Submitted by Renata Lopes (renatasil82@gmail.com) on 2017-01-12T12:29:32Z No. of bitstreams: 1 julianemarquesfelicissimo.pdf: 1079943 bytes, checksum: a9e0f1d1f97912241b0c7d91e6ed9aeb (MD5) / Approved for entry into archive by Diamantino Mayra (mayra.diamantino@ufjf.edu.br) on 2017-01-31T11:17:05Z (GMT) No. of bitstreams: 1 julianemarquesfelicissimo.pdf: 1079943 bytes, checksum: a9e0f1d1f97912241b0c7d91e6ed9aeb (MD5) / Made available in DSpace on 2017-01-31T11:17:05Z (GMT). No. of bitstreams: 1 julianemarquesfelicissimo.pdf: 1079943 bytes, checksum: a9e0f1d1f97912241b0c7d91e6ed9aeb (MD5) Previous issue date: 2014-08-11 / Legítima representante do rol de doenças tropicais negligenciadas, a esquistossomose causada pelos trematódeos do gênero Schistosoma spp. constitui uma enfermidade endêmica em 78 países, impondo grandes desafios à saúde das populações afetadas. Atualmente, a ausência de uma vacina eficaz reforça o papel da quimioterapia como o pilar do controle da morbidade e transmissão, a qual permanece restrita e ameaçada pela eminência de cepas resistentes ao praziquantel. Nos últimos anos, esforços vêm sendo empreendidos na tentativa de descobrir novos fármacos esquistossomicidas, com notável contribuição dos produtos naturais. Neste contexto, o flavonóide Licochalcona A - marcador quimiotaxonômico da espécie Glycyrrhiza inflata – que detém atividades biológicas diversas, como anti-inflamatória, antioxidante e antiprotozoária para espécies de Leishmania spp. e Plasmodium spp., demonstrou atividade esquistossomicida promissora em um estudo preliminar, sendo considerado o objeto do presente estudo. Desta forma, a proposta foi avaliar a progressão da esquistossomose mansônica em camundongos Swiss frente ao tratamento com LicoA, além de obter mais informações acerca de sua atividade contra vermes adultos in vitro. Após um período de 24 horas de incubação, a LicoA a partir de 50µM foi capaz de causar o escurecimento do tegumento dos vermes, a perda moderada da motilidade e áreas de intumescimento corporal. Além disso, produziu pontos de retenção do corante resorufin e consequentemente, a descontinuidade na marcação dos principais túbulos e ramos do sistema excretor dos esquistossomos. Este último pode ser a origem dos demais efeitos, contribuindo para o entendimento das potenciais influências da droga sobre receptores e/ou enzimas presentes nos esquistossomos. Além disso, a suposta inibição parcial das SmATPDases pode igualmente contribuir para o insucesso do parasitismo. Nos ensaios in vivo, o esquema de 50mg/Kg em duas doses administrado por via intraperitoneal foi o mais promissor, alcançado uma mediana de 25% da redução da carga parasitária e o maior deslocamento hepático dos vermes. Por outro lado, a droga não induziu alterações no oograma qualitativo ou no peso hepático e esplênico, mostrando relativa inércia sobre a cinética de oviposição. Mais estudos devem ser conduzidos para acumular evidências sobre o efeito esquistossomicida da Licochalcona A, principalmente os que contemplem um maior número de animais e de parâmetros analisados, como por exemplo, o perfil de citocinas e quimiocinas in vivo, além de outras metodologias in vitro e o aprimoramento daquelas que foram aqui empregadas, de modo a fornecer mais detalhes sobre a influência da LicoA em alguns sistemas intrínsecos ao parasito. / Schistosomiasis, one significant neglected tropical disease, is an infection caused by trematode worms of the genus Schistosoma spp. it is endemic in 78 countries, being a major public health challenge. Currently, the absence of an effective vaccine supports the chemotherapy as the mainstay of schistosomiasis control programs. However, the chemotherapy has limitations, such as, the emergence of praziquantel-resistant strains. In recent years, attempts to discover new antischistosomal drugs had remarkable contribution of natural products. In this context, the flavonoid Licochalcona A - chemotaxonomic marker of the specie Glycyrrhiza inflata - has several biological activities such as anti-inflammatory, antioxidant and anti-protozoan against species of Leishmania spp. and Plasmodium spp. Moreover, Licochalcona A showed promising schistosomicidal activity in a preliminary study. Thus, the aim of this study was to evaluate the progression of schistosomiasis in Swiss mice treated with LicoA and it activity against adult worms in vitro. After 24 hour incubation, concentrations from 50μM LicoA caused tegument darkening, moderate loss of motility and areas of swelling body. Moreover, the exposure to the compound produced accumulation of resorufin and hence the discontinuity in the labelling of the main branches and tubules in the excretory system of schistosomes. The latter may be the source of other effects, contributing to the understanding of the potential influence of the drug on receptors and / or enzymes in schistosomes. In addition, the alleged partial inhibition of SmATPDases can also contribute to the failure of parasitism. In vivo tests, the 50 mg/kg schedule of two doses administered intraperitoneally were the most promising reached a median 25% reduction of worm burden and increased hepatic displacement of the worms. Moreover, the drug did not induce changes in the qualitative or oogram liver and spleen weight relative inertia about showing the kinetics of oviposition. Further studies should be conducted to collect evidence on the effect of schistosomicidal Licochalcona A, especially those that consider a larger number of animals and analyzed parameters, such as the profile of in vivo cytokines and chemokines, and other in vitro methods and the improvement of those who were employed here in order to provide more details on the influence of LicoA in some systems intrinsic to the parasite.

