Analysis of the pharmacokinetics and metabolism of aloe‐emodin following intravenous and oral administrations in rats

Aloe‐emodin, a natural polyphenolic anthraquinone, has shown various beneficial bioactivities in vitro. The aim of this study was to investigate the pharmacokinetics and metabolism of aloe‐emodin. Aloe‐emodin was intravenously and orally administered to rats. The concentrations of aloe‐emodin and rhein, a metabolite of aloe‐emodin, were determined by HPLC method prior to and after hydrolysis with β‐glucuronidase and sulfatase/β‐glucuronidase. The results showed that the systemic exposures of aloe‐emodin and its metabolites were ranked as aloe‐emodin glucuronides (G) > rhein sulfates (S) > aloe‐emodin > rhein and rhein G when aloe‐emodin was given intravenously. In contrast, when aloe‐emodin was administered orally, the parent form of aloe‐emodin was not absorbed per se, and the systemic exposures of its metabolites were ranked as aloe‐emodin G > rhein G > rhein. In conclusion, the metabolites of aloe‐emodin are more important than the parent form for the bioactivities in vivo. Copyright © 2016 John Wiley & Sons, Ltd.     

Concurrent determination of olanzapine,risperidone and 9‐hydroxyrisperidone in human plasma by ultra performance liquid chromatography with diode array detection method: application to pharmacokinetic study

A simple and sensitive ultra‐performance liquid chromatography (UPLC) method has been developed and validated for simultaneous estimation of olanzapine (OLZ), risperidone (RIS) and 9‐hydroxyrisperidone (9‐OHRIS) in human plasma in vitro. The sample preparation was performed by simple liquid–liquid extraction technique. The analytes were chromatographed on a Waters Acquity H class UPLC system using isocratic mobile phase conditions at a flow rate of 0.3 mL/min and Acquity UPLC BEH shield RP₁₈ column maintained at 40°C. Quantification was performed on a photodiode array detector set at 277 nm and clozapine was used as internal standard (IS). OLZ, RIS, 9‐OHRIS and IS retention times were found to be 0.9, 1.4, .1.8 and 3.1 min, respectively, and the total run time was 4 min. The method was validated for selectivity, specificity, recovery, linearity, accuracy, precision and sample stability. The calibration curve was linear over the concentration range 1–100 ng/mL for OLZ, RIS and 9‐OHRIS. Intra‐ and inter‐day precisions for OLZ, RIS and 9‐OHRIS were found to be good with the coefficient of variation <6.96%, and the accuracy ranging from 97.55 to 105.41%, in human plasma. The validated UPLC method was successfully applied to the pharmacokinetic study of RIS and 9‐OHRIS in human plasma. Copyright © 2015 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 determination of cucurbitacin IIa and cucurbitacin IIb of Hemsleya amabilis by HPLC–MS/MS and their pharmacokinetic study in normal and indomethacin‐induced rats

A selective and sensitive HPLC–MS/MS method was developed for the simultaneous determination of cucurbitacin IIa (cuIIa) and cucurbitacin IIb (cuIIb), the major bioactive cucurbitacins of Hemsleya amabilis, in rat plasma using euphadienol as internal standard (IS). After liquid–liquid extraction with dichloromethane, separation was achieved on a Syncronis HPLC C₁₈ column (150 mm × 4.6 mm, 5 μm) using an isocratic mobile phase system consisting of acetonitrile–water (85:15, v/v) at a flow rate of 0.6 mL/min with a split ratio of 1:2. Detection was performed on a TSQ Quantum Ultra mass spectrometer equipped with an positive‐ion electrospray ionization source. The lower limits of quantification (LLOQs) were 0.25 and 0.15 ng/mL for cuIIa and cuIIb, respectively. The intra‐ and inter‐day precision was <11.5% for the LLOQs and each quality control level of the analytes, and accuracy was between ?9.1 and 7.6%. The extraction recoveries of the analytes and IS from rat plasma were all >87.1%. The method was fully validated and applied to compare the pharmacokinetic profiles of the two cucurbitacins in rat plasma after oral administration of H. amabilis extract between normal and indomethacin‐induced rats. Copyright © 2016 John Wiley & Sons, Ltd.     

