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LE300 is a novel dopamine receptor antagonist used to treat cocaine addiction. In the current study, a sensitive and fast liquid chromatography–tandem mass spectrometry (LC-MS/MS) has been established and validated for the simultaneous analysis of LE300 and its N-methyl metabolite, MLE300, in rat plasma with an application in a pharmacokinetic study. The chromatographic elution of LE300, MLE300, and Ponatinib (IS, internal standard), was carried out on a 50 mm C18 analytical column (ID: 2.1 mm and particle size: 1.8 μm) maintained at 22 ± 2 °C. The run time was 5 min at a flow rate of 0.3 mL/min. The mobile phase consisted of 42% aqueous solvent (10 mM ammonium formate, pH: 4.2 with formic acid) and 58% organic solvent (acetonitrile). Plasma samples were pretreated using protein precipitation with acetonitrile. The electrospray ionization (ESI) source was used to generate an ion-utilizing positive mode. A multiple reaction monitoring mass analyzer mode was utilized for the quantification of analytes. The linearity of the calibration curves in rat plasma ranged from 1 to 200 ng/mL (r2 = 0.9997) and from 2 to 200 ng/mL (r2 = 0.9984) for LE300 and MLE300, respectively. The lower limits of detection (LLOD) were 0.3 ng/mL and 0.7 ng/mL in rat plasma for LE300 and MLE300, respectively. Accuracy (RE%) ranged from −1.71% to −0.07% and −4.18% to −1.48% (inter-day), and from −3.3% to −1.47% and −4.89% to −2.15% (intra-day) for LE300 and MLE300, respectively. The precision (RSD%) was less than 2.43% and 1.77% for the inter-day, and 2.77% and 1.73% for intra-day of LE300 and MLE300, respectively. These results are in agreement with FDA guidelines. The developed LC-MS/MS method was applied in a pharmacokinetic study in Wistar rats. Tmax and Cmax were 2 h and 151.12 ± 12.5 ng/mL for LE300, and 3 h and 170.4 ± 23.3 ng/mL for MLE300. [ABSTRACT FROM AUTHOR]

Abstract JCC-02, N -(3,5-dimethyladamantan-1-yl)- N ′-(3-chlorophenyl) urea, has been developed as a novel N -methyl- d -aspartate (NMDA) receptor inhibitor for the treatment of Alzheimer's disease (AD). In this study, a liquid chromatography-tandem mass spectrometry (LC-MS/MS) method was developed to determine the concentration of JCC-02 in rat plasma and different tissues to investigate its pharmacokinetic behavior in vivo and distribution character in organs. The matrix samples were prepared by protein precipitation method with acetonitrile using gliclazide as the internal standard (IS). This validated method was successfully applied to JCC-02 pharmacokinetic study in rats after oral administration of low (0.7 mg·kg−1), medium (2 mg·kg−1) and high (6 mg·kg−1) concentration, intravenous administration (2 mg·kg−1) as well as tissue distribution in rats after administration of JCC-02 (2 mg·kg−1) orally. The results indicated that the area under the time curve (AUC 0-∞) and peak plasma concentration (C max) were directly proportional to dosage and the pharmacokinetic behavior of JCC-02 in rats was a linear process with respect to dosage. JCC-02 could be absorbed into blood circulation rapidly because of its short time to reach peak plasma concentration (t max). Meanwhile, JCC-02 has a low clearance and a high volume of distribution, which might result in its long half-time. Oral absolute bioavailability (F) of JCC-02 was (14.61 ± 5.81)%, which was turned out to be low relatively. In tissues, the differences of JCC-02 concentration were quite large. After administration, small intestine (22.29 ± 15.86 μg·mL−1), stomach (7.21 ± 2.87 μg·mL−1), large intestine (1.27 ± 0.57 μg·mL−1), liver (0.96 ± 0.52 μg·mL−1) and fat (0.48 ± 0.24 μg·mL−1) were the first five organs with the largest drug concentration. Small intestine could be the main part of drug absorption where most of the drug was distributed after oral administration. More importantly, JCC-02 could cross the blood-brain barrier (BBB), which may probably have a pretty good therapeutic effect on AD. Graphical abstract Unlabelled Image [ABSTRACT FROM AUTHOR]

Abstract (+)-Borneol, a bicyclic monoterpene, has been shown to possess valuable biological properties and potential as a pharmaceutical agent due to anti-inflammatory, anti-oxidant and GABA receptor-enhancing functions; it also enhances the permeability of the blood brain barrier to improve the efficacy of CNS drugs. In this study, we have developed a simple, selective, and rapid liquid chromatography-tandem mass spectrometry method for the assay of (+)-borneol in rat plasma. Verapamil was used as an internal standard. Plasma samples were deproteinized using methanol. The analyte was detected by a mass spectrometer with positive atmospheric pressure chemical ionization by multiple reaction monitoring mode for transitions at m / z [M + H]+ 137.2 → 81.0 for (+)-borneol and 455.2 → 165.1 for verapamil. The method has been fully validated to ensure good selectivity, a satisfactory lower limit of quantification at 10.0 ng/mL, acceptable intra- and inter-day accuracy, and high precision. The method was used for the pharmacokinetic evaluation of (+)-borneol in Sprague-Dawley rats after intravenous, oral, and sublingual administration. The results indicate that oral bioavailability of (+)-borneol was extremely low but sublingual administration yielded rapid absorption and favorable bioavailability of (+)-borneol. Graphical abstract Unlabelled Image Highlights • A simple, selective, and rapid LC-MS/MS method was validated for quantify (+)-borneol in rat plasma. • The sensitive, robust and high throughput method has been sucessfully applied for a pharmacokinetic study. • The pharmacokinetic profile of (+)-borneol as a stereoisomer was first reported. [ABSTRACT FROM AUTHOR]

Abstract A selective, sensitive and fully validated liquid chromatography-tandem mass spectrometry (LC-MS/MS) method was established for the determination of dihydromyricetin, dihydroquercetin, myricetin and quercetin in rat plasma after intragastric administration of Hoveniae Semen total flavonoids. Baicalin was selected as the internal standard. Analytes were extracted from the rat plasma by protein precipitation with acetonitrile and separated on a C18 chromatographic column (Agilent ZORBAX Eclipse Plus, 4.6 mm × 100 mm, 3.5 μm) using the mobile phase containing acetonitrile (A) and 0.1% formic acid-water (B) by gradient elution at 0.5 mL/min flow rate. A tandem mass spectrometer equipped with an electrospray ionization (ESI) source was used to detect analytes. The analytes were measured by multiple reaction monitoring (MRM) in the negative ionization mode. The lower limit of quantification of dihydromyricetin, dihydroquercetin, myricetin and quercetin were 0.70, 8.16, 1.62 and 0.56 ng/mL, respectively. The accuracy, intra-day and inter-day precision and recovery were all satisfactory and the compounds were stable in rat plasma under all tested conditions. The approach was successfully applied to study pharmacokinetic characteristics of the four bioactive flavonoids in plasma after administering Hoveniae Semen total flavonoids intragastrically to rat. Further investigation was carried out to assess pharmacokinetic comparability of the four bioactive flavonoids after intragastric administration of Hoveniae Semen total flavonoids to mixture of flavonoids. Highlights • Pharmacokinetics of 4 main flavonoids in Hoveniae Semen were determined. • Only 6.5 min was in need for one analytical run. • The pharmacokinetic of Hoveniae Semen was firstly studied. • Comparative pharmacokinetics of Hoveniae Semen total flavonoids and a mixture of flavonoids were firstly investigated. [ABSTRACT FROM AUTHOR]

Abstract Methylisothiazolinone (MI) is a preservative used in consumer products to control bacterial and fungal growth. MI can be toxic, act as a skin sensitizer and irritant, and initiate lung diseases; therefore, it is important to understand the mechanisms underlying the toxicity of MI in the body. In this study, we developed a method to analyze plasma MI by using an LC-MS/MS-coupled multiple reaction monitoring (MRM) technique, which follows the fragments of a target metabolite in rat plasma. The MRM transition of MI was m / z 116 ➔ 101, and the lower limit of quantification (LLOQ) was set at 10 ng/mL. Including the concentration of LLOQ, a seven-point calibration curve explained much of the variation in the response, and it was strongly linear (R2 = 0.9998); its intra- and inter-day accuracy and precision values were within 15% of the standard deviation (SD%) and along with the FDA and Korea Ministry of Food and Drug Safety guidelines. For intravenous (iv) pharmacokinetic studies of MI using rats, we developed an analytical method that was useful in detecting the profile of MI in the plasma. We also determined half-life, and area under the curve (AUC) of MI using a non-compartment model, and these might be useful for the study of toxic mechanisms of MI in the body. [ABSTRACT FROM AUTHOR]

