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Drug Efflux (drug + efflux)

Distribution by Scientific Domains
Medical Sciences55%
Life Sciences22%
Chemistry22%

Terms modified by Drug Efflux

  • drug efflux pump
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  • drug efflux transporter
    		•

    Selected Abstracts

    PRECLINICAL STUDY: Disposition of ,9 tetrahydrocannabinol in CF1 mice deficient in mdr1a P-glycoprotein

    ADDICTION BIOLOGY, Issue 3-4 2008
    Laurence Bonhomme-Faivre
    ABSTRACT P-glycoprotein (P-gp) plays a major role in drug efflux. All the transported substrates are more or less hydrophobic and amphiphatic in nature. Being lipophilic, ,9 tetrahydrocannabinol (THC), the main cannabis component, could be a potential P-gp substrate. The aim of this project was to determine the contribution of the mdr1a gene product to THC disposition. Therefore, oral THC and digoxin (substrate test for P-gp) pharmacokinetics have been investigated in the intestinal epithelium and in the brain capillary endothelium of CF1 mdr1a (,/,) mice (mice naturally deficient in P-gp). These pharmacokinetics were compared to THC and digoxin oral pharmacokinetics in wild type mice mdr1a (+/+) (not P-gp deficient). The application of Bailer's method showed that THC total exposure measured by the area under the plasma concentration time curve was 2.17-fold higher in CF1 mice naturally deficient in P-gp than in wild type mice after oral administration of 25 mg/kg of THC, and 2.4-fold higher after oral administration of 33 µg/kg of digoxin. As a consequence, the oral bioavailability of THC and digoxin was higher in naturally P-gp-deficient mice. We concluded that P-gp limits THC oral uptake and mediates direct drug excretion from the systemic circulation into the intestinal lumen. [source]

    ABCG2 overexpression in colon cancer cells resistant to SN38 and in irinotecan-treated metastases

    INTERNATIONAL JOURNAL OF CANCER, Issue 6 2004
    Laurent Candeil
    Abstract Overcoming drug resistance has become an important issue in cancer chemotherapy. Among all known mechanisms that confer resistance, active efflux of chemotherapeutic agents by proteins from the ATP-binding cassette family has been extensively reported. The aim of the present study was to determine the involvement of ABCG2 in resistance to SN38 (the active metabolite of irinotecan) in colorectal cancer. By progressive exposure to increasing concentrations of SN38, we isolated 2 resistant clones from the human colon carcinoma cell line HCT116. These clones were 6- and 53-fold more resistant to SN38 than the HCT116-derived sensitive clone. Topoisomerase I expression was unchanged in our resistant variants. The highest resistance level correlated with an ABCG2 amplification. This overexpression was associated with a marked decrease in the intracellular accumulation of SN38. The inhibition of ABCG2 function by Ko143 demonstrated that enhanced drug efflux from resistant cells was mediated by the activity of ABCG2 protein and confirmed that ABCG2 is directly involved in acquired resistance to SN38. Furthermore, we show, for the first time in clinical samples, that the ABCG2 mRNA content in hepatic metastases is higher after an irinotecan-based chemotherapy than in irinotecan-naive metastases. In conclusion, this study supports the potential involvement of ABCG2 in the development of irinotecan resistance in vivo. © 2004 Wiley-Liss, Inc. [source]

    Multidrug resistance in haematological malignancies

    JOURNAL OF INTERNAL MEDICINE, Issue 5 2000
    P. Sonneveld
    Abstract. Sonneveld P (University Hospital Rotterdam , Dijkzigt, The Netherlands). Multidrug resistance in haematological malignancies (Internal Medicine in the 21st Century). J Intern Med 2000; 247: 521,534. The development of refractory disease in acute myeloid or lymphoblastic leukaemias (AML, ALL) and multiple myeloma (MM) is frequently associated with the expression of one or several multidrug resistance (MDR) genes. MDR1, MRP1 and LRP have been identified as important adverse prognostic factors in AML, T-ALL and MM. Recently, it has become possible to reverse clinical multidrug resistance by blocking P-glycoprotein-mediated drug efflux. The potential relevance of these reversal agents of MDR and potential new approaches to treat refractory disease are discussed. [source]

