An in vitro study was carried out in order to examine the metabolic basis of the interaction between fibrates and statins. Metabolic inhibition of statins was noted in the presence of gemfibrozil. However, increase in the unchanged form was fairly small for pitavastatin, compared with other statins. Several CYP enzymes were shown to be principally responsible for the metabolism of gemfibrozil in contrast to other fibrates. In the presence of gemfibrozil, a focal point was obtained in Dixon plots, demonstrating that there was inhibition of CYP2C8-, CYP2C9- and CYP3A4-mediated metabolism. We propose that the increase of plasma concentration caused by co-administration of gemfibrozil and statins is at least partially due to CYP-mediated inhibition.