Abstract Disopyramide as an antiarrhythmic agent has been used for treating ventricular tachycardia and metabolized into its major metabolite, mono-isopropyl-disopyramide, by CYP3A4. We developed a novel, selective, highly sensitive, accurate, rapid method using liquid chromatography-tandem mass spectrometry (LC-MS/MS) for the simultaneous determination of disopyramide and mono-isopropyl-disopyramide in rat plasma. This study is the first report for the assay validation using LC-MS/MS in biological fluids after simple protein-precipitation method. The most sensitive signals by multiple reaction monitoring (MRM) showed at m/z 340.2 → 239.2 and 298.2 → 239.2 with same fragment ion for disopyramide and mono-isopropyl-disopyramide, respectively. The lower limit of quantification (LLOQ) was determined at 2 ng/mL for both analytes and the linear concentration ranges were found to be 2–2000 ng/mL for disopyramide and 2–1000 ng/mL for mono-isopropyl-disopyramide. Finally, this assay was successfully applied to pharmacokinetic analysis of disopyramide and mono-isopropyl-disopyramide after oral and intravenous administration of disopyramide. [ABSTRACT FROM AUTHOR]

A sensitive, selective, and reliable LC-MS/MS method was developed and validated for simultaneous quantification of venlafaxine (VEN) and its 5 metabolites (ODV, NDV, NNDDV, OHV and NODDV) in rat plasma. The calibration ranges are 15.0 to 6000 ng/mL for VEN, 1.00 to 400 ng/mL for ODV, 5.00 to 2000 ng/mL for NDV, 1.00 to 400 ng/mL for NNDDV, 10.0 to 4000 ng/mL for OHV, and 0.200 to 20.0 ng/mL for NODDV. Briefly, 50 μL of rat plasma was extracted using liquid-liquid extraction (LLE) with methyl tert -butyl ether (MTBE). The analytes were separated on an Agilent SB-Phenyl (50 mm × 4.6 mm, 3.5 μm) column using a binary gradient of 0.1% formic acid in water versus 0.1% formic acid in acetonitrile at a flow rate of 0.8 mL/min. The method was validated following FDA guidance for bioanalytical method validation. Validated method was successfully applied to a pharmacokinetic study of VEN orally administered to rats. [ABSTRACT FROM AUTHOR]

Arecoline is the primary active and toxic constituent of areca nut. Arecaidine and arecoline N -oxide are two major active metabolites of arecoline. In this work, an accurate and simple high performance liquid chromatography tandem mass spectrometry method for simultaneous quantification of arecoline, arecaidine and arecoline N -oxide in rat plasma was developed and fully validated to study their pharmacokinetic behaviors in rats. After extracted from rat plasma by protein precipitation with methanol and then concentrated, the analytes were chromatographic separated on a Sepax Sapphire C 18 analytical column. The mobile phase consisted of methanol and 2 mM ammonium acetate buffer solution containing 0.2% ( v/v ) formic acid (8:92, v/v ) under isocratic elution. The analytes were detected by multiple reaction monitoring (MRM) with an electrospray ionization source in the positive ion mode. The transitions of m / z 156.2 → 53.2,  m / z 142.2 → 44.2 and m / z 172.2 → 60.2 were selected for arecoline, arecaidine and arecoline N -oxide, respectively. The method was linear over the concentration range of 0.5–100 ng/mL for arecoline, 5–5000 ng/mL for arecaidine and arecoline N -oxide with no carry-over effect. The accuracies and intra- and inter-batch precisions were all within the acceptance limits. No matrix effect and potential interconversion between the analytes and other metabolites were observed in this method. The validated method was further employed to a preclinical pharmacokinetic study of arecoline, arecaidine and arecoline N -oxide after oral treatment with 20 mg/kg arecoline to rats. [ABSTRACT FROM AUTHOR]

QO-58 lysine (QO-58L) as a new potassium channel opener, reported to have a potential activity to cure neuropathic pain. The aim of this research is to develop and validate a high-performance liquid chromatography with tandem spectrometry (LC-MS/MS) method for the quantification of QO-58L in rat urine, feces and bile. In addition, analyze and identify the metabolites in urine and bile. The assay for this compound in samples detected with multiple reaction monitoring mode (MRM), and take nimodipine as internal standards (IS). To better understand the biotransformation of QO-58L, metabolites in urine and bile were identified by using ultra high performance liquid chromatography tandem quadrupole/time of flight mass spectrometry (UHPLC-Q-TOF-MS) in the positive and negative ion mode. Urine, feces and bile were quantified by three new methods. The results showed that: QO-58L was mainly eliminated through fecal route (92.94%), a small amount of it via biliary excretion (2.05%), and rarely through urinary excretion (0.024%). As a result, there are 11 metabolites were identified, including 8 phase I metabolites resulting from elimination, hydroxylation and dihydroxylation, and 3 phase II metabolites originating from sulfation, N -acetylcysteine conjugation and glucuronidation. Furthermore, the newly discoveries of excretion and metabolism significantly expanded our understanding and was going to be greatly helpful for QO-58L's further pharmacokinetic study in vivo. [ABSTRACT FROM AUTHOR]

Only focusing on the circulating levels is insufficient for the comprehensive understanding of the physiological disposition of herbal medicine in vivo . Therefore, we conducted the comprehensive investigation on the in vivo dynamic process of orally administrated Gouteng - Baitouweng (GB), a classical herb pair with anti-Parkinson potentials. Serving as the technical base, a sensitive and selective liquid chromatography–tandem mass spectrometry method was established and validated in the plasma, liver and brain, for simultaneous determination of five alkaloids (rhynchophylline, isorhynchophylline, corynoxeine, isocorynoxeine and geissoschizine methyl ether) and three saponins (anemoside B4, anemoside A3 and 23-hydroxybetulinic acid). Following liquid-liquid extraction, favorable chromatographic behaviors of eight analytes were obtained on Waters Xbrigde C18 column within 13 min. This method elicited good linearity for the analytes at the concentration range of 0.3–1000 or 1.8–6000 ng/mL with favorable precision, accuracy and stability. Following oral administration of GB (25 g/kg) in rats, this method was applied to the quantitative analysis in the portal vein plasma, liver, systemic plasma, and brain. Consequently, anemoside B4 was of the highest exposure, followed by 23-hydroxybetulinic acid, anemoside A3, rhynchophylline and isocorynoxeine in vivo . Notably, three saponins were all observed with certain exposure in the brain, along with rhynchophylline at low levels. Besides, five alkaloids and 23-hydroxybetulinic acid underwent serious liver first-pass effect. Hence, the pharmacokinetics, liver first-pass effect, liver and brain distribution of ingredients in GB were clarified, which laid a solid foundation for interpreting its efficacy and safety. [ABSTRACT FROM AUTHOR]

Mesupron, the first-in-class inhibitor of urokinase-type plasminogen activator (uPA) is known to regulate cell proliferation and migration, and is under investigation for the treatment of metastatic breast cancer. In this study, a quantification method was developed for the determination of mesupron in rat plasma using liquid chromatography with a tandem mass spectrometry (LC–MS/MS). After protein precipitation with acetonitrile including itraconazole (internal standard, IS), the analytes were chromatographed on a reversed phased column with a mobile phase of acetonitrile and water (7:3, v/v, including 0.1% formic acid). The ion transitions of the precursor to the product ion were principally protonated ion [M+H] + at m / z 630.4 → 398.3 for mesupron and 705.2 → 392.1 for the IS. The accuracy and precision of the assay were in accordance with FDA regulations for the validation of bioanalytical methods This method was successfully applied to a pharmacokinetic study of mesupron after intravenous administration in rats. [ABSTRACT FROM AUTHOR]

A sensitive, specific and rapid LC-ESI–MS/MS method has been developed and validated for the quantification of tideglusib in mice plasma using warfarin as an internal standard (I.S.) as per regulatory guidelines. Sample preparation was accomplished through liquid-liquid extraction process. Chromatographic separation was performed on Atlantis dC 18 column using mobile phase A (acetonitrile) and B (5 mM ammonium acetate in water) in a flow-gradient mode. Elution of tideglusib and the I.S. occurred at ∼2.06 and 1.29 min, respectively. The total chromatographic run time was 3.2 min. A linear response function was established in the concentration range of 20.2–1008 ng/mL. The intra- and inter-day accuracy and precision were in the range of 4.61–12.6 and 6.04–11.8%, respectively. This novel method has been applied to a pharmacokinetic study in mice. [ABSTRACT FROM AUTHOR]

