Intestinal Drug Transport Research Articles

Curcumin-carboxymethyl chitosan (CNC) conjugate and CNC/LHR mixed polymeric micelles as new approaches to improve the oral absorption of P-gp substrate drugs

The low oral bioavailability of numerous drugs has been mostly attributed to the significant effect of P-gp-mediated efflux on intestinal drug transport. Herein, we developed mixed polymeric micelles (MPMs) comprised of curcumin-carboxymethyl chitosan (CNC) conjugate, as a potential inhibitor of P-gp-mediated efflux and gastrointestinal absorption enhancer, and low-molecular-weight heparin-all-trans-retinoid acid (LHR) conjugate, as loading material, with the aim to improve the oral absorption of P-gp substrate drugs. CNC conjugate was synthesized by chemical bonding of curcumin (Cur) and carboxymethyl chitosan (CMCS) taking advantage of the inhibition of intestinal P-gp-mediated secretion by Cur and the intestinal absorption enhancement by CMCS. The chemical structure of CNC conjugate was characterized by 1H NMR with a degree of substitution of Cur of 4.52–10.20%. More importantly, CNC conjugate markedly improved the stability of Cur in physiological pH. Cyclosporine A-loaded CNC/LHR MPMs (CsA-CNC/LHR MPMs) were prepared by dialysis method, with high drug loading 25.45% and nanoscaled particle size (∼200 nm). In situ single-pass perfusion studies in rats showed that both CsA + CNC mixture and CsA-CNC/LHR MPMs achieved significantly higher Ka and Peff than CsA suspension in the duodenum and jejunum segments (p < 0.01), which was comparable to verapamil coperfusion effect. Similarly, CsA + CNC mixture and CsA-CNC/LHR MPMs significantly increased the oral bioavailability of CsA as compared to CsA suspension. These results suggest that CNC conjugate might be considered as a promising gastrointestinal absorption enhancer, while CNC/LHR MPMs had the potential to improve the oral absorption of P-gp substrate drugs.

The Proteome of Filter-Grown Caco-2 Cells With a Focus on Proteins Involved in Drug Disposition

Caco-2 cells are widely used in studies of intestinal cell physiology and drug transport. Here, the global proteome of filter-grown Caco-2 cells was quantified using the total protein approach and compared with the human colon and jejunum proteomes. In total, 8096 proteins were identified. In-depth analysis of proteins defining enterocyte differentiation—including brush-border hydrolases, integrins, and adherens and tight junctions—gave near-complete coverage of the expected proteins. Three hundred twenty-seven absorption, distribution, metabolism and excretion proteins were identified, including 112 solute carriers and 20 ATP-binding cassette transporters. OATP2B1 levels were 16-fold higher in Caco-2 cells than in jejunum. To investigate the impact of this difference on in vitro-in vivo extrapolations, we studied the uptake kinetics of the OATP2B1 substrate pitavastatin in Caco-2 monolayers, and found that the contribution of OATP2B1 was 60%-70% at clinically relevant intestinal concentrations. Pitavastatin kinetics was combined with transporter concentrations to model the contribution of active transport and membrane permeation in the jejunum. The lower OATP2B1 expression in jejunum led to a considerably lower transporter contribution (<5%), suggesting that transmembrane diffusion dominates pitavastatin absorption in vivo. In conclusion, we present the first in-depth quantification of the filter-grown Caco-2 proteome. We also demonstrate the crucial importance of considering transporter expression levels for correct interpretation of drug transport routes across the human intestine.

Interaction of Drug or Food with Drug Transporters in Intestine and Liver.