A furosemida é um fármaco de ação diurética e amplamente utilizado em tratamentos de doenças renais, cardíacas e pulmonares. Sua absorção é problemática e de alta variabilidade inter e intraindividual. Este fármaco tem sido classificado como pertencente às classes II (baixa solubilidade e alta permeabilidade) ou IV (baixa permeabilidade e baixa solubilidade) do Sistema de Classificação de Biofarmacêutica (SCB). Em estudos anteriores da equipe de pesquisa, SPRICIGO e colaboradores (2008) e SILVA (2014) desenvolveram complexos de furosemida com hidroxipropil-&#946;-ciclodextrina que permitiram a otimização da solubilidade deste fármaco. Entretanto, dados sobre a sua permeabilidade intestinal, quando complexado, não foram determinados. Somando-se a isto, a literatura apresenta informações distintas em relação a este parâmetro, o que corrobora a importância de se avaliar a permeabilidade deste fármaco. Diversas técnicas têm sido empregadas para a avaliação da permeabilidade intestinal dos fármacos. No presente trabalho empregou-se o modelo de perfusão in situ de passagem tripla, cuja técnica possibilita avaliar a permeabilidade em três segmentos diferentes em um mesmo animal e ainda, apresenta características interessantes, pois trata-se de um método que proporciona, durante todo o experimento, condições mais próximas daquelas encontradas durante o processo in vivo de absorção de fármacos no intestino tais como: suprimento sanguíneo, inervação intacta, preservação das proteínas transportadoras de membranas e presença da camada de muco. O presente trabalho foi dividido nas seguintes etapas: (i) obtenção da furosemida complexada com hidroxipropil-&#946;-ciclodextrina, (ii) caracterização dos fármacos utilizando técnicas de análises térmicas, (iii) estudo de perfusão in situ de passagem tripla nos três segmentos intestinais (duodeno, jejuno e íleo) de ratos machos Wistar na ausência e na presença de inibidores da glicoproteína P e de enzimas metabolizadoras CYP3A4 com posterior análise estatística do impacto da ciclodextrina e inibidores na permeabilidade da furosemida e; (iv) análise histológica das microvilosidades intestinais após o ensaio de perfusão in situ nos três segmentos intestinais. Os valores encontrados em cada segmento para furosemida complexada foram: 8,58 ± 0,002 x 10-5 cm.s-1; 9,15 ± 0,003 x10-5 cm.s-1 e; 8,06 ± 0,002 x 10-5 cm.s-1, respectivamente para duodeno, jejuno e íleo enquanto que para furosemida pura encontraram-se os seguintes: 3,42 ± 0,08 x 10-5 cm.s-1 para duodeno; 3,87 ± 0,11 x 10-5 cm.s-1 para jejuno e 3,08 ± 0,001 x 10-5 cm.s-1 para íleo. Assim sendo, os valores obtidos para a permeabilidade da furosemida complexada foram significativamente superiores (p < 0,05) aos da furosemida pura, sugerindo que, a ciclodextrina pode ter influência no mecanismo de transporte da furosemida, que é via passiva paracelular. Quanto aos mecanismos envolvidos na permeabilidade da furosemida através dos enterócitos, pode-se sugerir que observou-se pouca influência dos inibidores da glicoproteína P (P-gp) e da enzima CYP3A4, sugerindo que não há uma participação importante destes mecanismos em sua absorção intestinal. / Furosemide, which is a diuretic drug, is widely used in heart, kidney and pulmonary disease treatments. The absorption is problematic with high variability inter and intra individuals. This drug has been classified as belonging to class II (low solubility and high permeability) or IV (low permeability and low solubility) of the Biopharmaceutical Classification System (BCS). In previous studies of the research team, Spricigo and colleagues (2008) and Silva (2014) developed complex of furosemide with hydroxypropyl-&#946;-cyclodextrin which allowed the optimization of the solubility of this drug. However, datas concerning it\'s intestinal permeability, when complexed, have not been determined. Addicted to this, the literature shows many information regarding to this parameter, which confirms the importance of the evaluation of the permeability of this drug. Some techniques have been employed in order to evaluate the intestinal permeability of drugs. In the present work, a triple single-pass intestinal perfusion technique was used for three different segments. This technique enables the evaluation of the permeability of different segments in the same animal and also has interesting features such as: it provides during all the experiment conditions closer to those found in in vivo process