used to prepare samples. Chromatographic separation was achieved on a UPLC BEH C₁₈ column (2.1 × 100 mm, 1.7 µm) with 0.1% formic acid and acetonitrile as the mobile phase with gradient elution. An electrospray ionization source was applied and operated in positive ion mode; multiple reaction monitoring mode was used for quantification using target fragment ions m/z 416.3 → 98.0 for hupehenine, and m/z 430.3 → 138.2 for IS. Calibration plots were linear throughout the range 2–2000 ng/mL for hupehenine in rat plasma. Mean recoveries of hupehenine in rat plasma ranged from 92.5 to 97.3%. Relative standard deviations of intra‐day and inter‐day precision were both <6%. The accuracy of the method was between 92.7 and 107.4%. The method was successfully applied to a pharmacokinetic study of hupehenine after either oral or intravenous administration. For the first time, the bioavailability of hupehenine was reported as 13.4%. Copyright © 2015 John Wiley & Sons, Ltd.     

A validated LC‐MS/MS method for the determination of senkyunolide I in dog plasma and its application to a pharmacokinetic and bioavailability studies

Senkyunolide I is one of the major bioactive components in the herbal medicine Ligusticum chuanxiong. The aim of this study was to develop and validate a fast, simple and sensitive LC‐MS/MS method for the determination of senkyunolide I in dog plasma. The plasma samples were processed with acetonitrile and separated on a Waters Acquity UPLC BEH C₁₈ column (50 × 2.1 mm, 1.7 μm). The mobile phase consisted of 0.1% formic acid aqueous and acetonitrile was delivered at a flow rate of 0.3 mL min⁻¹. The detection was achieved in the positive selected reaction monitoring mode with precursor‐to‐product transitions at m/z 225.1 → 161.1 for senkyunolide I and at m/z 349.1 → 305.1 for an internal standard. The assay was linear over the tested concentration range, from 0.5 ng mL⁻¹ to 1000 ng mL⁻¹, with a correlation coefficient >0.9992. The mean extraction recovery from dog plasma was within the range of 85.78–93.25%, while the matrix effect of the analyte was within the range of 98.23–108.89%. The intra‐ and inter‐day precisions (RSD) were <12.12% and the accuracy (RR) ranged from 98.89% to 104.24%. The validated assay was successfully applied to pharmacokinetic and bioavailability studies of senkyunolide I in dogs. The results demonstrated that (a) senkyunolide I showed short elimination half‐life (<1 h) in dog, (b) its oral bioavailability was >40% and (c) senkyunolide I showed dose‐independent pharmacokinetic profiles in dog plasma over the dose range of 1–50 mg kg⁻¹.     

LC‐MS/MS methods for the determination of edaravone and/or taurine in rat plasma and its application to a pharmacokinetic study

Three liquid chromatography–tandem mass spectrometry (LC‐MS/MS) methods were respectively developed and validated for the simultaneous or independent determination of taurine and edaravone in rat plasma using 3‐methyl‐1‐p‐tolyl‐5‐pyrazolone and sulfanilic acid as the internal standards (IS). Chromatographic separations were achieved on an Agilent Zorbax SB‐Aq (100 × 2.1 mm, 3.5 µm) column. Gradient 0.03% formic acid–methanol, isocratic 0.1% formic acid–methanol (90:10) and 0.02% formic acid–methanol (40:60) were respectively selected as the mobile phase for the simultaneous determination of two analytes, taurine or edaravone alone. The MS acquisition was performed in multiple reaction monitoring mode with a positive and negative electrospray ionization source. The mass transitions monitored were m/z [M + H]⁺ 175.1 → 133.0 and [M + H]⁺ 189.2 → 147.0 for edaravone and its IS, m/z [M ? H]^? 124.1 → 80.0 and [M ? H]^? 172.0 → 80.0 for taurine and its IS, respectively. The validated methods were successfully applied to study the pharmacokinetic interaction of taurine and edaravone in rats after independent intravenous administration and co‐administration with a single dose. Our collective results showed that there were no significant alterations on the main pharmacokinetic parameters (area under concentration–time curve, mean residence time, half‐life and clearance) of taurine and edaravone, implying that the proposed combination therapy was pharmacologically feasible. Copyright © 2014 John Wiley & Sons, Ltd.     