Oral bioavailability (F) is determined as fraction of the drug dose absorbed through the gastrointestinal membranes (Fa), the unmetabolized fraction of the absorbed dose that passes through the gut into the portal blood (Fg), and the hepatic first pass availability (Fh), namely F is expressed as the product of Fa, Fg and Fh (F = Fa.Fg.Fh). Current evidence suggests that transporter proteins play a role in intestinal absorption and hepatobiliary clearance of drugs. Among those transporters, this review will focus on PEPT1 and OATP2B1 as influx transporter and p-glycoprotein (P-gp) and BCRP as efflux transporter in intestinal epithelial cells, and on OATP1B1 and 1B3 as influx transporter and MRP2 as efflux transporter in hepatocytes, respectively, because drug-drug (DDI) and -food (DFI) interactions on these transporter are considered to affect bioavailability of their substrate drugs. DDI and DFI may reduce systemic exposure to drug by blocking influx transporters in intestine, but increase it by modulating influx and efflux transporters in liver and efflux transporters in intestines. Namely, drug disposition and efficacy are likely affected by DDI and DFI, resulting in treatment failures or increase in adverse effect. Therefore, it is of significantly importance to understand precise mechanism of DDI and DFI. This review will present information about transporter-based DDI and DFI in the processes of intestinal absorption and hepatic clearance of drugs, and discuss about their clinical implication.

Aristolochic acid I is a substrate of BCRP but not P-glycoprotein or MRP2

Ethnopharmacological relevanceAristolochic acid nephropathy is a severe kidney disease caused by the administration of aristolochic acid, which is widely existed in plants of the Aristolochiaceae family. Aristolochic acid I (AAI) is the main toxic component in aristolochic acid. Aim of the studyThe roles of intestinal efflux drug transporters in the transport of AAI are unclear. This study investigates the interaction between AAI and main intestinal efflux transporters. Materials and MethodsFirstly, bidirectional transport of AAI in Caco-2 cell monolayers was investigated. Then, MDCK-MDR1 (gene of P-glycoprotein (P-gp)), MDCK-MRP2 and LLC-PK1-BCRP cell lines were used for further investigation. ResultsIn this study, we observed that the efflux ratio of AAI in Caco-2 cell monolayers was 5.8, which indicated that efflux transporters might be involved in the transport of AAI. AAI did not inhibit Rho123 efflux by P-gp and calcein efflux by MRP2, and intracellular accumulation of AAI in P-gp or MRP2 overexpressing cells was not different from their parental cells. These results indicated that AAI was not a substrate of P-gp or MRP2. In contrast, intracellular accumulation of AAI in LLC-PK1-BCRP cells was significantly lower than in their parental cells. The presence of GF120918, a BCRP inhibitor, significantly increased AAI accumulation in BCRP overexpressing cells but not in their parental cells. In addition, bidirectional transport assay of AAI in LLC-PK1-BCRP monolayers showed that the net efflux ratios of AAI were 13.8, 8.0 and 7.0 at 20, 40 and 80µM AAI, respectively, and decreased to 3.0, 1.9 and 2.0 by the addition of 10µM GF120918. ConclusionsThese results indicated that AAI was a substrate of BCRP but not P-gp or MRP2.

Intestinal and hepatic drug transporters: pharmacokinetic, pathophysiological, and pharmacogenetic roles.

The efficacy and safety of pharmacotherapies are determined by the complex processes involved in the interactions between drugs with the human body, including pharmacokinetic aspects. Among pharmacokinetic factors, it has been recognized that drug transporters play critical roles for absorption, distribution and excretion of drugs, regulating the membrane transport of drugs. The vast amounts of information on drug transporters collected in the past 20 years have been organized according to biochemical, molecular, genetic, and clinical analyses. Novel technologies, public databases, and regulatory guidelines have advanced the use of such information in drug development and clinical practice. In this review, we selected some clinically important drug transporters expressed in the intestine and liver, and introduced the research history and current knowledge of their pharmacokinetic, pathophysiological, and pharmacogenetic implications.

The Mesenteric Lymph Duct Cannulated Rat Model: Application to the Assessment of Intestinal Lymphatic Drug Transport

The Mesenteric Lymph Duct Cannulated Rat Model: Application to the Assessment of Intestinal Lymphatic Drug Transport

The mesenteric lymph duct cannulated rat model: application to the assessment of intestinal lymphatic drug transport.