Transcriptional coactivator with PDZ-binding motif (TAZ) is considered an attractive target for osteoporosis, obesity, and muscle regeneration. TM-53, a promising TAZ modulator, was recently introduced, and here, we developed a rapid, precise, and reliable analytical method for TM-53 and characterized its pharmacokinetic properties in rat plasma. The hybrid triple quadrupole/linear ion trap coupled to liquid chromatography method was developed and validated to quantify TM-53. Additionally, TM-53 concentrations in plasma were analyzed, and its pharmacokinetic parameters were calculated by non-compartmental analysis. Multiple reaction monitoring at m / z 569.4 → 207.1 showed the most sensitive signals for TM-53, and the linear scope of the standard curve was between 1.5 ng/mL and 500 ng/mL. The intra- and inter-day precisions of the quality control samples were <15%, and their accuracies were ranged from 86.2% to 111.0%. Furthermore, the matrix effects, extraction recoveries, and process efficiencies of this analytical method for evaluating TM-53 in rat plasma were 99.1%, 99.9%, and 99.1% respectively. In short- and long-term stability studies, TM-53 showed good stability under frozen conditions, but TM-53 hydrolysis in the plasma matrix was observed following storage at room temperature. This analytical method was successfully applied for pharmacokinetic analysis of TM-53 in rat plasma and demonstrated excellent sensitivity, selectivity, precision, and accuracy. These data indicated that this method can be applied for further preclinical studies of TM-53. [ABSTRACT FROM AUTHOR]

DA-9805 is a new botanical antiparkinson drug candidate formulated using an ethanolic extract of the root of Bupleurum falcatum , the root cortex of Paeonia suffruticosa , and the root of Angelica dahurica . In this study, a sensitive and rapid LC–MS/MS method was developed to simultaneously determine, saikosaponin a, paeonol, and imperatorin, three active/representative ingredients of DA-9805, in rat plasma. Plasma was extracted by mixture of ethyl acetate and methyl tertiary butyl ether. Chromatographic separation was carried out using a C 18 column and a gradient elution of mobile phases consisting of 5 mM formic acid in water and acetonitrile. Total chromatographic run time was 10.5 min. Multiple reaction monitoring mode was used for mass spectrometry; the transitions were m / z 779.5 → 617.2 for saikosaponin a in negative-ion mode, m / z 167 → 149 for paeonol and m / z 271.1 → 203 for imperatorin in positive-ion mode. Calibration curves were constructed in the range of 0.5–1000 ng/mL for saikosaponin a, 20–10000 ng/mL for paeonol, and 0.2–1000 ng/mL for imperatorin. All the validation data, including the selectivity, linearity, precision, accuracy, recovery, matrix effect, and stability satisfied the acceptance requirements. The method was successfully applied in a pharmacokinetic study of saikosaponin a, paeonol, and imperatorin following oral administration of DA-9805. [ABSTRACT FROM AUTHOR]

A high-performance liquid chromatography tandem mass spectrometry (HPLC–MS/MS) method was developed and fully validated for simultaneous determination of puerarin, 3′-hydroxy puerarin, 6″- O -xylosyl puerarin, 3′-methoxy puerarin, mirificin, puerarin-7- O -glucoside, daidzin, daidzein, daidzein-7- O -glucoside, ginsenoside-Rd, notoginsenoside-R1, ginsenoside-Re, ginsenoside-Rg1, ginsenoside-Rb1 in rat plasma after intravenous injection of 5 mL/kg Gegen-Sanqi compatibility solution (containing Pueraria flavonid 10.8 mg/mL and Panax notoginsenosidum 5.4 mg/mL). After addition of internal standard (IS) baicalin, the analytes and IS were recovered from rat plasma by protein precipitation using acetonitrile containing 0.1% formic acid. Chromatographic separation was performed on a Capcell pak MG C18 column (3.0 mm × 75 mm, 3.0 μm) at 35 °C with a flow rate of 0.75 mL/min. Mass spectrometry was conducted using multiple reaction monitoring in positive mode. The method was linear for all of the analytes over 1000 times concentration range with correlation coefficients greater than 0.99. The precision and accuracy of the LC–MS/MS assay based on the three analytical quality control (QC) levels were well within the acceptance criteria from FDA guidance for bioanalytical method validation. Method recoveries were higher than 75% and the matrix effects were minimal. All analytes were stable under tested conditions. It was the first time to study the pharmacokinetics of daidzein-7- O -glucoside in rat plasma. To the best of our knowledge, this is the first study for simultaneous determination of so many analytes in rat plasma after intravenous injection of Gegen-Sanqi compatibility solution. It was expected that the present work would provide some helpful references for the apprehension of the mechanism of action and further clinical efficacy studies of Gegen-Sanqi herb-pair. [ABSTRACT FROM AUTHOR]

Necrostatin-1 (Nec-1) is known as a specific and potent inhibitor of non-apoptotic cell death. In this study, a rapid and sensitive LC–MS/MS method that was developed for the determination of Nec-1 levels in plasma. Meanwhile, it has been used to explore pharmacokinetics and bioavailability of Nec-1 among rats. The m / z 260.1 → 131 was selected as the optimal MRM transition in analyzing Nce-1. The chromatographic separation was performed with SB-C18 analytical column using the optimized gradient elution mode. The extraction recoveries of Nec-1 ranged from 85.40% to 98.25% and the matrix effects were between 94.73% and 99.26%. Both the intra- and inter-day precision did not exceed 10.0%, respectively. Moreover, it is found that Nec-1 remained stable in plasma despite different processing and storage environment. The plasma concentration of Nec-1 was successfully determined among rats who received single dose via intravenous and oral route (5 mg/kg), respectively. A two-compartment model was fitted the concentration-time profile of the Nec-1 with C max 1733 μg L −1 and t 1/2 1.8 h for intravenous route, and C max 648 μg L −1 and t 1/2 1.2 h for oral route, respectively. The results showed that absolute bioavailability of Nec-1 was 54.8%. It is promising that the study is helpful to understand in vivo behaviors of Nec-1 and facilitate the future investigations of the compound. [ABSTRACT FROM AUTHOR]

Gentiopicroside is a natural secoiridoid glycoside that may require metabolic activation to exert pharmacological effects. In this study, two active metabolites of gentiopicroside (M1 and M2) were isolated from rat urines and identified with our previous method. Most importantly, a fast, sensitive and selective ultra high-performance liquid chromatography–tandem mass spectrometry method was developed to simultaneously determine gentiopicroside and its two metabolites in rat plasma. The analytes and internal standard (swertiamarin) were separated on an ACQUITY UPLC ® BEH C18 column (2.1 × 50 mm, 1.7 μm) using gradient elution by acetonitrile and 0.1% formic acid at a flow rate of 0.4 mL/min. The mass spectrometry detector was operated in the multiple reaction monitoring with positive ionization mode. The method had a good linearity over the concentration range of 0.2–10,000 ng/mL for gentiopicroside and 0.1–5000 ng/mL for the two metabolites. The validated method was successfully applied to the pharmacokinetic study of gentiopicroside and its metabolites after single oral administration of gentiopicroside (150 mg/kg) to rats (n = 8). The pharmacokinetic differences between gentiopicroside and its two metabolites were identified.Results provided the evidence for in vivo metabolism-based activation of gentiopicroside. [ABSTRACT FROM AUTHOR]

Crocin and crocetin in rat plasma were simultaneously analysed using ultra-performance liquid chromatography tandem mass spectroscopy (UPLC–MS/MS), and method was fully validated. For the first time, levels of both crocin and crocetin in plasma were profiled after oral administration of crocin, and this UPLC–MS/MS approach was applied to evaluate pharmacokinetics and relative bioavailability of crocin and crocetin in rats. It was shown that crocin transformed into crocetin quickly in the gastrointestinal tract, and crocetin was 56–81 fold higher exposed in rat plasma than crocin after oral administration of crocin. A comparison study revealed that an oral administration of equal molar crocin achieved higher exposure of crocetin in rat plasma than that of crocetin. It was suggested that oral administration of crocin has the advantages over crocetin, and crocetin may be the active component potentially responsible for the pharmacological effect of crocin. [ABSTRACT FROM AUTHOR]

To investigate the pharmacokinetic (PK) interaction between telmisartan (Tel) and pitavastatin (Pit), a rapid and sensitive ultra performance liquid chromatography-tandem mass spectrometric assay method had been successfully established and fully validated for the simultaneous quantification of Tel and Pit in rat plasma. A simple protein precipitation procedure was adopted for the sample preparation with satisfactory extraction recovery for both analytes and the internal standard. The samples were chromatographed on an Inertsil ODS-3 C18 column (100 mm × 2.1 mm, 2 μm) using a mixture of acetonitrile and 10 mM ammonium acetate containing 0.1% formic acid (60: 40, v/v) as the mobile phase at a flow rate of 0.4 mL/min. The calibration curves obtained were linear (r > 0.99) over the concentration range of 2–200 ng/mL for Tel and 1–100 ng/mL for Pit, respectively. The validated method was successfully applied to the PK study and the data did not reveal any evidence for the potential drug–drug interaction (DDI) between Tel and Pit. This information would provide the evidence for clinical rational use of Tel and Pit, and this study might be applied in therapeutic drug monitoring in patients receiving Tel/Pit combinations or single drug. [ABSTRACT FROM AUTHOR]

