Possible Interaction: Epirubicin and Quinidine

“The result demonstrated that verapamil, quinidine , tamoxifen, and oligomycin had an additive effect on the cytotoxicity of adriamycin and vinblastine against RCC8701 and RCC8701/ADR800 tumor cells.”

“Results highlight the utility of quinidine as a drug response modulator in a schedule-dependent manner to potentiate the cytotoxicity of ADR and MITO and warrants further studies into a possible role of quinidine to increase the chemotherapeutic efficacy of antineoplastic drugs in the clinics.”

“(2) Although both tea polyphenol and quinidine could not remarkably change the toxicity of adriamycin to MCF-7, they could improve the sensitivity of MCF-7/Adr to adriamycin.”

“A non-toxic concentration of quinidine (5 microM) enhanced the DNA biosynthesis inhibition induced by ADR (55 to 65%) and MITO (37 to 44%) in P388/ADR cells, indicating reversal of resistance, while in P388/S cells only a minimal increase in DNA biosynthesis inhibition was observed.”

“ Quinidine enhanced the cytotoxicity of both ADR and MITO in P388/S and P388/ADR cells, as assessed by the decrease in color intensity of formazan crystal in the MTT (3-[4,5-dimethylthiazol-2-yl]-2,5 diphenyl tetrazolium bromide) assay.”

“ Quinidine increased the cellular levels of ADR by 53 to 126% in P388/ADR cells in vitro, but failed to indicate such elevated levels of cellular ADR in P388/S cells.”

“The combination of quinidine at doses of 50 to 100 mg/kg significantly potentiated the antitumor activity of ADR and MITO in P388/ADR bearing mice, whereas the potentiation of ADR and MITO antitumor response was lower in P388/S bearing mice.”

“The antiarrhythmic drug, quinidine , and the detergent, Tween 80, also potentiated ADR activity in P388R cells to the same extent as VER.”

“ Quinidine also enhanced the cytotoxicity of Adriamycin , especially in the Adriamycin-resistant subline of P388 leukemia; this enhancement (8-fold) was less than that of VCR toxicity in the VCR-resistant tumor line.”