PURPOSE: S-(4-Nitrobenzyl)-6-thioinosine (NBMPR) is routinely used at concentrations of 0.10 μM and 0.10 mM to specifically inhibit transport of nucleosides mediated by equilibrative nucleoside transporters 1 (ENT1) and 2 (ENT2), respectively. We recently showed that NBMPR (0.10 mM) might also inhibit placental active efflux of [3H]zidovudine and [3H]tenofovir disoproxil fumarate. Here we test the hypothesis that NBMPR abolishes the activity of P-glycoprotein (ABCB1) and/or breast cancer resistance protein (ABCG2). METHODS: We performed accumulation assays with Hoechst 33342 (a model dual substrate of ABCB1 and ABCG2) and bi-directional transport studies with the ABCG2 substrate [3H]glyburide in transduced MDCKII cells, accumulation studies in choriocarcinoma-derived BeWo cells, and in situ dual perfusions of rat term placenta with glyburide. RESULTS: NBMPR inhibited Hoechst 33342 accumulation in MDCKII-ABCG2 cells (IC50 = 53 μM) but not in MDCKII-ABCB1 and MDCKII-parental cells. NBMPR (0.10 mM) also inhibited bi-directional [3H]glyburide transport across monolayers of MDCKII-ABCG2 cells and blocked ABCG2-mediated [3H]glyburide efflux by rat term placenta in situ. CONCLUSION: NBMPR at a concentration of 0.10 mM abolishes ABCG2 activity. Researchers using NBMPR to evaluate the effect of ENTs on pharmacokinetics must therefore interpret their results carefully if studying compounds that are substrates of both ENTs and ABCG2.

• Klíčová slova
• NBMPR, breast cancer resistance protein, equilibrative nucleoside transporters, inhibition, selectivity,
• MeSH
• ABC transportér z rodiny G, člen 2 antagonisté a inhibitory   metabolismus   MeSH
• antivirové látky metabolismus   farmakokinetika   MeSH
• biologický transport účinky léků   MeSH
• buněčné linie MeSH
• buňky MDCK MeSH
• krysa rodu Rattus MeSH
• lidé MeSH
• nádorové proteiny antagonisté a inhibitory   metabolismus   MeSH
• P-glykoproteiny antagonisté a inhibitory   metabolismus   MeSH
• placenta účinky léků   metabolismus   MeSH
• potkani Wistar MeSH
• psi MeSH
• těhotenství MeSH
• thioinosin analogy a deriváty   farmakologie   MeSH
• zvířata MeSH
• Check Tag
• krysa rodu Rattus MeSH
• lidé MeSH
• psi MeSH
• těhotenství MeSH
• ženské pohlaví MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• 4-nitrobenzylthioinosine MeSH Prohlížeč
• ABC transportér z rodiny G, člen 2 MeSH
• ABCB1 protein, human MeSH Prohlížeč
• ABCG2 protein, human MeSH Prohlížeč
• antivirové látky MeSH
• nádorové proteiny MeSH
• P-glykoproteiny MeSH
• thioinosin MeSH

Rilpivirine (TMC278) is a highly potent nonnucleoside reverse transcriptase inhibitor (NNRTI) representing an effective component of combination antiretroviral therapy (cART) in the treatment of HIV-positive patients. Many antiretroviral drugs commonly used in cART are substrates of ATP-binding cassette (ABC) and/or solute carrier (SLC) drug transporters and, therefore, are prone to pharmacokinetic drug-drug interactions (DDIs). The aim of our study was to evaluate rilpivirine interactions with abacavir and lamivudine on selected ABC and SLC transporters in vitro and assess its importance for pharmacokinetics in vivo Using accumulation assays in MDCK cells overexpressing selected ABC or SLC drug transporters, we revealed rilpivirine as a potent inhibitor of MDR1 and BCRP, but not MRP2, OCT1, OCT2, or MATE1. Subsequent transport experiments across monolayers of MDCKII-MDR1, MDCKII-BCRP, and Caco-2 cells demonstrated that rilpivirine inhibits MDR1- and BCRP-mediated efflux of abacavir and increases its transmembrane transport. In vivo experiments in male Wistar rats confirmed inhibition of MDR1/BCRP in the small intestine, leading to a significant increase in oral bioavailability of abacavir. In conclusion, rilpivirine inhibits MDR1 and BCRP transporters and may affect pharmacokinetic behavior of concomitantly administered substrates of these transporters, such as abacavir.

