Dose-individualization Efficiently Maintains Sufficient Exposure to Methotrexate without Additional Toxicity in High-dose Methotrexate Regimens for Pediatric Acute Lymphoblastic Leukemia.

OBJECTIVE: Methotrexate (MTX) can be safely administered to most patients but may cause severe toxicity in others. This study aimed to summarize the characteristics of high-dose methotrexate (HD-MTX) chemotherapy and to evaluate whether the modified dose-adjustment program was able to improve the maintenance of sufficient MTX exposure levels while minimizing toxicities. METHODS: We evaluated 1172 cycles of high-dose MTX chemotherapy from 294 patients who were treated according to the CCCG-ALL-2015 protocol (clinical trial number: ChiCTR-IPR-14005706) and analyzed the data of actual MTX dosage, MTX concentration, toxicity, and prognosis. We compared data between the dose-adjustment Program 1 (fixed 20% reduction in dose) and the dose-adjustment Program 2 (dose-individualization based on reassessment of the creatine clearance rate and the MTX concentration-monitoring point at 16 h), which were applied if the MTX clearance was delayed in the previous cycle. RESULTS: The patients who used Program 2 had higher actual MTX infusion doses and infusion rates and were able to better maintain the MTX concentration at 44 h at the established target value than those on Program 1 (P<0.001). No significant differences in toxicities were found between these two programs except that abnormal serum potassium levels and prolonged myelosuppression in intermediate-risk/high-risk patients were more frequently observed in patients using Program 2 (P<0.001). No significant correlations were observed between the MTX dose, dose-adjustment programs, or MTX concentrations and relapse-free survival. CONCLUSION: Adjusting the MTX dose using Program 2 is more efficient for maintaining sufficient MTX exposure without significantly increasing the toxicity.

Laminaria japonica increases plasma exposure of glycyrrhetinic acid following oral administration of Liquorice extract in rats.

The present study was designed to investigate the effects of Laminaria japonica (Laminaria) on pharmacokinetics of glycyrrhetinic acid (GA) following oral administration of Liquorice extract in rats. Following oral administrations of single-dose and multi-dose Liquorice extract and Liquorice-Laminaria extract, respectively, plasma samples were obtained at various times and the concentrations of GA, liquiritigenin, and isoliquiritigenin were measured by LC-MS. The effects of Laminaria extract on pharmacokinetics of GA were also investigated, following single-dose and multidose of glycyrrhizic acid (GL). The effects of Laminaria extract on intestinal absorption of GA and GL were studied using the in situ single-pass intestinal perfusion model. The metabolism of GL to GA in the contents of small and large intestines was also studied. The results showed Liquorice-Laminaria extract markedly increased the plasma concentration of GA, accompanied by a shorter Tmax. Similar alteration was observed following multidose administration. However, pharmacokinetics of neither liquiritigenin nor isoliquiritigenin was affected by Laminaria. Similarly, Laminaria markedly increased concentration and decreased Tmax of GA following oral GL were observed. The data from the intestinal perfusion model showed that Laminaria markedly increased GL absorption in duodenum and jejunum, but did not affect the intestinal absorption of GA. It was found that Laminaria enhanced the metabolism of GL to GA in large intestine. In conclusion, Laminaria increased plasma exposures of GA following oral administration of liquorice or GL, which partly resulted from increased intestinal absorption of GL and metabolism of GL to GA in large intestine.