The slightly Palbociclib price increased DILI susceptibility in CYP2E1*1A/*1A carriers may even be solely attributed to the reactive oxygen pathway without the need to postulate CYP2E1-mediated metabolism of acetylhydrazine to hepatotoxins. If this downstream mechanism played a major role, then CYP2E1*1A/*1A may even be a risk factor for DILI associated with other drugs, and this should be investigated in future studies. The genetically polymorphic NAT2 metabolizes some therapeutically important drugs such as isoniazid and sulfonamides. The *4 allele is considered
the wild-type because the resulting protein is functionally fully active. The prevalence of genetic NAT2 variants associated with intermediate and slow acetylator status is between 40% and 70% in Caucasians, and 10% and 40% in Asians.63, 64 In a rather small study, all six
patients who developed liver injury upon sulfonamide intake were phenotyped as NAT2 slow acetylators.65 For Etoposide isoniazid, a number of case series and case-control studies have identified NAT2 slow acetylator genotypes as risk factors for isoniazid-induced liver injury,66 but a recent meta-analysis confirmed such an association only for Asian populations (odds ratio 2.5) whereas an elevated risk was not confirmed when data from patients of different ethnic origins was analyzed.58 In the aforementioned prospective study with isoniazid monotherapy, no such association was observed either.59 The role of uridine diphosphate glucuronosyltransferase 2B7 (UGT2B7), along with CYP2C8 and adenosine triphosphate–binding cassette C2 (ABCC2), variants was investigated in a study comparing 24 patients with diclofenac hepatotoxicity to two
groups of controls: 48 patients on diclofenac and 112 who did not take the drug.41 The authors substantiated an elevated risk in patients harboring at least one UGT2B7*2 allele. Because UGT2B7*2 is believed to lead to an increased function of the enzyme, increased hepatotoxicity could be explained by the UGT2B7-mediated production selleck inhibitor of larger amounts of the diclofenac acyl glucuronide, which then forms covalent protein adducts leading to cell damage. Overall, the authors concluded that the UGT2B7*2 and the ABCC2 −24CT variants contributed significantly to the risk of diclofenac-induced DILI, whereas CYP2C8 plays no important role. Glutathione S-transferases (GSTs) are conjugation enzymes that may exert a double protective action against hepatotoxicity by “neutralizing” reactive phase 1 drug metabolites as well as other ROS involved in downstream hepatotoxic mechanisms. Based on such a possible nonspecific protective mechanism, a recent CGAS used a mixed DILI cohort and analyzed GST polymorphisms associated with DILI.30 Patients with a double GSTT1-GSTM1 null genotype had a significant 2.7-fold increased risk of DILI.