Population Pharmacokinetics of Caspofungin and Dosing Optimization in Children With Allogeneic Hematopoietic Stem Cell Transplantation.

Caspofungin is the first echinocandin antifungal agent that licented for pediatric use in invasive candidiasis and aspergillosis. In this study, we evaluated the population pharmacokinetics of caspofungin and investigate appropriate dosing optimization against Candida spp. in children with allogeneic hematopoietic stem cell transplantation (allo-HSCT) in order to improve therapeutic efficacy. All participants received a recommended caspofungin 70 mg/m2 loading dose followed by 50 mg/m2 maintenance dose. A one-compartment model with first-order elimination was best fitted the data from 48 pediatric patients. Body surface area and aspartate aminotransferase had significant influence on caspofungin clearance from covariate analysis. Our results reviewed that dose adjustment is not necessary in patients with mild liver dysfunction. Monte Carlo simulations were performed using pharmacokinetic data from our study to evaluate the probability of target attainment (PTA) of caspofungin regimen in terms of AUC24/MIC targets against Candida spp. The results of simulations predicted that a caspofungin 70 mg/m2 at first dose, 50 mg/m2 of daily dose may have a high probability of successful outcome against C. albicans and C. glabrata whilst 60 mg/m2 maintenance dose was required for fungistatic target against C. parapsilosis but may be not sufficient to achieve optimal fungicidal activity. Caspofungin standard regimen had high probability of successful outcome against C. albicans (MIC ⩽ 0.25 mg/L) and C. glabrata (MIC ⩽ 0.5 mg/L) but insufficient for C. parapsilosis with MIC > 0.25 mg/L. That may provide an evidence based support to caspofungin individualized administration and decrease the risk of therapeutic failure in allo-HSCT pediatric patients.

Population pharmacokinetics modeling of oxcarbazepine to characterize drug interactions in Chinese children with epilepsy.

AIM: To develop a population pharmacokinetics model of oxcarbazepine in Chinese pediatric patients with epilepsy, and to study the interactions between oxcarbazepine and other antiepileptic drugs (AEDs). METHODS: A total of 688 patients with epilepsy aged 2 months to 18 years were divided into model (n=573) and valid (n=115) groups. Serum concentrations of the main active metabolite of oxcarbazepine, 10-hydroxycarbazepine (MHD), were determined 0.5-48 h after the last dosage. A population pharmacokinetics (PPK) model was constructed using NLME software. This model was internally evaluated using Bootstrapping and goodness-of-fit plots inspection. The data of the valid group were used to calculate the mean prediction error (MPE), mean absolute prediction error (MAE), mean squared prediction error (MSE) and the 95% confidence intervals (95% CI) to externally evaluate the model. RESULTS: The population values of pharmacokinetic parameters estimated in the final model were as follows: Ka=0.83 h-1, Vd=0.67 L/kg, and CL=0.035 L·kg(-1)·h(-1). The enzyme-inducing AEDs (carbamazepine, phenytoin, phenobarbital) and newer generation AEDs (levetiracetam, lamotrigine, topiramate) increased the weight-normalized CL value of MHD by 17.4% and 10.5%, respectively, whereas the enzyme-inhibiting AED valproic acid decreased it by 3%. No significant association was found between the CL value of MHD and the other covariates. For the final model, the evaluation results (95% CI) were MPE=0.01 (-0.07-0.10) mg/L, MAE=0.46 (0.40-0.51) mg/L, MSE=0.39 (0.27-0.51) (mg/L)(2). CONCLUSION: A PPK model of OXC in Chinese pediatric patients with epilepsy is established. The enzyme-inducing AEDs and some newer generation AEDs (lamotrigine, topiramate) could slightly increase the metabolism of MHD.

Impact of SLCO1B1 521T > C variant on leucovorin rescue and risk of relapse in childhood acute lymphoblastic leukemia treated with high-dose methotrexate.

BACKGROUND: Recent studies suggest that SLCO1B1 c.521T > C variant decreases the clearance of methotrexate (MTX) and elevates its plasma concentration, hence leucovorin doses may need to be adjusted. However, high leucovorin doses may affect the cure rate in childhood acute lymphoblastic leukemia (ALL). Hitherto neither the appropriate dose of leucovorin in carriers of SLCO1B1 c.521T > C variant nor the impact of SLCO1B1 polymorphism on the risk of ALL relapse has been clarified. PROCEDURE: A double-blind and controlled study was conducted in 136 children with ALL. They were genotyped for rs4149056 single nucleotide polymorphism into wild-type group and variant group, and received MTX at 3-5 g/m(2) . Plasma concentration MTX and its metabolite were determined by HPLC. The toxicity of MTX, dose of leucovorin and 5-year relapse rate of ALL were recorded. RESULTS: Compared with wild-type group, area under the concentration time curve of MTX increased by 4.2-fold and peripheral clearance rate decreased significantly in variant group. Patients carrying rs4149056 C allele endured a remarkable longer time above the MTX safety threshold and suffered from a higher frequency of toxicity, so 2.2-fold leucovorin was given. However, no association was found between SLCO1B1 c.521T > C variant and the relapse risk in five years. CONCLUSIONS: The SLCO1B1 c.521T > C variant was an important determinant of MTX disposition and their carriers were exposed to increased intensity and time of MTX. An appropriate leucovorin dose raise in variant group was beneficial to reducing the serious toxicity. The c.521T > C variant wasn't associated with the risk of ALL relapse.

Protective effects of neferine on amiodarone-induced pulmonary fibrosis in mice.

The effects of neferine, a bisbenzylisoquinline alkaloid extracted from the Chinese traditional medicine seed embryo of Nelumbo nucifera Gaertn, on amiodarone-induced pulmonary fibrosis in mice were evaluated. Adult Kunming mice were induced to develop pulmonary fibrosis through intratracheal instillation of amiodarone (6.25 mg/kg) on the 1st, 3rd and 5th day. Mice were treated orally with saline, neferine (20 mg/kg), prednisolone (15 mg/kg), pirfenidone (100 mg/kg) twice a day after the third amiodarone instillation. On Day 21, all the lung tissues were collected for hydroxyproline measurement and the histological examination by hematoxylin-eosin and Masson staining. All the blood sample were collected for surfactant protein-D (SP-D) levels assay, Th1/Th2 balance valuation, CD4+CD25+ regulatory T cells (Tregs) analysis by Enzyme-linked immunosorbent assay and flow cytometry. Our data showed that neferine significantly restored the significant reductions in body weights, the increased levels of lung index and hydroxyproline, the abnormal histological findings, the serum SP-D increase, the Th1/Th2 imbalance by decreasing IL-4 and increasing IFN-γ levels and the increases in the population of CD4+CD25+ Tregs associated with amiodarone instillation in mice. Similar changes were also observed in the prednisolone or pirfenidone treated mice. In conclusion, these results indicated that neferine possessed a significant inhibitory effect on amiodarone-induced pulmonary fibrosis, probably due to its properties of anti-inflammation, SP-D inhibition and restoring increased CD4+CD25+ Tregs which may modulate Th1/Th2 imbalance by suppressing Th2 response (from Th2 polarity toward a Th1 dominant response).