Pharmacogenetics of drug-induced liver injury

Role of Gut Microecology in the Pathogenesis of Drug-Induced Liver Injury and Emerging Therapeutic Strategies

Drug-induced liver injury (DILI) is a common clinical pharmacogenic disease. In the United States and Europe, DILI is the most common cause of acute liver failure. Drugs can cause hepatic damage either directly through inherent hepatotoxic properties or indirectly by inducing oxidative stress, immune responses, and inflammatory processes. These pathways can culminate in hepatocyte necrosis. The role of the gut microecology in human health and diseases is well recognized. Recent studies have revealed that the imbalance in the gut microecology is closely related to the occurrence and development of DILI. The gut microecology plays an important role in liver injury caused by different drugs. Recent research has revealed significant changes in the composition, relative abundance, and distribution of gut microbiota in both patients and animal models with DILI. Imbalance in the gut microecology causes intestinal barrier destruction and microorganism translocation; the alteration in microbial metabolites may initiate or aggravate DILI, and regulation and control of intestinal microbiota can effectively mitigate drug-induced liver injury. In this paper, we provide an overview on the present knowledge of the mechanisms by which DILI occurs, the common drugs that cause DILI, the gut microbiota and gut barrier composition, and the effects of the gut microbiota and gut barrier on DILI, emphasizing the contribution of the gut microecology to DILI.

Drug-induced liver injury (DILI) ascribed to non-steroidal anti-inflammatory drugs (NSAIDs) in the USA-Update with genetic correlations

OBJECTIVE

To describe patients with NSAID-DILI, including genetic factors associated with idiosyncratic DILI.

METHODS

In DILIN, subjects with presumed DILI are enrolled and followed for at least 6 months. Causality is adjudicated by a Delphic approach. HLA sequencing of multiethnic NSAID-DILI patients and HLA allele imputation of matching population controls were performed following overall, class and drug-based association analysis. Significant results were tested in a non-Hispanic White (NHW) case-control replication cohort.

RESULTS

Between September 2004 and March 2022, causality was adjudicated in 2498, and 55 (41 [75%] women) were assessed as likely due to NSAIDs. Median age at onset was 55 y (range 22-83 y). Diclofenac was the causative drug in 29, celecoxib in 7, ibuprofen in 5, etodolac and meloxicam each in 4. Except for meloxicam and oxaprozin (n = 2), the liver injury was hepatocellular with median R 15-25. HLA-DRB1*04:03 and HLA-B*35:03 were significantly more frequent in NSAID-DILI patients than in non-NSAID DILI controls. Interestingly, 85% of the HLA-DRB1*04:03 carriers developed DILI due to the use of acetic acid derivative NSAIDs, supporting the hypothesis that HLA-DRB1*04:03 could be a drug and/or class risk factor. HLA-B*35:03 but not HLA-DRB1*04:03 association was confirmed in the independent NHW replication cohort, which was largely driven by diclofenac.

CONCLUSIONS

Despite prevalent use, NSAID-DILI is infrequent in the United States. Diclofenac is the most commonly implicated, and adherence to warnings of risk and close observation are recommended. The increased frequency of HLA-B*35:03 and DRB1*04:03, driven by diclofenac, suggests the importance of immune-mediated responses.

Fluorescence-based methods for studying activity and drug-drug interactions of hepatic solute carrier and ATP binding cassette proteins involved in ADME-Tox

In humans, approximately 70% of drugs are eliminated through the liver. This process is governed by the concerted action of membrane transporters and metabolic enzymes. Transporters mediating hepatocellular uptake of drugs belong to the SLC (Solute carrier) superfamily of transporters. Drug efflux either toward the portal vein or into the bile is mainly mediated by active transporters of the ABC (ATP Binding Cassette) family. Alteration in the function and/or expression of liver transporters due to mutations, disease conditions, or co-administration of drugs or food components can result in altered pharmacokinetics. On the other hand, drugs or food components interacting with liver transporters may also interfere with liver function (e.g., bile acid homeostasis) and may even cause liver toxicity. Accordingly, certain transporters of the liver should be investigated already at an early stage of drug development. Most frequently radioactive probes are applied in these drug-transporter interaction tests. However, fluorescent probes are cost-effective and sensitive alternatives to radioligands, and are gaining wider application in drug-transporter interaction tests. In our review, we summarize our current understanding about hepatocyte ABC and SLC transporters affected by drug interactions. We provide an update of the available fluorescent and fluorogenic/activable probes applicable in in vitro or in vivo testing of these ABC and SLC transporters, including near-infrared transporter probes especially suitable for in vivo imaging. Furthermore, our review gives a comprehensive overview of the available fluorescence-based methods, not directly relying on the transport of the probe, suitable for the investigation of hepatic ABC or SLC-type drug transporters.

