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Methotrexate (MTX) pharmacokinetics has substantial inter-individual variability and toxicity. In children with medulloblastoma treated with high-dose methotrexate (HD-MTX), the pharmacokinetic properties of methotrexate have not been established. A total of 660 serum samples from 105 pediatric patients with medulloblastoma were included in a population pharmacokinetic (PPK) analysis of methotrexate by using the nonlinear mixed-effects modeling method. The basic onecompartment population pharmacokinetic model was established by NONMEM software and the first-order conditional estimation (FOCE) method, and the final covariate model was obtained by the stepwise regression method. Weight (WT), creatinine clearance (CrCL), and whether the treatment was combined with dexamethasone (DEX) were covariates that had significant effects on the clearance rate (CL) of the model. The pharmacokinetic equation of CL in the final covariate model was as follows: CL i = 9.23× (1 + 0.0005× (θ CrCL -105.78)) × (1 + 0.0017× (θ WT -16)) × e ηcl,i (L/h), IF (θ DEX ) CL i = 1.19× CL i (L/h). The estimation accuracy of all pharmacokinetic parameters were acceptable (relative standard error < 14.74%). The goodness-of-fit diagram and bootstrap tests indicated that the final PPK model was stable with acceptable predictive ability. The PPK model may be useful for determining personalized medication levels in pediatric medulloblastoma patients undergoing HD-MTX therapy. K E Y W O R D S medulloblastoma, methotrexate, pediatric patients, personalized medicine, population pharmacokinetics

Xueshuantong Lyophilized Powder (XST), consisting of a series of saponins extracted from Panax notoginseng, is widely applied to treat acute cerebral infarction, stroke, and coronary heart disease in China. However, most adverse drug reactions (ADR) in clinic are caused by quality problems of XST. In this study, six batches of certainly abnormal, four batches of possibly abnormal XST, and eight batches of normal XST were obtained from the clinical practice. Their quality fluctuations were identified by ultra-performance liquid chromatography coupled with an electrospray ionization quadrupole time-of-flight mass spectrometry operating in MSE mode (UPLC-QTOF/MSE) and bioassays including antithrombin and proplasmin assay. Fourteen potential components responsible for clinical ADR were identified by UPLC-QTOF/MSE, especially ginsenoside Rg1, Rg3, Rb1 and notoginsenoside R1. In addition, 83.3% (5/6) and 50.0% (3/6) certainly abnormal samples could be identified by UPLC-QTOF/MSE and bioassay, respectively. Interestingly, further integration of the two methods could entirely identify all the certainly abnormal samples and inferred that all the possibly abnormal samples were closely related to their quality fluctuation. It indicates that it is advisable to combine UPLC-QTOF/MSE and bioassay for identifying quality fluctuation of XST, and thus reduce its ADR in clinic.

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Rapid and simple monitoring of vancomycin (VAN) concentration in blood is one vitally strategy for maximizing therapeutic efficacy, minimizing toxicity and developing a personalized treatment plan. In this work, a...