Nagy I.,SOLVO Biotechnology |
Toth B.,SOLVO Biotechnology |
Gaborik Z.,SOLVO Biotechnology |
Erdo F.,Pázmány Péter Catholic University |
Krajcsi P.,SOLVO Biotechnology
Current Pharmaceutical Design | Year: 2016
Membrane transporters expressed in barrier forming cell types provide a dual filtration system as unwanted xenobiotics are effluxed by ABC transporters, and compounds essential for the organism, such as nutrients or physiological substrates, are taken up by influx transporters. The majority of efflux transporters apically-localized in barrier forming cell types are ABC transporters that may limit absorption or distribution, and promote excretion. Pharmaceutical scientists are increasingly aware of the limitations these efflux transporters represent. Influx transporters are also critically important, as apically-located influx transporters may counteract the effect of co-localized efflux transporters, promoting absorption or reabsorption, as well as facilitating distribution of low passive permeability substrates into tissues that are otherwise heavily guarded by efflux transporters. In excretory organs, basolaterally-localized influx transporters cooperate with apically-localized efflux trransporters to efficiently drive transcellular movement of xenobiotics and their metabolites. Pharmacological inhibition of absorption or reabsorption of unwanted nutrients and endobiotics has become a great opportunity for pharmaceutical development. For drug developers, these transporters also offer the opportunity to target specific organs and cell types. Targeting drugs to cells and tissues harboring the pharmacological target not only makes drugs more efficient, but can also make them less toxic, as it allows for administration of lower doses and less distribution of drugs into non-target organs. © 2016 Bentham Science Publishers.
Zhang L.,Chinese University of Hong Kong |
Li C.,Chinese University of Hong Kong |
Lin G.,Chinese University of Hong Kong |
Krajcsi P.,SOLVO Biotechnology |
And 2 more authors.
AAPS Journal | Year: 2011
Baicalein (Ba) was found to be subject to serious first-pass metabolism after oral administration. We previously revealed the important role of intestine in the low oral bioavailability of Ba. The present study aims to evaluate the hepatic metabolism and disposition of Ba. Ba was given to Sprague-Dawley rats through bolus or infusion via intravenous or intra-portal route of administrations. Both plasma and bile samples at different time intervals were obtained. Concentrations of Ba and potential metabolites in the collected samples were analyzed with HPLC/UV and identified by LC/MS/MS, respectively. Plasma concentration versus time profiles of Ba obtained from intravenous and intra-portal administrations were compared to estimate the extent of hepatic metabolism. In addition, transport studies of baicalein-7-glucuronide (BG), one of the major metabolites of Ba, were carried out using transfected cell systems overexpressing various human organic anion-transporting polypeptide (OATP) isoforms to estimate the specific transporters involved in the hepatic disposition of Ba metabolites. The results showed that liver, in addition to intestine, also conferred extensive metabolism to Ba. Several mono- and di-conjugates of Ba, which were mainly glucuronides, sulfates, and methylates, were found in bile. The transport study demonstrated that besides MRPs and BCRP, human OATP2B1 and OATP1B3 in liver might also mediate the secretion of BG to bile. In summary, liver plays an important role in the metabolism of Ba and transport of its conjugated metabolites. © 2011 American Association of Pharmaceutical Scientists.
Taub M.E.,Boehringer Ingelheim Pharmaceuticals |
Mease K.,Boehringer Ingelheim Pharmaceuticals |
Sane R.S.,Boehringer Ingelheim Pharmaceuticals |
Watson C.A.,Glaxosmithkline |
And 6 more authors.
