Our findings indicate that MATEs account for the efflux of thiamine and perhaps carnitine as well as drugs into the urine. The urinary excretion of thiamine is useful to detect drug interaction involving MATEs in the kidney.

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Telaprevir-based triple therapy is a highly effective treatment for chronic hepatitis C. However, adverse reactions include reversible and dose-dependent elevation of serum creatinine levels. We speculated that this effect reflects inhibition of the renal organic cation transporters hOCT2, hMATE1, and hMATE2-K by telaprevir or its metabolites (VRT-127394 and VRT-0922061). Telaprevir, VRT-127394, and VRT-0922061 showed negligible or weak effects on hOCT2 at concentrations of ≥20 µM, but inhibited hMATE1 by 35, 38, and 53% and hMATE2-K by 47, 45, and 61% at 100 µM, respectively. Telaprevir or its metabolites (10 µM) did not affect basal-to-apical transport of MPP(+) across monolayers of hOCT2-hMATE1 double-transfected MDCKII cells, whereas pyrimethamine, a potent inhibitor of hMATE1, markedly inhibited MPP(+) transport. Taken together, inhibition of hOCT2, hMATE1, and hMATE2-K is unlikely to be clinically relevant because unbound plasma concentrations of telaprevir and its metabolites reach only 2 µM following oral administration of a dose of 750 mg telaprevir. Hence, elevated serum creatinine during telaprevir therapy may not be related to direct inhibition of renal organic cation transporters.

This study aimed to investigate the interactions of 3 anticoagulants, rivaroxaban, apixaban, and dabigatran, with 5 human solute carrier transporters, hOAT1, hOAT3, hOCT2, hOATP1B1, and hOATP1B3. Apixaban inhibited hOAT3, hOATP1B1, and hOATP1B3, and rivaroxaban inhibited hOAT3 and hOATP1B3, with IC values of >20 and >5 μM, respectively. The effect of dabigatran was negligible or very weak, so significant drug interactions at therapeutic doses are unlikely. Specific uptake of rivaroxaban was observed only in human and mouse OAT3-expressing cells. The K for mouse Oat3 (mOat3) was 1.01 ± 0.70 μM. A defect in mOat3 reduced the kidney-to-plasma concentration ratio of rivaroxaban by 38% in mice. Probenecid treatment also reduced the kidney-to-plasma concentration ratio of rivaroxaban in rats by 73%. Neither mOat3 defect nor probenecid administration in rats reduced the renal clearance of rivaroxaban. The uptake of rivaroxaban by monkey kidney slices was temperature dependent and inhibited by probenecid but not by tetraethylammonium. Taken together, organic anion transporters, mainly OAT3, may mediate basolateral uptake of rivaroxaban in kidneys. hOAT3 could be an additional factor that differentiates the potential drug-drug interactions of the 3 anticoagulants in the urinary excretion process in clinical settings.