Cyclosporine Inhibition of Hepatic and Intestinal CYP3A4, Uptake and Efflux Transporters: Application of PBPK Modeling in the Assessment of Drug-Drug Interaction Potential

Purpose

To apply physiologically-based pharmacokinetic (PBPK) modeling to investigate the consequences of reduction in activity of hepatic and intestinal uptake and efflux transporters by cyclosporine and its metabolite AM1.

Methods

Inhibitory potencies of cyclosporine and AM1 against OATP1B1, OATP1B3 and OATP2B1 were investigated in HEK293 cells +/? pre-incubation. Cyclosporine PBPK model implemented in Matlab was used to assess interaction potential (+/? metabolite) against different processes (uptake, efflux and metabolism) in liver and intestine and to predict quantitatively drug-drug interaction with repaglinide.

Results

Cyclosporine and AM1 were potent inhibitors of OATP1B1 and OATP1B3, IC₅₀ ranging from 0.019–0.093 μM following pre-incubation. Cyclosporine PBPK model predicted the highest interaction potential against liver uptake transporters, with a maximal reduction of >70% in OATP1B1 activity; the effect on hepatic efflux and metabolism was minimal. In contrast, 80–97% of intestinal P-gp and CYP3A4 activity was reduced due to the 50-fold higher cyclosporine enterocytic concentrations relative to unbound hepatic inlet. The inclusion of AM1 resulted in a minor increase in the predicted maximal reduction of OATP1B1/1B3 activity. Good predictability of cyclosporine-repaglinide DDI and the impact of dose staggering are illustrated.

Conclusions

This study highlights the application of PBPK modeling for quantitative prediction of transporter-mediated DDIs with concomitant consideration of P450 inhibition.     

Prediction of pharmacokinetic profile of valsartan in human based on in vitro uptake transport data

The aim of this study was to evaluate a strategy based on a physiologically based pharmacokinetic (PBPK) model for the prediction of PK profiles in human using in vitro data when elimination of compounds relies on active transport processes. The strategy was first applied to rat in vivo and in vitro data in order to refine the PBPK model. The model could then be applied to human in vitro uptake transport data using valsartan as a probe substrate. Plated rat and human hepatocytes, and cell lines overexpressing human OATP1B1 and OATP1B3 were used for in vitro uptake experiments. The uptake rate of valsartan was higher for rat hepatocytes (K _m,u = 28.4 ± 3.7 μM, V _max = 1318 ± 176 pmol/mg/min and P _dif = 1.21 ± 0.42 μl/mg/min) compared to human hepatocytes (K _m,u = 44.4 ± 14.6 μM, V _max = 304 ± 85 pmol/mg/min and P _dif = 0.724 ± 0.271 μl/mg/min). OATP1B1 and 1B3 parameters were correlated to human hepatocyte data using experimentally established relative activity factors (RAF). Resulting PBPK simulations using those in vitro data were compared for plasma (human and rat) and bile (rat) concentration–time profiles following i.v. bolus administration of valsartan. An uncertainty analysis indicated that the scaled in vitro uptake clearance had to be adjusted with an additional empirical scaling factor of 5 to match the plasma concentrations and biliary excretion profiles. Applying this model, plasma clearances (CL_P) for rat and human were predicted within two-fold relative to predictions based on respective in vitro data. The corrected hepatic uptake transport kinetic parameters enabled the prediction of valsartan in vivo PK profiles and plasma clearances, using PBPK modeling. Moreover, the interspecies difference in elimination rate observed in vivo was correctly reflected in the transport parameters determined in vitro. More data are needed to support more general applications of the proposed approach including its use for metabolized compounds.     

Contribution of organic anion transporting polypeptide (OATP) 1B1 and OATP1B3 to hepatic uptake of nateglinide, and the prediction of drug-drug interactions via these transporters

