Hubensack, Martina and Müller, Christine and Höcherl, Höcherl and Fellner, Stephan and Spruss, Thilo and Bernhardt, Günther and Buschauer, Armin (2008) Effect of the ABCB1 modulators elacridar and tariquidar on the distribution of paclitaxel in nude mice. Journal of Cancer Research and Clinical Oncology 134 (5), pp. 597-607.
PURPOSE: Previously, we studied the effect of co-administration of paclitaxel with the second generation ABCB1 (p-gp) modulator valspodar on the intracerebral growth of human U118-MG glioblastoma in nude mice. Valspodar significantly increased the brain levels of paclitaxel by inhibition of p-gp expressed at the blood brain barrier. Thus, the tumour burden was reduced by 90%, which was considered as a proof of concept. However, the paclitaxel dose had to be reduced because of toxic side effects resulting from increased drug levels due to p-gp modulation in peripheral tissues. Therefore, in the present study we examined the co-application of paclitaxel with the third generation ABCB1 modulators elacridar and tariquidar, which were supposed to preferentially modulate p-gp in brain capillaries. METHODS: The inhibitory activity of the modulators was measured by a flow cytometric and a chemosensitivity assay in vitro. To determine the distribution of paclitaxel in vivo, nude mice received 50 mg/kg of valspodar, elacridar or tariquidar p.o. (control: vehicle) 4 h before i.v. injection of 8 mg/kg of paclitaxel. Brain, liver, kidney and plasma were collected and analyzed by RP-HPLC. RESULTS: Our in vitro experiments demonstrate that the new modulators are about 80 times more effective in comparison to valspodar. Co-administration of paclitaxel with elacridar and tariquidar led to a long lasting fivefold increase in the concentration of the cytostatic in the brain. Although the increase (2.5- to 7-fold) tended to be lower compared to that induced by co-administered valspodar (six- to eightfold), the brain/plasma ratios achieved with the new modulators were 2-15 times higher. CONCLUSIONS: Elacridar and tariquidar seem to modulate p-glycoprotein preferentially at the blood-brain barrier. Our results suggest that the systemic toxicity of cytostatics combined with elacridar or tariquidar should be lower than in combination with valspodar.
|Institutions:||Chemistry and Pharmacy > Institute of Pharmacy > Pharmaceutical/Medicinal Chemistry II (Prof. Buschauer)|
|Subjects:||500 Science > 570 Life sciences|
600 Technology > 610 Medical sciences Medicine
|Refereed:||Yes, this version has been refereed|
|Created at the University of Regensburg:||Yes|
|Owner:||Prof. Armin Buschauer|
|Deposited On:||20 Feb 2008 15:51|
|Last Modified:||20 Jul 2011 21:14|