An amide derivative of gallic acid (GA), 3,4,5-trihydroxy-N-(8-hydroxyquinolin-2-yl)benzamide) (SG-HQ2) was recently synthesized, and its inhibitory actions were previously shown on histamine release and pro-inflammatory cytokine expression. In this study, a simultaneous quantification method was developed for the determination of SG-HQ2 and its possible metabolite, GA, in rat plasma using liquid chromatography with a tandem mass spectrometry (LC–MS/MS). After simple protein precipitation with acetonitrile including diclofenac (internal standard, IS), the analytes were chromatographed on a reversed phased column with a mobile phase of acetonitrile and water (60:40, v/v, including 0.1% formic acid). The ion transitions of the precursor to the product ion were principally protonated ion [M+H] + at m / z 313.2 → 160.6 for SG-HQ2, and deprotonated ions [M−H] − at m / z 168.7 → 124.9 for GA and 296.0 → 251.6 for the IS. The accuracy and precision of the assay were in accordance with FDA regulations for the validation of bioanalytical methods. This method was successfully applied to a pharmacokinetic study of SG-HQ2 after intravenous administration in rats. [ABSTRACT FROM AUTHOR]

A fast, selective and sensitive procedure for quantitation of the camphor-based anti-influenza agent camphecene in whole rat blood was developed and validated using dried blood spots and LC–MS/MS. The method was validated according to recommendations of the FDA and EMA in terms of selectivity, linearity, accuracy, precision, recovery, matrix factor, stability, and carry-over. Sample preparation included spotting 20 μL of whole blood taken from the tail vein onto the paper, drying and extracting the analyte, followed by evaporation of the solvent and analysis of the residue. HPLC separations were run on a reversed-phase microcolumn; the time of analysis was less than 2 min. MS/MS detection was performed on a triple quadrupole mass-spectrometer using multiple reaction monitoring (MRM) mode. Transitions 196.4 → 122.2/153.3 and 152.2 → 93.1/107.2 were monitored for camphecene and 2-adamantylamine hydrochloride (internal standard), respectively. The intra- and inter-day precisions and accuracies, matrix factor, carry-over and recovery were within acceptable limits. Despite low extraction recovery (less than 2%), the sensitivity of the method was enough to detect the analyte in the concentration range 50–2500 ng/mL. The application of the method was shown in pharmacokinetic studies of camphecene in rats at a dose of 10 mg/kg. [ABSTRACT FROM AUTHOR]

Gout is a common metabolic disorder caused by the deposition of monosodium urate crystals within joints. A new kind of xanthine oxidase inhibitor, WSJ-537, was developed as a potential drug. In order to investigate the pharmacokinetic behavior in vivo , a liquid chromatography-tandem mass spectrometry (LC–MS/MS) method for determination the concentration of WSJ-537 in rat plasma was developed. After extraction by protein precipitation method with acetonitrile, the chromatographic separation was accomplished on a Venusil ASB C 18 column(2.1 mm × 50 mm, 3 mm)at a flow rate of 0.3 mL min −1 with the mobile phase consisting of acetonitrile-ammonium acetate (33:67, v/v ). An electrospray ionization (ESI) source was applied and operated in the positive ion mode. The plasma concentration was detected by multiple reactions monitoring (MRM) mode with the target fragment ions m / z 410.2 → m / z 368.1 for WSJ-537 and m / z 244.1 → m / z 185.0 for the IS. Good linearity was observed in the range of 20–800 ng mL −1 (r = 0.9947). The recovery of WSJ-537 in rats plasma was more than 85%. This method was suitable for pharmacokinetic studies after oral administration of 10 mg/kg WSJ-537 in rats. [ABSTRACT FROM AUTHOR]

Deoxyglycychloxazol (TY501) is a glycyrrhetinic acid derivative which exhibits high anti-inflammatory activity and reduced pseudoaldosteronism compared to glycyrrhetinic acid. In this study, a sensitive and rapid liquid chromatography–tandem mass spectrometry (LC–MS/MS) method was established for the quantitation of TY501 in rat plasma. Plasma samples were treated by precipitating protein with methanol and supernatants were separated by a Symmetry C 8 column with the mobile phase consisting of methanol and 10 mM ammonium formate (containing 0.1% of formic acid) (90:10, v/v). The selected reaction monitoring (SRM) transitions were performed at m/z 647.4→191.2 for TY501 and m/z 473.3→143.3 for astragaloside aglycone (IS) in the positive ion mode with atmospheric pressure chemical ionization (APCI) source. Calibration curve was linear over the concentration range of 5–5000 ng/mL. The lower limit of quantification was 5 ng/mL. The mean recovery was over 88%. The intra- and inter-day precisions were lower than 6.0% and 12.8%, respectively, and the accuracy was within ±1.3%. TY501 was stable under usual storage conditions and handling procedure. The validated method has been successfully applied to a pharmacokinetic study after oral administration of TY501 to rats at a dosage of 10 mg/kg. [ABSTRACT FROM AUTHOR]

A sensitive, simple and rapid analytical method based on a liquid chromatography–tandem mass spetrometry (LC–MS/MS) has been established and validated for the determination of stachyose in rat plasma. Plasma samples were prepared by protein precipitation with acetonitrile. Separation of stachyose and nystose (internal standard, IS) was achieved using acetonitrile-water (55:45, v/v) as the mobile phase at a flow rate of 1 ml/min for 6 min on an Asahipak NH 2 P-50 4E column with an Asahipak NH2P-50G 4A guard column. Detection and quantification were conducted by LC–MS/MS method in the negative ion mode using multiple reaction monitoring (MRM) transitions at m / z [M–H] − 665.4 → 383.1 for stachyose and 665.5 → 485.0 for IS, respectively. The method was linear over the concentration ranges of 100–30000 ng/ml with a lower limit of quantification (LLOQ) of 100 ng/ml. The intra- and inter- day precision were all within 8.7% and the accuracy ranged from 97.2–108.4% and 98.3–102.4%, respectively. Stability studies indicated that stachyose was stable under short-term, long-term and three freeze-thaw storage conditions. The method was successfully applied to a pharmacokinetic study involving pulmonary administration of micronized Rehmannia glutinosa oligosaccharides (RGOS) to rats. [ABSTRACT FROM AUTHOR]

Lurbinectedin (PM01183) is a new synthetic tetrahydroisoquinoline alkaloid that binds to selected sequences in the minor groove of DNA, inducing PM01183-DNA adducts that stall replication, DNA repair and transcription and gives rise to double-strand breaks and finally, caspase-dependent apoptotic cell death. PM01183 has demonstrated clinical antitumor activity in platinum resistant/refractory ovarian cancer patients. A rapid and sensitive liquid chromatography/tandem mass spectrometry assay was developed and validated to quantify PM01183 in plasma from nonclinical species. The bioanalysis consisted of a supported liquid extraction, followed by a gradient phase chromatography and, detection by positive ion electrospray tandem mass spectrometry. The calibration range for PM01183 was established using PM01183 standards from 0.1 to 100 ng/mL in blank plasma. The multiple reaction monitoring, based on the transition m / z 767.3 → 273.0, was specific for PM01183, and that based on the transition m / z 771.4 → 277.0 was specific for the internal standard (deuterated PM01183). No endogenous material interfered with the analysis of PM01183 and the internal standard from blank plasma. The limit of detection (LOD) of the assay was calculated as 0.025 ng/mL. The correlation coefficients for the calibration curves ranged from 0.9937 to 0.9987. The mean inter-day accuracies for all calibration standards ranged from 92 to 108% (≤8% bias), and the mean inter-day precision for calibration standards was always less than 12%. The mean intra and inter-day assay accuracy for all quality control replicates remained between 91 and 109%. The mean intra and inter-day assay precision was less than 10% for all QC levels. The method was validated to demonstrate the specificity, recovery, limit of quantification, accuracy and precision of measurements. The assay has been used to support preclinical pharmacokinetic and toxicokinetic studies of PM01183 in nonclinical species. The main PK parameters in dogs (3 male and 3 female, respectively) were calculated as follows: maximum concentration ( C max , 12.9 ± 0.6 and 10.2 ± 3.0 ng/mL) and the area under the plasma concentration-time curve (AUC, 24.9 ± 0.7 and 22.6 ± 6.1 ng h/mL). The results showed that plasma samples could be monitored for PM01183 for long enough to accurately estimate pharmacokinetics information. [ABSTRACT FROM AUTHOR]

