The metabolism of Celecoxib is mediated mainly by the cytochrome P450 isoenzyme CYP2C9. Concomitant administration of other drugs that inhibit or are metabolized by this isoenzyme may result in changes in plasma concentration of Celecoxib co-administration of Fluconazole has resulted in increased plasma concentrations of celecoxib. Celecoxib is an inhibitor of the isoenzyme CYP2D6 and the potential therefore exists for an effect on drugs metabolized by this enzyme.