A Review of CYP-Mediated Drug Interactions: Mechanisms and In Vitro Drug-Drug Interaction Assessment

Drug metabolism is a major determinant of drug concentrations in the body. Drug-drug interactions (DDIs) caused by the co-administration of multiple drugs can lead to alteration in the exposure of the victim drug, raising safety or effectiveness concerns. Assessment of the DDI potential starts with in vitro experiments to determine kinetic parameters and identify risks associated with the use of comedication that can inform future clinical studies. The diverse range of experimental models and techniques has significantly contributed to the examination of potential DDIs. Cytochrome P450 (CYP) enzymes are responsible for the biotransformation of many drugs on the market, making them frequently implicated in drug metabolism and DDIs. Consequently, there has been a growing focus on the assessment of DDI risk for CYPs. This review article provides mechanistic insights underlying CYP inhibition/induction and an overview of the in vitro assessment of CYP-mediated DDIs.

Utilization of OATP1B Biomarker Coproporphyrin-I to Guide Drug-Drug Interaction Risk Assessment: Evaluation by the Pharmaceutical Industry

Drug-drug interactions (DDIs) involving hepatic organic anion transporting polypeptides 1B1/1B3 (OATP1B) can be substantial, however, challenges remain for predicting interaction risk. Emerging evidence suggests that endogenous biomarkers, particularly coproporphyrin-I (CP-I), can be used to assess in vivo OATP1B activity. The present work under the International Consortium for Innovation and Quality in Pharmaceutical Development was aimed primarily at assessing CP-I as a biomarker for informing OATP1B DDI risk. Literature and unpublished CP-I data along with pertinent in vitro and clinical DDI information were collected to identify DDIs primarily involving OATP1B inhibition and assess the relationship between OATP1B substrate drug and CP-I exposure changes. Static models to predict changes in exposure of CP-I, as a selective OATP1B substrate, were also evaluated. Significant correlations were observed between CP-I area under the curve ratio (AUCR) or maximum concentration ratio (Cmax R) and AUCR of substrate drugs. In general, the CP-I Cmax R was equal to or greater than the CP-I AUCR. CP-I Cmax R < 1.25 was associated with absence of OATP1B-mediated DDIs (AUCR < 1.25) with no false negative predictions. CP-I Cmax R < 2 was associated with weak OATP1B-mediated DDIs (AUCR < 2). A correlation was identified between CP-I exposure changes and OATP1B1 static DDI predictions. Recommendations for collecting and interpreting CP-I data are discussed, including a decision tree for guiding DDI risk assessment. In conclusion, measurement of CP-I is recommended to inform OATP1B inhibition potential. The current analysis identified changes in CP-I exposure that may be used to prioritize, delay, or replace clinical DDI studies.

An improved method for cytochrome p450 reaction phenotyping using a sequential qualitative-then-quantitative approach

Cytochrome P450 reaction phenotyping to determine the fraction of metabolism values (fm) for individual enzymes is a standard study in the evaluation of a new drug. However, there are technical challenges in these studies caused by shortcomings in the selectivity of P450 inhibitors and unreliable scaling procedures for recombinant P450 (rCYP) data. In this investigation, a two-step "qualitative-then-quantitative" approach to P450 reaction phenotyping is described. In the first step, each rCYP is tested qualitatively for potential to generate metabolites. In the second step, selective inhibitors for the P450s identified in step1 are tested for their effects on metabolism using full inhibition curves. Forty-eight drugs were evaluated in step 1 and there were no examples of missing an enzyme important to in vivo clearance. Five drugs (escitalopram, fluvastatin, pioglitazone, propranolol, and risperidone) were selected for full phenotyping in step2 to determine fm values, with findings compared to fm values estimated from single inhibitor concentration data and rCYP with intersystem-extrapolation-factor corrections. The two-step approach yielded fm values for major drug clearing enzymes that are close to those estimated from clinical data: escitalopram and CYP2C19 (0.42 vs 0.36-0.82), fluvastatin and CYP2C9 (0.76 vs 0.76), pioglitazone and CYP2C8 (0.72 vs 0.73), propranolol and CYP2D6 (0.68 vs 0.37-0.56) and risperidone and CYP2D6 (0.60 vs 0.66-0.88). Reaction phenotyping data generated in this fashion should offer better input to physiologically-based pharmacokinetic models for prediction of DDI and impact of genetic polymorphisms on drug clearance. The qualitative-then-quantitative approach is proposed as a replacement to standard reaction phenotyping strategies. Significance Statement P450 reaction phenotyping is important for projecting drug-drug interactions and interpatient variability in drug exposure. However, currently recommended practices can frequently fail to provide reliable estimates of the fractional contributions of specific P450 enzymes (fm) to drug clearance. In this report, we describe a two-step qualitative-then-quantitative reaction phenotyping approach that yields more accurate estimates of fm.

UPLC-MS/MS method for the simultaneous quantification of pravastatin, fexofenadine, rosuvastatin, and methotrexate in a hepatic uptake model and its application to the possible drug-drug interaction study of triptolide

A rapid and specific UPLC-MS/MS method with a total run time of 3.5 min was developed for the determination of pravastatin, fexofenadine, rosuvastatin, and methotrexate in rat primary hepatocytes. After protein precipitation with 70% acetonitrile (containing 30% H2 O), these four analytes were separated under gradient conditions with a mobile phase consisting of 0.03% acetic acid (v/v) and methanol at a flow rate of 0.50 mL/min. The linearity, recovery, matrix effect, accuracy, precision, and stability of the method were well validated. We evaluated drug-drug interactions based on these four compounds in freshly suspended hepatocytes. The hepatic uptake of pravastatin, fexofenadine, rosuvastatin, and methotrexate at 4°C was significantly lower than that at 37°C, and the hepatocytes were saturable with increased substrate concentration and culture time, suggesting that the rat primary hepatocyte model was successfully established. Triptolide showed a significant inhibitory effect on the hepatic uptake of these four compounds. In conclusion, this method was successfully employed for the quantification of pravastatin, fexofenadine, rosuvastatin, and methotrexate and was used to verify the rat primary hepatocyte model for Oatp1, Oatp2, Oatp4, and Oat2 transporter studies. Then, we applied this model to explore the effect of triptolide on these four transporters.

