Guangli Wei

Quantitation of ursolic acid in human plasma by ultra performance liquid chromatography tandem mass spectrometry and its pharmacokinetic study.

Ursolic acid is a hydroxy pentacyclic triterpene, which proved to have sedation, anti-inflammatory, antibacterial, antiulcer and anti-cancer activities. An ultra-performance liquid chromatography/tandem mass spectrometry (UPLC/MS/MS) method with high selectivity, sensitivity and throughput has been established and validated for quantitation of total ursolic acid in human plasma. Plasma samples were pretreated by liquid-liquid extraction with ethyl acetate and were chromatographed by an ACQUITY UPLC BEH C(8) column (100 mm×2.1 mm, I.D., 1.7 μm) using mobile phase consisting of acetonitrile and 10 mM ammonium formate (90:10, v/v) at 0.2 mL/min. The duration of chromatography analysis was 3 min. The multiple reaction monitoring (MRM) was performed at m/z 455.1→455.0 for ursolic acid and m/z 469.3→425.2 for glycyrrhetinic acid (internal standard, IS) in the negative ion mode with electrospray ionization (ESI) source. The assay showed good linearity over the range of 10-5000 ng/mL for ursolic acid in human plasma with a lower limit of quantitation of 10 ng/mL. The mean extraction recovery was 73.2±4.5% and the matrix ion suppression ranged from -11.4% to -5.6%. The intra- and inter-day precisions were less than 7.0% and 7.2%, respectively, and the accuracy was within ±2.0%. Ursolic acid was stable during the analysis and the storage period. The validated method has been successfully applied to a pharmacokinetic study after intravenous infusion of Ursolic Acid Nano-liposomes to healthy volunteers.

Improved HPLC method for doxorubicin quantification in rat plasma to study the pharmacokinetics of micelle‐encapsulated and liposome‐encapsulated doxorubicin formulations

An improved simple, rapid and accurate HPLC method for quantification of doxorubicin derived from micelle-encapsulated or liposome-encapsulated doxorubicin formulation in rat plasma was described. The mobile phase consisting of a mixture of methanol-water [containing 0.1% formic acid anhydrous and 0.1% ammonia solution (25%), pH 3.0], 60:40, was delivered at a flow rate of 1.0 mL/min. Sample preparation for micelle- or liposome-encapsulated doxorubicin in rat plasma were achieved directly by protein precipitation with acetonitrile. Doxorubicin and daunorubicin (internal standard, IS) were separated on a C(18) reversed-phase HPLC column and quantified by a fluoresence detection with an excitation wavelength of 475 nm and an emission wavelength of 580 nm. The linearity was obtained over the range of 5.0-1000.0 ng/mL and 1.0-200.0 microg/mL for doxorubicin and the lower limit of quantitation was 5.0 ng/mL. For each level of quality control samples, inter- and intra-assay precision was less than 9.6 and 5.1% (relative standard deviation), respectively, and percentage error was within +/-2.6%. The extraction recoveries of doxorubicin in the range of 10 ng/mL to 100 microg/mL in rat plasma were between 94.1 and 105.6%. This method was successfully applied to the pharmacokinetic study of doxorubicin formulations after i.v. administration to rats.

Determination of human insulin in dog plasma by a selective liquid chromatography-tandem mass spectrometry method: Application to a pharmacokinetic study

A simple, sensitive and selective LC-MS/MS method for quantitative analysis of human insulin was developed and validated in dog plasma. Insulin glargine was used as the internal standard. After a simple step of solid-phase extraction, the chromatographic separation of human insulin was achieved by using InertSustain Bio C18 column with a mobile phase of acetonitrile containing 1% formic acid (A)-water containing 1% formic acid (B). The detection was performed by positive ion electrospray ionization in multiple-reaction monitoring (MRM) mode. Good linearity was observed in the concentration range of 1-1000 μIU/mL (r2 > 0.99), and the lower limit of quantification was 1 μIU/mL (equal to 38.46 pg/mL). The intra- and inter-day precision (expressed as relative standard deviation, RSD) of human insulin were ≤12.1% and ≤13.0%, respectively, and the accuracy (expressed as relative error, RE) was in the range of -7.23-11.9%. The recovery and matrix effect were both within acceptable limits. This method was successfully applied for the pharmacokinetic study of human insulin in dogs after subcutaneous administration.

LC-MS/MS Method for Quantification of Liquiritigenin in Rat Plasma： Application to Pharmacokinetic Study of Liquiritin

Objective A simple, sensitive, and rapid LC-MS/MS method has been established and validated for the determination of liquiritigenin (LG) in rat plasma.

Determination of liraglutide in rat plasma by a selective liquid chromatography-tandem mass spectrometry method: Application to a pharmacokinetics study

A simple, sensitive and selective LC-MS/MS method was developed for the quantitative analysis of liraglutide and validated in rat plasma. Human insulin was used as the internal standard. After a simple protein precipitation step, liraglutide was chromatographically separated using an InertSustain Bio C18 column with mobile phases comprising acetonitrile with 0.1% formic acid (A) and water with 0.1% formic acid (B). Detection was achieved using positive ion electrospray ionization in multiple-reaction monitoring (MRM) mode. Good linearity was observed in the concentration range 0.5-250 ng/mL (r2 > 0.99). The intra- and inter-day precision values (expressed as relative standard deviation, RSD) of liraglutide ranged from 1.97-7.63% and 5.25-11.9, respectively. The accuracy (expressed as relative error, RE) ranged from -8.79-11.4%. Both the recovery and matrix effect were within acceptable limits. This method was successfully applied for the pharmacokinetics study of liraglutide in rats after subcutaneous administration.

Direct comparison of LC-MS/MS and RIA methods for the pharmacokinetics assessment of human insulin in preclinical development

Insulin is an effective therapeutic for diabetes, and the level of insulin in vivo is directly related to the health of diabetic patients. Traditionally, the concentrations of insulin in vivo are determined by the radioimmunoassay (RIA) method. In this study, we developed an LC-MS/MS method for the quantification of human insulin in dog plasma and directly compared the RIA and LC-MS/MS methods. Our LC-MS/MS method exhibited superior accuracy, efficiency and cost-effective for the pharmacokinetic (PK) assessment of human insulin. The LC-MS/MS method can quantitate human insulin and canine insulin simultaneously without cross-reactivity, making the analysis more efficient. The LLOQ of our LC-MS/MS method was 38.5 pg/mL, which was necessary to fully describe the PK profiles of endogenous and exogenous insulin in vivo. The direct comparison of PK data obtained from the two methods demonstrated that LC-MS/MS could be an alternative to the RIA method and should be widely used for the quantification of insulin drugs, especially in preclinical studies.