For the first time, a rapid and sensitive high-performance liquid chromatography-tandem mass spectrometry (LC–MS/MS) method was developed for the simultaneous determination of fraxin and its metabolite, fraxetin, in rat plasma, using esculin as the internal standard (IS). The plasma samples were precipitated with methanol before separation on an Nova-Pak C 18 column (150 mm × 3.9 mm, 3 μm) using a mobile phase consisting of 0.1% formic acid and methanol (55:45) at a flow rate of 0.8 mL/min. The analytes were detected by multiple reaction monitoring in the negative ion mode with the mass transitions at m / z 368.9→ m / z 191.9 (fraxin), m / z 206.9→ m / z 191.8 (fraxetin) and m / z 339.0→ m / z 176.9 (esculin, IS). The results demonstrated that the calibration curves for both analytes have good linearity (r ≥ 0.995) over a concentration range of 5.00–3000 ng/mL. The assay was validated according to the regulatory bioanalytical guidelines and proved acceptable. The intra- and inter-day precisions (R.S.D.%) were within 10.9% for both analytes, whereas the deviation of assay accuracies (R.E.%) ranged from −5.3 to 1.0%. The method was successfully applied to a pharmacokinetic study after a single oral dose of fraxin at 50 mg/kg to rats. [ABSTRACT FROM AUTHOR]

Pinostilbene (3-methoxyresveratrol or trans -3,4′-dihydroxy-5-methoxystilbene) is a naturally occurring monomethylether analogue of resveratrol ( trans -3,5,4′-trihydroxystilbene) that exhibits various pharmacological activities. To further examine its medicinal potential, a sensitive LC–MS/MS method was developed and validated for the determination of pinostilbene in rat plasma. Heavy Isotope labelled resveratrol was used as an internal standard. The ESI was operated in its negative ion mode while pinostilbene and resveratrol were measured by multiple reaction monitoring (MRM) using precursor-to-product ion transitions of m / z 241 → 181 and m / z 233 → 191, respectively. This LC–MS/MS method had excellent selectivity, sensitivity (LLOQ = 1 ng/ml), accuracy (both intra- and interday analytical recovery within 100 ± 15%) and precision (both intra- and interday RSD < 15%). The matrix effect was insignificant. The pharmacokinetics of pinostilbene was subsequently profiled in Sprague–Dawley rats. Upon intravenous administration (5 or 10 mg/kg), pinostilbene displayed rapid clearance (Cl = 129 ± 42 or 107 ± 31 ml/min/kg) and extremely short mean transit time (MTT = 6.24 ± 0.41 or 8.52 ± 1.38 min). After oral dosing (50 mg/kg), the bioavailability of pinostilbene was limited but highly erratic ( F = 1.87 ± 2.67%). Pharmacokinetic comparison among pinostilbene, resveratrol and some resveratrol analogues suggested that stilbenes with meta-hydroxyl group(s) may be associated with metabolic instability and subsequently suffer from rapid clearance and low oral bioavailability. The information obtained from this study will facilitate further exploration on pinostilbene as well as other resveratrol analogues. [ABSTRACT FROM AUTHOR]

A sensitive and accurate liquid chromatography–tandem mass spectrometry (LC–MS/MS) method has been developed and validated for determination of tulobuterol in rat plasma for the first time. Plasma samples were extracted by liquid–liquid extraction method with methyl tert -butyl ether and the analyte and clenbuterol (IS) were separated on a Venusil MP C 18 column (100 mm × 2.1 mm, 3 μm) using 0.1% formic acid–water–methanol as mobile phase, with a runtime of 5 min. The analyte was detected in multiple reaction monitoring (MRM) mode with positive electrospray ionization. Transitions of m / z 228.2 → 154.0 for tulobuterol and m / z 277.1 → 203.0 for the clenbuterol were monitored. The linear range was 0.5–100 ng/ml ( r = 0.9967) for tulobuterol with the lower limit of quantitation of 0.5 ng/ml. The intra-day and inter-day precisions were less than 10.3% for the analyte and the accuracy was less than −8.6%. The RSD of matrix effect and recovery yield were within ±15% of nominal concentrations and tulobuterol was stable during stability studies. The validated method has been successfully applied to a pharmacokinetic study of three doses of tulobuterol patch in rats for the first time. [ABSTRACT FROM AUTHOR]

We have developed a sensitive and specific LC–MS/MS method for the simultaneous determination of alisol A ( A ), alisol A 23-acetate ( A23 ) and alisol A 24-acetate ( A24 ), the major active components in Rhizoma Alismatis extract ( RAE ), in rat plasma. In brief, plasma samples were extracted by methyl tert -butyl ether and chromatographically separated by using a C 18 column. A tandem mass spectrometric detection with an electrospray ionization (ESI) interface was conducted via multiple reaction monitoring (MRM) under positive ionization mode. This method was validated for specificity, linearity, accuracy (within ±15.4%), intra- and inter-day precision (CV < 11.4%) over the concentration range of 25–5000 ng/mL for A, and 5–1000 ng/mL for both A23 and A24 . The significantly lower detection limit was determined as 25 ng/mL for A , 5 ng/mL for A23 and A24 . This validated method of ours was then used to study the pharmacokinetics of RAE in rat. The elimination half-lives ( t 1/2 ) of A , A23 and A24 was determined as 0.75, 0.83 and 0.82 h respectively after intravenous injection, and the oral absolute bioavailability of A , A23 and A24 was 43.1 ± 18.1%, 6.3 ± 1.5% and 7.9 ± 1.2%. This new determination method of us for alisols is proven to very useful to study the pharmacological activities of RAE in future. [ABSTRACT FROM AUTHOR]

To explore the brain-targeting of cyclovirobuxine D(CVB-D) after administered intranasally, the pharmacokinetics of CVB-D via three different drug delivery routes: intragastric (i.g.), intranasal (i.n.), and intravenous (i.v.) in rat brain and blood was compared. Firstly, an in vivo microdialysis method for sampling CVB-D in both plasma and brain of the rat was established. Secondly, a liquid chromatography-tandem mass spectrometry method has been developed and validated for determination of CVB-D in microdialysis samples. For plasma and brain microdialysis samples, liquid–liquid extraction was used and donepezil was chosen as internal standard. Both were followed by HPLC separation and positive electrospray ionization tandem mass spectrometry detection (ESI–MS/MS). Chromatographic separation was achieved on a agilent C18 column with a mobile phase of methanol–water (50:50, v/v) (pH 3.2) containing 0.1% formic acid and 5 mM ammonium acetate. Mass spectrometric detection in the positive ion mode was carried out by selected reaction monitoring (MRM) of the transitions at m / z 403.4 → 372.3 for CVB-D and m / z 380.2 → 243.1 for donepezil (IS). Good linearities were obtained in the range of 10–4000 ng/mL in rat microdialysates for CVB-D. The lowest limit of quantitation was 5 ng/mL, with an extraction recovery >75%, and no significant matrix effects. Intra- and inter-day precisions were all <15% with accuracies of 97.26–116.20%. All of which proved that the established method was successfully applied to the pharmacokinetic study of CVB-D. Simultaneously, brain uptake and pharmacokinetic studies were performed by determination of CVB-D concentration in blood and brain respectively for CVB-D i.g., i.n. and i.v.. Results showed that the intranasal CVB-D could improve brain targeting and had advantages for direct nose to brain transport of CVB-D when compared with injection and oral delivery routes, which indicates that intranasal administration of CVB-D could be a promising approach for the treatment of cerebrovascular disease. [ABSTRACT FROM AUTHOR]

A liquid chromatography–tandem mass (LC–MS/MS) method was developed for the determination of psammaplin A (PsA) and its newly synthesized derivatives (PsA 107, PsA 109, and PsA 123) in rat plasma using bupropion as an internal standard (IS). The plasma samples were deproteinized with acetonitrile. Chromatographic separation was performed on hydro-RP column (75 × 2.0 mm, 80 Å, 4 μm) with isocratic elution using 5 mM ammonium formate buffer/acetonitrile (30:70, v/v) at a flow rate of 0.4 mL/min and the total run time was 5 min. Mass spectrometric detection was performed with positive electrospray ionization (ESI) in multiple reaction monitoring (MRM) mode. The ion transitions monitored were m / z 663.2 → 331.0, 687.2 → 343.1, 587.3 → 293.1, 563.3 → 281.0, and 240.0 → 184.0 for PsA, PsA 107, PsA 109, PsA 123, and IS, respectively. All analytes showed good linearity over the concentration range of 5.00–5000 ng/mL ( r 2 ≥ 0.994). The lower limit of quantification was 5 ng/mL for PsA and its three PsA derivatives. Within- and between-run precisions (relative standard deviation, RSD) were less than 9.66% and accuracy (relative error, RE) ranged from −9.34% to 7.25%. Established method was successfully applied to the investigation of pharmacokinetic properties of PsA and its derivatives in rats after intravenous administration at a dose of 2 mg/kg. [ABSTRACT FROM AUTHOR]