The intestinal lymphatic system plays key roles in fluid transport, lipid absorption and immune function. Lymph flows directly from the small intestine via a series of lymphatic vessels and nodes that converge at the superior mesenteric lymph duct. Cannulation of the mesenteric lymph duct thus enables the collection of mesenteric lymph flowing from the intestine. Mesenteric lymph consists of a cellular fraction of immune cells (99% lymphocytes), aqueous fraction (fluid, peptides and proteins such as cytokines and gut hormones) and lipoprotein fraction (lipids, lipophilic molecules and apo-proteins). The mesenteric lymph duct cannulation model can therefore be used to measure the concentration and rate of transport of a range of factors from the intestine via the lymphatic system. Changes to these factors in response to different challenges (e.g., diets, antigens, drugs) and in disease (e.g., inflammatory bowel disease, HIV, diabetes) can also be determined. An area of expanding interest is the role of lymphatic transport in the absorption of orally administered lipophilic drugs and prodrugs that associate with intestinal lipid absorption pathways. Here we describe, in detail, a mesenteric lymph duct cannulated rat model which enables evaluation of the rate and extent of lipid and drug transport via the lymphatic system for several hours following intestinal delivery. The method is easily adaptable to the measurement of other parameters in lymph. We provide detailed descriptions of the difficulties that may be encountered when establishing this complex surgical method, as well as representative data from failed and successful experiments to provide instruction on how to confirm experimental success and interpret the data obtained.

Generation of enterocyte-like cells with pharmacokinetic functions from human induced pluripotent stem cells using small-molecule compounds.

The small intestine plays an important role in all aspects of pharmacokinetics, but there is no system for the comprehensive evaluation of small-intestinal pharmacokinetics, including drug metabolism and absorption. In this study, we aimed to construct an intestinal pharmacokinetics evaluation system and to generate pharmacokinetically functional enterocytes from human induced pluripotent stem cells. Using activin A and fibroblast growth factor 2, we differentiated these stem cells into intestinal stem cell-like cells, and the resulting cells were differentiated into enterocytes in a medium containing epidermal growth factor and small-molecule compounds. The differentiated cells expressed intestinal marker genes and drug transporters. The expression of sucrase-isomaltase, an intestine-specific marker, was markedly increased by small-molecule compounds. The cells exhibited activities of drug-metabolizing enzymes expressed in enterocytes, including CYP1A1/2, CYP2C9, CYP2C19, CYP2D6, CYP3A4/5, UGT, and sulfotransferase. Fluorescence-labeled dipeptide uptake into the cells was observed and was inhibited by ibuprofen, an inhibitor of the intestinal oligopeptide transporter solute carrier 15A1/PEPT1. CYP3A4 mRNA expression level was increased by these compounds and induced by the addition of 1α,25-dihydroxyvitamin D3. CYP3A4/5 activity was also induced by 1α,25-dihydroxyvitamin D3 in cells differentiated in the presence of the compounds. All these results show that we have generated enterocyte-like cells that have pharmacokinetic functions, and we have identified small-molecule compounds that are effective for promoting intestinal differentiation and the gain of pharmacokinetic functions. Our enterocyte-like cells would be useful material for developing a novel evaluation system to predict human intestinal pharmacokinetics.

Exploring the impact of drug properties on the extent of intestinal lymphatic transport - in vitro and in vivo studies.

Intestinal lymphatic transport of specific lipophilic drugs offers therapeutic advantages and maximises oral bioavailability. The aims of this study were; to compare intestinal lymphatic transport of a range of drugs and to investigate the influence of cyclosporine A on the mechanism/extent of lymphatic transport. Caco2 cells and an anaesthetised mesenteric lymphatic cannulated rat model were used for in vitro and in vivo studies. Lymphatic transport of three lipophilic drugs was directly compared in a long chain fatty acid formulation. In addition, the impact of cyclosporine A on triglyceride turnover was evaluated in vivo and in vitro. The extent of intestinal lymphatic transport in rats was positively correlated with drug solubility in triglyceride and negatively correlated with drug aqueous solubility. Cyclosporine A displayed non-linear lymphatic transport kinetics and reduced intestinal lymph triglyceride. In vitro experiments indicated that the cellular processes affected were intracellular lipid processing and/or lipid secretion. The linear correlations obtained using a range of lipophilic drugs confirm that the simplified approach of determining aqueous or triglyceride drug solubility is useful in predicting the extent of lymphatic transport. In vitro experiments correlated with in vivo observations, demonstrating the usefulness of the Caco-2 model for mechanistic investigations.

Ontogeny of human hepatic and intestinal transporter gene expression during childhood: age matters.