Coproporphyrin I Can Serve as an Endogenous Biomarker for OATP1B1 Inhibition: Assessment Using a Glecaprevir/Pibrentasvir Clinical Study

Organic anion transporting polypeptide (OATP) 1B1 and OATP1B3 are involved in the disposition of a variety of commonly prescribed drugs. The evaluation of OATP1B1/1B3 inhibition potential by investigational drugs is of interest during clinical drug development due to various adverse events associated with increased exposures of their substrates. Regulatory guidance documents on the in vitro assessment of OATP1B1/1B3 inhibition potential are conservative with up to a third of predictions resulting in false positives. This work investigated the utility of OATP1B1/1B3 endogenous biomarkers, coproporphyrin (CP)‐I and CP‐III, to assess clinical inhibition of OATP1B1/1B3 and potentially eliminate the need for prospective clinical drug‐drug interaction (DDI) studies. Correlations between CP‐I exposures and various OATP1B1 static DDI predictions were also evaluated. Glecaprevir/pibrentasvir (GLE/PIB) 300/120 mg fixed‐dose combination is known to cause clinical inhibition of OATP1B1/1B3. In a clinical study evaluating the relative bioavailability of various formulations of GLE/PIB regimen, CP‐I peak plasma concentration (C_max) ratio and 0–16‐hour area under the concentration‐time curve (AUC_0–16) ratio relative to baseline increased with increasing GLE exposures, whereas there was a modest correlation between GLE exposure and CP‐III C_max ratio but no correlation with CP‐III AUC_0–16 ratio. This suggests that CP‐I is superior to CP‐III as an endogenous biomarker for evaluation of OATP1B1 inhibition. There was a significant correlation between CP‐I and GLE C_max (R² = 0.65; P < 0.001) across individual subjects. Correlation analysis between GLE OATP1B1 R values and CP‐I exposures (C_max ratio and AUC_0–16 ratio) suggests that an R value of > 3 can predict a biologically meaningful inhibition of OATP1B1 when the inhibitor clinical pharmacokinetic parameters are available.

Improved Prediction of the Drug-Drug Interactions of Pemafibrate Caused by Cyclosporine A and Rifampicin via PBPK Modeling: Consideration of the Albumin-Mediated Hepatic Uptake of Pemafibrate and Inhibition Constants With Preincubation Against OATP1B

Pemafibrate (PMF) is highly albumin-bound (>99.8%) and a substrate for hepatic uptake transporters (OATP1B) and CYP enzymes. Here, we developed a PBPK model of PMF to capture drug-drug interactions (DDI) incurred by cyclosporine (CsA) and rifampicin (RIF), the two OATP1B inhibitors. Initial PBPK modeling of PMF utilized in vitro hepatic uptake clearance (PS_inf) obtained in the absence of albumin, but failed in capturing the blood PMF pharmacokinetic (PK) profiles. Based on the results that in vitro PS_inf of unbound PMF was enhanced in the presence of albumin, we applied the albumin-facilitated dissociation model and the resulting PS_inf parameters improved the prediction of the blood PMF PK profiles. In refining our PBPK model toward improved prediction of the observed DDI data (PMF co-administered with single dosing of CsA or RIF; PMF following multiple RIF dosing), we adjusted the previously obtained in vivo OATP1B inhibition constants (K_i,OATP1B) of CsA or RIF for pitavastatin by correcting for substrate-dependency. We also incorporated the induction of OATP1B and CYP enzymes after multiple RIF dosing. Sensitivity analysis informed that the higher gastrointestinal absorption rate constant could further improve capturing the observed DDI data, suggesting the possible inhibition of intestinal ABC transporter(s) by CsA or RIF.

The Necessity of Using Changes in Absorption Time to Implicate Intestinal Transporter Involvement in Oral Drug-Drug Interactions

INTRODUCTION

In drug discovery and development, it is of high interest to characterize the potential for intestinal drug-drug interactions to alter bioavailability of a victim drug. For drugs that are substrates of both intestinal transporters and enzymes, estimating the relative contribution of each process has proved challenging, especially since the susceptibility of drug to uptake or efflux transporters in vitro does not always translate to clinically significant in vivo involvement. Here we introduce a powerful methodology to implicate intestinal transporters in drug-drug interactions based on the theory that clinically relevant intestinal transporter interactions will result in altered rate of absorption of victim drugs.

METHODS AND MATERIALS

We present exemplary clinical drug-drug interaction studies that utilize well-characterized clinical substrates and perpetrators to demonstrate how mean absorption time (MAT) and time to maximum concentration (t_max) are expected to change (or remain unchanged) when either intestinal transporters or metabolic enzymes were/are altered. Apixaban was also selected to demonstrate the utility of the methodology, as the purported involvement of both intestinal enzymes and transporters has been suggested in its FDA package insert.

RESULTS AND DISCUSSION

Acute inhibition of gut efflux transporters resulted in decreased MAT and t_maxvalues, induction increased these values, while inhibition of intestinal metabolic enzymes did not result in altered MAT or t_max. Involvement of intestinal efflux transporters in apixaban disposition is unlikely.

CONCLUSION

Utilization of this simple but powerful methodology to implicate intestinal transporter involvement will have significant impact on how drug-drug interactions are interpreted.

Diltiazem on tacrolimus exposure and dose sparing in Chinese pediatric primary nephrotic syndrome: impact of CYP3A4, CYP3A5, ABCB1, and SLCO1B3 polymorphisms

PURPOSE

To evaluate the role of diltiazem on tacrolimus sparing in pediatric primary nephrotic syndrome (PNS) and its relation to CYP3A4, CYP3A5, ABCB1, and SLCO1B3 polymorphisms.

METHODS

The PNS children treated with tacrolimus and with steady-state trough concentration (C₀) were retrospectively collected. The impacts of diltiazem on tacrolimus dose-adjusted C₀ (C₀/D), target concentration achievement, and required dose were evaluated. Meanwhile, the relationship between the polymorphisms (including CYP3A4*1G, CYP3A5*3, ABCB1-C3435T, and SCLO1B3) and dose-sparing effect were investigated.

RESULTS

A total of 71 children with 535 concentrations, including 16 children with concomitant diltiazem, were involved. Significantly increased C₀/D (94.0 vs 83.8 ng/mL per mg/kg, p = 0.038) and lower required daily dose of tacrolimus (0.056 vs 0.064 mg/kg, p = 0.003) were observed in patients co-administered with diltiazem. Subpopulation carrying CYP3A4*1G, CYP3A5*1, ABCB1-3435TT, or SLCO1B3-699AA was presented with enhanced increment in tacrolimus C₀/D by 38.8-102.9%.

CONCLUSION

Moderate effect of diltiazem on tacrolimus sparing, which might relate to the polymorphisms of CYP3A4, CYP3A5, ABCB1, and SLCO1B3, was documented.