Prediction of biochemical nonresolution in patients with chronic drug-induced liver injury: A large multicenter study

BACKGROUND AND AIMS

To clarify high-risk factors and develop a nomogram model to predict biochemical resolution or biochemical nonresolution (BNR) in patients with chronic DILI.

APPROACH AND RESULTS

Retrospectively, 3655 of 5326 patients with chronic DILI were enrolled from nine participating hospitals, of whom 2866 underwent liver biopsy. All of these patients were followed up for over 1 year and their clinical characteristics were retrieved from electronic medical records. The endpoint was BNR, defined as alanine aminotransferase or aspartate aminotransferase >1.5× upper limit of normal or alkaline phosphatase >1.1× ULN, at 12 months from chronic DILI diagnosis. The noninvasive high-risk factors for BNR identified by multivariable logistic regression were used to establish a nomogram, which was validated in an independent external cohort. Finally, 19.3% (707 of 3655) patients presented with BNR. Histologically, with the increase in liver inflammation grades and fibrosis stages, the proportion of BNR significantly increased. The risk of BNR was increased by 21.3-fold in patients with significant inflammation compared to none or mild inflammation (p < 0.001). Biochemically, aspartate aminotransferase and total bilirubin, platelets, prothrombin time, sex, and age were associated with BNR and incorporated to construct a nomogram model (BNR-6) with a concordance index of 0.824 (95% CI, 0.798-0.849), which was highly consistent with liver histology. These results were successfully validated both in the internal cohort and external cohort.

CONCLUSIONS

Significant liver inflammation is a robust predictor associated with biochemical nonresolution. The established BNR-6 model provides an easy-to-use approach to assess the outcome of chronic DILI.

Stevens-Johnson Syndrome Following Non-steroidal Anti-inflammatory Drugs: A Real-World Analysis of Post-marketing Surveillance Data

BACKGROUND

The Stevens-Johnson syndrome (SJS) is a severe skin reaction to non-steroidal anti-inflammatory drugs (NSAIDs), and can even be life-threatening. However, there are still few real-world studies to compare the specific differences in the adverse effects of skin and mucosal invasion.

METHODS

Disproportionality analysis and Bayesian analysis were devoted to data-mining of the suspected SJS after using NSAIDs based on the FDA's Adverse Event Reporting System (FAERS) from January 2004 to March 2021. The times to onset, fatality, and hospitalization rates of antipyretic analgesic-associated SJS were also investigated.

RESULTS

A total of 1,868 reports of SJS adverse events were identified with NSAIDs. Among 5 NSAIDs monotherapies we studied (acetaminophen, ibuprofen, aspirin, diclofenac and celecoxib), ibuprofen had the highest association with SJS based on the highest reporting odds ratio (ROR = 7.06, 95% two-sided CI = 6.59-7.56), proportional reporting ratio (PRR = 6.98, χ² = 4201.14) and empirical Bayes geometric mean (EBGM = 6.78, 95% one-sided CI = 6.40). However, ibuprofen-associated SJS had the lowest fatality rate (6.87%, p < 0.0001) and the highest hospitalization rate (79.27%, p < 0.0001). Celecoxib-associated SJS had the latest time to onset (317.56 days, p < 0.0001). Diclofenac-associated SJS cases appeared to be associated with the highest risk of death (25.00%, p < 0.0001).

CONCLUSIONS

The analysis of FAERS data provides a more accurate profile of the incidence and prognosis of SJS after NSAIDs treatment, enabling continued surveillance and timely intervention in patients at risk of SJS following these NSAIDs.