Objectives We have investigated the contributions of organic anion transporting polypeptide (OATP) 1B1 and OATP1B3 to the hepatic uptake of nateglinide, and the possibility of drug–drug interactions via these transporters. Methods Uptake studies using transporter‐expressing HEK293 cells and cryopreserved human hepatocytes were performed to examine the contributions of each transporter. Inhibition studies using cryopreserved human hepatocytes were performed to examine the possibility of drug–drug interactions. Key findings The rate of saturable hepatic uptake of nateglinide using human hepatocytes was 47.6%. A certain increase in uptake was observed in the examination using transporter‐expressing HEK293 cells, indicating contributions of OATP1B1 and OATP1B3 to hepatic nateglinide uptake. The 50% inhibitory concentration (IC50) values of nateglinide using cryopreserved human hepatocytes for uptake of estrone 3‐sulfate (substrate of OATP1B1), and cholecystokinin octapeptide (substrate of OATP1B3) were 168 and 17.4 µmol/l, respectively. Moreover, ciclosporin inhibited saturable hepatic uptake of nateglinide with an IC50 value of 6.05 µmol/l. The calculated 1 + I_in,max,u/IC50 values for inhibition of OATP1B1 and OATP1B3 by nateglinide, and the inhibition of saturable uptake of nateglinide by ciclosporin, were all close to 1, indicating a low clinical risk of drug–drug interaction with nateglinide taken up via OATP1B1 and OATP1B3. Conclusions OATP1B1 and OATP1B3 may have contributed to the hepatic uptake of nateglinide, but the possibility of drug–drug interactions appeared to be low.     

Organic anion transporting polypeptides and organic cation transporter 1 contribute to the cellular uptake of the flavonoid quercetin

Flavonoids such as quercetin and kaempferol mediate several health protective effects, e.g., anticancer effects. They are inhibitors of organic anion transporting polypeptides (OATP) and organic cation transporters (e.g., OCT2). However, little is known whether such transporters contribute to the cellular uptake of flavonoids. Therefore, we investigated the cellular uptake of kaempferol and quercetin using HEK293 cell lines stably expressing different human OATPs or OCT1. Kaempferol was not a substrate of any of the investigated transporters (OATP1A2, OATP1B1, OATP1B3, OATP2A1, OATP2B1, OATP3A1, OATP4A1, OATP5A1, and OCT1). Quercetin showed a significantly higher uptake into the HEK293-OATP1A2, HEK293-OATP2A1, HEK293-OATP2B1, and HEK293-OCT1 cells compared to control cells. The OATP1A2-, OATP2B1-, and OCT1-mediated quercetin uptake was inhibited by known inhibitors such as naringin, cyclosporin A, and quinidine, respectively. The cellular accumulation of quercetin into HEK293-OATP2A1 cells was not inhibited by prostaglandin E₂ and diclofenac. The ionophore carbonyl cyanide 4-(trifluoromethoxy)phenylhydrazone (FCCP) reduced the net uptake of quercetin by increasing the uptake in the HEK293-control cells and causing no significant change in the HEK293-OATP2B1 cells indicating that quercetin follows the FCCP-driven proton flux through the plasma membrane. In addition to passive diffusion, the SLC transporters OATP1A2, OATP2B1, and OCT1 contribute to cellular accumulation of quercetin.     

The Influence of Oral Antidiabetic Drugs on Cellular Drug Uptake Mediated by Hepatic OATP Family Members

As patients with type 2 diabetes receiving oral antidiabetic drugs are often concomitantly treated with other drugs, they are of increased risk for drug interactions. Drugs have to be taken up into hepatocytes before their intracellular drug action or before they are metabolized, and therefore, uptake transporters are important modulators of drug pharmacokinetics and drug effects. To gain more insights into the role of uptake transporters for drug interactions, we investigated whether frequently prescribed oral antidiabetic drugs interact with the transport of drugs, mediated by the hepatic uptake transporters OATP1B1 (gene symbol SLCO1B1), OATP1B3 (gene symbol SLCO1B3) and OATP2B1 (gene symbol SLCO2B1). Using HEK293 cells recombinantly over‐expressing these uptake transporters, we analysed whether glibenclamide, glimepiride, nateglinide and pioglitazone influence the transport of the model transport substrate bromosulfophthalein. Furthermore, we investigated the influence of the same oral antidiabetic drugs and of repaglinide and rosiglitazone on the uptake of the HMG‐CoA‐reductase inhibitor atorvastatin. The oral antidiabetic drugs glibenclamide, glimepiride and nateglinide inhibited the transport of the model substrate bromosulfophthalein, particularly the OATP2B1‐mediated uptake. The OATP‐mediated atorvastatin uptake was inhibited in a similar manner. For glibenclamide, inhibitory constants (K_i values) of 13.6 μM, 8.1 μM and 0.5 μM for OATP1B1‐, OATP1B3‐ and OATP2B1‐mediated BSP uptake were determined. In conclusion, these in vitro results demonstrate that several oral antidiabetic drugs may influence hepatic OATP‐mediated drug uptake. The in vivo consequences of these results have to be analysed in further studies.     