    Modulation of P-glycoprotein activity by acridones and coumarins from Citrus sinensis

    PHYTOTHERAPY RESEARCH, Issue 4 2007
    C. Bayet
    Abstract Bioguided fractionation of the roots of Citrus sinensis (Rutaceae) led to the isolation and identification of five coumarins, namely, clausarin, suberosin, poncitrin, xanthyletin and thamnosmonin, seven acridones, namely, acrimarine B, 2-methoxycitpressine I, citpressine I, buntanine, acrimarine E, honyumine and acrimarine C, and one terpenoid, namely, limonin. Among these compounds, clausarin, 2-methoxycitpressine I and acrimarine E inhibited P-glycoprotein-mediated drug efflux in K562/R7 human leukemic cells over-expressing P-glycoprotein. Copyright © 2007 John Wiley & Sons, Ltd. [source]

    Differential pharmacological regulation of drug efflux and pharmacoresistant schizophrenia

    BIOESSAYS, Issue 2 2008
    Mary Bebawy
    Pharmacoresistant schizophrenia is a significant impediment to the successful management of the disease. The expression and function of P-glycoprotein (P-gp) has recently been implicated in this phenomenon. P-gp is a multidrug efflux transporter that prevents drug substrates from crossing the blood,brain barrier (BBB). Although the direct interaction between individual antipsychotic agents and P-gp has been demonstrated, the effect of antipsychotic drug combinations used in disease management on P-gp transport function remains to be elucidated. This could have important clinical implications in some individuals as dosage adjustments based on plasma drug concentration changes may not always be appropriate if drug,drug interactions and the resulting changes in drug concentration in the brain are not considered. This paper introduces the potential impact that combination antipsychotic therapy may have on P-gp function at the BBB and discusses the consequences of this in the prevention and circumvention of unfavourable therapeutic response in schizophrenic disorders. BioEssays 30:183,188, 2008. © 2008 Wiley Periodicals, Inc. [source]

    Contrasting in vitro effects for the combination of fludarabine, cytosine arabinoside (Ara-C) and granulocyte colony-stimulating factor (FLAG) compared with daunorubicin and Ara-C in P-glycoprotein-positive and P-glycoprotein-negative acute myeloblastic leukaemia

    BRITISH JOURNAL OF HAEMATOLOGY, Issue 2 2000
    Y. Higashi
    It has been suggested that the FLAG remission induction regimen comprising fludarabine (F-ara), cytosine arabinoside (Ara-C) and granulocyte colony-stimulating factor (G-CSF) may be capable of overcoming P-glycoprotein (P-gp)-related multidrug resistance (MDR) in patients with acute myeloblastic leukaemia (AML). We have investigated the in vitro response of P-gp-positive and -negative AML clones to FLAG and compared this with their response to treatment with Ara-C and daunorubicin (DNR). Twenty-four cryopreserved samples from patients with AML were studied using a flow cytometric technique for the enumeration of viable (7-amino actinomycin D negative) cells. Samples consisted of 12 P-gp-positive and 12 P-gp-negative cases, as measured by the MRK16 antibody. The results were analysed by calculating the comparative drug resistance (CDR), i.e. the percentage cell death caused by Ara-C + DNR subtracted from the percentage cell death, caused by FLAG after 48 h incubation in suspension culture. P-gp-positive clones were shown to have a significantly higher CDR than P-gp-negative clones (P = 0·001). Furthermore, a significant positive correlation (r2 = 0·40, P < 0·01) was found between P-gp protein expression and CDR. However, P-gp function, measured using cyclosporin modulation of rhodamine 123 (R123) uptake, was not associated with the CDR, demonstrating that there are other properties of P-gp, besides its role in drug efflux, that modulate the responsiveness of AML blasts to chemotherapy. These results are consistent with a potential benefit for FLAG in P-gp-positive AML, but not P-gp-negative AML, compared with standard anthracycline and Ara-C therapy. [source]