Environmental exposure as a risk-modifying factor in liver diseases: Knowns and unknowns

Liver diseases are considered to predominantly possess an inherited or xenobiotic etiology. However, inheritance drives the ability to appropriately adapt to environmental stressors, and disease is the culmination of a maladaptive response. Thus “pure” genetic and “pure” xenobiotic liver diseases are modified by each other and other factors, identified or unknown. The purpose of this review is to highlight the knowledgebase of environmental exposure as a potential risk modifying agent for the development of liver disease by other causes. This exercise is not to argue that all liver diseases have an environmental component, but to challenge the assumption that the current state of our knowledge is sufficient in all cases to conclusively dismiss this as a possibility. This review also discusses key new tools and approaches that will likely be critical to address this question in the future. Taken together, identifying the key gaps in our understanding is critical for the field to move forward, or at the very least to “know what we don't know.”

Role of immune dysfunction in drug induced liver injury

Drug-induced liver injury (DILI) is one of the leading causes of liver failure and withdrawal of drugs from the market. A poor understanding of the precipitating event aetiology and mechanisms of disease progression has rendered the prediction and subsequent treatment intractable. Recent literature suggests that some drugs can alter the liver’s repair systems resulting in injury. The pathophysiology of DILI is complex, and immune dysfunction plays an important role in determining the course and severity of the disease. Immune dysfunction is influenced by the host response to drug toxicity. A deeper understanding of these processes may be beneficial in the management of DILI and aid in drug development. This review provides a structured framework presenting DILI in three progressive stages that summarize the interplay between drugs and the host defence networks.

Zafirlukast ameliorates Docetaxel-induced activation of NOD-like receptor protein 3 (NLRP3) inflammasome, mediated by sirtuin1 (SIRT1) in hepatocytes

Docetaxel-associated liver injury has become a serious public health problem, resulting in therapy discontinuation, liver failure, and death. Zafirlukast is a typical leukotriene receptor antagonist used for prophylaxis and chronic treatment of asthma. In this study, we investigate whether treatment with Zafirlukast could alleviate Docetaxel-induced cytotoxicity in hepatocytes. Our results indicate that Zafirlukast mitigated Docetaxel-induced toxicity in LO-2 hepatocytes. Firstly, Zafirlukast reduced the production of 8-hydroxy-2p-deoxyguanosine (8-OHdG) and increased the levels of reduced glutathione (GSH) against Docetaxel. Secondly, Zafirlukast elevated the levels of mitochondrial membrane potential (ΔΨm) and adenosine triphosphate (ATP). Thirdly, Zafirlukast prevented Docetaxel-induced release of lactate dehydrogenase (LDH) and increased cell viability of LO-2 hepatocytes against Docetaxel. We also found that Zafirlukast ameliorated Docetaxel-induced apoptosis by reducing Caspase-3 and Caspase-9 activity. Mechanistically, our results demonstrate that Zafirlukast inhibited the activation of NOD-like receptor protein 3 (NLRP3), mediated by SIRT1. Based on these findings, we conclude that the administration of Zafirlukast might have a protective effect against Docetaxel-induced cytotoxicity in hepatocytes.

Research Progress of Pharmacogenomics in Drug-Induced Liver Injury

Background: Drug-induced liver injury (DILI) is a common and serious adverse drug reaction with insufficient clinical diagnostic strategies and treatment methods. The only clinically well-received method is the Roussel UCLAF Causality Assessment Method scale, which can be applied to both individuals and prospective or retrospective studies. However, in severe cases, patients with DILI still would develop acute liver failure or even death. Pharmacogenomics, a powerful tool to achieve precision medicine, has been used to study the polymorphism of DILI related genes.

Summary: We summarized the pathogenesis of DILI and findings on associated genes and variations with DILI, including but not limited to HLA genes, drug metabolizing enzymes, and transporters genes, and pointed out further fields for DILI related pharmacogenomics study to provide references for DILI clinical diagnosis and treatment.

Key Messages: At present, most of the studies are mainly limited to CGS and GWAS, and there is still a long way to achieve clinical transformation. DNA methylation could be a new consideration, and ethnic differences and special populations also deserve attention.