of a drug absorption in the gut; blood supply; intact innervations; preservation of membrane transporter proteins and presence of mucus layer. This study was divided into the following steps: (i) obtaining furosemide complexed with hydroxypropyl-&#946;-cyclodextrin, (ii) characterization of drugs using techniques of thermal analysis, (iii) perfusion study in situ triple passage in three segments (duodenum, jejunum and ileum) from male Wistar rats in the absence and presence of inhibitors of P-glycoprotein and metabolizing enzymes CYP3A4 and subsequential statistical analysis of the impact of the cyclodextrin and the inhibitors in the permeability of furosemide and (iv) histological analysis of intestinal microvilli after in situ perfusion assay in three segments. The values found in each segment for complexed furosemide were: 8,58 ± 0,002 x 10-5 cm.s-1; 9,15 ± 0,003 x 10-5 cm.s-1; 8,06 ± 0,002 x 10-5 cm.s-1, respectively for duodenum, jejunum and ileum while for pure furosemide, the values were: 3,42 ± 0,08 x 10-5 cm.s-1 to duodenum; 3,87 ± 0,11 x 10-5 cm.s-1 to jejunum and 3,08 ± 0,001 x 10-5 cm.s-1 to ileum. Thus, the values obtained for the permeability of the complexed furosemide were significantly higher (p < 0,05) than those found for pure furosemide, suggesting that the cyclodextrin might have an influence on the transport mechanism of furosemide, which is passive paracellular route. About the mechanisms involved in the permeability of furosemide through the enterocytes, it can be suggested that there was little effect of P-glycoprotein (P-gp) inhibitors and CYP3A4 enzyme, suggesting that there is an important role of these mechanisms in the furosemide intestinal absorption.

Les membranes cellulaires jouent un rôle important dans l’absorption des médicaments et la distribution de ceux-ci dans le corps humain. Elles contiennent différents transporteurs membranaires qui sont responsables des profils pharmacocinétiques, d’innocuité et d’efficacité des xénobiotiques. Lors du développement d’un médicament, il s’avère donc indispensable, de prédire l’interaction des nouveaux composés avec les transporteurs présents dans l’organisme. Le but du projet de recherche est de créer un nouvel outil pour étudier le comportement de la glycoprotéine-P (P-gp), un transporteur membranaire responsable du rejet de nombreux composés, sur différents médicaments. Pour cela, un modèle non cellulaire est développé en utilisant des protéoliposomes : des liposomes dans lesquels des transporteurs sont incorporés. La méthodologie consiste tout d’abord à produire, extraire et purifier la protéine d’intérêt à partir de deux systèmes d’expression : MDCK-MDR1 (cellules de chien transfectées avec le gène humain MDR1) et Pichia pastoris (levures) fin de déterminer les avantages et les limites de ces deux types cellulaires. Différentes méthodes de reconstitution dans des protéoliposomes ont ensuite été testées avec la P-gp obtenue. Puis, l’activité ATPasique de la P-gp reconstituée a été évaluée en présence de différents substrats. Les protocoles de culture cellulaire, d’extraction et de purification des deux systèmes d’expression ont été implémentés avec succès au sein du laboratoire. Les résultats montrent que les rendements obtenus sont supérieurs avec les levures qu’avec les cellules de mammifère. En outre, Pichia pastoris offre les avantages d’être facile et rapide à cultiver et peu couteux. Les premiers résultats d’activité ATPasique obtenus avec la P-gp reconstituée en protéoliposomes étaient prometteurs mais n’ont pas été reproduits en raison de la dégradation de la protéine membranaire. Les prochaines études du projet porteront sur un autre transporteur membranaire de la famille ABC, BCRP, une protéine de plus petite taille qui devrait montrer une plus grande stabilité pour mener à bien les tests. / Cellular membranes play an important role in the absorption and distribution of drugs in the human body. They contain different membrane transporters, which are responsible for the pharmacokinetic properties of drugs, as well as the safety and efficiency of their diffusion. When developing a new drug, it is thus of utmost importance to study the way that it will interact with the transporters present within the body. The aim of this study was to evaluate a new tool for measuring permeability in order to understand the function and mecanisms of P-glycoprotein (P-gp). P-gp is a transporter that is responsible for the rejection of