In vivo solid-phase microextraction for single rodent pharmacokinetics studies of carbamazepine and carbamazepine-10,11-epoxide in mice

The use of solid-phase microextraction (SPME) for in vivo sampling of drugs and metabolites in the bloodstream of freely moving animals eliminates the need for blood withdrawal in order to generate pharmacokinetics (PK) profiles in support of pharmaceutical drug discovery studies. In this study, SPME was applied for in vivo sampling in mice for the first time and enables the use of a single animal to construct the entire PK profile. In vivo SPME sampling procedure used commercial prototype single-use in vivo SPME probes with a biocompatible extractive coating and a polyurethane sampling interface designed to facilitate repeated sampling from the same animal. Pre-equilibrium in vivo SPME sampling, kinetic on-fibre standardization calibration and liquid chromatography–tandem mass spectrometry analysis (LC–MS/MS) were used to determine unbound and total circulating concentrations of carbamazepine (CBZ) and its active metabolite carbamazepine-10,11-epoxide (CBZEP) in mice (n = 7) after 2 mg/kg intravenous dosing. The method was linear in the range of 1–2000 ng/mL CBZ in whole blood with acceptable accuracy (93–97%) and precision (<17% RSD). The single dose PK results obtained using in vivo SPME sampling compare well to results obtained by serial automated blood sampling as well as by the more conventional method of terminal blood collection from multiple animals/time point. In vivo SPME offers the advantages of serial and repeated sampling from the same animal, speed, improved sample clean-up, decreased animal use and the ability to obtain both free and total drug concentrations from the same experiment.     

高效液相色谱-串联质谱法测定比格犬血浆中的莫诺苷浓度及其药代动力学

运用高效液相色谱-串联质谱联用技术,建立了简单、快速、灵敏的比格犬灌胃莫诺苷后血药浓度的检测方法。血浆样品采用蛋白质沉淀法处理,以芍药苷作为内标,色谱柱为Inertsil ODS-SP色谱柱(50 mm×2.1 mm,5μm),流动相为水(含1 mmol/L甲酸钠)-乙腈,梯度洗脱,流速0.4 mL/min。采用电喷雾离子源(ESI),正离子多反应监测(MRM)模式。绘制血药浓度-时间曲线,并采用DAS 2.0软件计算药代动力学参数。方法学实验结果表明内源性杂质不干扰莫诺苷和内标的测定,线性范围为2~5 000μg/L(r=0.996 6),定量限为2μg/L。方法精密度、准确度、回收率和基质效应均符合生物样品测定的要求,适合比格犬血浆中莫诺苷浓度的测定,可以应用该方法进行莫诺苷的药代动力学研究。比格犬灌胃莫诺苷3个剂量(5、15、45 mg/kg)后的血药浓度-时间曲线下面积(AUC(0-∞))分别为(1 631.20±238.50)、(3 984.05±750.38)、(10 397.64±3 156.34)μg/L·h,与给药剂量之间呈现良好的线性关系。     

A UPLC–MS/MS approach for simultaneous determination of eight flavonoids in rat plasma,and its application to pharmacokinetic studies of Fu‐Zhu‐Jiang‐Tang tablet in rats

