Investigation of the effects of axitinib on the pharmacokinetics of loperamide and its main metabolite N-demethylated loperamide in rats by UPLC-MS/MS

The multikinase inhibitor axitinib in the treatment of advanced hepatocellular carcinoma: the current clinical applications and the molecular mechanisms

Advanced hepatocellular carcinoma (HCC) is a formidable public health problem with limited curable treatment options. Axitinib, an oral tyrosine kinase inhibitor, is a potent and selective second-generation inhibitor of vascular endothelial growth factor receptor (VEGFR) 1, 2, and 3. This anti-angiogenic drug was found to have promising activity in various solid tumors, including advanced HCC. At present, however, there is no relevant review article that summarizes the exact roles of axitinib in advanced HCC. In this review, 24 eligible studies (seven studies in the ClinicalTrials, eight experimental studies, and nine clinical trials) were included for further evaluation. The included randomized or single-arm phase II trials indicated that axitinib could not prolong the overall survival compared to the placebo for the treatment of advanced HCC, but improvements in progression free survival and time to tumor progression were observed. Experimental studies showed that the biochemical effects of axitinib in HCC might be regulated by its associated genes and affected signaling cascades (e.g. VEGFR2/PAK1, CYP1A2, CaMKII/ERK, Akt/mTor, and miR-509-3p/PDGFRA). FDA approved sorafenib combined with nivolumab (an inhibitor of PD-1/PD-L1) as the first line regimen for the treatment of advanced HCC. Since both axitinib and sorafenib are tyrosine kinase inhibitors as well as the VEGFR inhibitors, axitinib combined with anti-PDL-1/PD-1 antibodies may also exhibit tremendous potential in anti-tumoral effects for advanced HCC. The present review highlights the current clinical applications and the molecular mechanisms of axitinib in advanced HCC. To move toward clinical applications by combining axitinib and other treatments in advanced HCC, more studies are still warranted in the near future.

Inhibition of Axitinib on Buspirone Metabolism in vitro and in vivo

Objective

To evaluate the effect of axitinib on buspirone metabolism in vitro and in vivo.

Methods

A microsome incubation assay was performed to study the effect and mechanism of axitinib on buspirone metabolizing. In vivo, buspirone was administered with or without axitinib to Sprague–Dawley rats. Plasma samples were collected and subjected to ultra-performance liquid chromatography–tandem mass spectrometry.

Results

In both human liver microsomes (HLMs) and rat liver microsomes (RLMs), axitinib (100 μM) decreased buspirone hydroxylation and N-dealkylation by >85%. Axitinib inhibited buspirone hydroxylation and N-dealkylation, with an IC₅₀ of 15.76 and 9.74 for RLMs, and 10.63 and 9.902 for HLMs. Axitinib showed noncompetitive inhibition of both 6′-hydroxylation and N-dealkylation. Moreover, coadministration of axitinib and buspirone led to an increase in the maximum plasma concentration (C_max) and area under the plasma concentration-time curve (AUC) of buspirone by 4.3- and 5.3-fold, respectively, compared with the control group.

Conclusion

Axitinib inhibited buspirone metabolism in vivo and in vitro, which increases the risk of the side effects of buspirone in the clinic. When coadministered with axitinib, a lower dosage of buspirone should be defined to avoid a toxic response. Axitinib is suspected to function as an inhibitor of CYP3A4.

Investigation of the Inhibitory Effect of Simvastatin on the Metabolism of Lidocaine Both in vitro and in vivo

Background

Lidocaine has cardiovascular and neurologic toxicity, which is dose-dependent. Due to CYP3A4-involved metabolism, lidocaine may be prone to drug-drug interactions.

Materials and Methods

Given statins have the possibility of combination with lidocaine in the clinic, we established in vitro models to assess the effect of statins on the metabolism of lidocaine. Further pharmacokinetic alterations of lidocaine and its main metabolite, monoethylglycinexylidide in rats influenced by simvastatin, were investigated.

Results

In vitro study revealed that simvastatin, among the statins, had the most significant inhibitory effect on lidocaine metabolism with IC₅₀ of 39.31 µM, 50 µM and 15.77 µM for RLM, HLM and CYP3A4.1, respectively. Consistent with in vitro results, lidocaine concomitantly used with simvastatin in rats was associated with 1.2-fold AUC_(0-t), 1.2-fold AUC_(0-∞), and 20%-decreased clearance for lidocaine, and 1.4-fold C_max for MEGX compared with lidocaine alone.

Conclusion

Collectively, these results implied that simvastatin could evidently inhibit the metabolism of lidocaine both in vivo and in vitro. Accordingly, more attention and necessary therapeutic drug monitoring should be paid to patients with the concomitant coadministration of lidocaine and simvastatin so as to avoid unexpected toxicity.