Epigallocatechin-3-gallate decreases the transport and metabolism of simvastatin in rats

1.?This study aimed to investigate the potential impact of epigallocatechin-3-gallate (EGCG) on the pharmacokinetic behaviors of simvastatin and its metabolite simvastatin acid and explored the possible role of metabolizing enzymes and transporters of this food–drug interaction.

2.?Female SD rats were intravenously administered with EGCG (5?mg/kg), ketoconazole (10?mg/kg) and rifampin (10?mg/kg), followed by intravenous administration of 2?mg/kg simvastatin. In vitro, the effects of EGCG on Cytochrome P450 enzymes (CYP450) and organic anion transporting polypeptides (OATPs) were studied using human hepatic microsomes and human embryonic kidney 293 (HEK293) cells overexpressing OATP1B1 or OATP1B3. The results showed that areas under concentration–time (AUC) curves of simvastatin and simvastatin acid increased by 2.21- and 1.4-fold while the clearance was reduced by 2.29- and 1.4-fold, respectively, when co-administered with EGCG. In vitro experiments suggested the inhibitory effect of EGCG on CYP enzymes (IC₅₀: 18.37?±?1.36?μM, 26.08?±?1.51?μM for simvastatin and simvastatin acid, respectively). Simvastatin transport by OATP1B1 and OATP1B3 was also inhibited by EGCG (IC₅₀: 8.68?±?1.27?μM and 22.67?±?1.42?μM, respectively).

3.?The presently reported novel food–drug interaction between EGCG and simvastatin involves the inhibition of not only CYP450 enzymes but also OATPs by EGCG.     

Characterization of ursodeoxycholic and norursodeoxycholic acid as substrates of the hepatic uptake transporters OATP1B1, OATP1B3, OATP2B1 and NTCP

Ursodeoxycholic acid (UDCA) is the only approved treatment for primary biliary cirrhosis, and norursodeoxycholic acid (norUDCA) is currently tested in clinical trials for future treatment of primary sclerosing cholangitis because of beneficial effects in cholestatic Mdr2 knock‐out mice. Uptake of UDCA and norUDCA into hepatocytes is believed to be a prerequisite for subsequent metabolism and therapeutic action. However, the molecular determinants of hepatocellular uptake of UDCA and norUDCA are poorly understood. We therefore investigated whether UDCA and norUDCA are substrates of the hepatic uptake transporters OATP1B1, OATP1B3, OATP2B1 and Na⁺‐taurocholate co‐transporting polypeptide (NTCP), which are localized in the basolateral membrane of hepatocytes. Uptake of [³H]UDCA and [¹⁴C]norUDCA into Human embryonic kidney (HEK) cells stably expressing OATP1B1, OATP1B3, OATP2B1 or NTCP was investigated and compared with uptake into vector control cells. Uptake ratios were calculated by dividing uptake into transporter‐transfected cells by uptake into respective control cells. Uptake ratios of OATP1B1‐, OATP1B3‐ and OATP2B1‐mediated UDCA and norUDCA uptake were at maximum 1.23 and 1.49, respectively. Uptake of UDCA was significantly higher into HEK‐NTCP cells only at the lowest tested concentration (1 μM, p < 0.001) compared with the control cells with an uptake ratio of 1.34‐fold. NorUDCA was not significantly transported by NTCP. The low uptake rates suggest that OATP1B1, OATP1B3, OATP2B1 and NTCP are not relevant for hepatocellular uptake and effects of UDCA and norUDCA in human beings.     

Interaction of sirolimus and everolimus with hepatic and intestinal organic anion-transporting polypeptide transporters

1. The goal of this study was to assess the interaction of the mTOR inhibitors (ImTORs) sirolimus and everolimus with the human organic anion-transporting polypeptides (OATPs) expressed in hepatocytes and enterocytes by conducting uptake experiments using (i) transfected HEK293T cells, (ii) the hepatocyte-like HepaRG cell line and (iii) the enterocyte-like Caco-2 cell line.

2. Sirolimus and everolimus inhibited in a dose-dependent manner the uptake of [³H]-estrone sulphate by OATP1A2 and OATP1B1 and that of mycophenolic acid 7-O-glucuronide (MPAG) by OATP1B3. ImTOR apparent 50% inhibitory concentrations (IC₅₀) for OATPs were 11.9 µM (OATP1A2), 9.8 µM (OATP1B1) and 1.3 µM (OATP1B3) for sirolimus and 4.2 µM (OATP1A2), 4.1 µM (OATP1B1) and 4.3 µM (OATP1B3) for everolimus.