Many drugs prescribed to children are drug transporter substrates. Drug transporters are membrane-bound proteins that mediate the cellular uptake or efflux of drugs and are important to drug absorption and elimination. Very limited data are available on the effect of age on transporter expression. Our study assessed age-related gene expression of hepatic and intestinal drug transporters. Multidrug resistance protein 2 (MRP2), organic anion transporting polypeptide 1B1 (OATP1B1), and OATP1B3 expression was determined in postmortem liver samples (fetal n = 6, neonatal n = 19, infant n = 7, child n = 2, adult n = 11) and multidrug resistance 1 (MDR1) expression in 61 pediatric liver samples. Intestinal expression of MDR1, MRP2, and OATP2B1 was determined in surgical small bowel samples (neonates n = 15, infants n = 3, adults n = 14). Using real-time reverse-transcription polymerase chain reaction, we measured fetal and pediatric gene expression relative to 18S rRNA (liver) and villin (intestines), and we compared it with adults using the 2(-∆∆Ct) method. Hepatic expression of MRP2, OATP1B1, and OATP1B3 in all pediatric age groups was significantly lower than in adults. Hepatic MDR1 mRNA expression in fetuses, neonates, and infants was significantly lower than in adults. Neonatal intestinal expressions of MDR1 and MRP2 were comparable to those in adults. Intestinal OATP2B1 expression in neonates was significantly higher than in adults. We provide new data that show organ- and transporter-dependent differences in hepatic and intestinal drug transporter expression in an age-dependent fashion. This suggests that substrate drug absorption mediated by these transporters may be subject to age-related variation in a transporter dependent pattern.

Developmental trajectory of intestinal MDR1/ABCB1 mRNA expression in children

Developmental trajectory of intestinal <scp>MDR1/ABCB1</scp> mRNA expression in children

Interactions entre pamplemousse et médicaments

The interaction between grapefruit and drugs is known since 25 years: 85 molecules are involved for the moment. The mechanisms go through an interaction with the intestinal metabolism by cytochrome P450 and an interaction with some intestinal drug transporters. Outcomes and precautions are given.

Intestinal drug transport: ex vivo evaluation of the interactions between ABC transporters and anthelmintic molecules

The family of ATP-binding cassette (ABC) transporters is composed of several transmembrane proteins that are involved in the efflux of a large number of drugs including ivermectin, a macrocyclic lactone (ML) endectocide, widely used in human and livestock antiparasitic therapy. The aim of the work reported here was to assess the interaction between three different anthelmintic drugs with substrates of the P-glycoprotein (P-gp) and the breast cancer resistance protein (BCRP). The ability of ivermectin (IVM), moxidectin (MOX) and closantel (CST) to modulate the intestinal transport of both rhodamine 123 (Rho 123), a P-gp substrate, and danofloxacin (DFX), a BCRP substrate, across rat ileum was studied by performing the Ussing chamber technique. Compared to the controls, Rho 123 efflux was significantly reduced by IVM (69%), CST (51%) and the positive control PSC833 (65%), whereas no significant differences were observed in the presence of MOX (30%). In addition, DFX efflux was reduced between 59% and 72% by all the assayed drug molecules, showing a higher potency than that observed in the presence of the specific BCRP inhibitor pantoprazole (PTZ) (52%). An ex vivo intestinal transport approach based on the diffusion chambers technique may offer a complementary tool to study potential drug interactions with efflux transporters such as P-gp and BCRP.

Factorial Design Studies and Biopharmaceutical Evaluation of Simvastatin Loaded Solid Lipid Nanoparticles for Improving the Oral Bioavailability

Statins are HMG-CoA reductase inhibitors, which lower the cholesterol level through reversible and competitive inhibition; they are involved in the biosynthesis of cholesterol and other sterols. Simvastatin exhibits poor oral bioavailability (&lt;5%) and undergoes extensive microsomal metabolism by CYP enzymes. CYP3A4 is the major metabolizing enzyme that metabolizes lactone form of simvastatin and significantly lowers intestinal uptake. The hydrophobic properties of simvastatin prevent complete dissolution of the drug in the intestinal fluid which also contributes to its lower bioavailability. SLNs are alternative carrier system to polymeric nanoparticles. SLNs are in submicron size range (1–1000 nm). To overcome the hepatic first pass metabolism and to enhance the bioavailability, intestinal lymphatic transport of drugs can be exploited. In the present study, attempt has been made to prepare solid lipid nanoparticles of simvastatin to improve the bioavailability. SLNs of simvastatin were prepared with Trimyristin by hot homogenization followed by ultrasonication method. The SLNs were characterized for various physicochemical properties and analytical techniques like PXRD, DSC to study thermal nature and morphology of formulation and excipients. Promising results of the study indicated the applicability of simvastatin solid lipid nanoparticles as potential tools for improvement of bioavailability of poorly soluble drugs.