Interpretation of Drug Interaction Using Systemic and Local Tissue Exposure Changes

Systemic exposure of a drug is generally associated with its pharmacodynamic (PD) effect (e.g., efficacy and toxicity). In this regard, the change in area under the plasma concentration-time curve (AUC) of a drug, representing its systemic exposure, has been mainly considered in evaluation of drug-drug interactions (DDIs). Besides the systemic exposure, the drug concentration in the tissues has emerged as a factor to alter the PD effects. In this review, the status of systemic exposure, and/or tissue exposure changes in DDIs, were discussed based on the recent reports dealing with transporters and/or metabolic enzymes mediating DDIs. Particularly, the tissue concentration in the intestine, liver and kidney were referred to as important factors of PK-based DDIs.

Recent progress in in vivo phenotyping technologies for better prediction of transporter-mediated drug-drug interactions

Clinical reports on transporter-mediated drug-drug interactions (TP-DDIs) have rapidly accumulated and regulatory guidance/guidelines recommend that sponsors consider performing quantitative prediction of TP-DDI risks in the process of drug development. In vitro experiments for characterizing the function of drug transporters have been established and various parameters such as the inhibition constant (K_i) of drugs and the intrinsic uptake/efflux clearance for a certain transporter can be obtained. However, many reports have indicated large discrepancies between the parameters estimated from in vitro experiments and those rationally explaining drug pharmacokinetics. Thus, it is essential to evaluate directly the function of each transporter isoform in vivo in humans. At present, several transporter substrate drugs and endogenous compounds have been recognized as probe substrates for a specific transporter and transporter function was evaluated by monitoring the plasma and urine concentration of those probes; however, few compounds specifically transported via a single transporter isoform have been found. For monitoring the intraorgan concentration of drugs, positron emission tomography can be a powerful tool and clinical examples for quantification of in vivo transporter function have been published. In this review, novel methodologies for in vivo phenotyping of transporter function are summarized.

Development of a new Japanese guideline on drug interaction for drug development and appropriate provision of information

Drug interactions, in particular with concomitant drugs having a narrow therapeutic range, sometimes cause serious adverse drug reactions or attenuation of the therapeutic effect. Therefore, evaluation of the characteristics and severities of possible drug interactions in drug development is essential to understand such interactions to help prevent any potential risk for patients. In Japan, a regulatory document which was notified in 2001 to outline the basic principles of drug interaction studies during drug development was revised as a new guideline after 17 years to present general procedures that are currently considered scientifically valid. This article aims to present an overview of development process of the new Japanese guideline for investigating drug interactions and show the impact of implementating this guideline on drug interaction evaluations, thereby providing future perspectives of regulatory activities on drug interactions.

Onco-cardiology: Drug-drug interactions of antineoplastic and cardiovascular drugs

Cardiovascular diseases (CVD) and cancer are still the leading causes of death. There are many common etiologic factors, especially smoking and obesity. Therefore, it is not uncommon for CVD and cancer to coexist. Drug-drug interactions (DDIs) inevitably occur in this group of patients, where polypharmacy is increasing due to older age and multiple comorbidities. However, multidisciplinary studies, especially close collaboration of medical oncologists and cardiologists, who deals with the diagnosis and treatment of these diseases, awareness and preventive approaches to DDIs may reduce serious morbidity and mortality. In this review, information about the common treatments used in cardiology and oncology and possible DDIs are discussed.

Evaluation of transporter-mediated hepatobiliary transport of newly developed 18F-labeled pitavastatin derivative, PTV-F1, in rats by PET imaging

Quantitative evaluations of the functions of uptake and efflux transporters directly in vivo is desired to understand an efficient hepatobiliary transport of substrate drugs. Pitavastatin is a substrate of organic anion transporting polypeptides (OATPs) and canalicular efflux transporters; thus, it can be a suitable probe for positron-emission tomography (PET) imaging of hepatic transporter functions. To characterize the performance of [¹⁸F]PTV-F1, an analogue of pitavastatin, we investigated the impact of rifampicin (a typical OATP inhibitor) coadministration or Bcrp (breast cancer resistance protein) knockout on [¹⁸F]PTV-F1 hepatic uptake and efflux in rats by PET imaging. After intravenous administration, [¹⁸F]PTV-F1 selectively accumulated in the liver, and the radioactivity detected in plasma, liver, and bile mainly derived from the parent PTV-F1 during the PET study (∼40 min). Coadministration of rifampicin largely decreased the hepatic uptake of [¹⁸F]PTV-F1 by 73%. Because of its lower clearance in rats, [¹⁸F]PTV-F1 is more sensitive for monitoring changes in hepatic OATP1B function that other previously reported OATP1B PET probes. Rifampicin coadministration also significantly decreased the biliary excretion of radioactivity by 65%. Bcrp knockout did not show a significant impact on its biliary excretion.[¹⁸F]PTV-F1 enables quantitative analysis of the hepatobiliary transport system for organic anions.

The mechanisms of pharmacokinetic food-drug interactions - A perspective from the UNGAP group

The simultaneous intake of food and drugs can have a strong impact on drug release, absorption, distribution, metabolism and/or elimination and consequently, on the efficacy and safety of pharmacotherapy. As such, food-drug interactions are one of the main challenges in oral drug administration. Whereas pharmacokinetic (PK) food-drug interactions can have a variety of causes, pharmacodynamic (PD) food-drug interactions occur due to specific pharmacological interactions between a drug and particular drinks or food. In recent years, extensive efforts were made to elucidate the mechanisms that drive pharmacokinetic food-drug interactions. Their occurrence depends mainly on the properties of the drug substance, the formulation and a multitude of physiological factors. Every intake of food or drink changes the physiological conditions in the human gastrointestinal tract. Therefore, a precise understanding of how different foods and drinks affect the processes of drug absorption, distribution, metabolism and/or elimination as well as formulation performance is important in order to be able to predict and avoid such interactions. Furthermore, it must be considered that beverages such as milk, grapefruit juice and alcohol can also lead to specific food-drug interactions. In this regard, the growing use of food supplements and functional food requires urgent attention in oral pharmacotherapy. Recently, a new consortium in Understanding Gastrointestinal Absorption-related Processes (UNGAP) was established through COST, a funding organisation of the European Union supporting translational research across Europe. In this review of the UNGAP Working group "Food-Drug Interface", the different mechanisms that can lead to pharmacokinetic food-drug interactions are discussed and summarised from different expert perspectives.