3. No transport of sirolimus or everolimus by OATP1A2, OATP1B1 or OATP1B3 was observed in HEK-transfected cells and the OAT/OATP/MRP chemical inhibitor probenecid did not significantly decrease the uptake of sirolimus and everolimus in HepaRG and Caco-2 cells, but tended to increase their intracellular accumulation presumably through efflux inhibition.

4. In conclusion, our data suggest that the major OATP transporters expressed in the liver and the intestine do not contribute to the pharmacokinetics of sirolimus and everolimus. However, ImTORs are inhibitors of these transporters.

     

Characterization of the transport of the bicyclic peptide phalloidin by human hepatic transport proteins

Phalloidin, the major phallotoxin of the mushroom Amanita phalloides, enters hepatocytes by a carrier-mediated mechanism. The molecular identity of the transport proteins mediating phalloidin uptake was so far unknown. Earlier studies in rat liver indicated that phalloidin may share a common mechanism of uptake with organic anions like bile salts. In the current study on human transporters, we analyzed the uptake of phalloidin into transfected HEK293 cells stably expressing the recombinant hepatocyte-specific organic anion uptake transporters OATP2 (also termed OATP1B1, OATP-C, LST1, symbol SLC21A6) or OATP8 (OATP1B3 or SLC21A8). Time-dependent uptake of phalloidin was observed with SLC21A6-expressing cells and was inhibited by typical substrates of SLC21A6 such as bromosulfophthalein or cholyltaurine. A K_m value of 39±11 µM was determined for SLC21A6-mediated phalloidin uptake. Additional inhibitors of phalloidin uptake mediated by SLC21A6 included the immunosuppressive drugs cyclosporin A, FK506, and rapamycin, whereas -amanitin was only a weak inhibitor. Cyclosporin A was a most potent competitive inhibitor for SLC21A6-mediated phalloidin transport with a K_i value of 51 nM.     

Effects of fibrates on human organic anion-transporting polypeptide 1B1-, multidrug resistance protein 2- and P-glycoprotein-mediated transport

The effects of different fibric acid derivatives (bezafibrate, clofibrate, clofibric acid, fenofibrate, fenofibric acid and gemfibrozil) on human organic anion transporting-polypeptide 1B1 (OATP2, OATP-C, SLC21A6), multidrug resistance protein 2 (MRP2/ABCC2) and MDR1-type P-glycoprotein (P-gp/ABCB1) were examined in vitro. Cyclosporin A (a known inhibitor of OATP1B1 and P-gp), MK-571 (a known inhibitor of MRP2) and cimetidine (an organic cation) were also tested. Bezafibrate, fenofibrate, fenofibric acid and gemfibrozil showed concentration-dependent inhibition of estradiol 17-β-D-glucuronide uptake by OATP1B1-stably transfected HEK cells, whereas clofibrate and clofibric acid did not show any significant effects up to 100?µM. Inhibition kinetics of gemfibrozil, which exhibited the most significant inhibition on OATP1B1, was shown to be competitive with a K_i?=?12.5?µM. None of the fibrates showed any significant inhibition of MRP2-mediated transport, which was evaluated by measuring the uptake of ethacrynic acid glutathione into MRP2-expressing Sf9 membrane vesicles. Only fenofibrate showed moderate P-gp inhibition as assessed by measuring cellular accumulation of vinblastine in a P-gp overexpressing cell-line. Cyclosporin A significantly inhibited OATP1B1 and P-gp, whereas only moderate inhibition was observed on MRP2. The rank order of inhibitory potency of MK-571 was determined as OATP1B1 (IC₅₀: 0.3?µM)?>?MRP2 (4?µM)?>?P-gp (25?µM). Cimetidine did not show any effects on these transporters. In conclusion, neither MRP2- nor P-gp-mediated transport is inhibited significantly by the fibrates tested. Considering the plasma protein binding and IC₅₀ values for OATP1B1, only gemfibrozil appeared to have a potential to cause drug–drug interactions by inhibiting OATP1B1 at clinically relevant concentrations.     

