Fanlong Bu

Determination of brusatol in plasma and tissues by LC–MS method and its application to a pharmacokinetic and distribution study in mice

OBJECTIVES The quassinoid brusatol, which can be isolated from Brucea javanica (L.) Merr., becomes popularly studied because of its anti-tumor activity. In order to further investigate brusatol and extend its applications, a sensitive analytical method for determination of brusatol in biological samples is essential. However, few methods had been reported until now. In this study, a highly sensitive and reproducible LC-MS method for simultaneous quantification of brusatol in mouse plasma and tissues was developed and validated. METHOD Plasma samples and tissue homogenate were extracted with diethyl ether after addition of the internal standard solution(IS). The supernatant was blown to dryness with nitrogen and residual was reconstituted with 100μl of methanol. The separation was performed on an Intersil ODS-3 column and gradient elution was conducted with the mobile phase of water and methanol (0-5min 47:53, 5-5.5min 47:53-10:90, 5.5-9min 10:90, posttime 4min 47:53) at a flow rate of 0.8mL/min. Quantification was performed in the selected ion monitoring (SIM) mode at m/z 543.2 for brusatol and 220.0 for IS (ornidazole). The method was validated by analyzing quality control plasma and tissue homogenate samples, and was applied to analyze samples obtained from mice after injections of brusatol via the tail vein. RESULTS With ornidazole as the internal standard, calibration curve of the method ranged from 10 to 320ng/ml for plasma and 10-240ng/ml for tissues. Recovery rate of brusatol from plasma and tissues were between 71.09%-94.91%. Relative standard deviation (RSD) for inter- and intra-day precision was less than 15%, and the accuracy was between 96.1%-111.8%. The pharmacokinetics and distribution study of brusatol in mice after three single doses via the tail vein were carried out based on this method. The concentration of brusatol in plasma decreased rapidly and a more than 10 fold concentration of brusatol was found as compared to that in other tissues. CONCLUSIONS This is the first reported LC-MS method for detecting brusatol in tissues and can accurately determine the concentrations of these compounds in plasma and different tissues. Further research on the metabolism of brusatol in vivo is still needed.

Determination of the active metabolite of moguisteine in human plasma and urine by LC–ESI-MS method and its application in pharmacokinetic study ☆

In this study, a sensitive and reproducible electro-spray ionization liquid chromatography-mass spectrometry (LC-ESI-MS) method was established to determine the concentration of M1, the main active metabolite of moguisteine in human plasma and urine. The analysis was performed on a Diamonsil® C₁₈(2) column (150 mm × 4.6 mm, 5 μm) with the mobile phase consisting of 0.1% formic acid-acetonitrile (57:43, v/v, pH=3.0) at a flow rate of 0.8 mL min⁻¹. The pseudo-molecular ions [M+H]+ (m/z 312.2 for M1 and 446.3 for glipizide) were selected as the target ions for quantification in the selected ion monitoring (SIM) mode. Plasma samples were analyzed after being processed by acidification with formic acid and protein precipitation with acetonitrile. Urine samples were appropriately diluted with blank urine for analysis. Calibration curve was ranged from 0.02 to 8 μg mL⁻¹. The extraction recovery in plasma was over 90%. Both the inter- and intra-day precision values were less than 7.5%, and the accuracy was in the range from -6.0% to 6.0%. This is the first reported LC-ESI-MS method for analyzing M1 in human plasma and urine. The method was successfully applied to the pharmacokinetic study after oral administration of single-dose and multiple-dose of moguisteine tablets in healthy Chinese subjects.

Bioequivalence Study of Warfarin in Healthy Chinese Volunteers With a Validated High‐Performance Liquid Chromatography‐Mass Spectrometry Method

This study was designed to investigate the pharmacokinetics of an innovative film‐coated warfarin sodium tablet and to compare it with the marketed sugar‐coated warfarin sodium tablet in humans. A single‐dose, open‐label, randomized, two‐way crossover study was performed in 24 healthy Chinese male volunteers. They were administered 2.5 mg of innovative film‐coated warfarin sodium tablets or the marketed sugar‐coated warfarin sodium tablets. Blood samples were collected at different time points after dosing for investigation of the pharmacokinetics of warfarin in human plasma. A sensitive liquid chromatography mass spectrometry method was established to determine warfarin in plasma. Drug and Statistics 2.1.1 was applied to calculate the pharmacokinetics parameters. The main pharmacokinetic parameters for film‐coated and sugar‐coated warfarin were the following: t½, 103.5 ± 18.8 and 105.8 ± 21.3 hours; Tmax, 0.7 ± 0.5 and 1.3 ± 0.8 hours; Cmax, 347.8 ± 74.8 and 322.9 ± 75.7 ng/mL; AUC0∼360, 16,024.2 ± 3713.9 and 15,586.6 ± 3477.0 ng·mL−1·h; AUC0∼∞, 17,335.7 ± 4089.1 and 16,912.0 ± 3911.2 ng·mL−1·h, respectively. The human pharmacokinetics of film‐coated and sugar‐coated warfarin were slightly different. The oral absorption and bioavailability of innovative film‐coated warfarin were slightly higher than those of the sugar‐coated warfarin. This study is vital to clinical usage of warfarin not only because of the pharmacokinetic parameters of the 2 pharmaceutical dosage forms of warfarin but also to obtain data on the prevalence of CYP2C9 and VKORC1 genes and their influence on the concentration of warfarin.