Conflicting alterations in hepatic expression of CYP3A and enzyme kinetics in rats exposed to 5-fluorouracil: relevance to pharmacokinetics of midazolam.

1. 5-Fluorouracil (5-FU) is a pyrimidine derivative widely used for the treatment of cancer. In this study, we investigated the effects of 5-FU on the protein expression of hepatic CYP3A and their enzyme activity for metabolizing midazolam (MDZ), a typical substrate of CYP3A, in rat liver microsomes.