( E )-Methyl-4-aryl-4-oxabut-2-enoate (YH-8) is a novel PKnB protein kinase inhibitor with good anti-tuberculosis activity. To evaluate its pharmacokinetics in rats, a sensitive and selective high performance liquid chromatography–tandem mass spectrometric (LC--MS/MS) method has been developed and validated for the quantification of YH-8 in rat plasma for the first time. Samples were pre-treated using a liquid--liquid extraction with ethyl acetate and the chromatographic separation was performed on a C18 column by gradient elution with methanol--water as the mobile phase. YH-8 was detected using a tandem mass spectrometer in positive selected reaction monitoring (SRM) mode. Method validation revealed good linearity over the range of 1–500 ng/mL for YH-8 with a lower limit of quantification (LLOQ) of 1 ng/mL. Intra- and inter-day precision of YH-8 assay in rat plasma samples were 2.0%–6.8%, with accuracy of the method being 100.69%–106.18%. Stability test showed that when spiked into rat plasma, YH-8 was stable for 12 h at room temperature, for up to 15 days at −70 °C, and after three freeze-thaw cycles. Extracted samples were found to be stable over 12 h in an auto-sampler. The method was successfully applied to the pharmacokinetic study of YH-8 in rats after oral administration at 100 mg/kg and 200 mg/kg. [ABSTRACT FROM AUTHOR]

A specific, sensitive and rapid liquid chromatography tandem mass spectrometry (LC–MS/MS) method has been developed and validated for simultaneous quantification of doxorubicin and curcumin in rat plasma after intravenous administration. The analytes of doxorubicin and curcumin were extracted with methanol precipitation using glibenclamide as internal standard (IS). The chromatographic separation was performed on a C 18 column with acetonitrile and 0.1% formic acid water as mobile phase and with gradient elution at a flow rate of 0.2 mL/min. Calibration curves were linear over the ranges of 2–8000 ng/mL for doxorubicin and 5–2000 ng/mL for curcumin ( r > 0.99). The lower limit of quantification (LLOQ) was 2 ng/mL for DOX and 5 ng/mL for Cur. Finally, this developed method was successfully applied in the pharmacokinetic study of doxorubicin and curcumin in rats and evaluated the effects of curcumin on the absorption of doxorubicin after intravenous administration. [ABSTRACT FROM AUTHOR]

A bioanalytical method for the quantification of rosiglitazone on rat dried blood spots (DBS) and rat urine using liquid chromatography, electrospray ionization coupled with tandem mass spectrometry (LC–ESI-MS/MS) was developed and validated. The chromatographic separation was achieved on a Nova-Pak C 18 Column (150 mm × 4.6 mm i.d., 4 μm), using 30 mM ammonium acetate (pH 4.0 adjusted with acetic acid) and acetonitrile (75:25, v/v) as a mobile phase at ambient temperature. LC–MS detection was performed with selected ion monitoring using target ions at m / z 358 and m / z 356 for rosiglitazone and pioglitazone respectively. The calibration curve showed a good linearity in the concentration range of 0.05–100 ng/mL. The effect of hematocrit, blood volume and punch location for DBS samples was studied. The mean recoveries of rosiglitazone from DBS and urine were 93.30% and 92.49% respectively. The intra and inter-day precisions of RSD were less than 4.82% in DBS as well as urine. The limit of detections and quantifications were 0.015 and 0.052 ng/mL in DBS and 0.023 and 0.075 ng/mL in urine samples respectively. The method was validated as per FDA guidelines and successfully applied to a pharmacokinetic study of rosiglitazone in rats. [ABSTRACT FROM AUTHOR]

Notoginsenoside Fc (NGFc) is a protopanaxadiol-type (PPD-type) saponin from Panax notoginseng , which has perfect anti-platelet aggregatory effect. However, its pharmacokinetics and metabolism in vivo remain unknown. In this study, a simple and sensitive liquid chromatography/electrospray ionization tandem mass spectrometry (LC–MS/MS) method was first developed for the determination of NGFc in rat plasma. After methanol-mediated protein precipitation, separation was achieved on a C 18 column with MS detection operated in negative SRM mode at m / z 604.56 → m / z 783.90 and m / z 799.93 → m / z 637.64 for NGFc and IS, respectively. The assay was linear over the concentration range ( r > 0.995) with the LLOQ of 0.002 μg/ml. The intra- and inter-day precisions (R.S.D.) were 2.45–12.36% and 3.67–14.22%, respectively; whereas accuracy ranged from (R.R.) 93.90% to 99.41%. The extraction recovery, stability, and matrix effect were within the acceptable limits. The validated LC–MS/MS method was successfully applied to the pre-clinical pharmacokinetic studies of NGFc in rat. After oral and intravenous administration, NGFc showed dose-independent pharmacokinetic behaviors with a t 1/2 of >22 h and its oral bioavailability was 0.10–0.14%. In addition, a total of 10 metabolites were detected and structurally characterized by UPLC–Q/TOF-MS technique, which suggested that deglycosylation was the major metabolic pathway for NGFc in rats. [ABSTRACT FROM AUTHOR]

Vam3 is a potential pharmacologically active ingredient isolated from Vitis amurensis Rupr. A rapid, simple and sensitive method to determine Vam3 levels in rat plasma and tissue was developed based on LC-MS/MS. Vam3 and an internal standard (IS) were chromatographed on a C18 short column with acetonitrile–0.1% formic acid in water by gradient elution. MS detection was performed by electrospray ionization in negative ion multiple reaction–monitoring modes. This method monitored the transitions m / z 451.0→345.0 and m / z 301.0→164.0 for Vam3 and IS, respectively. The calibration curve was linear over a concentration range of 1.64–1000 ng/mL. The inter-day and intra-day variabilities in precision was less than 12.8%, while the inter-day and intra-day accuracies ranged from –10.60% to 9.08% in plasma and tissue homogenates. This method was applied to investigate the pharmacokinetics and tissue distribution of Vam3 in rats. The results indicated that Vam3 had poor absorption into systemic circulation and extensive tissue distribution after oral administration, and the absolute bioavailability was low (0.79%). Vam3 had a relatively long terminal elimination half-life in lung, and the highest concentration was found in small intestinal tissue. The developed method and the pharmacokinetic data can provide a basis for further studies on the bioactivity of Vam3. [ABSTRACT FROM AUTHOR]

A simple and selective specific high-performance liquid chromatography–tandem mass spectrometry (LC–MS/MS) method for determination of isobavachalcone (IBC) in rat plasma was developed. Neobavaisoflavone was used as an internal standard (IS). After protein precipitation with acetonitrile (2:1, v/v), the analyte and IS were separated on a 2.6 μm Kinetex C 18 column (100 mm × 2.1 mm i.d., Phenomenex) by isocratic elution with acetonitrile:water (60:40, v/v) as the mobile phase at a flow rate of 0.2 mL/min. An electrospray ionization (ESI) source was applied and operated in the negative ion mode; multiple reactions monitoring (MRM) mode was used for quantification, and the target fragment ions m / z 323.0 → 118.9 for IBC and m / z 321.1 → 265.0 for the IS were chosen. Good linearity was observed in the concentration range of 3.79–484.5 ng/mL for IBC in rat plasma. The recovery of IBC in plasma was in the range of 81.2–89.8%. Intra-day and inter-day precision were both lower than 10%. This method was suitable for pharmacokinetic studies after oral administration of 80 mg/kg IBC in rats. We also obtained pharmacokinetic parameters and concentration–time profiles for IBC after oral administration of IBC in rats. [ABSTRACT FROM AUTHOR]

CAT ((+)-(13aS)-deoxytylophorinine) is a novel anticancer drug belonging to phenanthroindolizidine alkaloids. A sensitive and reliable liquid chromatography–tandem mass spectrometry (LC–MS/MS) method for simultaneous quantification of CAT and its pharmacologically active 3-O-desmethyl metabolite (S-4) was developed and validated in rat plasma using rotundine as the internal standard (IS). CAT, S-4 and IS were extracted by acetonitrile protein precipitation and separated on an Eclipse XDB-C18 column (1.8 μm, 4.6 mm × 50 mm) with acetonitrile–water (27:73, v/v) mobile phase containing 0.1% formic acid at a 0.4 mL/min flow rate. Positive ion electrospray ionization in multiple reaction monitoring mode was employed to measure CAT, S-4 and IS by monitoring the transitions m/z 364.2 → 70.1 for CAT, 350.1 → 70.1 for S-4 and 356.2 → 192.2 for IS. Good linear correlation ( r 2 > 0.991) was achieved for CAT and S-4 over the range of 0.214–128.16 and 0.044–11.00 ng/mL, respectively. The lower limit of quantification was 0.214 ng/mL for CAT and 0.044 ng/mL for S-4, using 50 μL rat plasma samples. The intra- and inter-day precisions were not exceed 15% and the accuracy ranged between 94.80% and 108.22%. The average extraction recoveries of both analytes were greater than 94.62%. The method was successfully applied to the pharmacokinetic study of CAT and S-4 in rats after oral administration. [ABSTRACT FROM AUTHOR]