Physiologically-Based Pharmacokinetic Modeling Analysis for Quantitative Prediction of Renal Transporter-Mediated Interactions Between Metformin and Cimetidine

Metformin is an important antidiabetic drug and often used as a probe for drug–drug interactions (DDIs) mediated by renal transporters. Despite evidence supporting the inhibition of multidrug and toxin extrusion proteins as the likely DDI mechanism, the previously reported physiologically‐based pharmacokinetic (PBPK) model required the substantial lowering of the inhibition constant values of cimetidine for multidrug and toxin extrusion proteins from those obtained in vitro to capture the clinical DDI data between metformin and cimetidine.¹ We constructed new PBPK models in which the transporter‐mediated uptake of metformin is driven by a constant membrane potential. Our models successfully captured the clinical DDI data using in vitro inhibition constant values and supported the inhibition of multidrug and toxin extrusion proteins by cimetidine as the DDI mechanism upon sensitivity analysis and data fitting. Our refined PBPK models may facilitate prediction approaches for DDI involving metformin using in vitro inhibition constant values.

Biomarkers for In Vivo Assessment of Transporter Function

Drug-drug interactions are a major concern not only during clinical practice, but also in drug development. Due to limitations of in vitro-in vivo predictions of transporter-mediated drug-drug interactions, multiple clinical Phase I drug-drug interaction studies may become necessary for a new molecular entity to assess potential drug interaction liabilities. This is a resource-intensive process and exposes study participants, who frequently are healthy volunteers without benefit from study treatment, to the potential risks of a new drug in development. Therefore, there is currently a major interest in new approaches for better prediction of transporter-mediated drug-drug interactions. In particular, researchers in the field attempt to identify endogenous compounds as biomarkers for transporter function, such as hexadecanedioate, tetradecanedioate, coproporphyrins I and III, or glycochenodeoxycholate sulfate for hepatic uptake via organic anion transporting polypeptide 1B or N¹-methylnicotinamide for multidrug and toxin extrusion protein-mediated renal secretion. We summarize in this review the currently proposed biomarkers and potential limitations of the substances identified to date. Moreover, we suggest criteria based on current experiences, which may be used to assess the suitability of a biomarker for transporter function. Finally, further alternatives and supplemental approaches to classic drug-drug interaction studies are discussed.

Advancing Predictions of Tissue and Intracellular Drug Concentrations Using In Vitro, Imaging and Physiologically Based Pharmacokinetic Modeling Approaches

This white paper examines recent progress, applications, and challenges in predicting unbound and total tissue and intra/subcellular drug concentrations using in vitro and preclinical models, imaging techniques, and physiologically based pharmacokinetic (PBPK) modeling. Published examples, regulatory submissions, and case studies illustrate the application of different types of data in drug development to support modeling and decision making for compounds with transporter-mediated disposition, and likely disconnects between tissue and systemic drug exposure. The goals of this article are to illustrate current best practices and outline practical strategies for selecting appropriate in vitro and in vivo experimental methods to estimate or predict tissue and plasma concentrations, and to use these data in the application of PBPK modeling for human pharmacokinetic (PK), efficacy, and safety assessment in drug development.

The Extended Clearance Concept Following Oral and Intravenous Dosing: Theory and Critical Analyses

PURPOSE

To derive the theoretical basis for the extended clearance model of organ elimination following both oral and IV dosing, and critically analyze the approaches previously taken.

METHODS

We derived from first principles the theoretical basis for the extended clearance concept of organ elimination following both oral and IV dosing and critically analyzed previous approaches.

RESULTS

We point out a number of critical characteristics that have either been misinterpreted or not clearly presented in previously published treatments. First, the extended clearance concept is derived based on the well-stirred model. It is not appropriate to use alternative models of hepatic clearance. In analyzing equations, clearance terms are all intrinsic clearances, not total drug clearances. Flow and protein binding parameters should reflect blood measurements, not plasma values. In calculating the AUCR-factor following oral dosing, the AUC terms do not include flow parameters. We propose that calculations of AUCR may be a more useful approach to evaluate drug-drug and pharmacogenomic interactions than evaluating rate-determining steps. Through analyses of cerivastatin and fluvastatin interactions with cyclosporine we emphasize the need to characterize volume of distribution changes resulting from transporter inhibition/induction that can affect rate constants in PBPK models. Finally, we note that for oral doses, prediction of systemic and intrahepatic drug-drug interactions do not require knowledge of fu,H or Kp,uu for substrates/victims.

CONCLUSIONS

The extended clearance concept is a powerful tool to evaluate drug-drug interactions, pharmacogenomic and disease state variance but evaluating the AUCR-factor may provide a more valuable approach than characterizing rate-determining steps.

LC-MS/MS bioanalysis of plasma 1, 14-tetradecanedioic acid and 1, 16-hexadecanedioic acid as candidate biomarkers for organic anion-transporting polypeptide mediated drug-drug interactions

AIM

A robust LC-MS/MS assay was developed to quantify endogenous 1, 14-tetradecanedioic acid (TDA) and 1, 16-hexadecanedioic acid (HDA) in human plasma as potential biomarkers for evaluating drug-drug interactions mediated by the hepatic drug transporters, organic anion-transporting polypeptides.

RESULTS

This assay was validated using fit-for-purpose approach over standard curve range of 2.5-1000 nM for TDA and HDA using analyte-free charcoal-stripped human plasma as the surrogate matrix. Chromatographic separation condition was successfully optimized to separate TDA from an interference peak while maintaining both analytes in neutral forms to minimize carryover issue.

CONCLUSION

The described assay is currently applied to a clinical study for evaluating TDA/HDA as potential substitute biomarkers for drug-drug interaction studies.

In Vitro Stimulation of Multidrug Resistance-Associated Protein 2 Function Is Not Reproduced In Vivo in Rats

Previously we reported that coproporphyrin-I (CP-I) is an optimal probe substrate for multidrug resistance-associated protein 2 (MRP2), and stimulation of MRP2-mediated transport is probe substrate-dependent. In the present investigation, we assessed if the in vitro stimulation is physiologically relevant. Similar to human MRP2 transport, CP-I was transported by rat Mrp2 in a typical Michaelis-Menten kinetics with apparent K_m and V_max values of 15 ± 6 µM and 161 ± 20 pmol/min/mg protein, respectively. In vivo Mrp2 functions were monitored by biliary and renal secretion of CP-I and its isomer CP-III, in bile-duct cannulated rats before and after treatment with mitoxantrone, progesterone, and verapamil. These compounds stimulated Mrp2-mediated CP-I transport in vitro. No significant increase in biliary or renal clearances, as well as in the cumulative amount of CP-I or CP-III eliminated in bile, were detected following treatment with the in vitro stimulators, indicating an in vitro to in vivo disconnect. In presence of 10 µM bilirubin, the in vitro stimulation was suppressed. We concluded that the in vitro stimulation of CP-I transport mediated by Mrp2 is not translatable in vivo, and proposed that the presence of endogenous compounds such as bilirubin in the liver may contribute to the in vitro to in vivo disconnect.

