Interactions of Fluoroquinolone Antibacterials, DX-619 and Levofloxacin, with Creatinine Transport by Renal Organic Cation Transporter hOCT2

Summary:Interactions of DX-619, a novel fluoroquinolone antibacterial, and levofloxacin (LVFX) with the human renal organic cation transporter hOCT2 were studied. The intracellular accumulation of [14 C]creatinine in stable transfectants of HEK293 cells expressing hOCT2 (hOCT2-HEK293) as well as vector-transfected HEK293 cells (VEC-HEK293) was evaluated in the presence of DX-619 and LVFX at various concentrations. When added extracellularly, both DX-619 and LVFX inhibited the uptake of [14 C]creatinine (5 μM) by hOCT2-HEK293 cells in a dose-dependent manner. Unlike in hOCT2-HEK293 cells, the uptake in VEC-HEK293 cells was not inhibited by either fluoroquinolone suggesting that hOCT2 was specifically involved in the inhibition. The apparent IC 50 value for the inhibition of [14 C]creatinine uptake in hOCT2-HEK293 cells was 1.29± 0.23 μM for DX-619 and 127± 27 μM for LVFX, indicating DX-619 to be ~ 100-fold more potent than LVFX at inhibiting the transport of [14 C]creatinine by hOCT2. A Dixon plot revealed that the inhibition by DX-619 of the hOCT2-mediated transport of [14 C]creatinine was competitive. Fluoroquinolone antibacterials have the ability to inhibit the transport of creatinine by hOCT2, with DX-619 being much more effective than LVFX.