Determination of genkwanin in rat plasma by liquid chromatography-tandem mass spectrometry: application to a bioavailability study.

We developed and validated a sensitive, rapid, and specific liquid chromatography tandem mass spectrometry method to determine genkwanin in rat plasma. Genistein was used as the internal standard. After liquid-liquid extraction with ethyl acetate, the chromatographic separation of genkwanin was achieved by using a reversed-phase HPLC using Agela Venusil MP-C18 analytical column (2.1 mm × 50 mm, 5 μm particles) with a mobile phase of methanol (A)-water (B) (65:35, v/v) containing 5mM ammonium acetate and 0.1% formic acid. The detection was performed by negative ion electrospray ionization in multiple-reaction monitoring mode by using transitions of m/z 283.1→268.1 and m/z 269.1→133.0 for genkwanin and IS, respectively. Good linearity was observed in the concentration range of 3.84 ng/ml to 3,840 ng/ml (r(2)>0.99), and the lower limit of quantification was 3.84 ng/ml in 100 μl of rat plasma. The intra- and inter-day accuracy and precision of genkwanin were both within acceptable limits. This present method was successfully applied to a pharmacokinetic study of genkwanin in rats following oral (50mg/kg) and intravenous (5mg/kg) administration. For the oral administration group, the maximum mean concentration of genkwanin in plasma (Cmax, 36.9 ± 9.4 ng/ml) was achieved at 3.83 ± 1.33 h (Tmax), and the area under the plasma concentration versus time curve from 0 h to 12h (AUC0-12h) was 218 ± 40 ngh/ml. For the intravenous administration group, essential pharmacokinetic parameters such as Cmax (1,755 ± 197 ng/ml) and AUC0-12h (2,349 ± 573 ngh/ml) were shown. The result showed that the compound was poorly absorbed with an absolute bioavailability of approximately 1.1%.

Song Y ，Zhang S ，Liu H ，Jin X ... -  《-》

Determination of chamaechromone in rat plasma by liquid chromatography-tandem mass spectrometry: application to pharmacokinetic study.

A rapid, simple and accurate method was developed for the determination of chamaechromone in rat plasma using liquid chromatography tandem mass spectrometry (LC-MS-MS). Rosuvastatin was used as the internal standard. The plasma samples were extracted by liquid-liquid extraction with ethyl acetate. Chromatographic separation was performed on Xbridge™ C(18) column (2.1mm×50mm, 3.5μm) with linear gradient elution using water and methanol, both of which were acidified with 0.1% aqueous formic acid. The flow rate was 0.4mL/min and the total run time was 6min. Detection was performed on a triple-quadrupole tandem mass spectrometer using positive ion mode electrospray ionization (ESI) in the multiple reaction monitoring (MRM) mode. The MS/MS ion transitions monitored were m/z 543.3→198.9 and 481.9→258.3 for chamaechromone and rosuvastatin, respectively. Good linearity was observed over the concentration range of 8-6400ng/mL in 0.1mL of rat plasma. The lowest concentration (8ng/mL) in the calibration curve was estimated as LLOQ with both deviation of accuracy and RSD of precision <20% (n=6). Intra-assay and inter-assay variability were less than 11% in plasma. This method was successfully applied to a pharmacokinetic study of chamaechromone in rats after intravenous (5mg/kg) and oral (100mg/kg) administration. Following oral administration the concentration-time curve of chamaechromone exhibited a biphasic absorption profile. The maximum mean concentration in plasma (C(max), 795.9±14.6ng/L) was achieved at 11.3±0.8h (T(max)) and the area under curve (AUC(0-60)) was 6976.7±1026.9ngh/L. After single intravenously administration of chamaechromone, the essential pharmacokinetic parameters C(max), AUC(0-48) were 4300.7±113.6ng/L and 3672.1±225.4ngh/L, respectively. The result showed that the compound was poorly absorbed with an absolute bioavailability being approximately 8.9%.

Lou Y ，Hu H ，Liu Y ，Yu Q ，Li L ，Ping L ，Yu L ，Jiang H ，Zeng S ... -  《-》

Determination of tegaserod by LC-ESI-MS/MS and its application to a pharmacokinetic study in healthy Chinese volunteers.