Validation of cell-based OATP1B1 assays to assess drug transport and the potential for drug–drug interaction to support regulatory submissions

1. Transporters are carrier proteins that may influence pharmacokinetic, pharmacodynamic, and toxicological characteristics of drugs. The development of validated in vitro transporter models is imperative to support regulatory submissions of drug candidates. This study is focused on utilizing human embryonic kidney (HEK) 293 cell cultures genetically transfected with the human organic anion transporting polypeptides (OATP) 1B1 transporter to identify substrates and inhibitors in drug development.

2. The kinetics of OATP1B1-mediated uptake of [³H]-oestradiol 17β-glucuronide and inhibition of uptake by rifamycin SV were used to determine K_m, V_max, and IC₅₀ values over a range of passage numbers to investigate accuracy and precision. The mean K_m and V_max values were found to be 6.3?±?1.2 μM and 460?±?96 pmol min^?1 mg^?1, respectively. The mean IC₅₀ value for rifamycin SV was 0.23?±?0.07 μM on uptake of 1 μM [³H]-oestradiol 17β-glucuronide. These data were similar to previously reported values (accuracy greater than 82%), reproducible (precision less than 29%) and exhibited low standard deviations (SDs) obviating the need to study test compounds on more than one occasion.

3. [³H]-oestrone 3-sulfate and [³H]-pravastatin exhibited concentration-dependent OATP1B1 uptake, and statistically significant differences were observed at each concentration between uptake rates of HEK293-OATP1B1 and HEK293-MOCK cells (uptake ratios greater than or equal to 3). Propranolol showed no positive uptake ratio. Bezafibrate and gemfibrozil exhibited concentration-dependent inhibition of OATP1B1-mediated uptake of [³H]-oestradiol 17β-glucuronide with mean IC₅₀ values of 16 and 27 μM, respectively.

4. Based on the validation results, acceptance criteria to identify a test compound as a substrate and/or inhibitor using these specific cell lines were determined. These validated OATP1B1 assays were robust, reproducible, and suitable for routine in vitro evaluation of candidate drugs.

     

Identification of natural products as modulators of OATP2B1 using LC-MS/MS to quantify OATP-mediated uptake

Context: Organic anion-transporting polypeptide 2B1 (OATP2B1) which is highly expressed in enterocytes and hepatocytes could be a key determinant for the intestinal absorption and hepatic uptake of its substrate drugs. Natural products are commonly used in traditional Chinese medicine, foods, and beverages.

Objective: The objective of this study is to determine the OATP2B1-mediated drug interactions that could occur between natural products and OATP2B1 substrate drugs.

Materials and methods: Human OATP2B1 was transiently expressed in human embryonic kidney (HEK293) cells and characterized by immunofluorescence, Western blot, and uptake assay. Liquid chromatography–tandem mass spectrometry (LC–MS/MS) methods for detecting OATP2B1 substrates estrone-3-sulfate (E3S) and three statins had been developed and were employed to investigate the effects of 27 frequently used natural products on the function of OATP2B1. Uptake of 5?μM E3S and 1?μM statins in the absence or presence of natural products was measured at 37?°C for 2?min with empty vector- and OATP2B1-transfected HEK293 cells. The IC₅₀ values of inhibitors for OATP2B1-mediated 5?μM E3S uptake were determined.

Results: Our results showed that mulberrin, scutellarin, quercetin, and glycyrrhetinic acid were strong inhibitors of OATP2B1-mediate E3S uptake with IC₅₀ values being 1.8, 2.0, 7.5, and 13.0?μM, which were comparable with their plasma concentrations in clinical trials. They also inhibited OATP-mediated uptake of atorvastatin, fluvastatin, and rosuvastatin. These results indicated that clinically relevant drug interactions could occur between these natural compounds and OATP2B1 substrate drugs.

Discussion and conclusion: The information obtained from this study might be helpful to predict and to avoid potential OATP2B1-mediated drug interactions.     

