CYP2C9 and hepatitis B virus infection: However, LEF leads to drug-induced liver injury or even acute drug-induced hepatitis, probably by inhibiting the activity of CYP2C9 enzyme that catalyzes the metabolisms of many endogenous and exogenous substances in human body.7 In addition, the AST and ALT levels of all patients were raised after LEF treatment, of which 14 cases underwent increases twice of the normal limit, including one case of chronic HBV infection complicated with alcoholism who was diagnoses as fatty liver disease, and 5 cases with HBV-DNA increases that were related with hepatitis B activity.