Determination and Pharmacokinetics of PA-824 in the Plasma of Beagle Dogs by HPLC-MS/MS / 中国药师

Objective: To establish a high performance liquid chromatography-tandem mass spectrometric method ( HPLC-MS/MS) method for the determination of PA-824 in the plasma of Beagle dogs, and study the pharmacokinetics of PA-824 in Beagle dogs. Methods:Carbamazepine was used as the internal standard, and the plasma samples were pretreated with ethyl acetate for the liquid-liquid extraction of PA-824. An Eclipse Plus C18 column (100 mm × 2. 1 mm, 3. 5 μm) was used with the mobile phase consisting of methanol-water (90 :10). The flow rate was 0. 6 ml·min-1 and the column temperature was 30 ℃. The injection volume was 5 μl and the sample analysis time was 5 min. The determination was performed with an electrospray ionization ( ESI) source in the positive multiple reaction monitoring (MRM) mode. The ion pairs were m/z 360. 1→m/z 175. 0 (collision energy of 35, solution cluster volt-age of 65) for PA-824 and m/z 237. 2→m/z 194. 0 (collision energy of 28, solution cluster voltage of 83) for carbamazepine. After the oral administration, PA-824 in plasma was measured at different time points, and then the pharmacokinetic parameters were calcu-lated by DAS 2. 0 software. Results: PA-824 showed a good linear relationship within the range of 50-10000 ng · ml-1 ( r =0. 9991). The recovery was 97. 7%-105. 1%, and the RSDs of intra-day and inter-day were less than 5. 0%. At three different dosa-ges (100, 200 and 500 mg) of PA-824, AUC0-twere (5735. 18 ± 1918. 76),(11548. 47 ± 1838. 04) and (21987. 88 ± 4587. 58) ng·min·ml-1,t1/2 were(14.17 ±5.97),(11.11 ±4.39) and (13.13 ±5.46)h,and Cmaxwere(626.66 ±188.48),(2399.13 ± 516.51) and (4861.33 ±2253.61)ng·ml-1, respectively. Conclusion:The method is simple, accurate, rapid and reproducible, and suitable for the pharmacokinetic study of PA-824 in the plasma of Beagle dogs.

Cordyceps sinensis promotes immune regulation and enhances bacteriostatic activity of PA-824 via IL-10 in Mycobacterium tuberculosis disease

PA-824 is a novel bicyclic nitroimidazole anti-tuberculosis (TB) drug. Cordyceps sinensis (Berk.) Sacc. (CS) was proven to be a good immunomodulatory compound. This research aimed to investigate the effect of CS on PA-824 in Mycobacterium tuberculosis (M.tb) infected mice (female CBA/J mice, 6 to 8 weeks of age and 20±2 g of weight). Mice were randomly assigned to 4 groups: PA-824, CS, PA-824+CS, and control. To verify the effect of PA-824 and CS on M.tb, after drug administration, mice lungs were harvested and bacterial colony formations were measured. Cells were isolated from infected lungs and spleens to analyze the percentage of CD4+ T cells (CD11a positive). Lung cells were cultured to detect the secretion of interferon-γ (IFN-γ) and interleukin-10 (IL-10) by ELISA. IFN-γ and IL-10 double-positive CD4+ cells in peripheral blood were measured by flow cytometry. The expression levels of IL-2 and IL-10 in mice lungs were analyzed by real-time PCR and western blot. Results showed that PA-824 combined with CS led to the lowest lung colony-forming units (CFU) counts among treated groups. Furthermore, this beneficial outcome might be associated with the decreased CD11a on CD4+ cells in mice lungs and spleens. Moreover, the suppressed secretion of IFN-γ and IL-10, and IL-10 expressions, as well as the decreased IFN-γ and IL-10 double-positive CD4+ cells in blood, could also be associated with the positive effect. However, no significant effect on IL-2 production was found. The combination of PA-824 and CS had more effective bacteriostatic and immunomodulatory effects on M.tb infected mice than PA-824 alone. In conclusion, CS has the potential to be an effective adjuvant in TB treatment.

Determination of PA-824 in Rat Plasma by HPLC-MS/MS and Application in Pharmaco-kinetic Study / 医药导报

Objective To develop an HPLC-MS/ MS method for quantitative determination of PA-824 in rat plasma and to study the pharmacokinetics of PA-824 in rat after oral administration. Methods An HPLC-MS/ MS method was developed and validated for determination of PA-824 in rat plasma using metronidazole as internal standard.The proteins in plasma samples were precipitated with methanol,and PA-824 was enriched for analysis by HPLC-MS/ MS.An Inertsil? ODS3 C18 column (150 mm×4.6 mm,5 μm) was applied with mobile phase composed of methanol- 0.03% triethylamine (TEA) in water (90:10) ,at a flow rate of 0. 5 mL ? min-1 and column temperature of 30 ℃ . Quantitation was performed on a triple quadrupole mass spectrometer applying electrospray ionization technique and operating in multiple reaction monitoring (MRM) and positive ion mode with transitions at 360.1/ 175.0 for PA-824 and 172.0/ 128.0 for metronidazole.The concentration of PA-824 in plasma was tested after oral administration at various time points and the data were processed with software DAS.2.0. Results The standard calibration curve for spiked rat plasma containing PA-824 was linear over the range of 0. 1 - 10. 0 μg?mL-1 . The recoveries obtained for PA-824 were greater than 92.13%.Intra-day and inter-day coefficient of variation were less than 6.6%.After oral administration,the main pharmacokinetic parameters were AUC(0-t) : ( 3 297. 503 ± 320. 958) mg ? L-1 ? min-1 , AUC(0-∞ ) :(3 558.315±338.860)mg?L-1?min-1 ,tmax:(360.000±64.143)min,Cmax:(3.5±0.3)μg?mL-1 . Conclusion The method is rapid,accurate,simple,and successfully applied in a pharmacokinetic study of fixed dose oral administration of PA-824 in rats.