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Effect of rat enzymes on the metabolism of tyrosine kinase inhibitors in vitro and in vivo
Škriabová, Simona ; Indra, Radek (advisor) ; Ptáčková, Renata (referee)
Tyrosine kinase inhibitors are small molecules, orally available, well-tolerated and globally approved drugs for the treatment of several types of tumors. These drugs include vandetanib, cabozantinib, and lenvatinib, which are used to treat thyroid cancer. Vandetanib and cabozantinib are drugs approved for the treatment of medullary thyroid cancer, and lenvatinib is approved for the treatment of differentiated thyroid cancer. In the presented diploma thesis, the in vitro and in vivo metabolism of vandetanib, cabozantinib and lenvatinib was studied. Microsomes isolated from the liver of rats premedicated with pregnenolone carbonitrile were used to study in vitro metabolism. Plasma and urine samples of rats premedicated with individual tyrosine kinase inhibitors were used to study in vivo metabolism. The resulting metabolites were analyzed by high-performance liquid chromatography and subsequently identified using the mass spectrometry method. In the study of in vitro metabolism, when NADPH and cofactors (glucuronic acid and glutathione) were added to the samples, it was found that the most metabolites appeared for all three drugs during a longer incubation periods, and at the same time, it was found that glucuronic acid and glutathione can influence the structure, properties and functions of the...
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The effect of NADPH:cytochrome P450 reductase and cytochrome b5 on metabolism of vandetanib by cytochrome P450 3A5
Škriabová, Simona ; Indra, Radek (advisor) ; Mrízová, Iveta (referee)
There are several ways for cancer treatment. One of them is chemotherapy, when cancer patients are given a cytostatic or a combination of multiple types of drugs. The aim of this bachelor thesis was to study the metabolism of the anticancer drug vandetanib. Vandetanib is a tyrosine kinase inhibitor, that has been used in Europe since 2012 for treatment of symptomatic or progressive medullary thyroid cancer. The kinetics of vandetanib oxidation by cytochromes P450 3A5 was studied in this thesis. Oxidation was investigated by two different systems. The first were recombinant cytochromes P450 3A5 expressed in baculovirus-transfected insect cells (SupersomesTM ) and the second were human recombinant cytochromes P450 3A5 expressed in E.coli cells (Bactosomes). Furthermore, the effect of NADPH:CYP reductase and cytochrome b5 on vandetanib oxidation was investigated. Both systems formed the demethylated metabolite of vandetanib, N-desmethylvandetanib, which was separated by HPLC. The study of enzyme kinetics of vandetanib oxidation by human CYP3A5R, 3A5BR, 3A5BLR in Bactosomes indicates that two vandetanib molecules can bind into the active site of the enzyme, resulting in more efficient oxidation. The results also indicate that not only NADPH: CYP reductase, but also cytochrome b5 affects vandetanib...
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