Effects of organic anions and bile acid conjugates on biliary excretion of pravastatin in the rat

Purpose, Biliary organic anion excretion is mediated by an ATP-dependent primary active transporter, a so-called canalicular multispecific organic anion transporter (cMOAT). As there appear to be many canalicular organic.anion transports, we examined the effects of various organic anions and bile acid conjugates on the biliary excretion of pravastatin in rats. Methods. [C-14]pravastatin was intravenously injected into rats with bile drainage in the presence and absence of the continuous infusion of organic anions and bile acids, and radioactivity of its biliary excretion was studied. Results, Biliary excretion of [C-14]pravastatin was markedly inhibited by sulfobromophthalein-glutathione, taurolithocholate-3-sulfate, ursodeoxycholate-3,7-sulfate, and ursodeoxycholate-3-O-glucuronide. In contrast, dibromosulfophthalein only slightly inhibited biliary pravastatin excretion, and cefpiramide did not affect biliary pravastatin excretion. Conclusions, These findings further support the multiplicity of canalicular organic anion transport, and pravastatin is considered to be excreted through a canalicular transporter which is absent in EHBR in addition to through cMOAT.