Transport characteristics and transporter‐based drug–drug interactions of TM‐25659, a novel TAZ modulator

The in vitro metabolic stability and transport mechanism of TM‐25659, a novel TAZ modulator, was investigated in human hepatocytes and human liver microsomes (HLMs) based on the preferred hepatobiliary elimination in rats. In addition, the in vitro transport mechanism and transporter‐mediated drug–drug interactions were evaluated using oocytes and MDCKII cells overexpressing clinically important drug transporters. After a 1 h incubation in HLMs, 92.9 ± 9.5% and 95.5 ± 11.6% of the initial TM‐25659 remained in the presence of NADPH and UDPGA, respectively. Uptake of TM‐25659 readily accumulated in human hepatocytes at 37 ºC (i.e. 6.7‐fold greater than that at 4 ºC), in which drug transporters such as OATP1B1 and OATP1B3 were involved. TM‐25659 had a significantly greater basal to apical transport rate (5.9‐fold) than apical to basal transport rate in the Caco‐2 cell monolayer, suggesting the involvement of an efflux transport system. Further studies using inhibitors of efflux transporters and overexpressing cells revealed that MRP2 was involved in the transport of TM‐25659. These results, taken together, suggested that TM‐25659 can be actively influxed into hepatocytes and undergo biliary excretion without substantial metabolism. Additionally, TM‐25659 inhibited the transport activities of OATP1B1 and OATP1B3 with IC₅₀ values of 36.3 and 25.9 μm , respectively. TM‐25659 (100 μm ) increased the accumulation of the probe substrate by 160% and 213%, respectively, through the inhibition of efflux function of P‐gp and MRP2. In conclusion, OATP1B1, OATP1B3, P‐gp and MRP2 might be major transporters responsible for the pharmacokinetics and drug–drug interaction of TM‐25659, although their contribution to in vivo pharmacokinetics needs to be further investigated. Copyright © 2013 John Wiley & Sons, Ltd.     

Characterization of Hepatobiliary Transport Systems of a Novel α4β1/α4β7 Dual Antagonist, TR-14035

Purpose Our previous pharmacokinetic studies have demonstrated that TR-14035, a novel dual antagonist for α4β1/α4β7 integrin, selectively and strongly accumulated in the liver and was mainly excreted in bile as an unchanged drug. In the present study, we investigated the hepatobiliary transport system in detail.Materials and Methods Uptake by hepatocytes and organic anion transporting polypeptide (OATP)-expressing Xenopus laevis oocytes or Flp-In-293 cells was performed in vitro. Biliary excretion was investigated in mdr1a/b-knockout mice, Bcrp-knockout mice and Mrp2-defective Eisai hyperbilirubinemic rats (EHBRs).Results TR-14035 was taken up by rat and human hepatocytes by an apparently single saturable mechanism with K _m of 6.7 and 2.1 μM, respectively, and taurocholate and digoxin reduced this uptake. OATP1B1/OATP-C and OATP1B3/OATP8 expressed in oocytes mediated the TR-14035 uptake with K _m of 7.5 and 5.3 μM, respectively. OATP1B1*15, a genetic variant of OATP1B1, exhibited a decreased transport of TR-14035 compared with OATP1B1*1a. Biliary excretion and total body clearance of unchanged TR-14035 in EHBRs were significantly lower than those in normal rats, while there was no difference in the clearances between wild and mdr1a/b- or Bcrp-knockout mice.Conclusion These results indicate that OATP1B1 and OATP1B3 are at least partly responsible for the accumulation of TR-14035 into hepatocytes, and Mrp2 principally mediates the biliary excretion of TR-14035. Furthermore, genetic polymorphisms of OATP1B1 may cause an interindividual variability in the pharmacokinetics of TR-14035.     

