Assessment of the ex vivo interaction of antiparasitic drugs with efflux transporter proteins in rat intestine.

BALLENT, M.; LIFSCHITZ, A.; VIRKEL, G.; SALLOVITZ, J.; MATÉ, L.; LANUSSE, C.

Buenos Aires

Congreso; 22th International Conference of the World Association for the Advancement of; 2011

Transport proteins play an important role in the intestinal secretion of different drug molecules widely used in veterinary therapeutics. An active intestinal efflux of different antiparasitic compounds has been described. Although the main interaction of such drugs with efflux transporters seems to be mediated by P-gp, the tissue distribution of the breast cancer resistance protein (BCRP) overlaps extensively with that of P-gp, suggesting a similar role in substrate transport. The aim of the study was to characterize the ex vivo interaction of ivermectin and moxidectin with the efflux transporters P-gp and BCRP. The intestinal transport studies were carried out by the Ussing chamber technique. The ileal segment obtained from male Wistar rats was opened along the mesenteric border and the resulting flat sheets of gut mucosa were mounted into the Ussing-chambers. After a 20 min equilibrium period, rhodamine 123 (Rho 123) (5 µM) as P-gp substrate, and danofloxacin (DFX) (50 µM) as a BCRP substrate, were added to both mucosal (M) and serosal (S) sides. Ivermectin (IVM) and moxidectin (MXD), used as inhibitors, were added at equimolar concentrations (10 µM). Additionally, PSC833 and pantoprazole (PTZ) were used as specific P-gp and BCRP inhibitors, respectively. The amount of permeated Rho 123 and DFX was determined by spectrofluorometric detection. The apparent permeability coefficients per unit of membrane surface area (Peff) (cm/s) were calculated. The efflux transport of Rho 123 and DFX in rat intestine was demonstrated (Efflux ratio of 4.26 and 4.38 respectively). The Peff S-M (secretion) of Rho 123 was significantly reduced (P<0.05) by IVM, whereas no differences were observed for MXD. On the other hand, the DFX efflux ratio (PeffS-M/PeffM-S) was significantly reduced by both IVM (1.24) and MXD (1.67) compared to the control, suggesting inhibition of the active secretion process. The work permitted to demonstrate the ileal permeability of the efflux transporter substrates. The antiparasitic molecules under study showed a differential inhibitory effect on P-gp and BCRP-mediated intestinal transport. These preliminary results demonstrated the usefulness of this experimental approach for testing the mechanisms involved in the absorption/excretion processes for anthelmintic drugs, which may have therapeutic relevance.