RESUMO
BACKGROUND: In predictions about hepatic clearance (CLH), a number of studies explored the role of albumin and transporters in drug uptake by liver cells, challenging the traditional free-drug theory. It was proposed that liver uptake can occur for transporter substrate compounds not only from the drug's unbound form but also directly from the drug-albumin complex, a phenomenon known as uptake facilitated by albumin. In contrast to albumin, dextran does not exhibit binding properties for compounds. However, as a result of its inherent capacity for stabilization, it is widely used to mimic conditions within cells. METHODS: The uptake of eight known substrates of the organic anion-transporting polypeptide 1B3 (OATP1B3) was assessed using a human embryonic kidney cell line (HEK293), which stably overexpresses this transporter. An inert polymer, dextran, was used to simulate cellular conditions, and the results were compared with experiments involving human plasma and human serum albumin (HSA). RESULTS: This study is the first to demonstrate that dextran increases compound uptake in cells with overexpression of the OATP1B3 transporter. Contrary to the common theory that highly protein-bound ligands interact with hepatocytes to increase drug uptake, the results indicate that dextran's interaction with test compounds does not significantly increase concentrations near the cell membrane surface. CONCLUSIONS: We evaluated the effect of dextran on the uptake of known substrates using OATP1B3 overexpressed in the HEK293 cell line, and we suggest that its impact on drug concentrations in liver cells may differ from the traditional role of plasma proteins and albumin.
Assuntos
Dextranos , Transportadores de Ânions Orgânicos , Humanos , Membro 1B3 da Família de Transportadores de Ânion Orgânico Carreador de Soluto/genética , Membro 1B3 da Família de Transportadores de Ânion Orgânico Carreador de Soluto/metabolismo , Membro 1B3 da Família de Transportadores de Ânion Orgânico Carreador de Soluto/farmacologia , Transportador 1 de Ânion Orgânico Específico do Fígado/genética , Transportador 1 de Ânion Orgânico Específico do Fígado/metabolismo , Transportador 1 de Ânion Orgânico Específico do Fígado/farmacologia , Células HEK293 , Transportadores de Ânions Orgânicos/genética , Transportadores de Ânions Orgânicos/metabolismo , Hepatócitos/metabolismo , Fígado , Proteínas de Membrana Transportadoras/metabolismo , Albuminas , Transportadores de Ânions Orgânicos Sódio-Independentes/genética , Transportadores de Ânions Orgânicos Sódio-Independentes/metabolismoRESUMO
The therapeutic use of glimepiride and gliclazide shows substantial inter-individual variation in pharmacokinetics and pharmacodynamics in human populations, which might be caused by genetic differences among individuals. The aim of this study was to assess the effect of CYP2C9 and OATP1B1 genetic polymorphisms on the metabolism and transport of glimepiride and gliclazide. The uptake of glimepiride and gliclazide was measured in OATP1B1*1a, *5 and *15-HEK293T cells, and their metabolism was measured using CYP2C9*1, *2 and *3 recombinase by LC-MS. Glimepiride in OATP1B1*1a, *5 and *15-HEK293T cells had Vmax values of 155 ± 18.7, 80 ± 9.6, and 84.5 ± 8.2 pmol/min/mg, while gliclazide had Vmax values of 15.7 ± 4.6, 7.2 ± 2.5, and 8.7 ± 2.4 pmol/min/mg, respectively. The clearance of glimepiride and gliclazide in OATP1B1*5 and *15 was significantly reduced compared to the wild-type. Glimepiride in the presence of CYP2C9*1, *2 and *3 recombinase had Vmax values of 21.58 ± 7.78, 15.69 ± 5.59, and 9.17 ± 3.03 nmol/min/mg protein, while gliclazide had Vmax values of 15.73 ± 3.11, 10.53 ± 4.06, and 6.21 ± 2.94 nmol/min/mg protein, respectively. The clearance of glimepiride and gliclazide in CYP2C9*2 and *3 was significantly reduced compared to the wild-type. These findings collectively indicate that OATP1B1*5 and *15 and CYP2C9*2 and *3 have a significant effect on the transport and metabolism of glimepiride and gliclazide.