many different compounds found in various drugs. This study thus seeks to use proteoliposomes to develop non-cellular models of membrane permeability including efflux and uptake transporters. This novel model of permeability will be utilized to study the underlying mechanisms of membrane permeability to xenobiotics. The human P-gp was produced, extracted and purified using two different expression systems: MDCK-MDR1 cells (Madin-Darby canine kidney cells transfected with the human MDR1 gene) and Pichia pastoris. Both expression systems were studied in order to compare the strengths and weaknesses of each system. We then tested different methods of reconstituting the P-gp into protéoliposomes. Finally, we measured the level of ATPase activity using different substrates. The protocols of cell culture, extraction and purification of both expression systems were accomplished in a laboratory during this study. These results demonstrated that expressing P-gp using yeast was more effective than that of mammalian cells. Furthermore, working with Pichia pastoris offers multiple advantages: expressing P-gp was easier, faster and cheaper than working with mammalian cells. The first measurements of ATPase activity using reconstituted P-gp proteoliposomes were promising, however they proved difficult to reproduce due to the possible degradation of the membrane protein.Further studies in this project will look to evaluate another ABC membrane transporter, BCRP. This smaller protein should prove to be more stable than P-gp, facilitating experimentation.

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No description available.

α-Tocopherol has a well known antioxidant action but is also considered likely to exert significant non-antioxidant effects in cell membranes. Due to its lipophilic nature α-tocopherol inserts into biological membranes where it influences the organisation of the component lipids and may therefore influence biophysical parameters including the membrane dipole potential. The dipole potential has been demonstrated to modulate the function of several membrane associated proteins and perturbation of this physical parameter by α-tocopherol may prove to be a significant non-antioxidant mechanism underlying several of its cellular effects. This study investigates the influence of α-tocopherol, and the non-antioxidant structural analogue α-tocopherol succinate, on the membrane dipole potential employing fluorescence spectroscopy techniques with the dipole potential sensitive probe Di-8-ANEPPS. Similar techniques are utilised with the surface potential sensitive probe FPE to investigate the interaction of the charged α-tocopherol succinate molecule with membranes. α-Tocopherol and α-tocopherol succinate are shown to decrease the dipole potential of egg-phosphatidylcholine vesicles and Jurkat T-lymphocyte cell membranes. This effect is placed in the context of the significant influence of membrane cholesterol oxidation on the dipole potential. 7-ketocholesterol, an oxidised form of cholesterol, significantly influences several cellular processes and is thought to mediate these effects, in part, through its physical effects on the cell membrane. These include altering the composition, and therefore biophysical properties, of rafts; structures which are considered to support the function of a host of membrane proteins. This study attempts to correlate the effect of 7-ketocholesterol on the dipole potential of microdomains with the influence of the oxysterol on the function of two microdomains associated receptors: P-glycoprotein and the insulin receptor, assessed by determining the extent of ligand binding using flow fluorocytometry. α-Tocopherol has been suggested to inhibit the raft-mediated effects of 7-ketocholesterol and the influence of this molecule on the effect of 7-ketocholesterol on the dipole potential are investigated as a potential mechanism for this inhibition. It is hypothesized that α-tocopherols may protect against the deleterious effects of cholesterol oxidation in cell membranes by excluding 7-ketocholesterol from specific microdomains, of which rafts are a subset, acting to preserve their dipole potential and maintain the function of the proteins they support. However, where significant cholesterol oxidation has previously occured the concurrent changes in the microdomain landscape of the membrane is suggested to prevent α-tocopherol succinate from eliciting this protective effect.