Evaluation Of Drug Interaction Profile Of Idelalisib and Its Major Circulating Metabolite, GS-563117, In Healthy Subjects

AbstractAbstract 5574 BackgroundIdelalisib (IDELA) is a potent PI3K. inhibitor in Phase 3 development for hematologic malignancies. IDELA is metabolized primarily by aldehyde oxidase to form GS-563117 and to a lesser extent by CYP3A and UGT1A4. In vitro, IDELA inhibits Pgp (IC50: 7.7 mM), OATP1B1 (IC50: 10.1 mM), OATP1B3 (IC50: 7.0 mM), but is not an inhibitor of common metabolizing enzymes and other uptake or secretory transporters at clinically relevant concentration. GS563117 shows time-dependent inhibition of CYP3A (IC50: 5.1 mM, KI: 0.18 mM, and kinact: 0.033 min-1), but is not an inhibitor of other common metabolizing enzymes, or of uptake or secretory transporters at clinically relevant concentration. The present study evaluated the potential for IDELA to affect Pgp and OATP1B1/OATP1B3, GS-563117 to affect CYP3A, and effect of a strong inducer, rifampin, on IDELA pharmacokinetics (PK). MethodsProbe substrates of Pgp (digoxin), OATP1B1/1B3 (rosuvastatin), and CYP3A (midazolam) were each given orally as a single dose either alone or in combination with multiple doses of IDELA 150 mg BID. Additionally, a single dose of IDELA 150 mg was administered either alone or in combination with multiple doses of rifampin at 600 mg QD. Plasma exposures of digoxin, rosuvastatin, midazolam and 1'-hydroxy midazolam, rifampin, IDELA, and GS-563117 were determined using LC/MS/MS. Analysis of variance (ANOVA) using a mixed-effects model was fitted to the natural logarithmic transformation of PK parameters. The 90% confidence intervals were constructed for the ratio of geometric means of PK parameters when each of the probe drugs (or IDELA) is dosed in combination with IDELA (or rifampin) versus when dosed alone, with 70-143% defined as the lack of interaction boundaries. Safety assessments were performed throughout the study. ResultsA total of 24 subjects were enrolled in the study and randomized to two cohorts. The majority of subjects were male, white, and median age was 38.The most frequently reported adverse events (AE) were headache (∼25% subjects) and pyrexia (∼17%). Treatment-emergent Grade 3 increase in transaminases occurred in 5/24 subjects, and were reversible. Two subjects experienced serious AE following completion of study treatment. There were no clinically significant changes in vital signs or safety ECGs.Digoxin and rosuvastatin PK were unaffected when given in combination with IDELA 150 mg BID vs dosing alone (Table 1).Coadministration with IDELA resulted in increased plasma exposures of midazolam increased and decreased 1'-OH-midazolam consistent with the in vitro finding of CYP3A inhibition by IDELA's major metabolite, GS-563117.Coadministration of IDELA with rifampin caused a substantial decrease in IDELA and GS-563117 exposures, indicating greater contribution of CYP3A to IDELA metabolism under a strongly induced state. ConclusionGS-563117, which is the major metabolite of IDELA, is a moderate inhibitor of CYP3A; accordingly, caution is necessary when coadministering narrow therapeutic index agents that are CYP3A substrates with IDELA. Coadministration of strong inducers of CYP3A with IDELA should also be avoided to prevent decreased exposure to IDELA. Overall, IDELA and its metabolite do not affect common intestinal, hepatic or renal drug transporters. Disclosures:Jin:Gilead Sciences: Employment, Equity Ownership. Robeson:Gilead Sciences: Employment, Equity Ownership. Zhou:Gilead Sciences: Employment, Equity Ownership. Moyer:Gilead Sciences: Employment, Equity Ownership. Wilbert:Gilead Sciences: Employment, Equity Ownership. Murray:Gilead Sciences: Employment, Equity Ownership. Ramanathan:Gilead Sciences: Employment, Equity Ownership.