Cyclic AMP Signaling Promotes the Differentiation of Human Induced Pluripotent Stem Cells into Intestinal Epithelial Cells

To develop a novel in vitro system for predicting intestinal drug absorption using human induced pluripotent stem (iPS) cell-derived intestinal epithelial cells, the cells need to have sufficient drug-metabolizing enzyme and drug transporter activities. We found that cyclic adenosine monophosphate (cAMP) signaling plays an important role in the differentiation of human iPS cells into intestinal epithelial cells. In this study, we aimed to demonstrate the effects of signaling activation in the intestinal differentiation of human iPS cells and the pharmacokinetic characteristics of human iPS cell-derived intestinal epithelial cells. Human iPS cells were differentiated into intestinal stem cells using activin A and fibroblast growth factor 2. Subsequently, the intestinal stem cells were maturated into intestinal epithelial cells by treatment with 8-bromo-cyclic adenosine monophosphate (8-Br-cAMP) and 3-isobutyl-1-methylxanthine (IBMX), which activate cAMP signaling. The expression levels of intestinal markers and pharmacokinetics-related genes in the differentiated cells were markedly increased by using 8-Br-cAMP and IBMX. In the cells differentiated with the compound we observed cytochrome P450 (CYP) 3A4 inducibility via pregnane X receptor and vitamin D receptor. The metabolic activities of CYP2C9, CYP2C19, CYP2D6, CYP3A4/5, and UDP-glucuronosyltransferase, which are expressed in the human small intestine, were also markedly increased. Furthermore, uptake of glycylsarcosine via peptide transporter 1 was markedly increased. The cells differentiated with the compounds also had drug transporter activities via organic anion transporters and P-glycoprotein. This study is the first to report that the activation of cAMP signaling promotes differentiation of human iPS cell-derived intestinal epithelial cells.

Glycyrrhizin has a high likelihood to be a victim of drug-drug interactions mediated by hepatic organic anion-transporting polypeptide 1B1/1B3

BACKGROUND AND PURPOSE

Intravenous glycyrrhizin, having anti-inflammatory and hepatoprotective properties, is incorporated into the management of liver diseases in China. This investigation was designed to elucidate the molecular mechanism underlying hepatobiliary excretion of glycyrrhizin and to investigate its potential for drug-drug interactions on organic anion-transporting polypeptide (OATP)1B.

EXPERIMENTAL APPROACH

Human transporters mediating hepatobiliary excretion of glycyrrhizin were characterized at the cellular and vesicular levels and compared with rat hepatic transporters. The role of Oatp1b2 in glycyrrhizin's elimination and pharmacokinetics was evaluated in rats using the inhibitor rifampin. A physiologically based pharmacokinetic (PBPK) model for glycyrrhizin, incorporating transporter-mediated hepatobiliary excretion, was established and applied to predict potential drug-drug interactions related to glycyrrhizin in humans.

KEY RESULTS

Hepatobiliary excretion of glycyrrhizin involved human OATP1B1/1B3 (Oatp1b2 in rats)-mediated hepatic uptake from blood and human multidrug resistance-associated protein (MRP)2/breast cancer resistance protein (ABCP)/bile salt export pump (BSEP)/multidrug resistance protein 1 (Mrp2/Abcp/Bsep in rats)-mediated hepatic efflux into bile. In rats, rifampin impaired hepatic uptake of glycyrrhizin significantly increasing its systemic exposure. Glomerular-filtration-based renal excretion of glycyrrhizin was slow due to extensive protein binding in plasma. Quantitative analysis using the PBPK model demonstrated that OATP1B1/1B3 have critical roles in the pharmacokinetics of glycyrrhizin, which is highly likely to be a victim of drug-drug interactions when co-administered with potent dual inhibitors of these transporters.

CONCLUSIONS AND IMPLICATIONS

Transporter-mediated hepatobiliary excretion governs glycyrrhizin's elimination and pharmacokinetics. Understanding glycyrrhizin's potential drug-drug interactions on OATP1B1/1B3 should enhance the therapeutic outcome of glycyrrhizin-containing drug combinations on liver diseases.

Efficient Generation of Cynomolgus Monkey Induced Pluripotent Stem Cell-Derived Intestinal Organoids with Pharmacokinetic Functions

In preclinical studies, the cynomolgus monkey (CM) model is frequently used to predict the pharmacokinetics of drugs in the human small intestine, because of its evolutionary closeness to humans. Intestinal organoids that mimic the intestinal tissue have attracted attention in regenerative medicine and drug development. In this study, we generated intestinal organoids from CM induced pluripotent stem (CMiPS) cells and analyzed their pharmacokinetic functions. CMiPS cells were induced into the hindgut; then, the cells were seeded on microfabricated culture vessel plates to form spheroids. The resulting floating spheroids were differentiated into intestinal organoids in a medium containing small-molecule compounds. The mRNA expression of intestinal markers and pharmacokinetic-related genes was markedly increased in the presence of small-molecule compounds. The organoids possessed a polarized epithelium and contained various cells constituting small intestinal tissues. The intestinal organoids formed functional tight junctions and expressed drug transporter proteins. In addition, in the organoids generated, cytochrome P450 3A8 (CYP3A8) activity was inhibited by the specific inhibitor ketoconazole and was induced by rifampicin. Therefore, in the present work, we successfully generated intestinal organoids, with pharmacokinetic functions, from CMiPS cells using small-molecule compounds.

Comparative Study of the Dose-Dependence of OATP1B Inhibition by Rifampicin Using Probe Drugs and Endogenous Substrates in Healthy Volunteers

PURPOSE

To evaluate association of the dose-dependent effect of rifampicin, an OATP1B inhibitor, on the plasma concentration-time profiles among OATP1B substrates drugs and endogenous substrates.

METHODS

Eight healthy volunteers received atorvastatin (1 mg), pitavastatin (0.2 mg), rosuvastatin (0.5 mg), and fluvastatin (2 mg) alone or with rifampicin (300 or 600 mg) in a crossover fashion. The plasma concentrations of these OATP1B probe drugs, total and direct bilirubin, glycochenodeoxycholate-3-sulfate (GCDCA-S), and coproporphyrin I, were determined.