Les propriétés pharmacocinétiques d’un nouveau médicament et les risques d’interactions médicamenteuses doivent être investigués très tôt dans le processus de recherche et développement. L’objectif principal de cette thèse était de concevoir des approches prédictives de modélisation du devenir du médicament dans l’organisme en présence et en absence de modulation d’activité métabolique et de transport. Le premier volet de recherche consistait à intégrer dans un modèle pharmacocinétique à base physiologique (PBPK), le transport d’efflux membranaire gouverné par les glycoprotéines-P (P-gp) dans le cœur et le cerveau. Cette approche, basée sur des extrapolations in vitro-in vivo, a permis de prédire la distribution tissulaire de la dompéridone chez des souris normales et des souris déficientes pour les gènes codant pour la P-gp. Le modèle a confirmé le rôle protecteur des P-gp au niveau cérébral, et a suggéré un rôle négligeable des P-gp dans la distribution tissulaire cardiaque pour la dompéridone. Le deuxième volet de cette recherche était de procéder à l’analyse de sensibilité globale (ASG) du modèle PBPK précédemment développé, afin d’identifier les paramètres importants impliqués dans la variabilité des prédictions, tout en tenant compte des corrélations entre les paramètres physiologiques. Les paramètres importants ont été identifiés et étaient principalement les paramètres limitants des mécanismes de transport à travers la membrane capillaire. Le dernier volet du projet doctoral consistait à développer un modèle PBPK apte à prédire les profils plasmatiques et paramètres pharmacocinétiques de substrats de CYP3A administrés par voie orale à des volontaires sains, et de quantifier l’impact d’interactions médicamenteuses métaboliques (IMM) sur la pharmacocinétique de ces substrats. Les prédictions des profils plasmatiques et des paramètres pharmacocinétiques des substrats des CYP3A ont été très comparables à ceux mesurés lors d’études cliniques. Quelques écarts ont été observés entre les prédictions et les profils plasmatiques cliniques mesurés lors d’IMM. Cependant, l’impact de ces inhibitions sur les paramètres pharmacocinétiques des substrats étudiés et l’effet inhibiteur des furanocoumarins contenus dans le jus de pamplemousse ont été prédits dans un intervalle d’erreur très acceptable. Ces travaux ont contribué à démontrer la capacité des modèles PBPK à prédire les impacts pharmacocinétiques des interactions médicamenteuses avec une précision acceptable et prometteuse. / Early knowledge of pharmacokinetic properties of a new drug candidate and good characterization of the impact of drug-drug interaction (DDI) on those properties is of crucial importance in the process of drug research and development. The main objective of this thesis consisted in the conception of PBPK models able to predict the drug disposition in the absence and presence of metabolic and transport activity modulation. The first part of this work aimed to develop a PBPK model that incorporates the efflux function of P-gp expressed in various tissues, in order to predict the impact of P-gp activity modulation on drug distribution. This approach, based on in vivo-in vitro extrapolation for estimating the transport-related parameters, allowed the prediction of domperidone distribution in heart and brain of wild-type mice and P-gp deficient mice. The model pointed out the protective function of P-gp in brain whereas it showed the negligible protective effect of P-gp in heart. The second part of the project aimed to perform the global sensitivity analysis of the previous PBPK model, in order to investigate how the uncertainly and variability of the correlated physiological parameters influence the outcome of the drug distribution process. While a moderate variability of the model predictions was observed, this analysis confirmed the importance for a better quantitative characterization of parameters related to the transport processes trough the blood-tissue membrane. Accounting for the input correlation allowed the delineation of the true contribution of each input to the variability of the model outcome. The last part of the project consisted in predicting the pharmacokinetics of selected CYP3A substrates administered at a single oral dose to human, alone or with an inhibitor. Successful predictions were obtained for a single administration of the CYP3A substrates. Some deviations were observed between the predictions and in vivo plasma profiles in the presence of DDI. However, the impact of inhibition on the PK parameters of the selected substrates and the impact of grapefruit juice-mediated inhibition on the extent of intestinal pre-systemic elimination were predicted within a very acceptable error range. Overall, this thesis demonstrated the ability of PBPK models to predict DDI with promising accuracy.

Thèse numérisée par la Division de la gestion de documents et des archives de l'Université de Montréal.