Efficacy assessments using a combination of ibrutinib and lenalidomide necessitate the development of an analytical method for determination of both drugs in plasma with precision. A high performance liquid chromatography–tandem mass spectrometry (LC–MS/MS) method was developed for the simultaneous determination of lenalidomide, ibrutinib, and its active metabolite PCI45227 in rat plasma. Extraction of lenalidomide, ibrutinib, PCI45227 and tolbutamide (internal standard; IS) from 50 μl rat plasma was carried out by liquid–liquid extraction with ethyl acetate:dichloromethane (90:10) ratio. Chromatographic separation of analytes was performed on YMC pack ODS AM (150 mm × 4.6 mm, 5 μm) column under gradient conditions with acetonitrile:0.1% formic acid buffer as the mobile phases at a flow rate of 1 ml/min. Precursor ion and product ion transition for analytes and IS were monitored on a triple quadrupole mass spectrometer, operated in the selective reaction monitoring with positive ionization mode. Method was validated over a concentration range of 0.72–183.20 ng/ml for ibrutinib, 0.76–194.33 ng/ml for PCI-45227 and 1.87–479.16 ng/ml for lenalidomide. Mean extraction recovery for ibrutinib, PCI-45227, lenalidomide and IS of 75.2%, 84.5%, 97.3% and 92.3% were consistent across low, medium, and high QC levels. Precision and accuracy at low, medium and high quality control levels were less than 15% across analytes. Bench top, wet, freeze–thaw and long term stability was evaluated for all the analytes. The analytical method was applied to support a pharmacokinetic study of simultaneous estimation of lenalidomide, ibrutinib, and its active metabolite PCI-45227 in Wistar rat. Assay reproducibility was demonstrated by re-analysis of 18 incurred samples. [ABSTRACT FROM AUTHOR]

A simple, rapid and sensitive high-performance liquid chromatography tandem mass-spectrometric method (LC-MS/MS) for the novel multiple tyrosine kinase inhibitor (TKI) cabozantinib was developed and validated using erlotinib as internal standard (IS). Plasma samples were pre-treated by liquid–liquid extraction with ethyl acetate. Separation was achieved on a reversed phase C18 column (50 × 2 mm, 5 μm) at ambient temperature using isocratic elution with acetonitrile-water (45:55, v/v) containing 5 mM ammonium formate buffer (finally adjusted to apparent pH* = 5.0 with formic acid) at a flow rate of 0.4 mL/min. The analytes were monitored by a triple quadrupole tandem mass spectrometer with electrospray ionization source in the positive ion mode. Calibration curve was linear ( r > 0.99) in a concentration range of 0.5–1000 ng/mL with the lower limit of quantification (LLOQ) of 0.5 ng/mL. Intra- and inter-day accuracy and precision were validated by relative error values (RE) and relative standard deviation values (RSD), respectively, which were both lower than the limit of 15%. This method was successfully applied to a pharmacokinetic study of cabozantinib in rats. [ABSTRACT FROM AUTHOR]

A simple, rapid and sensitive liquid chromatography–tandem mass spectrometry (LC–MS/MS) method was developed and validated for simultaneous determination of six components including apigenin, quercetin, apigenin-7- O -β- d -glucoside, quercetin-3- O -β- d -glucoside, 3′-methoxyluteolin-7- O -β- d -glucoside, and tricin-7- O -β- d -glucopyranoside in rat plasma using formononetin as the internal standard (IS). The plasma samples were pretreated by a one-step liquid–liquid extraction with dichloromethane. The chromatographic separation was carried out on a ZORBAX SB-Aq column with a gradient mobile phase consisting of acetonitrile and 2 mM aqueous ammonium acetate. All analytes and IS were quantitated through electrospray ionization in negative ion multiple reaction monitoring mode. The mass transitions were as follows: m / z 269.1 → 117.2 for apigenin, m / z 301.2 → 151.2 for quercetin, m / z 431.3 → 311.2 for apigenin-7- O -β- d -glucoside, m / z 463.2 → 300.2 for quercetin-3- O -β- d -glucoside, m / z 461.3 → 283.1 for 3′-methoxyluteolin-7- O -β- d -glucoside, m / z 491.3 → 313.1 for tricin-7- O -β- d -glucopyranoside, and m / z 267.2 → 252.2 for IS, respectively. All calibration curves exhibited good linearity with correlation coefficient ( r ) > 0.995. The intra-day and inter-day precisions (RSD) at three QC levels were both less than 14.0% and the accuracies ranged from 89.8% to 113.8%. The extraction recoveries of six compounds ranged from 82.3% to 92.5%. The validated method was successfully applied to pharmacokinetic study of the six components in male rat plasma after oral administration of Paulownia tomentosa flower extract. [ABSTRACT FROM AUTHOR]

A highly sensitive and selective liquid chromatography–tandem mass spectrometry (LC–MS/MS) method was developed and fully validated for quantification of arotinolol enantiomers in rat plasma using haloperidol as the internal standard. After solid phase extraction of 50.0 μL rat plasma in 96 well plate, a baseline resolution of arotinolol enantiomers was achieved on a CHIRALPAK AD-H column using the mobile phase of n-hexane and ethanol in 0.02% diethylamine (20:80, v/v) at a flow rate of 0.550 mL/min within 11.0 min. Acquisition of mass spectrometric data was performed on a triple-quadrupole mass spectrometer in multiple-reaction-monitoring (MRM) mode with an ESI source using the transition m / z 372.1 → 316.1 for (±)-arotinolol and m / z 376.1 → 165.1 for haloperidol. The calibration curves of both enantiomers were linear over the range of 1.00–200.0 ng/mL ( r 2 > 0.992) and the lower limit of quantification was 1.00 ng/mL. Intra- and inter-day precision ranged from 5.6% to 8.9% for R-(−)-arotinolol and 4.6–7.4% for S-(+)-arotinolol. Accuracy varied from 0.0% to 7.0% for R-(−)-arotinolol and 5.0–10.0% for S-(+)-arotinolol. For R-(−)-arotinolol, the recovery ranged from 87.2% to 99.2% and the matrix factor was 1.03–1.09; for S-(+)-arotinolol, the recovery ranged from 88.0% to 92.4% and the matrix factor was 0.84–0.95, both were not concentration dependent. The method was demonstrated with acceptable accuracy, precision and specificity for the determination of arotinolol enantiomers and has been successfully applied to a stereoselective pharmacokinetic study. [ABSTRACT FROM AUTHOR]

Acrylamide (AA) is a heat-generated food toxicant formed when starchy foods are fried or baked. This study describes a simple and sensitive liquid chromatography–tandem mass spectrometry assay for the simultaneous quantification of AA and its active metabolite, glycidamide (GA) in rat plasma, urine, and 14 different tissues. The assay utilized a simple method of protein precipitation and achieved a lower limit of quantification of 5, 10 and 25 ng/mL of AA and 10, 20 and 100 ng/mL of GA for plasma, tissues and urine, respectively. The assay was fully validated to demonstrate the linearity, sensitivity, accuracy, precision, process recovery, and stability using matrix matched quality control samples. The mean intra- and inter-day assay accuracy was 91.6–110% for AA and 92.0–109% for GA, and the mean intra- and inter-day assay precisions were ≤10.9% for AA and ≤8.60% for GA. The developed method was successfully applied to a pharmacokinetic study of AA and GA following intravenous and oral administration of AA in rats. Tissue distribution characteristics of AA and GA were also determined under steady-state conditions. [ABSTRACT FROM AUTHOR]

A simple, rapid and specific high performance liquid chromatography–electrospray ionization tandem mass spectrometry method was developed for simultaneous determination of dabigatran etexilate (BIBR 1048 MS), the intermediate metabolite (BIBR 1087 SE) and dabigatran (BIBR 953 ZW). In this method, a stacked protein precipitation with methanol was performed in Sirocco 96-well filtration plates to extract analytes using only 50 μL plasma. The analysis was performed on an Ultimate TM XB-C18 (4.6 × 50 mm, 5 μm) column using gradient elution with a mobile phase composed of methanol containing 0.01% formic acid and pure water at a flow rate of 0.3 mL/min. The gradient was set to 90% methanol containing 0.01% formic acid for the first 1.0 min, after which it dropped to 10%, and then was kept at 10% for the next 5 min followed by an additional 1.0 min at the initial composition of 90% methanol containing 0.01% formic acid for equilibration. Detection was performed on a triple-quadrupole mass spectrometer electrospray ionization interface in positive ion mode. Linear calibration curves were obtained over the concentration ranges of 1–500 ng/mL for all analytes. The validated LC–MS/MS method for its selectivity, sensitivity, linearity, precision, accuracy, recovery, matrix effect and stability had been successfully applied to a pharmacokinetic study of analytes in rat plasma following a single oral administration of 15 mg/kg dabigatran etexilate. [ABSTRACT FROM AUTHOR]