The purpose of this study is to establish and validate a UPLC–MS/MS approach to determine eight flavonoids in biological samples and apply the method to pharmacokinetic study of Fu‐Zhu‐Jiang‐Tang tablet. A Waters BEH C₁₈ UPLC column was employed with methanol/0.1% formic acid–water as mobile phases. The mass analysis was carried out in a triple quadrupole mass spectrometer using multiple reaction monitoring with negative scan mode. A one‐step protein precipitation by methanol was used to extract the analytes from blood. Eight major flavonoids were selected as markers. Our results showed that calibration curves for 3′‐hydroxypuerarin, mirificin, puerarin, 3′‐methoxypuerarin, daidzin, rutin, astragalin and daidzein displayed good linear regression (r ² > 0.9986). The intra‐day and inter‐day precisions (RSD) of the eight flavonoids at high, medium and low levels were <8.03% and the bias of the accuracies ranged from −5.20 to 6.75%.The extraction recoveries of the eight flavonoids were from 91.4 to 100.5% and the matrix effects ranged from 89.8 to 103.8%. The validated approach was successfully applied to a pharmacokinetic study in Sprague–Dawley rats after oral administration of FZJT tablet. Double peaks were emerged in curves of mean plasma concentration for 3′‐methoxypuerarin, which was reported for the first time.     

UHPLC–MS/MS determination and pharmacokinetic study of plantamajoside in rat plasma after oral administration of single plantamajoside and Plantago asiatica extract

A sensitive and reliable ultra‐high performance liquid chromatography coupled with tandem quadrupole mass spectrometry (UHPLC–MS/MS) method was developed for quantitation of plantamajoside in rat plasma. First, this study compared the pharmacokinetic properties of plantamajoside after oral administration of Plantago asiatica extract and pure plantamajoside in rat plasma with approximately the same dosage of 8.98 mg/kg. Second, chromatographic separation was performed on an Acquity HSS C₁₈ column (50 × 2.1 mm, p.d.1.7 μm) with isocratic elution using methanol–water (80:20, v /v) as mobile phase at a flow rate of 0.25 mL/min. The calibration curves were linear over the range of 0.1–100 ng/mL for plantamajoside. At different time points (0, 0.083, 0.167, 0.25, 0.5, 0.75, 1, 2, 3, 4, 5, 6 and 8 h) after administration, the concentrations of plantamajoside in plasma were measured and the main pharmacokinetic parameters were estimated. The study indicates that the pharmacokinetics of plantamajoside in rat plasma have significant differences between two groups.     

Quantification of furosemide in camel plasma by high resolution mass spectrometry,application on pharmacokinetics

We developed and validated a high‐resolution liquid chromatography mass spectrometry method for the quantification of furosemide in camel plasma which was used for a pharmacokinetic study in camels. Plasma samples were extracted by supported liquid extraction and furosemide and internal standard (furosemide‐D5) were separated on a an Agilent Zorbax XDB C₁₈ column (50 × 2.1 mm i.d., 3.5 μm). Data was acquired in full‐scan mode over a mass range of 200–400 Da in negative electrospray mode at a resolution of 70,000. Linear calibration curves were obtained over the concentration ranges of 1.0–10,000 ng/mL. The validated method was then successfully applied in evaluating the pharmacokinetics and metabolites of furosemide in six camels (Camelus dromedarus ) and we were able to advice on a withdrawal time of furosemide treatment before racing.     

Application of a liquid chromatography–tandem mass spectrometry method to the pharmacokinetics,tissue distribution and excretion in the study of anemoside B4, a novel antiviral agent candidate,in rats

A simple, sensitive and reliable LC–MS/MS method was developed and validated for the quantification of anemoside B4, a potential antiviral constituent isolated from Pulsatilla chinensis in rat plasma, tissue, bile, urine and feces. All biological samples were prepared by protein precipitation method, and ginsenoside‐Rg1 was chosen as the internal standard (IS). The analyte and IS were separated using a C₁₈ column (2.1 × 50 mm, 1.8 μm) and a mobile phase consisting of 0.1% formic acid in water (v /v) and acetonitrile running at a flow rate of 0.2 mL/min for 5 min. The multiple reaction monitoring transitions were monitored at m /z 1219.5–749.5 for anemoside B4 and 845.4–637.4 for ginsenoside‐Rg1 in electrospray ionization negative mode. The calibration curve was linear in the range of 10–2000 ng/mL for all biological matrices with a lower limit of quantification of 10 ng/mL. The validated method was successfully applied to a pharmacokinetics, tissue distribution and excretion study. These preclinical data will be beneficial for further development of anemoside B4 in future studies.