Febuxostat, But Not Allopurinol, Markedly Raises the Plasma Concentrations of the Breast Cancer Resistance Protein...

Xanthine oxidase inhibitors febuxostat and allopurinol are commonly used in the treatment of gout. Febuxostat inhibits the breast cancer resistance protein (BCRP) in vitro. Rosuvastatin is a BCRP substrate and genetic variability in BCRP markedly affects rosuvastatin pharmacokinetics. In this study, we investigated possible effects of febuxostat and allopurinol on rosuvastatin pharmacokinetics. In a randomized crossover study with 3 phases, 10 healthy volunteers ingested once daily placebo for 7 days, 300 mg allopurinol for 7 days, or placebo for 3 days, followed by 120 mg febuxostat for 4 days, and a single 10 mg dose of rosuvastatin on day 6. Febuxostat increased the peak plasma concentration and area under the plasma concentration-time curve of rosuvastatin 2.1-fold (90% confidence interval 1.8-2.6; P = 5 × 10^-5 ) and 1.9-fold (1.5-2.5; P = 0.001), but had no effect on rosuvastatin half-life or renal clearance. Allopurinol, on the other hand, did not affect rosuvastatin pharmacokinetics. In vitro, febuxostat inhibited the ATP-dependent uptake of rosuvastatin into BCRP-overexpressing membrane vesicles with a half-maximal inhibitory concentration of 0.35 µM, whereas allopurinol showed no inhibition with concentrations up to 200 µM. Taken together, the results suggest that febuxostat increases rosuvastatin exposure by inhibiting its BCRP-mediated efflux in the small intestine. Febuxostat may, therefore, serve as a useful index inhibitor of BCRP in drug-drug interaction studies in humans. Moreover, concomitant use of febuxostat may increase the exposure to BCRP substrate drugs and, thus, the risk of dose-dependent adverse effects.