• Klíčová slova
• ABC transporters, abacavir, drug transporter, drug-drug interactions, oral bioavailability, pharmacokinetics, rilpivirine,
• MeSH
• ABC transportér z rodiny G, člen 2 metabolismus   MeSH
• biologický transport fyziologie   MeSH
• buněčné linie MeSH
• buňky MDCK MeSH
• Caco-2 buňky MeSH
• dideoxynukleosidy metabolismus   farmakologie   MeSH
• inhibitory reverzní transkriptasy metabolismus   farmakologie   MeSH
• intestinální absorpce fyziologie   MeSH
• krysa rodu Rattus MeSH
• lamivudin metabolismus   farmakologie   MeSH
• lékové interakce fyziologie   MeSH
• lidé MeSH
• membránové transportní proteiny metabolismus   MeSH
• nádorové buněčné linie MeSH
• P-glykoprotein metabolismus   MeSH
• potkani Wistar MeSH
• psi MeSH
• rilpivirin metabolismus   farmakologie   MeSH
• zvířata MeSH
• Check Tag
• krysa rodu Rattus MeSH
• lidé MeSH
• mužské pohlaví MeSH
• psi MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• abacavir MeSH Prohlížeč
• ABC transportér z rodiny G, člen 2 MeSH
• dideoxynukleosidy MeSH
• inhibitory reverzní transkriptasy MeSH
• lamivudin MeSH
• membránové transportní proteiny MeSH
• P-glykoprotein MeSH
• rilpivirin MeSH

Cyclin-dependent kinase inhibitors (CDKi) have high potential applicability in anticancer therapy, but various aspects of their pharmacokinetics, especially their interactions with drug efflux transporters, have not yet been evaluated in detail. Thus, we investigated interactions of five CDKi (purvalanol A, olomoucine II, roscovitine, flavopiridol and SNS-032) with the ABCB1 transporter. Four of the compounds inhibited efflux of two ABCB1 substrates, Hoechst 33342 and daunorubicin, in MDCKII-ABCB1 cells: Olomoucine II most strongly, followed by roscovitine, purvalanol A, and flavopiridol. SNS-032 inhibited ABCB1-mediated efflux of Hoechst 33342 but not daunorubicin. In addition, purvalanol A, SNS-032 and flavopiridol lowered the stimulated ATPase activity in ABCB1 membrane preparations, while olomoucine II and roscovitine not only inhibited the stimulated ATPase but also significantly activated the basal ABCB1 ATPase, suggesting that these two CDKi are ABCB1 substrates. We further revealed that the strongest ABCB1 inhibitors (purvalanol A, olomoucine II and roscovitine) synergistically potentiate the antiproliferative effect of daunorubicin, a commonly used anticancer drug and ABCB1 substrate, in MDCKII-ABCB1 cells as well as in human carcinoma HCT-8 and HepG2 cells. We suggest that this pronounced synergism is at least partly caused by (i) CDKi-mediated inhibition of ABCB1 transporter leading to increased intracellular retention of daunorubicin and (ii) native cytotoxic activity of the CDKi. Our results indicate that co-administration of the tested CDKi with anticancer drugs that are ABCB1 substrates may allow significant dose reduction in the treatment of ABCB1-expressing tumors.

• MeSH
• adenosintrifosfatasy metabolismus   MeSH
• buněčná membrána účinky léků   metabolismus   MeSH
• buněčné linie MeSH
• cyklin-dependentní kinasy antagonisté a inhibitory   MeSH
• daunomycin farmakologie   MeSH
• inhibitory proteinkinas farmakologie   MeSH
• lidé MeSH
• messenger RNA genetika   metabolismus   MeSH
• P-glykoproteiny antagonisté a inhibitory   genetika   MeSH
• proliferace buněk účinky léků   MeSH
• protinádorové látky farmakologie   MeSH
• puriny farmakologie   MeSH
• regulace genové exprese účinky léků   MeSH
• roskovitin MeSH
• synergismus léků MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• 6-((3-chloro)anilino)-2-(isopropyl-2-hydroxyethylamino)-9-isopropylpurine MeSH Prohlížeč
• ABCB1 protein, human MeSH Prohlížeč
• adenosintrifosfatasy MeSH
• cyklin-dependentní kinasy MeSH
• daunomycin MeSH
• inhibitory proteinkinas MeSH
• messenger RNA MeSH
• olomoucine II MeSH Prohlížeč
• P-glykoproteiny MeSH
• protinádorové látky MeSH
• puriny MeSH
• roskovitin MeSH