Clinical Relevance of a 16-Gene Pharmacogenetic Panel Test for Medication Management in a Cohort of 135 Patients

There is a growing number of evidence-based indications for pharmacogenetic (PGx) testing. We aimed to evaluate clinical relevance of a 16-gene panel test for PGx-guided pharmacotherapy. In an observational cohort study, we included subjects tested with a PGx panel for variants of ABCB1, COMT, CYP1A2, CYP2B6, CYP3A4, CYP3A5, CYP2C9, CYP2C19, CYP2D6, CYP4F2, DPYD, OPRM1, POR, SLCO1B1, TPMT and VKORC1. PGx-guided pharmacotherapy management was supported by the PGx expert system SONOGEN XP. The primary study outcome was PGx-based changes and recommendations regarding current and potential future medication. PGx-testing was triggered by specific drug-gene pairs in 102 subjects, and by screening in 33. Based on PharmGKB expert guidelines we identified at least one "actionable" variant in all 135 (100%) tested patients. Drugs that triggered PGx-testing were clopidogrel in 60, tamoxifen in 15, polypsychopharmacotherapy in 9, opioids in 7, and other in 11 patients. Among those, PGx variants resulted in clinical recommendations to change PGx-triggering drugs in 33 (32.4%), and other current pharmacotherapy in 23 (22.5%). Additional costs of panel vs. single gene tests are moderate, and the efficiency of PGx panel testing challenges traditional cost-benefit calculations for single drug-gene pairs. However, PGx-guided pharmacotherapy requires specialized expert consultations with interdisciplinary collaborations.

Association of CYP1A1 and CYP1B1 inhibition in in vitro assays with drug-induced liver injury

Drug-induced liver injury (DILI) is one of the major causes for the discontinuation of drug development and withdrawal of drugs from the market. Since it is known that reactive metabolite formation and being substrates or inhibitors of cytochrome P450s (P450s) are associated with DILI, we systematically investigated the association between human P450 inhibition and DILI. The inhibitory activity of 266 DILI-positive drugs (DILI drugs) and 92 DILI-negative drugs (no-DILI drugs), which were selected from Liver Toxicity Knowledge Base (US Food and Drug Administration), against 8 human P450 forms was assessed using recombinant enzymes and luminescent substrates, and the threshold values showing the highest balanced accuracy for DILI discrimination were determined for each P450 enzyme using receiver operating characteristic analyses. The results showed that among the P450s tested, CYP1A1 and CYP1B1 were inhibited by DILI drugs more than no-DILI drugs with a statistical significance. We found that 91% of drugs that showed inhibitory activity greater than the threshold values against CYP1A1 or CYP1B1 were DILI drugs. The results of internal 5-fold cross-validation confirmed the usefulness of CYP1A1 and CYP1B1 inhibition data for the threshold-based discrimination of DILI drugs. Although the contribution of these P450s to drug metabolism in the liver is considered minimal, our present findings suggest that the assessment of CYP1A1 and CYP1B1 inhibition is useful for screening DILI risk of drug candidates at the early stage of drug development.

Congenital dyserythropoietic anemia and drug-induced liver injury present as bland cholestasis: A case report

Anemias and drug-induced liver injury(DILI) are separate disorders, which are difficult to diagnose. The clinical effects of DILI vary among individuals. However, the outcome determinants remain to be fully established. To the best of our knowledge, the role of anemia in DILI has yet to be reported. The present study reported on the case of one Chinese patient (male; age, 21 years) who experienced obvious drug-induced cholestasis. Of note, the hepatocyte injury was minimal compared with that in previously reported cases treated with the same drug. In addition, the patient suffered from mild hemolytic anemia with no obvious cause. A genetic pedigree analysis revealed compound heterozygous mutations in the congenital anemia-associated gene codanin 1, including the novel rare p.R1067H mutation. Treatment with ursodeoxycholic acid alone sufficed and the outcome was good. Therefore, whilst chronic hemolysis predisposed the liver to cholestasis, it could have shielded the liver from further injuries, since bilirubin, a by-product of hemolysis, is a known antioxidant. The results of the present study indicated that genetic screening may be used for the diagnosis of liver injury concurring with undiagnosed anemia.

