MDR1 and BCRP Transporter-Mediated Drug-Drug Interaction between Rilpivirine and Abacavir and Effect on Intestinal Absorption

Abstract

Rilpivirine (TMC278) is a highly potent nonnucleoside reverse transcriptase inhibitor (NNRTI) representing an effective component of combination antiretroviral therapy (cART) in the treatment of HIV-positive patients. Many antiretroviral drugs commonly used in cART are substrates of ATP-binding cassette (ABC) and/or solute carrier (SLC) drug transporters and, therefore, are prone to pharmacokinetic drug-drug interactions (DDIs). The aim of our study was to evaluate rilpivirine interactions with abacavir and lamivudine on selected ABC and SLC transporters in vitro and assess its importance for pharmacokinetics in vivo Using accumulation assays in MDCK cells overexpressing selected ABC or SLC drug transporters, we revealed rilpivirine as a potent inhibitor of MDR1 and BCRP, but not MRP2, OCT1, OCT2, or MATE1. Subsequent transport experiments across monolayers of MDCKII-MDR1, MDCKII-BCRP, and Caco-2 cells demonstrated that rilpivirine inhibits MDR1- and BCRP-mediated efflux of abacavir and increases its transmembrane transport. In vivo experiments in male Wistar rats confirmed inhibition of MDR1/BCRP in the small intestine, leading to a significant increase in oral bioavailability of abacavir. In conclusion, rilpivirine inhibits MDR1 and BCRP transporters and may affect pharmacokinetic behavior of concomitantly administered substrates of these transporters, such as abacavir.

Keywords: ABC transporters; abacavir; drug transporter; drug-drug interactions; oral bioavailability; pharmacokinetics; rilpivirine.

FIG 1

Inhibitory effect of rilpivirine on efflux of Hoechst 33342 (80 μM) from MDCK-MDR1 (A), MDCK-BCRP (E), and MDCK-PAR (B and F) cell lines; efflux of rhodamine 123 (10 μM) from MDCK-MDR1 (C) and MDCK-PAR (D) cells; and efflux of calcein AM (0.25 μM) from MDCK-MRP2 (G) and MDCK-PAR (H) cell lines. LY335979 (1 μM), Ko143 (2.5 μM), and MK-571 (50 μM), the model inhibitors of MDR1, BCRP, and MRP2, respectively, were used as positive controls. Data are shown as mean values ± SD from at least three experiments performed in triplicate. Statistical significance was analyzed by one-way ANOVA followed by Bonferroni's test. **, P ≤ 0.01; ***, P ≤ 0.001.

FIG 2

Effect of rilpivirine on accumulation of ASP⁺ (1 μM) in MDCK-OCT1 (A), MDCK-OCT2 (B), MDCK-MATE1 (C), and MDCK-Co (D) cell lines. Mitoxantrone (MTX), a model inhibitor of OCT1, OCT2, and MATE1, was used as a positive control at a concentration of 2 μM. Data are shown as mean values ± SD from four experiments performed in triplicate. Statistical significance was analyzed by one-way ANOVA followed by Bonferroni's test. ***, P ≤ 0.001.

FIG 3

Concentration equilibrium assay of [³H]abacavir (300 nM) in MDCK-MDR1 (A) and MDCK-BCRP (B) cells. The percentage of initial concentration (C₀) of abacavir obtained in the basolateral (black columns) or apical compartment (white columns) after 6 h of incubation with or without rilpivirine is shown. LY335979 (1 μM) or Ko143 (2.5 μM) was used as a positive control. The ratio (r_e) between concentrations in the apical and basolateral compartments measured at the end of the experiment is shown. Data are shown as mean values ± SD from three experiments performed in duplicate. Statistical significance was analyzed by Student's t test. ***, P ≤ 0.001; ns, not significant.

FIG 4

Effect of 10 μM rilpivirine and 2 μM GF120918 on bidirectional permeation of 300 nM abacavir through Caco-2 monolayers. Apical-to-basolateral (A-to-B) P_app (black columns) or basolateral-to-apical (B-to-A) P_app (white columns) after 1 h of incubation with or without rilpivirine or GF120918 is shown. The efflux ratio (ER) was defined as the B-to-A P_app divided by the A-to-B P_app. Data are shown as mean values ± SD from three experiments performed in duplicate. Statistical significance was analyzed by Student's t test. ***, P ≤ 0.001; ns, not significant.

FIG 5

Influence of rilpivirine (300 μM) on plasma concentration of abacavir (300 μM) after i.d. administration. Data are shown as means ± SD (n = 6). Statistical significance was analyzed by unpaired t test. *, P ≤ 0.05. The rilpivirine AUC_{0–240 min} was calculated using the trapezoid rule, where the formula ΔX × (Y1 + Y2)/2 was used repeatedly by GraphPad Prism 6.0 software (GraphPad Software, Inc., San Diego, CA, USA).