Zou JJ ，Bian XJ ，Ding L ，Zhu YB ，Fan HW ，Xiao DW ... -  《JOURNAL OF CHROMATOGRAPHY B-ANALYTICAL TECHNOLOGIES IN THE BIOMEDICAL AND LIFE SCIENCES》

LC-MS/MS determination of nevadensin in rat plasma and its application in pharmacokinetic studies.

A simple, sensitive and specific liquid chromatography-electrospray tandem mass spectrometry (LC-MS/MS) method was developed and validated to quantitate nevadensin in rat plasma using genistein as the internal standard (IS). The assay was based on protein precipitation treatment with acetonitrile and liquid chromatography performed on a reverse-phase Zorbax SB-C(18) column (50 mm × 2.1 mm, 1.8 μm). Elution was achieved with a mobile phase consisted of aqueous solution containing 0.1% formic acid (solvent A) and methanol solution containing 0.1% formic acid (solvent B) at a flow rate of 300 μL/min (30:70, v/v). Quantification was through tandem-mass spectrometry with positive electrospray ionization (ESI) and multiple reaction monitoring (MRM) at m/z 345.1→315.1 and 271.1→215.1 for nevadensin and IS, respectively. Calibration curves were linear over the nevadensin rat plasma concentration range of 0.1-300 ng/mL. The lower limit of quantification (LLOQ) was 0.100 ng/mL and the inter- and intra-day accuracy and precision ranged between -1.67% and 7.60%. The average recovery of nevadensin was 95.6-99.1%. The validated method was successfully applied to the pharmacokinetic evaluation of nevadensin using the rat as an animal model following an oral administration of 50mg/kg nevadensin.

Liu H ，Yan C ，Li C ，Lin L ... -  《-》

Determination of geniposide in adjuvant arthritis rat plasma by ultra-high performance liquid chromatography tandem mass spectrometry method and its application to oral bioavailability and plasma protein binding ability studies.

A specific, sensitive and high throughput ultra-high performance liquid chromatography-electrospray ionization tandem mass spectrometric method (UHPLC-ESI-MS/MS) was established and validated to assay geniposide (GE), a promising anti-inflammatory drug, in adjuvant arthritis rat plasma: application to pharmacokinetic and oral bioavailability studies and plasma protein binding ability. Plasma samples were processed by de-proteinised with ice-cold methanol and separated on an ACQUITY UPLC™ HSS C18 column (100 mm × 2.1mm i.d., 1.8 μm particle size) at a gradient flow rate of 0.2 mL/min using acetonitrile-0.1% formic acid in water as mobile phase, and the total run time was 9 min. Mass detection was performed in selected reaction monitoring (SRM) mode with negative electro-spray ionization includes the addition of paeoniflorin (Pae) as an internal standard (IS). The mass transition ion-pair was followed as m/z 387.4 → 122.4 for GE and m/z 479.4 → 449.0 for IS. The calibration curves were linear over the concentration range of 2-50,000 ng/mL with lower limit of quantification of 2 ng/mL. The intra-day and inter-day precisions (RSD, %) of the assay were less than 8.4%, and the accuracy was within ± 6.4% in terms of relative error (RE). Extraction recovery, matrix effect and stability were satisfactory in adjuvant arthritis rat plasma. The UHPLC-ESI-MS/MS method was successfully applied to a pharmacokinetic study of GE after oral administration of depurated GE at 33, 66, 132 mg/kg and intravenous injection at 33, 66, 132 mg/kg in adjuvant arthritis (AA) rats. In addition, it was found that GE has rapid absorption and elimination, low absolute bioavailability, high plasma protein binding ability in AA rats after oral administration within the tested dosage range. It suggested that GE showed slow distribution into the intra- and extracellular space, and the binding rate was not proportionally dependent on plasma concentration of GE when the concentration of GE was below 5.0 μg/mL.

Chen J ，Wu H ，Xu GB ，Dai MM ，Hu SL ，Sun LL ，Wang W ，Wang R ，Li SP ，Li GQ ... -  《-》