Polimorfizm genu oksydoreduktazy cytochromu P450 a farmakokinetyka pantoprazolu u zdrowych ochotników

Genetycznie uwarunkowana aktywność enzymów metabolizujących leki może mieć znaczenie dla bezpieczeństwa i skuteczności leczenia. We wcześniejszych badaniach wykazano, że na aktywność enzymatyczną CYP2C19 może wpływać nie tylko polimorfizm genu kodującego ten cytochrom, lecz także zawartość reduktazy cytochromu P450 (POR) w mikrosomach ludzkich hepatocytów. Ludzki gen POR wykazuje dużą zmienność, a allel POR*28 jest związany ze zwiększoną aktywnością reduktazy, co w konsekwencji może prowadzić do zwiększonej aktywności układu CYP P450, w tym enzymu CYP2C19. Celem badania było określenie związku pomiędzy polimorfizmem genu POR a parametrami farmakokinetycznymi pantoprazolu, substratu CYP2C19 w grupie zdrowych ochotników. W analizie uwzględniono także warianty genu CYP2C19. U 30 osób, u których wykonano badanie pod kątem występowania jednonukleotydowych polimorfizmów: rs4244285 (681G>A, CYP2C19*2), rs12248560 (-806C>T, CYP2C19*17) oraz rs1057868 (31696C>T, POR*28). Stężenia pantoprazolu w osoczu zmierzono metodą wysokosprawnej chromatografii cieczowej w ciągu 8 godz. od przyjęcia pojedynczej doustnej dawki leku (40 mg). Nie stwierdzono istotnych różnic w stężeniu pantoprazolu pomiędzy osobami o różnych genotypach POR (*1/*1, *1/*28 i *28/*28). Analiza wieloczynnikowa wykazała, że genotyp CYP2C19 istotnie wpływał na wartość wszystkich analizowanych parametrów farmakokinetycznych (p < 0.05), podczas gdy genotyp POR nie był istotnie związany z żadnym z nich. Wyniki badania wskazują, że polimorfizm genu POR nie wpływa istotnie na farmakokinetykę pantoprazolu.It has recently been demonstrated that CYP2C19 activity may be influenced not only by CYP2C19 polymorphism, but also cytochrome P450 oxidoreductase (POR) protein abundance in human liver microsomes. The human POR gene is highly polymorphic and a common POR*28 allele is associated with increased POR activity, which may result in increased CYP P450 activity (including CYP2C19). The aim of the current study was to evaluate the association between POR and CYP2C19 polymorphisms and CYP2C19 substrate pharmacokinetics, i.e. pantoprazole, in Polish Caucasian healthy volunteers. The study enrolled 30 subjects, genotyped for rs4244285 (681G>A, CYP2C19*2), rs12248560 (-806C>T, CYP2C19*17) and rs1057868 (31696C>T, POR*28). Pantoprazole concentration in plasma was determined by validated highperformance liquid-chromatography method 1 h, 2 h, 3 h, 4 h, 6 h and 8 h after a single oral 40 mg dose of the drug. No significant differences in the drug concentrations between POR*1/*1, POR*1/*28 and POR*28/*28 carriers were observed. Multivariate analysis revealed that the CYP2C19 genotype significantly influenced all the investigated pharmacokinetic parameters (p < 0.05), while the POR genotype was not associated with any of the parameters. The results of the current study suggest that POR polymorphism does not significantly influence pantoprazole pharmacokinetics

Monocarboxylate Transporter 1 (MCT1) in Liver Pathology

Membrane monocarboxylate transporter 1 (SLC16A1/MCT1) plays an important role in hepatocyte homeostasis, as well as drug handling. However, there is no available information about the impact of liver pathology on the transporter levels and function. The study was aimed to quantify SLC16A1 mRNA (qRT-PCR) and MCT1 protein abundance (liquid chromatography–tandem mass spectrometry (LC¬¬–MS/MS)) in the livers of patients diagnosed, according to the standard clinical criteria, with hepatitis C, primary biliary cirrhosis, primary sclerosing hepatitis, alcoholic liver disease (ALD), and autoimmune hepatitis. The stage of liver dysfunction was classified according to Child–Pugh score. Downregulation of SLC16A1/MCT1 levels was observed in all liver pathology states, significantly for ALD. The progression of liver dysfunction, from Child–Pugh class A to C, involved the gradual decline in SLC16A1 mRNA and MCT1 protein abundance, reaching a clinically significant decrease in class C livers. Reduced levels of MCT1 were associated with significant intracellular lactate accumulation. The MCT1 transcript and protein did not demonstrate significant correlations regardless of the liver pathology analyzed, as well as the disease stage, suggesting posttranscriptional regulation, and several microRNAs were found as potential regulators of MCT1 abundance. MCT1 membrane immunolocalization without cytoplasmic retention was observed in all studied liver pathologies. Overall, the study demonstrates that SLC16A1/MCT1 is involved in liver pathology, especially in AL

Protein Abundance of Drug Transporters in Human Hepatitis C Livers

Transmembrane drug transport in hepatocytes is one of the major determinants of drug pharmacokinetics. In the present study, ABC transporters (P-gp, MRP1, MRP2, MRP3, MRP4, BCRP, and BSEP) and SLC transporters (MCT1, NTCP, OAT2, OATP1B1, OATP1B3, OATP2B1, OCT1, and OCT3) were quantified for protein abundance (LC-MS/MS) and mRNA levels (qRT-PCR) in hepatitis C virus (HCV)-infected liver samples from the Child–Pugh class A (n = 30), B (n = 21), and C (n = 7) patients. Protein levels of BSEP, MRP3, MCT1, OAT2, OATP1B3, and OCT3 were not significantly affected by HCV infection. P-gp, MRP1, BCRP, and OATP1B3 protein abundances were upregulated, whereas those of MRP2, MRP4, NTCP, OATP2B1, and OCT1 were downregulated in all HCV samples. The observed changes started to be seen in the Child–Pugh class A livers, i.e., upregulation of P-gp and MRP1 and downregulation of MRP2, MRP4, BCRP, and OATP1B3. In the case of NTCP, OATP2B1, and OCT1, a decrease in the protein levels was observed in the class B livers. In the class C livers, no other changes were noted than those in the class A and B patients. The results of the study demonstrate that drug transporter protein abundances are affected by the functional state of the liver in hepatitis C patients