The Association of 3-Hydroxy-3-Methylglutaryl-CoA Reductase, Apolipoprotein E, and Solute Carrier Organic Anion Genetic Variants with Atorvastatin Response among Jordanian Patients with Type 2 Diabetes

Atorvastatin is commonly used among type 2 diabetic (DM2) patients at the University of Jordan Hospital to prevent cardiovascular complication. However, we noticed that there is a wide inter-individual variation in the efficacy and toxicity of atorvastatin. This study aimed to find out the effects of major genetic variants in 3-Hydroxy-3-Methylglutaryl-CoA Reductase (HMGCR), Apolipoprotein E (APOE), and Solute Carrier Organic Anion (SLCO1B1) genes on atorvastatin response among DM2 patients. A sample of 139 DM2 patients on 20 mg of atorvastatin was included in this study. The lipid and glycemic profile and the levels of hepatic enzymes alanine aminotransferase (ALT) and aspartate transaminase were recorded before and after 3 months of atorvastatin treatment. Additionally, the genetic variants HMGCR rs17244841,APOE rs7412 and rs429357, and SLCO1B1 rs2306283 and rs11045818 were genotyped using an Applied Biosystems DNA sequencing method (ABI3730×1). We found that atorvastatin reduced total cholesterol and low-density lipoprotein (LDL) more significantly (p-value < 0.05) in patients with wild genotype than variant alleles APOE rs7412C > T and SLCO1B1 rs2306283A > G. Furthermore, the ALT level was elevated significantly (p-value < 0.05) by 27% in patients with heterozygous SLCO1B1 rs11045818 G/A genotype, while it was not elevated among wild genotype carriers. Additionally, atorvastatin reduced total cholesterol more significantly (p-value < 0.05) in patients with SLCO1B1 rs2306283A and rs11045818G haplotypes and increased ALT levels by 27% (p-value < 0.05) in patients with SLCO1B1 rs2306283G and rs11045818A haplotypes. In conclusion, it was found in this study that APOE rs7412, SLCO1B1 rs2306283, and rs11045818 genotypes can be considered as potential genetic biomarkers of atorvastatin response among DM2 patients of Jordanian Arabic origin. Further clinical studies with larger sample numbers are needed to confirm these findings.

Levetiracetam-Induced Hepatic Dysfunction

Although levetiracetam is the antiepileptic of choice in patients after hepatic transplantation and patients with hepatic dysfunction, we report a patient in whom levetiracetam was the most probable cause of hepatic dysfunction. Treatment of this hepatic dysfunction is to have a high degree of suspicion and withdraw the drug at the earliest to prevent morbidity and rarely mortality. Though rare, this is an important unwanted side effect of this highly useful medication.

Superoxide Dismutase 2 Val16Ala Polymorphism is Associated with Amiodarone-Associated Liver Injury

Association of SOD2 V16A single-nucleotide polymorphism (rs4880) with drug hepatotoxicity were reported but relationships with amiodarone prescriptions remained unexplored. Research was an exploratory, controlled prospective clinical trial. Patients hospitalized and treated in Clinical Center in Kragujevac, Serbia (in year 2017) were divided into experimental (using amiodarone, having liver injury, n=29, 19 males, the mean age 66.8±10.4 years), control A (neither amiodarone use nor hepatotoxicity, n=29, 19, 66.1±10.3) and control B group (using amiodarone, not having hepatotoxicity, n=29, 19, 66.8±9.8). From blood samples, among other routine biochemistry, genotyping for SOD2 polymorphism Val16Ala was conducted using real-time PCR method with TaqMan® Genotyping Master Mix and TaqMan® DME Genotyping Assay for rs4880. Patients taking amiodarone and having liver injury were mostly carriers of Val/Val (TT) genotype (13 of 24 patients, 54.2%) while Val/Ala (TC) and Ala/Ala (CC) genotypes prevailed in control group A (19 of 40, 47.5%) and control group B (9 of 23, 39.1%), respectively (2=10.409, p=0.034). Frequency of Val (T) and Ala (C) alleles were 0.51 and 0.49, respectively in the whole study sample (Hardy Weinberg equilibrium, 2=0.56, p=0.454). Carriers of TT genotype had significantly higher ALT (437.0±1158.0 vs 81.9131.5 U/L), total bilirubin (28.320.5 vs 15.313.0 mol/L) and total bile acid concentrations (10.910.2 vs 6.45.3 mol/L) compared to carriers of TC genotype (U=2.331, p=0.020, U=3.204, p=0.001 and U=2.172, p=0.030, respectively). Higher incidence of 47T allele of SOD2 was inpatients with amiodarone-associated liver injury as compared to patients on amiodarone not experiencing hepatotoxic effects.