基于药物转运体的元胡止痛方药效成分延胡索乙素、巴马汀、原阿片碱、欧前胡素和异欧前胡素跨血脑屏障机制研究

目的 基于药物转运体研究元胡止痛方药效成分延胡索乙素、巴马汀、原阿片碱、欧前胡素和异欧前胡素跨血脑屏障转运机制。方法 建立hCMEC/D3-U87双层细胞模型研究延胡索乙素、巴马汀、原阿片碱、欧前胡素和异欧前胡素的跨血脑屏障吸收情况;通过实时荧光定量PCR （qRT-PCR）法测定hCMEC/D3细胞中相关转运体蛋白多药耐药蛋白1（MDR1）、乳腺癌耐药蛋白（BCRP）、有机阳离子转运体1（OCT1）、OCT2、OCT3、有机阴离子转运体1（OCTN1）、OCTN2、OATP1A2、OATP2B1的mRNA表达水平;使用6株过表达人转运体的细胞株（S2-OCT1、S2-OCT3、S2-OCTN1、S2-OCTN2、HEK293-OATP1A2、HEK293-OATP2B1）进行摄取实验,判断各药物成分是否为转运体蛋白的底物。结果 各成分均可以一定程度地跨越血脑屏障,延胡索乙素、欧前胡素、异欧前胡素具有更好的跨血脑屏障特性,巴马汀和原阿片碱的跨血脑屏障能力较弱。外排型转运蛋白MDR1、BCRP和摄入型转运蛋白OCTN1、OATP2B1、OATP1A2在hCMECD3细胞中有相对高的mRNA表达水平。延胡索乙素是OCT1、OCTN1和OATP1A2的底物;巴马汀是OCT1、OCT3、OCTN1、OCTN2和OATP2B1的底物;原阿片碱是OCT1、OCTN1和OCTN2的底物;欧前胡素、异欧前胡素是OCT3的底物。结论 延胡索乙素可能通过转运体OATP1A2、OCT1、OCTN1跨越血脑屏障进入脑组织细胞;巴马汀可能通过OATP2B1、OCT1、OCT3、OCTN1、OCTN2传递进入脑组织细胞;原阿片碱可能通过OCT1、OCTN1和OCTN2传递进入脑组织细胞;欧前胡素、异欧前胡素可能通过OCT3传递进入脑组织细胞。     

In vitro assessment of the roles of drug transporters in the disposition and drug–drug interaction potential of olaparib

1.?In vitro assessments were conducted to examine interactions between olaparib (a potent oral inhibitor of poly[ADP-ribose] polymerase) and drug transporters.

2.?Olaparib showed inhibition of the hepatic drug uptake transporters OATP1B1 (IC₅₀ values of 20.3?μM and 27.1?μM) and OCT1 (IC₅₀ 37.9?μM), but limited inhibition of OATP1B3 (25% at 100?μM); inhibition of the renal uptake transporters OCT2 (IC₅₀ 19.9?μM) and OAT3 (IC₅₀ 18.4?μM), but limited inhibition of OAT1 (13.5% at 100?μM); inhibition of the renal efflux transporters MATE1 and MATE2K (IC₅₀s 5.50?μM and 47.1?μM, respectively); inhibition of the efflux transporter MDR1 (IC₅₀ 76.0?μM), but limited inhibition of BCRP (47% at 100?μM) and no inhibition of MRP2. At clinically relevant exposures, olaparib has the potential to cause pharmacokinetic interactions via inhibition of OCT1, OCT2, OATP1B1, OAT3, MATE1 and MATE2K in the liver and kidney, as well as MDR1 in the liver and GI tract. Olaparib was found to be a substrate of MDR1 but not of several other transporters.

3.?Our assessments indicate that olaparib is a substrate of MDR1 and may cause clinically meaningful inhibition of MDR1, OCT1, OCT2, OATP1B1, OAT3, MATE1 and MATE2K.     

Organic anion-transporting polypeptide (OATP) 2B1 contributes to the cellular uptake of theaflavin

Organic anion-transporting polypeptide (OATP) 2B1 has been reported in the apical membranes of the human small intestinal epithelium, where it contributes to the intestinal absorption of pharmacologically active drugs. To investigate the potential for OATP2B1-mediated drug–food interactions, the effects of several polyphenolic compounds on OATP2B1-mediated estrone-3-sulfate (E3S) transport were studied by using OATP2B1-expressing HEK293 cells. Our results showed that some compounds, especially theaflavin, were strong inhibitors of OATP2B1-mediated E3S uptake. Theaflavin showed a significantly higher uptake into the OATP2B1-expressing HEK293 cells than the control cells. The concentration dependence of the uptake of theaflavin was determined over a range of concentrations (0.5–100 μM) and the kinetic parameters (K_m and V_max) of theaflavin uptake were found to be 5.12 ± 0.67 μM and 41.6 ± 1.3 pmol/mg protein/min, respectively. The OATP2B1-mediated theaflavin uptake was inhibited by known OATP2B1 substrates such as E3S, bromsulphthalein (BSP), dehydroepiandrosterone-3-sulfate (DHEAS), and fluvastatin. Our results indicate that theaflavin is a novel substrate of OATP2B1. The results of this study might be helpful to predict the potential OATP2B1-mediated drug–theaflavin interactions and to avoid undesirable clinical consequences.     