Mechanistic Study of the Uptake/Permeation of Cell-Penetrating Peptides Across a Caco-2 Monolayer and Their Stimulatory Effect on Epithelial Insulin Transport

Our recent studies have demonstrated the potential of cell-penetrating peptides (CPPs) to significantly stimulate the intestinal absorption of therapeutic peptides and proteins. This study examined the mechanisms underlying the intestinal epithelial uptake and permeation of CPPs and their contribution to the enhanced absorption of insulin. Fluorescein-tagged octaarginine (R8) and penetratin were used as the promising CPPs, and in vitro uptake and permeation assays were conducted using Caco-2 cell monolayer. The assay conducted under low temperature conditions revealed that energy-dependent pathways are not involved in d-form arginines (d-R8) uptake or its stimulatory effect on insulin uptake. The Km value (3.82 μM), calculated from the dose dependence of d-R8 uptake, suggested that a part of the d-R8 uptake was saturated at the functional concentration (60 μM d-R8). An analysis based on the binding parameters of insulin and d-R8 also showed an increase in the uptake clearance of the insulin/d-R8 complex, even at a saturated concentration of d-R8, implying that this complex is taken up by Caco-2 cells via pathways that differ from those that take up unbound d-R8. Thus, this study suggests that CPPs such as oligoarginines stimulate the intestinal epithelial transport of peptide and protein drugs via energy-independent unsaturable internalization.

Mass Spectrometry-Based Targeted Proteomics as a Tool to Elucidate the Expression and Function of Intestinal Drug Transporters

Intestinal transporter proteins affect the oral bioavailability of many drugs in a significant manner. In order to estimate or predict their impact on oral drug absorption, data on their intestinal expression levels are needed. So far, predominantly mRNA expression data are available which are not necessarily correlated with the respective protein content. All available protein data were assessed by immunoblotting techniques such as Western blotting which both possess a number of limitations for reliable protein quantification. In contrast to this, mass spectrometry-based targeted proteomics may represent a promising alternative method to provide comprehensive protein expression data. In this review, we will summarize so far available intestinal mRNA and protein expression data for relevant human multidrug transporters. Moreover, recently observed mass spectrometry-based targeted proteomic data will be presented and discussed with respect to potential functional consequences. Associated to this, we will provide a short tutorial how to set up these methods and emphasize critical aspects in method development. Finally, potential limitations and pitfalls of this emerging technique will be discussed. From our perspective, LC-MS/MS-based targeted proteomics represents a valuable new method to comprehensively analyse the intestinal expression of transporter proteins. The resulting expression data are expected to improve our understanding about the intestinal processing of drugs.

Disease, Drug Metabolism, and Transporter Interactions

Drug metabolism is a highly complex process involving the cooperative function of drug transporter proteins and drug-conjugating and -metabolizing enzymes, as well as targeted programs of gene activation and the proteasomal degradation pathway. The transport and metabolism of drugs in intestine and liver mediates the systemic delivery of therapeutic compounds, protects the body from drug toxicity, and initiates droves of signaling cascades that collectively work to maintain the body’s homeostatic conditions. The multifaceted nature of drug homeostasis requires a high level of regulation on multiple levels, and thus a disturbance in homeostatic conditions can have major detrimental effects on patient health. There are several disease states (inflammation/diabetes/morbid obesity/cancer) that can profoundly alter key drug transport and/or drug metabolic pathways in liver and intestine. However, the specific molecular mechanisms responsible for producing aberrant drug handling by the body are only beginning to be fully understood. This special theme issue of Pharmaceutical Research entitled “Disease, Drug Metabolism and Transporter Interactions” focuses on the molecular impact that specific pathological states have upon the transport and metabolism of drugs in the body, with particular emphasis on disease states that affect the entero-hepatic system. Experts from multiple fields have presented the most recent advances pertaining to the effect of disease states on signaling cascades, drug transporter function and expression, gene transcription, and cellular stress with the intent of presenting novel therapeutic targets to aid in the treatment, prevention and diagnosis of potentially fatal diseases.