Quantitative determination of euphol in rat plasma by LC‐MS/MS and its application to a pharmacokinetic study

Euphol is a potential pharmacologically active ingredient isolated from Euphorbia kansui. A simple, rapid, and sensitive method to determine euphol in rat plasma was developed based on liquid chromatography‐tandem mass spectrometry (LC‐MS/MS) for the first time. The analyte and internal standard (IS), oleanic acid, were extracted from plasma with methanol and chromatographied on a C₁₈ short column eluted with a mobile phase of methanol–water–formic acid (95:5:0.1, v/v/v). Detection was performed by positive ion atmospheric pressure chemical ionization in selective reaction monitoring mode. This method monitored the transitions m/z 409.0 → 109.2 and m/z 439.4 → 203.2 for euphol and IS, respectively. The assay was linear over the concentration range 27–9000 ng/mL, with a limit of quantitation of 27 ng/mL. The accuracy was between –7.04 and 4.11%, and the precision was <10.83%. This LC‐MS/MS method was successfully applied to investigate the pharmacokinetic study of euphol in rats after intravenous (6 mg/kg) and oral (48 mg/kg) administration. Results showed that the absolute bioavailability of euphol was approximately 46.01%. Copyright © 2014 John Wiley & Sons, Ltd.     

Development of a fast LC‐MS/MS assay for the determination of deferiprone in human plasma and application to pharmacokinetics

A fast and accurate liquid chromatography/tandem mass spectrometric (LC‐MS/MS) assay was first developed and validated for the determination of deferiprone in human plasma. The analytes were extracted with acetonitrile from only 50 μL aliquots of human plasma to achieve the protein precipitation. After extraction, chromatographic separation of analytes in human plasma was performed using a Synergi Fusion‐RP 80A column at 30 °C. The mobile phase consisted of methanol and 0.2% formic acid containing 0.2 mM EDTA (60:40, v/v). The flow rate of the mobile phase was 0.8 mL/min. The total run time for each sample analysis was 4 min. Detection was performed using electrospray ionization in positive ion multiple reaction monitoring mode by monitoring the precursor‐to‐parent ion transitions m/z 140.1 → 53.1 for deferiprone and m/z 143.1 → 98.1 for internal standard. A linear range was established from 0.1 to 20 µg/mL. The limit of detection was determined as 0.05 µg/mL. The validated method was estimated for linearity, recovery, stability, precision and accuracy. Intraday and interday precisions were 4.3–5.5 and 4.6–7.3%, respectively. The recovery of deferiprone was in the range of 80.1–86.8%. The method was successfully applied to a pharmacokinetic study of deferiprone in six thalassemia patients. Copyright © 2012 John Wiley & Sons, Ltd.     

A rapid and sensitive UHPLC–MS/MS method for the determination of celosin A in rat plasma with application to pharmacokinetic study

Celosin A (CA), a natural compound isolated from Celosia argentea L., has been shown significant hepatoprotective effect on AHNP‐induced liver injury. This study described a rapid and sensitive ultra‐high‐pressure liquid chromatography–tandem mass spectrometry (UHPLC–MS/MS) assay for determination of CA in rat plasma. Methanol‐mediated precipitation was used for sample pretreatment. Chromatographic separation was achieved on a T3 column with gradient elution using water and acetonitrile as mobile phase. Determination was obtained using an electrospray ionization source in negative selected reaction monitoring mode at the transitions of m/z 793.3 → m/z 661.2 and m/z 955.6 → m/z 793.2 for CA and IS, respectively. The assay was linear over the concentration range 0.25–2500 ng/mL (r > 0.995) with a lowest limit of quantification (LLOQ) of 0.25 ng/mL. The intra‐ and inter‐day precisions (RSD) were 1.65–9.84 and 2.46–13.49%, respectively, while accuracy (RR) ranged from 96.21 to 99.45%, respectively. The recovery ranged from 95.09 to 102.22% and the matrix effect from 98.29 to 100.13%. The analyte was stable under the tested storage conditions. The method has been successfully applied to a preclinical pharmacokinetic study in rats after a single intravenous (2 mg/kg) or oral (50 mg/kg) administration. The oral bioavailability of CA was ~1.94%; in addition, there was no difference between male and female rats. This is the first time of the use of an UHPLC–MS/MS method for determination of CA concentration in rat plasma and for evaluation of its pharmacokinetic behavior.     