RESULTS

The most striking effect of 600 mg rifampicin was on atorvastatin (6.0-times increase) and GCDCA-S (10-times increase). The AUC_0-24h of atorvastatin was reasonably correlated with that of pitavastatin (r² = 0.73) and with the AUC_0-4h of fluvastatin (r² = 0.62) and sufficiently with the AUC_0-24h of rosuvastatin (r² = 0.32). The AUC_0-24h of GCDCA-S was reasonably correlated with those of direct bilirubin (r² = 0.74) and coproporphyrin I (r² = 0.78), and sufficiently with that of total bilirubin (r² = 0.30). The AUC_0-24h of GCDCA-S, direct bilirubin, and coproporphyrin I were reasonably correlated with that of atorvastatin (r² = 0.48-0.70) [corrected].

CONCLUSION

These results suggest that direct bilirubin, GCDCA-S, and coproporphyrin I are promising surrogate probes for the quantitative assessment of potential OATP1B-mediated DDI.

A Clinical Quantitative Evaluation of Hepatobiliary Transport of [11C]Dehydropravastatin in Humans Using Positron Emission Tomography

Various positron emission tomography (PET) probes have been developed to assess in vivo activities in humans of drug transporters, which aid in the prediction of pharmacokinetic properties of drugs and the impact of drug-drug interactions. We developed a new PET probe, sodium (3R, 5R)-3, 5-dihydroxy-7-((1S, 2S, 6S, 8S)-6-hydroxy-2-methyl-8- ((1-[¹¹C]-(E)-2-methyl-but-2-enoyl) oxy) -1, 2, 6, 7, 8, 8a-hexahydronaphthalen-1-yl) heptanoate ([¹¹C]DPV), and demonstrated its usefulness for the quantitative investigation of Oatps (gene symbol SLCO) and Mrp2 (gene symbol ABCC2) in rats. To further analyze the species differences and verify the pharmacokinetic parameters in humans, serial PET scanning of the abdominal region with [¹¹C]DPV was performed in six healthy volunteers with and without an OATP1Bs and MRP2 inhibitor, rifampicin (600 mg, oral), in a crossover fashion. After intravenous injection, [¹¹C]DPV rapidly distributed to the liver and kidney followed by secretion into the bile and urine. Rifampicin significantly reduced the liver distribution of [¹¹C]DPV 3-fold, resulting in a 7.5-fold reduced amount of excretion into the bile and the delayed elimination of [¹¹C]DPV from the blood circulation. The hepatic uptake clearance (CL_{uptake, liver}) and canalicular efflux clearance (CL_{int, bile}) of [¹¹C]DPV (544 ± 204 and 10.2 ± 3.5 µl/min per gram liver, respectively) in humans were lower than the previously reported corresponding parameters in rats (1800 and 298 µl/min per gram liver, respectively) (Shingaki et al., 2013). Furthermore, rifampicin treatment significantly reduced CL_{uptake, liver} and CL_{int, bile} by 58% and 44%, respectively. These results suggest that PET imaging with [¹¹C]DPV is an effective tool for quantitatively characterizing the OATP1Bs and MRP2 functions in the human hepatobiliary transport system.

Importance of Hepatic Transporters in Clinical Disposition of Drugs and Their Metabolites

This review provides a practical clinical perspective on the relevance of hepatic transporters in pharmacokinetics and drug-drug interactions (DDIs). Special emphasis is placed on transporters with clear relevance to clinical DDIs, efficacy, and safety. Basolateral OATP1B1 and 1B3 emerged as important hepatic drug uptake pathways, sites for systemic DDIs, and sources of pharmacogenetic variability. As the first step in hepatic drug removal from the circulation, OATPs are an important determinant of systemic pharmacokinetics, specifically influencing systemic absorption, clearance, and hepatic distribution for subsequent metabolism and/or excretion. Biliary excretion of parent drugs is a less prevalent clearance pathway than metabolism or urinary excretion, but BCRP and MRP2 are critically important to biliary/fecal elimination of drug metabolites. Inhibition of biliary excretion is typically not apparent at the level of systemic pharmacokinetics but can markedly increase liver exposure. Basolateral efflux transporters MRP3 and MRP4 mediate excretion of parent drugs and, more commonly, polar metabolites from hepatocytes into blood. Basolateral excretion is an area in need of further clinical investigation, which will necessitate studies more complex than just systemic pharmacokinetics. Clinical relevance of hepatic uptake is relatively well appreciated, and clinical consequences of hepatic excretion (biliary and basolateral) modulation remain an active research area.

Use of PET Imaging to Evaluate Transporter-Mediated Drug-Drug Interactions

Several membrane transporters belonging to the adenosine triphosphate-binding cassette (ABC) and solute carrier (SLC) families can transport drugs and drug metabolites and thereby exert an effect on drug absorption, distribution, and excretion, which may potentially lead to transporter-mediated drug-drug interactions (DDIs). Some transporter-mediated DDIs may lead to changes in organ distribution of drugs (eg, brain, liver, kidneys) without affecting plasma concentrations. Positron emission tomography (PET) is a noninvasive imaging method that allows studying of the distribution of radiolabeled drugs to different organs and tissues and is therefore the method of choice to quantitatively assess transporter-mediated DDIs on a tissue level. There are 2 approaches to how PET can be used in transporter-mediated DDI studies. When the drug of interest is a potential perpetrator of DDIs, it may be administered in unlabeled form to assess its influence on tissue distribution of a generic transporter-specific PET tracer (probe substrate). When the drug of interest is a potential victim of DDIs, it may be radiolabeled with carbon-11 or fluorine-18 and used in combination with a prototypical transporter inhibitor (eg, rifampicin). PET has already been used both in preclinical species and in humans to assess the effects of transporter-mediated DDIs on drug disposition in different organ systems, such as brain, liver, and kidneys, for which examples are given in the present review article. Given the growing importance of membrane transporters with respect to drug safety and efficacy, PET is expected to play an increasingly important role in future drug development.

Investigation of Glycochenodeoxycholate Sulfate and Chenodeoxycholate Glucuronide as Surrogate Endogenous Probes for Drug Interaction Studies of OATP1B1 and OATP1B3 in Healthy Japanese Volunteers

PURPOSE

To assess the use of glycochenodeoxycholate-3-sulfate (GCDCA-S) and chenodeoxycholate 3- or 24-glucuronide (CDCA-3G or -24G) as surrogate endogenous substrates in the investigation of drug interactions involving OATP1B1 and OATP1B3.

