Differential effect of P-gp and MRP2 on cellular translocation of gemifloxacin.

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Vadlapatla RK, Vadlapudi AD, Kwatra D, Pal D, Mitra AK

Differential effect of P-gp and MRP2 on cellular translocation of gemifloxacin.

Int J Pharm. 2011 Nov 25;420(1):26-33. doi: 10.1016/j.ijpharm.2011.08.009. Epub 2011 Aug 16.

PubMed ID

21864659 [ View in PubMed

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Abstract

Fluoroquinolones are broad spectrum antibiotics widely indicated in the treatment of both human and animal diseases. The primary objective of this study was to assess short and long term affinities of gemifloxacin towards efflux transporters (P-gp, MRP2) and nuclear hormone receptor (PXR). Uptake and dose dependent inhibition studies were performed with [(14)C] erythromycin (0.25 muCi/ml) on MDCKII-MDR1 and MDCKII-MRP2 cells. Cellular accumulation of calcein-AM was further determined to confirm the affinity of gemifloxacin towards P-gp and MRP2. Transport studies were conducted to determine bi-directional permeability and to assess efflux ratio of gemifloxacin. LS-180 cells were treated with three different concentrations of gemifloxacin for 72 h and real-time PCR analysis was performed to study the quantitative gene expression levels of PXR, MDR1 and MRP2. Further, [(14)C] erythromycin uptake was also performed on LS-180 treated cells to better delineate the functional activity of efflux transporters. Results from our study suggest that gemifloxacin may be a substrate of both the efflux transporters studied. This compound inhibited both P-gp and MRP2 mediated efflux of [(14)C] erythromycin in a dose dependent manner with IC(50) values of 123 +/- 2 muM and 16 +/- 2 muM, respectively. The efflux ratio of [(14)C] erythromycin lowered from 3.56 to 1.63 on MDCKII-MDR1 cells and 4.93 to 1.26 on MDCKII-MRP2 cells. This significant reduction in efflux ratio further confirmed the substrate specificity of gemifloxacin towards P-gp and MRP2. Long term exposure significantly induced the expression of PXR (18 fold), MDR1 (6 fold) and MRP2 (6 fold). A decrease (20%) in [(14)C] erythromycin uptake further confirmed the elevated functional activity of P-gp and MRP2. In conclusion, our studies demonstrated that gemifloxacin is effluxed by both P-gp and MRP2. Long term exposure induced their gene expression and functional activity. This substrate specificity of gemifloxacin towards these efflux transporters may be one of the major factors accounting for low oral bioavailability (71%). Better understanding of these mechanistic interactions may aid in the development of newer strategies to achieve adequate therapeutic levels and higher bioavailability.

DrugBank Data that Cites this Article

Drug Transporters

Drug	Transporter	Kind	Organism	Pharmacological Action	Actions
Erythromycin	Canalicular multispecific organic anion transporter 1	Protein	Humans	Unknown	Substrate	Details
Erythromycin	P-glycoprotein 1	Protein	Humans	No	Substrate Inhibitor	Details