Development and validation of an LC‐ESI‐MS/MS method for the quantitation of hemslecin A in rhesus monkey plasma and its application in pharmacokinetics

In this study, a new LC‐ESI‐MS/MS‐based method was validated for the quantitation of hemslecin A in rhesus monkey plasma using otophylloside A as internal standard (IS). Hemslecin A and the IS were extracted from rhesus monkey plasma using liquid–liquid extraction as the sample clean‐up procedure, and were subjected to chromatography on a Phenomenex Luna CN column (150 × 2.0 mm, 3.0 µm) with the mobile phase consisting of methanol and 0.02 mol/mL ammonium acetate (55:45, v/v) at a flow rate of 0.2 mL/min. Detection was performed on an Agilent G6410B tandem mass spectrometer by positive ion electrospray ionization in multiple reaction monitoring mode, monitoring the transitions m/z 580.5 [M + NH₄]⁺ → 503.4 and m/z 518.2 [M + NH₄]⁺ → 345.0 for hemslecin A and IS, respectively. The assay was linear over the concentration range of 0.5–200 ng/mL and was successfully applied to a pharmacokinetic study in rhesus monkeys. Copyright © 2013 John Wiley & Sons, Ltd.     

Assessment of pharmacokinetic interaction between piracetam and l‐carnitine in healthy subjects

A rapid, sensitive and specific method for quantifying piracetam in human plasma using Piracetam d‐8 as the internal standard (IS) is described. The analyte and the IS were extracted from plasma by one‐step precipitation of protein using an acetonitrile (100%). The extracts were analyzed by high‐performance liquid chromatography coupled with electrospray tandem mass spectrometry (HPLC‐MS/MS). The method had a chromatographic run time of 3.8 min and a linear calibration curve over the range 0.5–50 µg/mL (r > 0.99). This LC‐MS‐MS procedure was used to assess the bioavailability of two piracetam formulations: piracetam + l‐carnitine (Piracar®; 270/330 mg tablet) and piracetam (Nootropil®; 800 mg tablet) in healthy volunteers of both sexes. The geometric means with corresponding 90% confidence interval (CI) for test/reference percentage ratios were 88.49% (90% CI = 81.19 – 96.46) for peak concentration/dose and 102.55% (90% CI = 100.62 – 104.51) for AUC_inf/dose. The limit of quantitation of 0.5 µg/mL is well suited for pharmacokinetic studies in healthy volunteers. It was concluded that piracetam (Piracar®; 270/330 mg tablet) has a bioavailability equivalent to the piracetam (Nootropil®; 800 mg tablet) formulation with regard to both the rate and the extent of absorption. Copyright © 2015 John Wiley & Sons, Ltd.     

Simultaneous quantification of hyperin,reynoutrin and guaijaverin in mice plasma by LC‐MS/MS: application to a pharmacokinetic study

A specific and sensitive LC‐MS/MS assay was developed to simultaneously quantify three structurally similar flavonoid glycosides – hyperin, reynoutrin and guaijaverin – in mouse plasma. Biosamples were prepared by solid‐phase extraction. Isocratic chromatographic separation was performed on an AichromBond‐AQ C₁₈ column (250 × 2.1 mm, 5 μm) with methanol–acetonitrile–water–formic acid (20:25:55:0.1) as the mobile phase. Detection of hyperin, reynoutrin, guaijaverin and internal standard [luteolin‐7‐O‐β‐d ‐apiofuranosyl‐(1 → 6)‐β‐d ‐glucopyranoside] was achieved by ESI‐MS/MS in the negative ion mode using m/z 463 → m/z 300, m/z 433 → m/z 300, m/z 433 → m/z 300 and m/z 579 → m/z 285 transitions, respectively. Linear concentration ranges of calibration curves were 4.0–800.0 ng/mL for hyperin and reynoutrin and 8.0–1600.0 ng/mL for guaijaverin when 100 μL of plasma was analyzed. We used this validated method to study the pharmacokinetics of hyperin, reynoutrin and guaijaverin in mice following oral and intravenous administration. All three quercetin‐3‐O‐glycosides showed poor oral absorption in mice, and the absolute bioavailability of hyperin after oral administration of 100 mg/kg was 1.2%. Pretreatment with verapamil increased the peak concentration and area under the concentration–time curve of hyperin, which were significantly higher than the control values. The half‐life of hyperin with verapamil was significantly prolonged compared with that of the control. Copyright © 2016 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.     