La multichimiorésistance est caractérisée par une résistance simultanée à des agents chimiothérapeutiques de structures diverses, induite notamment par l’efflux des substances actives hors des cellules. Les transporteurs ABC (ATP-Binding Cassette) sont des protéines transmembranaires impliquées dans cet efflux et qui participent à l’échec du traitement de certains cancers. Par ailleurs, ce mécanisme d’efflux a également été évoqué dans le cadre de la résistance de certains microorganismes aux antimicrobiens. Dans cette étude, nous avons conçu et synthétisé des dérivés susceptibles d’inhiber certains transporteurs ABC, en particulier, la glycoprotéine-P (Pgp) impliquée dans la multichimiorésistance des tumeurs humaines, et CpABC3, rencontré chez le parasite Cryptosporidium parvum. Dans un premier temps, nous avons synthétisé trois dérivés de type 4-alkyl-imidazo[4,5-b]pyridin-7-one, hétérocycles destinés à se fixer sur le site à ATP des transporteurs ABC. L’activité de ces composés a été évaluée vis-à-vis d’un fragment recombinant (H6-NBD1) de CpABC3, et un de ceux-ci a montré une liaison (faible) à ce fragment. Nous avons ensuite préparé dix-sept dérivés bivalents susceptibles d’inhiber la Pgp, constitués d’une molécule d’adénine (ciblant le site à ATP) reliée à la progestérone (ciblant le site aux stéroïdes) par un bras de géométrie variable. Ces dérivés ont été testés sur des lignées cellulaires K562/R7 surexprimant la Pgp, et un de ceux-ci a montré une activité supérieure à celle de la progestérone. Enfin, nous avons mis au point une synthèse de chaînes de type oligocyclohexylidène, qui sont de bons candidats pour constituer des bras espaceurs rigides / Multi-drug resistance (MDR) is characterized by a simultaneous resistance to a wide range of structurally unrelated chemotherapeutic agents, partly caused by the efflux of active compounds out of the cell. ABC transporters (ATP-Binding Cassette) are transmembrane proteins implicated in this efflux, and thus, they contribute to the failure of some cancer treatments. Furthermore, this mechanism was evoked in some microorganism resistances to antimicrobial agents. In this study, we designed and synthesized potential inhibitors of ABC transporters, especially P-glycoprotein (Pgp) implicated in human tumors multi-drug resistance, and CpABC3, a transporter found in a human parasite, Cryptosporidium parvum. First, we synthesized three 4-alkyl-imidazo[4,5-b]pyridin-7-one derivatives, targeting ATP-binding site of ABC transporters. Their biological activities were evaluated toward a recombinant fragment of the CpABC3 transporter (H6-NBD1 fragment). One of these compounds showed a weak-binding to this fragment. Next, we prepared seventeen progesterone-adenine hybrids as potential bivalent ligands which may bind simultaneously to the ATP-binding site and the steroid-binding region. We chose to synthesize derivatives with rather short-length linkers with different conformational flexibilities. These bivalent compounds were tested on K562/R7 human leukemic cells overexpressing Pgp. One of them has showed a better activity than progesterone. Finally, we optimized the synthesis of oligocyclohexylidene chains, which are good candidates to constitute rigid linkers

Charles University Faculty of Pharmacy in Hradec Králové Department of Pharmacology & Toxicology Student: Veronika Křečková Supervisor: PharmDr. Lukáš Červený, Ph.D. Title of diploma thesis: Role of drug transporters in placental transfer of entecavir Entecavir (ETV), an analogue of guanosine, is a highly efficient anti-hepatitis B antiviral drug. It is the first-line therapy for both adults and children. Its use in pregnancy is limited due to a number of factors, including lack of data on placental pharmacokinetics. The placental transition of drugs is frequently controlled by drug transporters. ATP-binding (ABC) transporters, P-glycoprotein (P-gp), breast cancer resistance protein (BCRP) or multidrug resistance-associated protein 2 (MRP2) localized in the apical membrane of syncytiotrophoblast and pumping their substrates in the feto-maternal direction belong to most significant determinants of placental pharmacokinetics. Moreover placental transport of nucleoside-derived drugs can be affected by the activity of nucleoside transporters (NTs); equilibrative nucleoside transporters (ENTs) mediate facilitated diffussion, while the concentrative nucleoside transporters (CNTs) control active influx of their substrates. The aim of the diploma thesis was to describe the role of P-gp, BCRP, MRP2 and NTs (ENTs and...