Rapid and sensitive method for simultaneous determination of first-line anti-tuberculosis drugs in human plasma by HPLC-MS/MS: Application to therapeutic drug monitoring.

First-line anti-tuberculosis drugs are playing vital roles for curbing rapid spread of tuberculosis. Multidrug therapies are commonly applied in clinical to achieve better treatment outcomes. However, drug resistance and adverse reactions come along with this therapies and therapeutic drug monitoring is a feasible way to precaution them. For this reasons, a simple and sensitive method based on liquid chromatography-tandem mass spectrometry (LC-MS/MS) and single protein precipitation was developed and validated for simultaneously quantifying of pyrazinamide, isoniazid, ethambutol, streptomycin and rifampicin in human plasma. Optimized chromatographic separation was achieved on a ZORBAX SB-C18 column with heptafluorobutyric acid, an ion-pair reagent, in the mobile phase at a flow rate of 0.3 mL/min. The mass detection was achieved using electrospray ionization in the positive ion mode with a multiple reaction monitoring mode. The lower limit of quantification (LLOQ) and dynamic range of pyrazinamide, isoniazid, ethambutol, streptomycin and rifampicin were 200-4000 ng/mL, 80-2000 ng/mL, 0.2-1000 ng/mL, 2000-200000 ng/mL and 200-4000 ng/mL, respectively. The Inter-day and intra-day accuracy and precision were within ±15.0% and less than 15%. The method had been successfully applied to simultaneous determination of four first-line Anti-tuberculosis drugs in plasma from tuberculosis patients.

Comparison of LC-MS/MS vs chemiluminescent microparticle immunoassay in measuring the valproic acid concentration in plasma of epilepsy patients in a new perspective.

OBJECTIVES: This study was designed to compare the performance of LC-MS/MS with chemiluminescent microparticle immunoassay (CMIA) for determination of VPA in epilepsy patients in the perspective of metabolites' hepatotoxicity. METHOD: Samples were collected and then analyzed using both LC-MS/MS and CMIA. A LO2 cells (normal human hepatic cells) experiment was carried out to confirm VPA metabolites' hepatotoxicity using AST(Aspertate Aminotransferase, AST), ALT(Alanine aminotransferase, ALT) and LDH(lactate dehydrogenase, LDH) in supernate as index. RESULTS: The regression equation analysis showed as LC-MS/MS=1.0094CMIA-1.8937, with the concordance correlation coefficient of 0.9700, and the CUSUM test proved no significant deviation from linearity (P>.05). CMIA compared to LC-MS/MS gave a positive bias of 1.2 µg/mL. In LO2 experiment, VPA and its metabolites groups showed an obvious increment of AST, ALT, and LDH in supernate. CONCLUSION: The LC-MS/MS is largely consistent with the CMIA in analytical time and quantification ability for VPA, but the LC-MS/MS can simultaneously determinate VPA and its metabolites in plasma, and is also a higher cost-efficiency method in consideration of toxic metabolites monitoring. The overestimation of VPA by CMIA showed no clinical significance. The metabolites 3-OH-VPA and 5-OH-VPA damage the LO2 cells and the results presented a statistical significance (P<.05). It is vital to monitor the metabolites' concentrations for VAP's clinical safety application, and now is the occasion that laboratory and clinic consider the LC-MS/MS method as a more advantageous alternative to CMIA method in therapeutic monitoring of VPA.

Quantification of 18 amino acids in human plasma: application in renal transplant patient plasma by targeted UHPLC-MS/MS.

AIM: Quantification of amino acids in human plasma has become an important and essential analysis parameter in life science. In this paper, we developed a targeted UHPLC-MS/MS method for 18 amino acids in the renal transplant patients. METHODS & RESULTS: Plasma in small volume (150 µl) was pretreated by a one-step protein precipitant extraction for analysis. Detection was executed by MS/MS in the MRM mode. Assays were validated according to current bioanalytical guidelines, with good linearity (R > 0.99), intraday and interday precision (CV < 11.6%, RE ≤ ± 14.8%), extraction recovery (between 77.4 and 117.6%), matrix effect (73.3-118.0%) and stability (RE≤ ±14.7%). CONCLUSION: The method was successfully applicable for amino acid analysis in the renal transplant patient.