72 research outputs found
Influence of OATP1B1 Function on the Disposition of Sorafenib-β-D-Glucuronide
The oral multikinase inhibitor sorafenib undergoes extensive UGT1A9-mediated formation of sorafenib-β-D-glucuronide (SG). Using transporter-deficient mouse models, it was previously established that SG can be extruded into bile by ABCC2 or follow a liver-to-blood shuttling loop via ABCC3-mediated efflux into the systemic circulation, and subsequent uptake in neighboring hepatocytes by OATP1B-type transporters. Here we evaluated the possibility that this unusual process, called hepatocyte hopping, is also operational in humans and can be modulated through pharmacological inhibition. We found that SG transport by OATP1B1 or murine Oatp1b2 was effectively inhibited by rifampin, and that this agent can significantly increase plasma levels of SG in wildtype mice, but not in Oatp1b2-deficient animals. In human subjects receiving sorafenib, rifampin acutely increased the systemic exposure to SG. Our study emphasizes the need to consider hepatic handling of xenobiotic glucuronides in the design of drug-drug interaction studies of agents that undergo extensive phase II conjugation
Pazopanib exposure decreases as a result of an ifosfamide-dependent drug-drug interaction: Results of a phase I study
Background:The vascular endothelial growth factor receptor (VEGFR) pathway plays a pivotal role in solid malignancies and is probably involved in chemotherapy resistance. Pazopanib, inhibitor of, among other receptors, VEGFR1-3, has activity as single agent and is attractive to enhance anti-tumour activity of chemotherapy. We conducted a dose-finding and pharmacokinetic (PK)/pharmacodynamics study of pazopanib combined with two different schedules of ifosfamide.Methods:In a 3+3+3 design, patients with advanced solid tumours received escalating doses of oral pazopanib combined with ifosfamide either given 3 days continuously or given 3-h bolus infusion daily for 3 days (9 g m -2 per cycle, every 3 weeks). Pharmacokinetic data of ifosfamide and pazopanib were obtained. Plasma levels of placental-derived growth factor (PlGF), vascular endothelial growth factor-A (VEGF-A), soluble VEGFR2 (sVEGFR2) and circulating endothelial cells were monitored as biomarkers.Results:Sixty-one patients were included. Pazopanib with continuous ifosfamide infusion appeared to be safe up to 1000 mg per day, while combination with bolus infusion ifosfamide turned out to be too toxic based on a variety of adverse events. Ifosfamide-dependent decline in pazopanib exposure was observed. Increases in PlGF and VEGF-A with concurrent decline in sVEGFR2 levels, consistent with pazopanib-mediated VEGFR2 inhibition, were observed after addition of ifosfamide.Conclusion:Continuous as opposed to bolus infusion ifosfamide can safely be combined with pazopanib. Ifosfamide co-administration results in lower exposure to pazopanib, not hindering biological effects of pazopanib. Recommended dose of pazopanib for further studies combined with 3 days continuous ifosfamide (9 g m -2 per cycle, every 3 weeks) is 800 mg daily
Green function techniques in the treatment of quantum transport at the molecular scale
The theoretical investigation of charge (and spin) transport at nanometer
length scales requires the use of advanced and powerful techniques able to deal
with the dynamical properties of the relevant physical systems, to explicitly
include out-of-equilibrium situations typical for electrical/heat transport as
well as to take into account interaction effects in a systematic way.
Equilibrium Green function techniques and their extension to non-equilibrium
situations via the Keldysh formalism build one of the pillars of current
state-of-the-art approaches to quantum transport which have been implemented in
both model Hamiltonian formulations and first-principle methodologies. We offer
a tutorial overview of the applications of Green functions to deal with some
fundamental aspects of charge transport at the nanoscale, mainly focusing on
applications to model Hamiltonian formulations.Comment: Tutorial review, LaTeX, 129 pages, 41 figures, 300 references,
submitted to Springer series "Lecture Notes in Physics
Purification of a trypsin inhibitor from Cocculus hirsutus and identification of its biological activity
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