Metabolic Fate of Pitavastatin, a New Inhibitor of HMG-CoA Reductase—Effect of cMOAT Deficiency on Hepatobiliary Excretion in Rats and of mdr 1a/b Gene Disruption on Tissue Distribution in Mice

Abstract

Pitavastatin is a potent competitive inhibitor of HMG-CoA reductase. In the current study, to elucidate the hepatobiliary excretion of pitavastatin, we investigated the plasma concentration and biliary excretion of 14C-pitavastatin in EHBR. We also evaluated the distribution of pitavastatin in mdr1a/b knockout mice by whole body autoradiography and quantitative radioassay. In view of the widespread clinical use of pitavastatin and the importance of drug-drug interaction, the inhibitory effect on Pgp-mediated activation of ATPase was also investigated. No marked difference was observed in the plasma concentration and biliary excretion of radioactivity between SDR and EHBR after dosing of 14C-pitavastatin. Little radioactive transfer into the brain was detected in mdr1a/b knockout mice and the ATPase activity of human Pgp was negligible in the presence of pitavastatin. Moreover, no inhibitory effect on the Pgp-mediated activation of ATPase by verapamil was found in the presence of pitavastatin over a wide concentration range. These results indicated that a cMOAT and Pgp-mediated transport mechanism did not play a major role in the distribution of pitavastatin.