Drug-induced liver injury

Drug-induced liver injury (DILI) is an adverse reaction to drugs or other xenobiotics that occurs either as a predictable event when an individual is exposed to toxic doses of some compounds or as an unpredictable event with many drugs in common use. Drugs can be harmful to the liver in susceptible individuals owing to genetic and environmental risk factors. These risk factors modify hepatic metabolism and excretion of the DILI-causative agent leading to cellular stress, cell death, activation of an adaptive immune response and a failure to adapt, with progression to overt liver injury. Idiosyncratic DILI is a relative rare hepatic disorder but can be severe and, in some cases, fatal, presenting with a variety of phenotypes, which mimic other hepatic diseases. The diagnosis of DILI relies on the exclusion of other aetiologies of liver disease as specific biomarkers are still lacking. Clinical scales such as CIOMS/RUCAM can support the diagnostic process but need refinement. A number of clinical variables, validated in prospective cohorts, can be used to predict a more severe DILI outcome. Although no pharmacological therapy has been adequately tested in randomized clinical trials, corticosteroids can be useful, particularly in the emergent form of DILI related to immune-checkpoint inhibitors in patients with cancer.

Genome-Wide Analysis of DNA Methylation and Antituberculosis Drug-Induced Liver Injury in the Han Chinese Population

Tuberculosis (TB) is one of the most prevalent infections. However, anti-TB drugs induce adverse liver injury in up to 40% of patients. Studies on candidate genes have suggested that single-nucleotide polymorphisms account for only a small contribution to the occurrence of anti-TB drug-induced liver injury (ATLI). In this study, whole-genome DNA methylation analysis was performed to systematically screen the ATLI-associated factors in a 49 vs. 51 case-control population. Next, 34 identified candidate probes were validated using MassARRAY in 296 cases and 288 controls. Our results indicated that 12 CpG sites on seven probes were positively associated with ATLI risk. Furthermore, we applied a CRISPR/Cas9-mediated methylation modifiable cell model and demonstrated that four CpGs in or near the gene region of AK2, SLC8A2, and PSTPIP2 affected the cellular response to rifampicin treatment. This study provides new biomarkers associated with ATLI occurrence.

Association between genetic polymorphisms of SLCO1B1 and susceptibility to methimazole-induced liver injury

Methimazole (MMI) has been used in the therapy of Grave's disease (GD) since 1954, and drug-induced liver injury (DILI) is one of the most deleterious side effects. Genetic polymorphisms of drug-metabolizing enzymes and drug transporters have been associated with drug-induced hepatotoxicity in many cases. The aim of this study was to investigate genetic susceptibility of the drug-metabolizing enzymes and drug transporters to the MMI-DILI. A total of 44 GD patients with MMI-DILI and 118 GD patients without MMI-DILI development were included in the study. Thirty-three single nucleotide polymorphisms (SNPs) in twenty candidate genes were genotyped. We found that rs12422149 of SLCO2B1, rs2032582_AT of ABCB1, rs2306283 of SLCO1B1 and rs4148323 of UGT1A1 exhibited a significant association with MMI-DILI; however, no significant difference existed after Bonferroni correction. Haplotype analysis showed that the frequency of SLCO1B1*1a (388A521T) was significantly higher in MMI-DILI cases than that in the control group (OR = 2.21, 95% CI = 1.11-4.39, P = 0.023), while the frequency of SLCO1B1*1b (388G521T) was significantly higher in the control group (OR = 0.52, 95% CI = 0.29-0.93, P = 0.028). These results suggested that genetic polymorphisms of SLCO1B1 were associated with susceptibility to MMI-DILI. The genetic polymorphism of SLCO1B1 may be important predisposing factors for MMI-induced hepatotoxicity.