OATP1B1/1B3 activity in plated primary human hepatocytes over time in culture

Primary human hepatocytes are widely used as an in vitro model for evaluation of drug metabolism and transport. However, it has been shown that the gene expression of many drug-metabolizing enzymes and transporters change in culture. The aim of the present study was to evaluate the activity of organic anion-transporting polypeptide 1B1 (OATP1B1) and 1B3 (OATP1B3) in plated primary human hepatocytes over time in culture. The uptake kinetics of the OATP1B1/1B3 substrate [³H]-estradiol-17β-d-glucuronide was determined in cells from five donors. An extensive and variable decrease in OATP1B1/1B3 activity and/or increase in passive diffusion was observed over time. Already after 6 h in culture, the OATP1B1/1B3 activity was not possible to determine in liver cells from one donor, while after 24 h, the uptake activity was not measurable in one additional donor. In the other three, the decrease in CL_int (V_max/K_m) values ranged from 15% to 86% after 24 h in culture compared to the values measured at 2 h. Visual examination of OATP1B1 protein expression by confocal microscopy showed localization to the plasma membrane as expected, and an extensive decrease in OATP1B1 expression over time in culture supported the decline in activity. The significant reduction in SLCO1B1 and SLCO1B3 gene expression over time determined by RT-PCR also supported the loss of OATP1B1/1B3 activity. In conclusion, plated primary human hepatocytes are useful as an in vitro model for OATP1B1/1B3-mediated uptake studies, but the culture time may substantially change the uptake kinetics.     

Physiologically Based Modeling of Pravastatin Transporter-Mediated Hepatobiliary Disposition and Drug-Drug Interactions

Purpose

To develop physiologically based pharmacokinetic (PBPK) model to predict the pharmacokinetics and drug-drug interactions (DDI) of pravastatin, using the in vitro transport parameters.

Methods

In vitro hepatic sinusoidal active uptake, passive diffusion and canalicular efflux intrinsic clearance values were determined using sandwich-culture human hepatocytes (SCHH) model. PBPK modeling and simulations were implemented in Simcyp (Sheffield, UK). DDI with OATP1B1 inhibitors, cyclosporine, gemfibrozil and rifampin, was also simulated using inhibition constant (Ki) values.

Results

SCHH studies suggested active uptake, passive diffusion and efflux intrinsic clearance values of 1.9, 0.5 and 1.2?μL/min/10⁶cells, respectively, for pravastatin. PBPK model developed, using transport kinetics and scaling factors, adequately described pravastatin oral plasma concentration-time profiles at different doses (within 20% error). Model based prediction of DDIs with gemfibrozil and rifampin was similar to that observed. However, pravastatin-cyclosporine DDI was underpredicted (AUC ratio 4.4 Vs ~10). Static (R-value) model predicted higher magnitude of DDI compared to the AUC ratio predicted by the PBPK modeling.

Conclusions

PBPK model of pravastatin, based on in vitro transport parameters and scaling factors, was developed. The approach described can be used to predict the pharmacokinetics and DDIs associated with hepatic uptake transporters.     

Reduced Physiologically-Based Pharmacokinetic Model of Repaglinide: Impact of OATP1B1 and CYP2C8 Genotype and Source of In Vitro Data on the Prediction of Drug-Drug Interaction Risk

Purpose

To investigate the effect of OATP1B1 genotype as a covariate on repaglinide pharmacokinetics and drug-drug interaction (DDIs) risk using a reduced physiologically-based pharmacokinetic (PBPK) model.

Methods

Twenty nine mean plasma concentration-time profiles for SLCO1B1 c.521T>C were used to estimate hepatic uptake clearance (CL_uptake) in different genotype groups applying a population approach in NONMEM v.7.2.

Results

Estimated repaglinide CL_uptake corresponded to 217 and 113 μL/min/10⁶ cells for SLCO1B1 c.521TT/TC and CC, respectively. A significant effect of OATP1B1 genotype was seen on CL_uptake (48% reduction for CC relative to wild type). Sensitivity analysis highlighted the impact of CL_met and CL_diff uncertainty on the CL_uptake optimization using plasma data. Propagation of this uncertainty had a marginal effect on the prediction of repaglinide OATP1B1-mediated DDI with cyclosporine; however, sensitivity of the predicted magnitude of repaglinide metabolic DDI was high. In addition, the reduced PBPK model was used to assess the effect of both CYP2C8*3 and SLCO1B1 c.521T>C on repaglinide exposure by simulations; power calculations were performed to guide prospective DDI and pharmacogenetic studies.

Conclusions

The application of reduced PBPK model for parameter optimization and limitations of this process associated with the use of plasma rather than tissue profiles are illustrated.