A highly selective and sensitive method for simultaneous quantitation of osthole, bergapten and isopimpinellin in rat plasma and tissues was developed by liquid chromatography–tandem quadrupole mass spectrometry (LC–MS/MS). After liquid–liquid extraction of samples with methyl tert-butyl ether, the analytes and dextrorphan (internal standard, IS) were separated by a Hypersil GOLD AQ C18 column with gradient elution of acetonitrile and water containing 0.5‰ formic acid. Three determinands were detected using an electrospray ionization (ESI) tandem mass spectrometry in the multiple reaction monitoring (MRM) modes with positive electrospray ionization. Calibration curves were recovered over the concentration ranges of 1–200 ng/ml, 1–500 ng/ml, 0.25–200 ng/ml for osthole, bergapten and isopimpinellin in plasma; 1–100 ng/ml, 1–500 ng/ml, 0.5–100 ng/ml for osthole, bergapten and isopimpinellin in tissues, respectively. The intra-day precision (R.S.D.) was within 13.90% and the intra-day accuracy (R.E.) was within −6.27 to 6.84% in all biological matrixes. The inter-day precision (R.S.D.) was less than 13.66% and the inter-day accuracy (R.E.) was within −10.64 to 13.04%. Then the method was successfully applied to investigate plasma pharmacokinetic study and tissue distribution of osthole, bergapten and isopimpinellin in rats after oral administration of Fructus Cnidii extraction, especially for testis/uterus tissue distribution. The results demonstrated that osthole, bergapten and isopimpinellin were absorbed and eliminated rapidly with wide distributions in rats. Distribution data of these three bioactive components in testis/uterus tissues could offer useful information for the further preclinical and clinical studies of Fructus Cnidii in the treatment of genital system disease. [ABSTRACT FROM AUTHOR]

In the present study, a new LC–MS/MS method for the determination of roemerine in rat plasma and tissue samples was developed and successfully used to study the pharmacokinetics and tissue distribution of roemerine after oral and intravenous (i.v.) administration in rats. The plasma and tissue samples were processed by liquid–liquid extraction with n -hexane. Isocorydine was used as the internal standard (IS) for sample processing and analysis. The MS/MS detection was carried out by monitoring the transitions of m/z 280→249 and m/z 342→279 for roemerine and the IS, respectively. The calibration curve displayed excellent linearity over the concentration range of 10–2000 ng/mL ( n = 8, r 2 ≥ 0.995), and the lower limit of quantification (LLOQ) was determined to be 10 ng/mL. This method was rapid, accurate, highly sensitive, and fully validated. The pharmacokinetic study showed that roemerine was rapidly absorbed and eliminated with a t max of 0.22 ± 0.08 h, t 1/2 of 1.59 ± 0.46 h, CL of 4.44 ± 0.42 L/h/kg, and V d of 10.16 ± 2.95 μg/L following oral administration. Additionally, roemerine showed an excellent oral bioavailability of 84% and a wide tissue distribution with brain penetration. Highest concentrations of roemerine were found in the liver and lung, followed by kidney, spleen, heart, and brain, in that order. [ABSTRACT FROM AUTHOR]

A rapid, sensitive and selective liquid chromatography/tandem mass spectrometry method (LC-MS/MS) was developed and validated for determination of dehydrocorydaline (DHC) in rat plasma using nitidine chloride as an internal standard. The analytes were solid-phase extracted and eluted on a C18 chromatography column using a mobile phase of acetonitrile and water (containing 0.8% formic acid and 10 mM ammonium acetate) (28:72, v/v). Detection was performed using positive ion electrospray ionization in multiple reaction monitoring modes. The assay was linear over the concentration range 0.625-250 ng/mL with a quantification limit of 0.625 ng/mL. The precision was <13.7%, the accuracy >93.1%, and extraction recovery ranged from 92.1% to 107%. The validated method was successfully applied to the pharmacokinetics and excretion study of DHC in rat plasma after oral administration of pure DHC and an effective fraction of Corydalis yanhusuo (EFY). The pharmacokinetic parameters showed that DHC from EFY was absorbed more rapidly and eliminated more slowly than pure DHC. The result suggests that the differences might be due to the presence of P-glycoprotein (P-gp) inhibitors and that other alkaloids co-existing in the EFY may compete with DHC for transportation by P-gp, metabolization by P450, and binding to plasma proteins. [ABSTRACT FROM AUTHOR]

Nigella glandulifera Freyn et Sit is a folk medicinal plant, whose seeds show significant anticancer activities attributed to triterpene saponins and volatile oil. In this study, an in vitro cytotoxicity assay demonstrated that Nigella A, the major component of triterpene saponins extracted from N. glandulifera , exhibited growth inhibition in the human lung carcinoma A-549 cell line. Due to this potential activity, a reliable liquid chromatography–tandem mass spectrometry (LC–MS/MS) method to quantify Nigella A in rat plasma for a pharmacokinetic study was developed. Nigella A and pravastatin, as internal standard (IS), were extracted from rat plasma using acetonitrile to precipitate protein. Separation was performed on an Agilent Zorbax SB-Aq (3.0 × 150 mm, 3.5 μm) column using a gradient elution method with acetonitrile–0.1% formic acid in water at a flow rate of 0.35 mL/min. Detection was performed using an electrospray ionization in a negative ion multiple reaction monitoring mode. The deprotonated precursor to product ion transitions monitored for Nigella A and IS was at m / z 1352.7→882.6 and m / z 423.1→321.0, respectively. The linear range was 0.240–120 μg/mL with a square regression coefficient ( r = 0.9996). The intra-day and inter-day precision was less than 6.93%. The simple extraction procedure provided recovery ranged from 92.32 to 95.44% for both analyte and IS. The method was proved to be reliable, precise, and accurate, and was successfully applied to a pharmacokinetic study of Nigella A in rats after i.v. administration via the tail vein at doses of 10, 20, and 30 mg/kg. [ABSTRACT FROM AUTHOR]

A sensitive, specific and rapid liquid chromatography–mass spectrometry (LC–MS/MS) method has been developed and validated for the simultaneous determination of swertiamarin, gentiopicroside, sweroside, mangiferin, isoorientin and isovitexin in rat plasma, bile, urine and feces after oral administration of Swertia pseudochinensis extract using sulfamethalazole (SMZ) as an internal standard (IS). The samples were pretreated and extracted by liquid-liquid extraction as the sample clean-up procedure. The chromatographic separation was performed on a C 18 column with a linear gradient elution using a mobile phase consisted of 0.1% formic acid and methanol at a flow rate of 0.8 mL/min. The total run time was 10 min. Determination and quantification of the analytes were achieved by use of a hybrid quadrupole linear ion-trap mass spectrometer. A multiple-reaction monitoring scanning (MRM) method with electrospray ionization (ESI) source was employed with simultaneously monitoring the positive and negative electrospray ion source polarity in a single run. A full validation of the method was performed. The linearity of the analytical response was good, with correlation coefficients greater than 0.9953. The intra-day and inter-day precisions (RSD %) exhibited within 10.4%, and the accuracy (RE %) ranged from −8.7% to 9.5%. A non-compartmental model was employed to calculate the parameters. The values of elimination rate constants ( K e ) ranged from 0.0026 to 0.0118 and the elimination half-life ( T 1/2 ) ranged from 58.4 to 263.0 min. This is the first report on pharmacokinetic and excretion study of Swertia pseudochinensis extract after oral administration. The results provided a meaningful basis for the clinical application of this herb. [ABSTRACT FROM AUTHOR]

The deuterohemin-peptide conjugate (DhHP-6) is a microperoxidase mimetic, which has demonstrated substantial benefits in vivo as a scavenger of reactive oxygen species. This paper reports the development of a sensitive and rapid liquid chromatography tandem mass spectrometry (LC-MS/MS) method for the determination of DhHP-6 in rat plasma using triptorelin as an internal standard (IS). 50 μL plasma was used in sample preparation, and a simple protein precipitation procedure with acetonitrile was involved. Satisfactory peak shapes of analyte and IS were obtained on an Agilent HC-C18 column by using a gradient elution with 10 mM ammonium acetate-0.5% formic acid (v:v) and acetonitrile, there was no significant interference impacting the determination. A calibration curve obtained from this method was linear within the concentration range 10-3000 ng/mL with intra- and inter-day precisions of 4.2-6.8% and 3.2-8.9%, respectively and accuracy of -1.3% to 2.1%. The recovery was above 80% with low matrix effects. The method was successfully applied to support a preclinical pharmacokinetic study in rat. [ABSTRACT FROM AUTHOR]