Quantitation of melatonin and n‐acetylserotonin in human plasma by nanoflow LC‐MS/MS and electrospray LC‐MS/MS

Melatonin (MEL) and its chemical precursor N‐acetylserotonin (NAS) are believed to be potential biomarkers for sleep‐related disorders. Measurement of these compounds, however, has proven to be difficult due to their low circulating levels, especially that of NAS. Few methods offer the sensitivity, specificity and dynamic range needed to monitor MEL and its precursors and metabolites in small blood samples, such as those obtained from pediatric patients. In support of our ongoing study to determine the safety, tolerability and PK dosing strategies for MEL in treating insomnia in children with autism spectrum disorder, two highly sensitive LC‐MS/MS assays were developed for the quantitation of MEL and precursor NAS at pg/mL levels in small volumes of human plasma. A validated electrospray ionization (ESI) method was used to quantitate high levels of MEL in PK studies, and a validated nanospray (nESI) method was developed for quantitation of MEL and NAS at endogenous levels. In both assays, plasma samples were processed by centrifugal membrane dialysis after addition of stable isotopic internal standards, and the components were separated by either conventional LC using a Waters SymmetryShield RP18 column (2.1 × 100 mm, 3.5 µm) or on a polyimide‐coated, fused‐silica capillary self‐packed with 17 cm AquaC18 (3 µm, 125 Å). Quantitation was done using the SRM transitions m/z 233 → 174 and m/z 219 → 160 for MEL and NAS, respectively. The analytical response ratio versus concentration curves were linear for MEL (nanoflow LC: 11.7–1165 pg/mL, LC: 1165–116500 pg/mL) and for NAS (nanoflow LC: 11.0–1095 pg/mL). Copyright © 2012 John Wiley & Sons, Ltd.     

Quantification of polygalasaponin F in rat plasma using liquid chromatography–tandem mass spectrometry and its pharmacokinetics application

A rapid and highly selective liquid chromatography–tandem mass spectrometric (LC‐MS/MS) method for determination of polygalasaponin F (PF) in rat plasma was developed and validated. The chromatographic separation was achieved on a reverse‐phase Zorbax SB‐C₁₈ column (150 × 4.6 mm, 5 µm), using 2 mm ammonium acetate (pH adjusted to 6.0 with acetic acid) and acetonitrile (25:75, v/v) as a mobile phase at 30 °C. MS/MS detection was performed using an electrospray ionization operating in positive ion multiple reaction monitoring mode by monitoring the ion transitions from m/z 1091.5 → 471.2 (PF) and m/z 700.4 → 235.4 (internal standard), respectively. The calibration curve showed a good linearity in the concentration range 0.0544–13.6 µg/mL, with a limit of quantification of 0.0544 µg/mL. The intra‐ and inter‐day precisions were <9.7% in rat plasma. The method was validated as per US Food and Drug Administration guidelines and successfully applied to pharmacokinetic study of PF in rats. Copyright © 2015 John Wiley & Sons, Ltd.     

A validated HPLC‐MS/MS method for the quantification of caderofloxacin in human plasma and its application to a clinical pharmacokinetic study

A simple, selective and rapid HPLC‐MS/MS method was developed and validated for the determination of caderofloxacin in human plasma. Sparfloxacin was used as the internal standard (IS). After precipitation with methanol and dilution with the mobile phase, the samples were injected into the HPLC‐MS/MS system. The chromatographic separation was performed on a Zorbax XDB Eclipse C₁₈ column (150 × 4.6 mm, 5 µm) with a mobile phase of ammonium acetate buffer (20 mm, pH 3.0)–methanol, 45:55 (v/v). The MS/MS analysis was done in positive mode. The multiple reaction monitoring transitions monitored were m/z 412.3 → 297.1 for caderofloxacin and m/z 393.2 → 292.2 for the IS. The calibration curve was linear over the range of 50.0–8000 ng/mL with an aliquot of 100 μL plasma. The precision of the assay was 2.0–9.4 and 6.6–11.5% for the intra‐ and inter‐run variability, respectively. The intra‐ and inter‐run accuracy (relative error) was 4.4–10.0 and ?1.2–4.0%. The total run time was 3.5 min. The assay was fully validated in accordance with the US Food and Drug Administration guidance. It was successfully applied to a pharmacokinetic study of caderofloxacin in healthy Chinese volunteers. Copyright © 2015 John Wiley & Sons, Ltd.     