    Reversing Effect of Agosterol A, a Spongean Sterol Acetate, on Multidrug Resistance in Human Carcinoma Cells

    CANCER SCIENCE, Issue 8 2001
    Shunji Aoki
    The effect of agosterol A, a novel polyhydroxylated sterol acetate isolated from a marine sponge, on P-glycoprotein (P-gp)-mediated multidrug-resistant cells (KB-C2) and the multidrug resistance associated protein (MRPl)-mediated multidrug-resistant cells (KB-CV60) was examined. Agosterol A reversed the resistance to colchicine in KB-C2 cells and also the resistance to vincristine in KB-CV60 cells at 3 to 10 ,M concentration. Agosterol A at 3 ,M increased the vincristine concentration in both KB-C2 cells and KB-CV60 cells to the level in parental KB-3-1 cells. Agosterol A also decreased the efflux of vincristine from both KB-C2 cells and KB-CV60 cells to the level seen in KB-3-1 cells. Agosterol A inhibited the [3H]azidopine-photolabeling of P-gp and also inhibited the uptake of [3H]S-(2,4-dinitrophenyl)glutathione (DNP-SG) in inside-out membrane vesicles prepared from KB-CV60 cells. We conclude that agosterol A directly inhibited drug efflux through P-gp and/or MRP1. [source]

    Total Synthesis and Biological Assessment of Benzimidazole-Based Analogues of Epothilone A: Ambivalent Effects on Cancer Cell Growth Inhibition

    CHEMBIOCHEM, Issue 1 2006
    Fréderic Cachoux Dr.
    Benzimidazole-based analogues of cis - and trans -Epo A, 2 and 3, have been prepared through stereoselective total synthesis. Both compounds are highly potent antiproliferative agents, but the effects of side-chain replacement on cellular activity are ambivalent. While significantly enhanced potency is observed against a drug-sensitive human cancer cell line, 2 and 3 more susceptible to P-gp-mediated drug efflux than Epo A or trans -Epo A. [source]

    Synthesis and Biological Evaluation of New Geiparvarin Derivatives

    CHEMMEDCHEM, Issue 5 2009
    Stefano Chimichi Prof.
    Abstract New geiparvarin derivatives modified at the alkenyloxy bridge, where the 3,-methyl group was replaced by a hydrogen atom, were synthesized and evaluated against a panel of human tumor cell lines in,vitro. Compounds (R)- 4 and (R)- 5 show greater inhibitory activity toward cell growth than the parent geiparvarin. New geiparvarin derivatives modified at the unsaturated alkenyloxy bridge, where a hydrogen atom replaces the 3,-methyl group, were synthesized and evaluated against a panel of human tumor cell lines in,vitro. These compounds demonstrated an increase in growth inhibitory activity relative to the parent compound, geiparvarin. The activity increased even further in the series of demethylated compounds, with the introduction of a methyl group at the 1,-position of the alkenyloxy chain. In contrast, a remarkable decrease in activity was observed with the introduction of a methyl group at the 2,-position. Interestingly, the new derivatives fully inhibited the growth of drug-resistant cell lines, suggesting that they are not subject to pump-mediated drug efflux. On the basis of their cytotoxic profiles, the most active compounds (R)- 4 and (R)- 5 were selected for further biological evaluation in comparison with the lead compound. The new derivatives strongly induce apoptosis in a promyelocytic leukemia cell line (HL-60) mediated by depolarization of mitochondrial transmembrane potential and mitochondrial production of reactive oxygen species (ROS). [source]