Clinical factors predicting drug-induced liver injury due to flucloxacillin

Objectives

Drug-induced liver injury (DILI) is a serious adverse reaction due to flucloxacillin. The pathogenesis is not fully understood. Female sex, age over 60 years, and a longer treatment duration have been suggested to be predisposing factors. Carriers of HLA-B*57:01 have an 80-fold increased risk, but due to the rarity of the reaction, testing of all patients is not cost-effective. We aimed to validate and detect clinical risk factors for flucloxacillin DILI.

Methods

Clinical characteristics of flucloxacillin-treated patients with (n=50) and without DILI (n=2,330) were compared in a retrospective case control study. Cases were recruited from the Swedish database of spontaneously reported adverse drug reactions. Treated controls were selected from the Swedish Twin Registry. Statistical comparisons were made using chi-squared test and logistic regression. The significance threshold was set to P<0.00357 to correct for multiple comparisons. Reliable variables were tested in a multiple regression model.

Results

DILI was associated with female sex, OR 2.79, 95% CI 1.50-5.17, P=0.0011, and with a history of kidney stones, OR 5.51, 95% CI 2.21-13.72, P=0.0003. Cases were younger than controls, OR per increase in years 0.91, 95% CI 0.88-0.94, P<0.0001, probably due to selection bias. No difference in treatment duration was detected, OR 1.03, 95% CI 0.98-1.08, P=0.1790.

Conclusion

We established female sex as a risk factor for flucloxacillin-induced DILI, and a history of kidney stones was identified as a potential risk factor. Clinical risk factors for flucloxacillin-induced DILI could be used to indicate whom to test for HLA-B*57:01 before treatment.

In vivo phenotyping of cytochrome 450 isoforms involved in the metabolism of anti-HIV and anti-tubercular drugs in human using cocktail approach: An LC-MS/MS analysis

PURPOSE

In vivo phenotyping of CYP isoforms involved in the metabolism of anti-HIV and antitubercular drugs is important to determine therapeutic dose levels in HIV/AIDS-TB coinfections. In this study, we used a cocktail of bupropion, losartan and dapsone for in vivo phenotyping of CYP2B6, CYP2C9 and N-acetyltransferase-2 (NAT2) in plasma. CYP2B6 is the main catalyst of anti-HIV efavirenz, while NAT2 is involved in antitubercular drug isoniazid metabolism. CYP2C9 has a significant association with antitubercular drug-induced reactions. The activity level of these isoforms has a significant bearing on therapeutic dose in rapid and poor metabolizers.

METHODS

Briefly, a cocktail of probe drugs was administered to human volunteers and the drugs and metabolites were determined by an inhouse LC-MS/MS method in 250 μl plasma. The mobile phase and drug/metabolite extraction methods were optimized before analysis. Retention time, Cmax and tmax were calculated from the same sample and the values were used for phenotyping the isoforms.

RESULTS

Retention time of drugs and metabolites was calculated. The method was sensitive (4.5-8.2 %CV) and no interfering peak was observed in any batch. %Accuracy of the calibrator and QC was 85-115%. %CV of storage stability testing was within FDA approved limits. Cmax and tmax were comparable to the values reported for individual drugs.

CONCLUSIONS

This study advocates the use of a cocktail of bupropion, losartan and dapsone for in vivo phenotyping of CYP2B6, CYP2C9 and NAT2, which is important in determining therapeutic dose levels of anti-HIV and anti-TB drugs in HIV/AIDS-TB coinfections.

Drug-Induced Liver Injury: Why is the Roussel Uclaf Causality Assessment Method (RUCAM) Still Used 25 Years After Its Launch?