LC‐MS/MS method for the determination of agomelatine in human plasma and its application to a pharmacokinetic study

A sensitive and selective LC‐MS/MS method for the determination of agomelatine in human plasma was developed and validated. After simple liquid–liquid extraction, the analytes were separated on a Zorbax SB‐C₁₈ column (150 × 2.1 mm i.d., 5 µm) with an isocratic mobile phase consisting of 5 mm ammonium acetate solution (containing 0.1% formic acid) and methanol (30:70, v/v) at a flow‐rate of 0.3 mL/min. The MS acquisition was performed in multiple reaction monitoring mode with a positive electrospray ionization source. The mass transitions monitored were m/z 244.1 → 185.3 and m/z 285.2 → 193.2 for agomelatine and internal standard, respectively. The methods were validated for selectivity, carry‐over, matrix effects, calibration curves, accuracy and precision, extraction recoveries, dilution integrity and stability. The validated method was successfully applied to a pharmacokinetic study of agomelatine in Chinese volunteers following a single oral dose of 25 mg agomelatine tablet. Copyright © 2013 John Wiley & Sons, Ltd.     

Development of an LC/MS/MS method in order to determine arctigenin in rat plasma: its application to a pharmacokinetic study

In this study, a simple and sensitive LC/MS/MS method was developed and validated for the determination of arctigenin in rat plasma. The MS detection was performed using multiple reaction monitoring at the transitions of m/z 373.2 → 137.3 for arctigenin and m/z 187.1 → 131.0 for psoralen (internal standard) with a Turbo IonSpray electrospray in positive mode. The calibration curves fitted a good linear relationship over the concentration range of 0.2–500 ng/mL. It was found that arctigenin is not stable enough at both room temperature and ?80 °C unless mixed with methanol before storage. The validated LC/MS/MS method was successfully applied for the pharmacokinetic study of arctigenin in rats. After intravenous injection of 0.3 mg/kg arctigenin injection to rats, the maximum concentration, half‐life and area under the concentration–time curve were 323 ± 65.2 ng/mL, 0.830 ± 0.166 and 81.0 ± 22.1 h ng/mL, respectively. Copyright © 2013 John Wiley & Sons, Ltd.     

A rapid and sensitive LC‐MS/MS method for evaluation of the absolute oral bioavailability of a novel c‐Met tyrosine kinase inhibitor QBH‐196 in rats

A sensitive, selective and high‐throughput UPLC‐MS/MS method was developed and validated for the determination of a novel c‐Met tyrosine kinase inhibitor, QBH‐196, in rat plasma. QBH‐196 and its analog BH357 (IS) were extracted from rat plasma using a mixture of dichloromethane and N‐hexane (2:3, v/v). The chromatographic separation was carried out on Phenomenex C₁₈ column (50 × 2.1 mm, 2.6 µm particle size) with a gradient mobile phase of methanol (A) and water containing 0.05% formic acid (B) at a flow rate of 0.2 mL/min. The assay was performed by positive electrospray ionization in multiple reaction monitoring mode using transitions of m/z 622.68 → 140.41 for QBH‐196 and m/z 591.19 →126.21 for the IS, respectively. Good linearity was obtained over the concentration range of 8.0–4000 ng/mL (r² > 0.99) for QBH‐196 and the lower limit of quantification was 8.0 ng/mL in rat plasma. Validations of the method, including its sensitivity, extraction recovery, matrix effect, intra‐ and inter‐day precision, accuracy and stability, were all within acceptable limits. The established method was successfully applied to determine absolute oral bioavailability of QBH‐196 in rats for the first time. The mean oral absolute bioavailability of QBH‐196 was found to be about 40.8% and the elimination half‐life was 40.0 ± 13.1 h. This result suggested that QBH‐196 exhibits good oral absorption in vivo, which is very important for the further development of QBH‐196 as a new oral anticancer drug. Copyright © 2015 John Wiley & Sons, Ltd.