METHODS

Uptake of GCDCA-S and CDCA-24G was examined in HEK293 cells transfected with cDNA for OATP1B1, OATP1B3, and NTCP and in cryopreserved human hepatocytes. Plasma concentrations of bile acids and their metabolites (GCDCA-S, CDCA-3G, and CDCA-24G) were determined by LC-MS/MS in eight healthy volunteers with or without administration of rifampicin (600 mg, po).

RESULTS

GCDCA-S and CDCA-24G were substrates for OATP1B1, OATP1B3, and NTCP. The uptake of [³H]atorvastatin, GCDCA-S, and CDCA-24G by human hepatocytes was significantly inhibited by both rifampicin and pioglitazone, whereas that of taurocholate was inhibited only by pioglitazone. Rifampicin elevated plasma concentrations of GCDCA-S more than those of other bile acids. The area under the plasma concentration-time curve for GCDCA-S was 20.3 times higher in rifampicin-treated samples. CDCA-24G could be detected only in plasma from the rifampicin-treatment phase, and CDCA-3G was undetectable in both phases.

CONCLUSIONS

We identified GCDCA-S and CDCA-24G as substrates of NTCP, OATP1B1, and OATP1B3. GCDCA-S is a surrogate endogenous probe for the assessment of drug interactions involving hepatic OATP1B1 and OATP1B3.

Evaluation of New Chemical Entities as Substrates of Liver Transporters in the Pharmaceutical Industry: Response to Regulatory Requirements and Future Steps

This article discusses the evaluation of drug candidates as hepatic transporter substrates. Recently, research on the applications of hepatic transporters in the pharmaceutical industry has improved to meet the requirements of the regulatory guidelines for the evaluation of drug interactions. To identify the risk of transporter-mediated drug-drug interactions at an early stage of drug development, we used a strategy of reviewing the in vivo animal pharmacokinetics and tissue distribution data obtained in the discovery stage together with the in vitro data obtained for regulatory submission. In the context of nonclinical evaluation of new chemical entities as medicines, we believe that transporter studies are emerging as a key strategy to predict their pharmacological and toxicological effects. In combination with the recent progress in systems approaches, the estimation of effective concentrations in the target tissues, by using mathematical models to describe the transporter-mediated distribution and elimination, has enabled us to identify promising compounds for clinical development at the discovery stage.

Human transporters, PEPT1/2, facilitate melatonin transportation into mitochondria of cancer cells: An implication of the therapeutic potential

Melatonin is present in virtually all organisms from bacteria to mammals, and it exhibits a broad spectrum of biological functions, including synchronization of circadian rhythms and oncostatic activity. Several functions of melatonin are mediated by its membrane receptors, but others are receptor-independent. For the latter, melatonin is required to penetrate membrane and enters intracellular compartments. However, the mechanism by which melatonin enters cells remains debatable. In this study, it was identified that melatonin and its sulfation metabolites were the substrates of oligopeptide transporter (PEPT) 1/2 and organic anion transporter (OAT) 3, respectively. The docking analysis showed that the binding of melatonin to PEPT1/2 was attributed to their low binding energy and suitable binding conformation in which melatonin was embedded in the active site of PEPT1/2 and fitted well with the cavity in three-dimensional space. PEPT1/2 transporters play a pivotal role in melatonin uptake in cells. Melatonin's membrane transportation via PEPT1/2 renders its oncostatic effect in malignant cells. For the first time, PEPT1/2 were identified to localize in the mitochondrial membrane of human cancer cell lines of PC3 and U118. PEPT1/2 facilitated the transportation of melatonin into mitochondria. Melatonin accumulation in mitochondria induced apoptosis of PC3 and U118 cells. Thus, PEPT1/2 can potentially be used as a cancer cell-targeted melatonin delivery system to improve the therapeutic effects of melatonin in cancer treatment.

Cellular Models and In Vitro Assays for the Screening of modulators of P-gp, MRP1 and BCRP

Adenosine triphosphate (ATP)-binding cassette (ABC) transporters are highly expressed in tumor cells, as well as in organs involved in absorption and secretion processes, mediating the ATP-dependent efflux of compounds, both endogenous substances and xenobiotics, including drugs. Their expression and activity levels are modulated by the presence of inhibitors, inducers and/or activators. In vitro, ex vivo and in vivo studies with both known and newly synthesized P-glycoprotein (P-gp) inducers and/or activators have shown the usefulness of these transport mechanisms in reducing the systemic exposure and specific tissue access of potentially harmful compounds. This article focuses on the main ABC transporters involved in multidrug resistance [P-gp, multidrug resistance-associated protein 1 (MRP1) and breast cancer resistance protein (BCRP)] expressed in tissues of toxicological relevance, such as the blood-brain barrier, cardiovascular system, liver, kidney and intestine. Moreover, it provides a review of the available cellular models, in vitro and ex vivo assays for the screening and selection of safe and specific inducers and activators of these membrane transporters. The available cellular models and in vitro assays have been proposed as high throughput and low-cost alternatives to excessive animal testing, allowing the evaluation of a large number of compounds.

Polyphenols Beyond Barriers: A Glimpse into the Brain

BACKGROUND

Ageing can be simply defined as the process of becoming older, which is genetically determined but also environmentally modulated. With the continuous increase of life expectancy, quality of life during ageing has become one of the biggest challenges of developed countries. The quest for a healthy ageing has led to the extensive study of plant polyphenols with the aim to prevent age-associated deterioration and diseases, including neurodegenerative diseases. The world of polyphenols has fascinated researchers over the past decades, and in vitro, cell-based, animal and human studies have attempted to unravel the mechanisms behind dietary polyphenols neuroprotection.

METHODS

In this review, we compiled some of the extensive and ever-growing research in the field, highlighting some of the most recent trends in the area.

RESULTS

The main findings regarding polypolyphenols neuroprotective potential performed using in vitro, cellular and animal studies, as well as human trials are covered in this review. Concepts like bioavailability, polyphenols biotransformation, transport of dietary polyphenols across barriers, including the blood-brain barrier, are here explored.

CONCLUSION

The diversity and holistic properties of polypolyphenol present them as an attractive alternative for the treatment of multifactorial diseases, where a multitude of cellular pathways are disrupted. The underlying mechanisms of polypolyphenols for nutrition or therapeutic applications must be further consolidated, however there is strong evidence of their beneficial impact on brain function during ageing. Nevertheless, only the tip of the iceberg of nutritional and pharmacological potential of dietary polyphenols is hitherto understood and further research needs to be done to fill the gaps in pursuing a healthy ageing.