Drug Metabolism and Disposition | Year: 2011
Digoxin, an orally administered cardiac glycoside cardiovascular drug, has a narrow therapeutic window. Circulating digoxin levels (maximal concentration of ∼1.5 ng/ml) require careful monitoring, and the potential for drug-drug interactions (DDI) is a concern. Increases in digoxin plasma exposure caused by inhibition of Pglycoprotein (P-gp) have been reported. Digoxin has also been described as a substrate of various organic anion-transporting polypeptide (OATP) transporters, posing a risk that inhibition of OATPs may result in a clinically relevant DDI similar to what has been observed for P-gp. Although studies in rats have shown that Oatps contribute to the disposition of digoxin, the role of OATPs in the disposition of digoxin in humans has not been clearly defined. Using two methods, Boehringer Ingelheim, GlaxoSmithKline, Pfizer, and Solvo observed that digoxin is not a substrate of OATP1A2, OATP1B1, OATP1B3, and OATP2B1. However, digoxin inhibited the uptake of probe substrates of OATP1B1 (IC 50 of 47 μM), OATP1B3 (IC 50 > 8.1 μM), and OATP2B1 (IC 50 > 300 μM), but not OATP1A2 in transfected cell lines. It is interesting to note that digoxin is a substrate of a sodium-dependent transporter endogenously expressed in HEK293 cells because uptake of digoxin was significantly greater in cells incubated with sodium-fortified media compared with incubations conducted in media in which sodium was absent. Thus, although digoxin is not a substrate for the human OATP transporters evaluated in this study, in addition to P-gp-mediated efflux, its uptake and pharmacokinetic disposition may be partially facilitated by a sodium-dependent transporter. Copyright © 2011 by The American Society for Pharmacology and Experimental Therapeutics.
Klukovits A.,SOLVO Biotechnology |
Krajcsi P.,SOLVO Biotechnology
Expert Opinion on Drug Metabolism and Toxicology | Year: 2015
Introduction: The ATP-binding cassette transporters are among the largest transmembrane protein families in humans and are expressed in a wide variety of tissues. By promoting outward transport, they protect cells from the accumulation of undesirable substrates. This protection might lead to suboptimal concentration of chemotherapeutics in the tumor cells, resulting in therapy resistance and poor disease prognosis. In the past decades, a considerable effort was made to reverse multidrug resistance (MDR).Areas covered: We briefly summarize the present knowledge on the clinical efficacy of MDR reversing agents in various types of cancer and discuss their availability in a non-cancerous disease (rheumatoid arthritis). The classical and novel pharmacological approaches directly inhibiting the transporters' function and their extensive investigations in human clinical studies are also mentioned. Furthermore, the article highlights the methodological concerns raised by these investigations.Expert opinion: The development of chemotherapeutics lacking transporter-inducing effects, gene therapy approaches, nanomedicinal formulations and the identification of natural compounds to modulate transporter function are intriguing but face serious delivery challenges. Understanding and mapping molecular mechanisms of drug resistance will make it easier to design clinical treatment regimes that avoid escalation of MDR, by utilizing collateral sensitivity. © 2015 Informa UK, Ltd.
Kis E.,Solvo Biotechnology
Toxicology in vitro : an international journal published in association with BIBRA | Year: 2012
Bile salt export pump (BSEP, ABC11) is a membrane protein that is localized in the cholesterol-rich canalicular membrane of hepatocytes. Its function is to eliminate unconjugated and conjugated bile acids/salts from hepatocyte into the bile. In humans there is no compensatory mechanism for the loss of this transporter. Mutations of BSEP result in a genetic disease, called progressive familial intrahepatic cholestasis type 2 (PFIC2), that is characterized with decreased biliary bile salt secretion, leading to decreased bile flow and accumulation of bile salts inside the hepatocyte, inflicting damage. BSEP inhibitor drugs produce similar bile salt retention that may lead to severe cholestasis and liver damage. Drug-induced liver injury is a relevant clinical issue, in severe cases ending in liver transplantation. Therefore, measurement of BSEP inhibition by candidate drugs has high importance in drug discovery and development. Although several methods are suitable to detect BSEP-drug interactions, due to interspecies differences in bile acid composition, differences in hepatobiliary transporter modulation, they have limitations. This review summarizes appropriate in vitro methods that could be able to predict BSEP-drug candidate interactions in humans before the start of clinical phases. Copyright © 2011 Elsevier Ltd. All rights reserved.
Jani M.,Solvo Biotechnology |
Krajcsi P.,Solvo Biotechnology
Drug Discovery Today: Technologies | Year: 2014
Drug transporter proteins recruit to pharmacological barrier tissues and profoundly affect the ADME properties of a large number of drugs. In vitro assays optimized for drug transporters have grown into routine tools in the determination of molecular level interactions as well as prediction of barrier penetration and system level pharmacokinetics. Regulatory position mandates increasing interest in the application of these assays during drug development. © 2014 Elsevier Ltd.
