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

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 affinity of gemifloxacin towards efflux transporters (P-gp, MRP2) and nuclear hormone receptor (PXR). Uptake and dose dependent inhibition studies were performed with [14C] erythromycin (0.25μCi/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 72hrs and real-time PCR analysis was performed to study the quantitative gene expression levels of PXR, MDR1 and MRP2. Further, [14C] 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 [14C] erythromycin in a dose dependent manner with IC50 values of 123 ± 2μM and 16 ± 2μM, respectively. The efflux ratio of [14C] 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 [14C] 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.

Sodium Dependent Multivitamin Transporter (SMVT): A Potential Target for Drug Delivery

“…Hydrophilic drug molecules which fail to efficiently permeate biological lipid membrane can be conveniently delivered via transporter targeted delivery systems [20–23]. Especially, compounds which serve as substrates for efflux transporters or metabolizing enzymes could be efficiently delivered via this approach [10, 11, 24, 25]. Targeting nutrient transporters has emerged as an exciting strategy to enhance bioavailability of poorly permeating drugs.…”

Prodrug approach to improve absorption of prednisolone

“…Interactions of VVP, VP and prednisolone with P-gp have been examined by uptake and transport studies across MDCK-MDR1 cells. This transfected cell line has been selected as it has been extensively employed to delineate P-gp interaction and transport of a wide range of compounds in our laboratory (Jain et al, 2004; Luo et al, 2011; Minocha et al, 2012; Patel et al, 2014a; Patel et al, 2014b; Patel et al, 2014c; Vadlapatla et al, 2011). The regeneration of prednisolone from VVP has been examined by conducting SIRC cell homogenate study.…”

Targeted lipid based drug conjugates: A novel strategy for drug delivery

“…The study is performed using the similar procedure described earlier in section 2.6. The data is fitted to calculate the half maximal inhibitory concentration (IC 50 ) following a previously published method (Kwatra et al, 2010; Vadlapatla et al, 2011). …”