Abstract 883: Imatinib-induced modulation of gastrointestinal and hepatic membrane transporters in mice.

Abstract Drug-induced changes in the expression or activity of ADME genes may critically affect the pharmacokinetics (PK) and the efficacy of chemotherapy as well as the incidence and severity of unwanted side effects. Drug uptake and efflux transporters are likely to be involved in the intestinal absorption, distribution and hepatic excretion of imatinib, an oral tyrosine kinase inhibitor approved for the treatment of CML and GIST. Previously, we demonstrated that imatinib is a substrate drug of both ABCB1 and ABCG2. Furthermore, we showed that prolonged imatinib exposure in Caco-2 cell cultures leads to increased expression of these drug efflux transporters. Evidently, some GIST patients chronically treated with imatinib show a time-dependent decrease in imatinib plasma levels. Altered transporter activity in the intestine and/or liver affecting the PK of imatinib may (partially) account for the observed PK resistance. We hypothesized that acquired PK resistance by decreased absorption and/or increased clearance of imatinib may be attributable to induction of intestinal and hepatic transport proteins. So, we investigated in mice whether imatinib-induced modulation of drug transporters occurs over time upon prolonged daily use of imatinib. To mimic the clinical situation we chronically treated C57/Bl6 mice, either with imatinib or with a solute control (H2O) for 4, 8 or 12 weeks. Imatinib (100 mg/kg once daily) was administered to the mice via oral gavage (∼300 μl / mice). We collected all organs involved in the absorption and elimination of imatinib including the liver and the complete GI-tract (esophagus, stomach, small and large intestine and caecum) and subsequently isolated total RNA and protein from these tissues. We performed mRNA and miRNA profiling using mouse genome 430 PM (Affymetrix) and LNA-modified oligonucleotide arrays (Exiqon), respectively, and examined the expression of &amp;gt;80 transporter genes using the RT2 Profiler PCR array system (SABiosciences). Prolonged imatinib treatment resulted in the modulation of various intestinal and hepatic drug transporters and clearly changed the mRNA and miRNA profiles of ADME-involved organs. Apart from the imatinib-associated transporters Abcb1a/b, Abcg2, Slc22a1 and Slco1b2, indicating proof of concept, our search identified various other potential imatinib transporter which are currently tested in uptake experiments using transporter-transfected HEK293 cells. In summary, we showed that continuous exposure of mice to daily dosages of imatinib markedly affects the expression of drug transporters and changes the mRNA and miRNA expression profiles in organs involved in uptake, distribution and elimination of imatinib. These imatinib-induced changes may critically affect the PK, efficacy and adverse events of imatinib chemotherapy. Citation Format: Herman Burger, Alexander T. den Dekker, Antonius WM Boersma, Peter de Bruijn, Jaap Verweij, Ron HJ Mathijssen, Erik AC Wiemer. Imatinib-induced modulation of gastrointestinal and hepatic membrane transporters in mice. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 883. doi:10.1158/1538-7445.AM2013-883

A new function of Vitamin E-TPGS in the intestinal lymphatic transport of lipophilic drugs: Enhancing the secretion of chylomicrons

The purpose of this study was to examine whether Vitamin E-TPGS had a function in promoting the secretion of chylomicrons in enterocytes. Therefore, we simulated the human intestinal epithelial cells by Caco-2 cell model to study the effect of Vitamin E-TPGS on the chylomicron secretion in vitro. Meanwhile, chylomicron flow blocking rat model and mesenteric lymph cannulated rat model were used for the studies in vivo to evaluate the effect and probucol was chosen as the model drug. The results of cell experiments indicated that Vitamin E-TPGS at low concentration had a strong enhancement on the secretion of chylomicrons. The results of animal experiments indicated that Vitamin E-TPGS could significantly enhance the lymphatic transport of probucol by the same role consistently with the results obtained from cell experiments. However, the role would reach the plateau and saturate after a concentration dependent increase. These studies first demonstrate the function of Vitamin E-TPGS in the intestinal lymphatic transport of lipophilic drugs, which can significantly promote the secretion of chylomicrons by the intestinal epithelial cells.