Unequivocal evidence supporting the segregated flow intestinal model that discriminates intestine versus liver first-pass removal with PBPK modeling

Merits of the segregated flow model (SFM), highlighting the intestine as inert serosa and active enterocyte regions, with a smaller fractional (f_Q < 0.3) intestinal flow (Q_I ) perfusing the enterocyte region, are described. Less drug in the circulation reaches the enterocytes due to the lower flow (f_Q Q_I ) in comparison with drug administered into the gut lumen, fostering the idea of route-dependent intestinal removal. The SFM has been found superior to the traditional model (TM), which views the serosa and enterocytes totally as a well-mixed tissue perfused by 100% of the intestinal flow, Q_I . The SFM model is able to explain the lower extents of intestinal metabolism of enalapril, morphine and midazolam with i.v. vs. p.o. dosing. For morphine, the urine/bile ratio of the metabolite, morphine glucuronide MGurineMGbile for p.o. was 2.6× that of i.v. This was due to the higher proportion of intestinally formed morphine glucuronide, appearing more in urine than in bile due to its low permeability and greater extent of intestinal formation with p.o. administration. By contrast, the TM predicted the same MGurineMGbile for p.o. vs. i.v. The TM predicted that the contributions of the intestine:liver to first-pass removal were 46%:54% for both p.o. and i.v. The SFM predicted same 46%:54% (intestine:liver) for p.o., but 9%:91% for i.v. By contrast, the kinetics of codeine, the precursor of morphine, was described equally well by the SFM- and TM-PBPK models, a trend suggesting that intestinal metabolism of codeine is negligible. Fits to these PBPK models further provide insightful information towards metabolite formation: available fractions and the fractions of hepatic and total clearances that form the metabolite in question. The SFM-PBPK model is useful to identify not only the presence of intestinal metabolism but the contributions of the intestine and liver for metabolite formation. Copyright © 2016 John Wiley & Sons, Ltd.

Quantitative Analyses of Hepatic OATP-Mediated Interactions Between Statins and Inhibitors Using PBPK Modeling With a Parameter Optimization Method

This study aimed to construct a widely applicable method for quantitative analyses of drug-drug interactions (DDIs) caused by the inhibition of hepatic organic anion transporting polypeptides (OATPs) using physiologically based pharmacokinetic (PBPK) modeling. Models were constructed for pitavastatin, fluvastatin, and pravastatin as substrates and cyclosporin A (CsA) and rifampicin (RIF) as inhibitors, where enterohepatic circulations (EHC) of statins were incorporated. By fitting to clinical data, parameters that described absorption, hepatic elimination, and EHC processes were optimized, and the extent of these DDIs was explained satisfactorily. Similar in vivo inhibition constant (K_i ) values of each inhibitor against OATPs were obtained, regardless of the substrates. Estimated K_i values of CsA were comparable to reported in vitro values with the preincubation of CsA, while those of RIF were smaller than reported in vitro values (coincubation). In conclusion, this study proposes a method to optimize in vivo PBPK parameters in hepatic uptake transporter-mediated DDIs.

Intracellular Unbound Atorvastatin Concentrations in the Presence of Metabolism and Transport

Accurate prediction of drug target activity and rational dosing regimen design require knowledge of drug concentrations at the target. It is important to understand the impact of processes such as membrane permeability, partitioning, and active transport on intracellular drug concentrations. The present study aimed to predict intracellular unbound atorvastatin concentrations and characterize the effect of enzyme-transporter interplay on these concentrations. Single-pass liver perfusion studies were conducted in rats using atorvastatin (ATV, 1 µM) alone at 4°C and at 37°C in presence of rifampin (RIF, 20 µM) and 1-aminobenzotriazole (ABT, 1 mM), separately and in combination. The unbound intracellular ATV concentration was predicted with a five-compartment explicit membrane model using the parameterized diffusional influx clearance, active basolateral uptake clearance, and metabolic clearance. Chemical inhibition of uptake and metabolism at 37°C proved to be better controls relative to studies at 4°C. The predicted unbound intracellular concentration at the end of the 50-minute perfusion in the +ABT , +ABT+RIF, and the ATV-only groups was 6.5 µM, 0.58 µM, and 5.14 µM, respectively. The predicted total liver concentrations and amount recovered in bile were within 0.94-1.3 fold of the observed value in all groups. The fold difference in total liver concentration did not always extrapolate to the fold difference in predicted unbound concentration across groups. Together, these results support the use of compartmental modeling to predict intracellular concentrations in dynamic organ-based systems. These predictions can provide insight into the role of uptake transporters and metabolizing enzymes in determining drug tissue concentrations.

Characteristic Analysis of Intestinal Transport in Enterocyte-Like Cells Differentiated from Human Induced Pluripotent Stem Cells

We previously demonstrated that differentiated enterocytes from human induced pluripotent stem (iPS) cells exhibited drug-metabolizing activities and cytochrome P450 CYP3A4 inducibility. The aim of this study was to apply human iPS cell-derived enterocytes in pharmacokinetic studies by investigating the characteristics of drug transport into enterocyte-like cells. Human iPS cells cultured on feeder cells were differentiated into endodermal cells using activin A. These endodermal-like cells were then differentiated into intestinal stem cells by fibroblast growth factor 2. Finally, epidermal growth factor and small-molecule compounds induced the maturation of the intestinal stem cell-like cells. After differentiation, we performed transepithelial electrical resistance (TEER) measurements, immunofluorescence staining, and transport studies. TEER values increased in a time-dependent manner and reached approximately 100 Ω × cm(2) Efflux transport of Hoechst 33342, a substrate of breast cancer resistance protein (BCRP), was observed and inhibited by the BCRP inhibitor Ko143. The uptake of peptide transporter 1 substrate glycylsarcosine was also confirmed and suppressed when the temperature was lowered to 4°C. Using immunofluorescence staining, villin and Na(+)-K(+) ATPase were expressed. These results suggest that human iPS cell-derived enterocytes had loose tight junctions, polarity, as well as uptake and efflux transport functions. In addition, the rank order of apparent membrane permeability coefficient (Papp) values of these test compounds across the enterocyte-like cell membrane corresponded to the fraction absorbance (Fa) values. Therefore, differentiated enterocytes from human iPS cells may provide a useful comprehensive evaluation model of drug transport and metabolism in the small intestine.