Fig 1.
Inhibition of OCT1-, OCT2-, MATE1-, and MATE2-K-mediated net metformin uptake by efavirenz (0.01–50 μM) in MDCK-OCT1 (A), MDCK-OCT2 (B), MDCK-MATE1 (C), and HEK-MATE2-K (D) cells. Data are shown as means ± SD of at least four experiments performed in triplicate (MDCK cell lines) or three experiments performed in duplicate (HEK-MATE2-K cells). Calculated IC50 values and the associated 95% confidence intervals are shown where appropriate.
Fig 2.
Effect of efavirenz (10 μM) on transcellular transport of 2 nM[3H]-MPP+ (A) and 10 nM [3H]-lamivudine (C) from the basal to the apical compartment, and intracellular accumulation of [3H]-MPP+ (B) and [3H]-lamivudine (D) in monolayers of MDCK-OCT1, MDCK-OCT2, MDCK-MATE1, MDCK-OCT1-MATE1, MDCK-OCT2-MATE1, and control MDCK-Co cells over 2 hours. Data are shown as means ± SD of at least three independent experiments performed in duplicate. Results were analysed using the multiple t-test **P≤ 0.01 ***P ≤ 0.001.
Fig 3.
Inhibitory effect of efavirenz on MDR1, BCRP, and MRP2 transporters.
Efavirenz was applied at concentrations of 0.01–50 μM to evaluate its inhibition of Hoechst 33342 accumulation in the MDCK-MDR1 (A), MDCK-BCRP (B), and parental MDCK (C) cell lines, as well as its inhibition of calcein efflux from the MDCK-MRP2 (D) and parental MDCK (E) lines. Model inhibitors of MDR1, BCRP and MRP2, namely LY335979 (LY, 1 μM), Ko143 (2.5 μM), and MK571 (10 μM), respectively, were used as positive controls at the minimal concentrations causing maximal inhibition in the corresponding cellular system and assay. Relative and absolute IC50 values were calculated as the concentrations of efavirenz needed to achieve 50% transporter inhibition. The relative IC50 was determined from the maximum and minimum extremes of the relevant non-linear regression plot showing the inhibitory effect of efavirenz alone (maximal inhibition = 100%, non-inhibited control = 0%). The absolute IC50 was determined from the relevant non-linear regression plot of the inhibitory effect of the control inhibitor (100%) and the accumulation observed in control non-inhibited cells (0%). Data were analyzed by one-way ANOVA followed by Bonferroni’s multiple comparison test (* P ≤ 0.05, ** P ≤ 0.01, *** P ≤ 0.001) and are presented as means ± SD of at least three experiments (n = 3–5) performed in triplicate.
Fig 4.
Total recovery of [3H]-lamivudine from urine (A) and bile (C), and its accumulation in renal (B) and liver (D) tissue at 240 minutes after i.v. administration with or without co-administration of efavirenz (2.53 mg/kg) or cimetidine (a control inhibitor of the OCT and MATE transporters; 60,6 mg/kg). Data are shown as means ± SD (n = 5) and were analysed using one-way ANOVA followed by Dunnett`s multiple comparison test * P ≤ 0.05, *** P ≤ 0.001, n.s. not significant.
Table 1.
Effects of efavirenz and cimetidine on the pharmacokinetics of lamivudine in rats.