Quantitation of bivalirudin,a novel anticoagulant peptide,in human plasma by LC-MS/MS:Method development,validation and application to pharmacokinetics

A rapid and sensitive method based on liquid chromatographtandem mass spectrometry （LC-MS/MS） for the determination of a novel anticoagulant peptide bivalirudin in human plasma has been developed and validated. Plasma samples were precipitated protein with acetonitrile and reextracted with dichloromethane, after which the analyte and triptorelin as an internal standard （IS） were separated on a 300SB-Cl8 column （150 mm x 4.6 mm i.d., 5 gm particle size） using 0.1% formic acid：methanol （45：55, v/v） as mobile phase. The triple-quadrupole mass spectrometer, equipped with electrospray ionization （ESI） interface, was operated in the positive ion mode, and the multiplereaction monitoring （MRM） transitions of bivalirudin and IS were at m/z 1091.0-650.4 and m/z656.5 - 249.3, respectively. The lower limit of quantification （LLOQ） was 1 ng/mL for 100 ng/mL plasma sample and the assay was linear over the concentration range 1 1000 ng/mL. The accuracy was within a range from -0.4% to 0.5% in terms of relative error （RE） and the intra- and inter-day precisions in terms of relative standard deviation （RSD） were 〈2.92 and 〈 3.36, respectively. The method was successfully applied to a pharmacokinetic study involving intravenous administration of bivalirudin （0.5 mg/kg） to Chinese volunteers.

Hepatoprotective effect of Cichorium intybus L.,a traditional Uighur medicine,against carbon tetrachloride-induced hepatic fibrosis in rats

AIM: To investigate the hepatoprotective effect of a Cichorium intybus L. extract (CIE) on CCl4-induced hepatic fibrosis in rats.

Determination of repaglinide in human plasma by high-performance liquid chromatography–tandem mass spectrometry

A rapid and sensitive method based on high-performance liquid chromatography–tandem mass spectrometry(LC–MS/MS)has been developed for the determination of repaglinide in human plasma.The analyte and internal standard(I.S.),diazepam,were extracted from plasma(25 mL)by liquid–liquid extraction with diethyl ether–dichloromethane(60:40,v/v)and separated on a XDB-C_(18) column using acetonitrile–ammonium acetate buffer(pH 6.8,0.01 mol/L)as mobile phase.The retention times of repaglinide and I.S.were 1.95 and 2.35 min,respectively.Detection was carried out using API 4000 mass spectrometer with an ESI interface operating in the multiple reaction monitoring(MRM)mode.The assay was linear over the concentration range 0.050–50 ng/mL with a limit of detection(LOD)of 0.010 ng/mL.Intra-and inter-day precisions(as relative standard deviation,R.S.D.)were ≤5.07%and ≤11.2%,respectively,and accuracy(as relative error,R.E.)was from-0.593%to -1.26%.The assay was successfully applied to a pharmacokinetic study involving a single oral administration of a tablet containing 2 mg repaglinide to each of 10 healthy volunteers.

Characterization and mapping of the multi-component release kinetics of a Traditional Chinese Medicine dosage form using a modified LC/MS/MS method and chemomic release kinetic theory

It is essential to develop effective methods for the quality control of the traditional medicine with multiple components.However,few researches on the quality control have been conducted to interpret the holistic characteristics of the traditional medicine in terms of dissolution/release.In this study,the multi-component release kinetics of Traditional Chinese Medicine(TCM)dosage forms was characterized and mapped by multivariate analysis techniques in the field of‘‘-omics’’.The Liuweidihuang pill was used as a model formulation.The multi-component release kinetics of the concentrated and water-honeyed Liuweidihuang pills at rotation speeds of 50 and 100 rpm were analyzed by chemomic release kinetic theory and modified LC/MS/MS method.Mass features of 103(concentrated pills)and 101(water-honeyed pills)were selected with a linear correlation coefficient Z0.99 between mass responses and concentrations.To compose the chemomic standard spectrum,the relative abundance of both mass features was no less than 1%as compared with an internal standard.The correlation coefficients between six samples of various solutions were in line with analytical requirements of precision(rZ0.985).The score plots of principal component analysis showed that the concentrated Liuweidihuang pills presented better chemomic release reproducibility than the water-honeyed pills.Conversely,the impact of rotation speed on the chemomic release was less obvious.The heat maps of hierarchical clustering analysis did not show significant changes in individual clusters of mass features along different time intervals,reflecting the release integrity of the mass features.Therefore,both multivariate analysis methods,the principal component analysis and the hierarchical clustering analysis,seemed to be effective techniques to demonstrate the multiple component release performance of TCM.The research provided the basis of a new strategy for the quality control procedures of the dissolution/release for the traditional medicine and multi-component natural products to address increasing regulatory requirements and scrutiny across the world.