Marki-Zay J.,Solvo Biotechnology |
Jakab K.T.,Solvo Biotechnology |
Krajcsi P.,Solvo Biotechnology |
Szeremy P.,Solvo Biotechnology
Clinical and Experimental Rheumatology | Year: 2013
MDR-ABC transporters are widely expressed in cell types relevant to pathogenesis of rheumatoid arthritis. Many reports demonstrate the interaction of small molecule drugs with MDR-ABC transporters. Cell-based assays for disease relevant cell types can be easily gated and could reveal specific drug targets and may increase significance and utilisation of data in clinical practice. Many commonly used DMARDs (e.g. methotrexate, sulfasalazine, leflunomide/ teriflunomide, hydroxychloroquine) are ABCG2 substrates. Consequently, the activity of this transporter in patients should be determined to understand the disposition and pharmacokinetics of the therapy. In addition, MDR-ABC transporters transport a variety of endobiotics that play important roles in cell proliferation, cell migration, angiogenesis and inflammation. Therefore, MDR-ABC transporters are important biomarkers in rheumatoid arthritis. © Clinical and Experimental Rheumatology 2013.
Jani M.,Solvo Biotechnology |
Ambrus C.,Solvo Biotechnology |
Magnan R.,Solvo Biotechnology |
Jakab K.T.,Solvo Biotechnology |
And 3 more authors.
Archives of Toxicology | Year: 2014
The discovery and characterization of breast cancer resistance protein (BCRP) as an efflux transporter conferring multidrug resistance has set off a remarkable trajectory in the understanding of its role in physiology and disease. While the relevance in drug resistance and general pharmacokinetic properties quickly became apparent, the lack of a characteristic phenotype in genetically impaired animals and humans cast doubt on the physiological importance of this ATP-binding cassette family member, similarly to fellow multidrug transporters, despite well-known endogenous substrates. Later, high-performance genetic analyses and fine resolution tissue expression data forayed into unexpected territories concerning BCRP relevance, and ultimately, the rise of quantitative proteomics allows putting observed interactions into absolute frameworks for modeling and insight into interindividual and species differences. This overview summarizes existing knowledge on the BCRP transporter on molecular, tissue and system level, both in physiology and disease, and describes a selection of experimental procedures that are the most widely applied for the identification and characterization of substrate and inhibitor-type interactions. © 2014 Springer-Verlag.
Jemnitz K.,Institute of Biomolecular Chemistry |
Heredi-Szabo K.,SOLVO Biotechnology |
Janossy J.,SOLVO Biotechnology |
Ioja E.,SOLVO Biotechnology |
And 2 more authors.
Drug Metabolism Reviews | Year: 2010
ABCC2/Abcc2 (MRP2/Mrp2) is expressed at major physiological barriers, such as the canalicular membrane of liver cells, kidney proximal tubule epithelial cells, enterocytes of the small and large intestine, and syncytiotrophoblast of the placenta. ABCC2/Abcc2 always localizes in the apical membranes. Although ABCC2/Abcc2 transports a variety of amphiphilic anions that belong to different classes of molecules, such as endogenous compounds (e.g., bilirubin- glucuronides), drugs, toxic chemicals, nutraceuticals, and their conjugates, it displays a preference for phase II conjugates. Phenotypically, the most obvious consequence of mutations in ABCC2 that lead to Dubin-Johnson syndrome is conjugate hyperbilirubinemia. ABCC2/Abcc2 harbors multiple binding sites and displays complex transport kinetics. © 2010 Informa UK Ltd.
Heredi-Szabo K.,Solvo Biotechnology |
Kis E.,Solvo Biotechnology |
Krajcsi P.,Solvo Biotechnology
Current Protocols in Toxicology | Year: 2012
The canalicular membrane of hepatocytes contains several transport proteins that use the energy of ATP to efflux potentially toxic molecules to the bile. Probably the two most important proteins at this location are MRP2 and BSEP, which transport phase II conjugates of xenobiotics and endobiotics and conjugated bile salts, respectively. The impaired function of either of these transporter proteins reduces the clearance of the toxic conjugates, resulting in their accumulation in the hepatocytes and eventually the plasma. Conjugated bile salts and phase II metabolites are compounds with low passive permeability; therefore, the most commonly used test system to investigate MRP2-and BSEP-mediated transport processes is the vesicular transport assay. The concentration of probe substrates and inhibitors used in the experiment is close to their free concentration in the hepatocytes, providing an advantage when calculating kinetic parameters (Km, Ki, Vmax). The protocols aim to assist scientists to set up a transport assay for a known or potential substrate and test small molecule inhibition of the transporters. © 2012 by John Wiley & Sons, Inc.