Launched in 1993 and partially based on the results of an international consensus meeting organized under the auspices of the Council of International Organizations of Medical Sciences (CIOMS), the Roussel Uclaf Causality Assessment Method (RUCAM) is the most used causality assessment tool worldwide for the diagnosis of drug-induced liver injury (DILI) and herb-induced liver injury (HILI) in a large number of epidemiological studies, case reports, and case series. The 25-year experience of RUCAM use confirmed that the success was due to its objective, standardized, and liver-injury-specific approach structured with defined key elements derived from a series of DILI cases with positive rechallenge. Using this series, the validation procedure avoided arbitrary definitions and confirmed scores to key items. The algorithm provides a quantitative causality grading of highly probable, probable, possible, unlikely, or excluded relationship between the liver injury and the suspected product(s). Despite challenges, prospective use of RUCAM fosters case data completeness and transparent causality adjudication in real time, as opposed to subjective opinion resulting from several rounds by experts lacking defined key elements and scores. In 2016, RUCAM was updated with specification of alcohol use and Hepatitis E Virus (HEV) biomarkers and simplified item handling to further reduce inter-observer variability. RUCAM-based probable and highly probable DILI and HILI cases are essential for the detection of new hepatotoxins, confirmation of new biomarkers, description of clinical features and risk factors, and determination of incidence in pharmacoepidemiological studies. This article is intended to encourage systematic use of sophisticated causality assessment methods such as RUCAM to improve DILI and HILI case evaluation and to increase confidence in published cases.

Genetic Association of Single Nucleotide Polymorphisms with Acetaminophen-Induced Hepatotoxicity

Acetaminophen is commonly used to reduce pain and fever. Unfortunately, overdose of acetaminophen is a leading cause of acute liver injury and failure in many developed countries. The majority of acetaminophen is safely metabolized in the liver and excreted in the urine; however, a small percentage is converted to the highly reactive N-acetyl-p-benzoquinone imine (NAPQI). At therapeutic doses, NAPQI is inactivated by glutathione S-transferases, but at toxic levels, excess NAPQI forms reactive protein adducts that lead to hepatotoxicity. Individual variability in the response to both therapeutic and toxic levels of acetaminophen suggests a genetic component is involved in acetaminophen metabolism. In this review, we evaluate the genetic association studies that have identified 147 single nucleotide polymorphisms linked to acetaminophen-induced hepatotoxicity. The identification of novel genetic markers for acetaminophen-induced hepatotoxicity provides a rich resource for further evaluation and may lead to improved prognosis, prevention, and treatment.

Oxidative Stress and First-Line Antituberculosis Drug-Induced Hepatotoxicity

Hepatotoxicity induced by antituberculosis drugs is a serious adverse reaction with significant morbidity and even, rarely, mortality. This form of toxicity potentially impacts the treatment outcome of tuberculosis in some patients. Covering only first-line antituberculosis drugs, this review addresses whether and how oxidative stress and, more broadly, disturbance in redox homeostasis alongside mitochondrial dysfunction may contribute to the hepatotoxicity induced by them. Risk factors for such toxicity that have been identified, in addition to genetic factors, principally include old age, malnutrition, alcoholism, chronic hepatitis C and chronic hepatitis B infection, HIV infection, and preexisting liver disease. Importantly, these comorbid conditions are associated with oxidative stress. Thus, the shared pathogenetic mechanism(s) for liver injury might be in operation due to disease-drug interaction. Our current ability to predict, prevent, or treat hepatotoxicity (other than removing potentially hepatotoxic drugs) remains limited. More translational research to unravel the pathogenesis, inclusive of the underlying molecular basis, regarding antituberculosis drug-induced hepatotoxicity is needed, and so is clinical research pertaining to the advances in therapy with antioxidants and drugs related to antioxidants, especially those for management of mitochondrial dysfunction. The role of pharmacogenetics in the clinical management of drug-induced hepatotoxicity also likely merits further evaluation.

Efficacy and safety of direct oral anticoagulants approved for cardiovascular indications: Systematic review and meta-analysis

BACKGROUND

Direct oral anticoagulants (DOACs) have emerged as promising alternatives to vitamin K antagonists (VKAs) for patients with non-valvular atrial fibrillation (NVAF) or venous thromboembolism (VTE). Few meta-analyses have included all DOACs that have received FDA approval for these cardiovascular indications, and their overall comparisons against VKAs have shortcomings in data and methods. We provide an updated overall assessment of the efficacy and safety of those DOACs at dosages currently approved for NVAF or VTE, in comparison with VKAs.

METHODS

We used data from Phase 3 randomized trials that compared an FDA-approved DOAC with VKA for primary prevention of stroke in patients with NVAF or for treatment of acute VTE.

RESULTS

Among trial participants with NVAF, DOAC recipients had a lower risk of stroke or systemic embolism [Pooled Odds Ratio (OR) 0.76, 95% Confidence Interval (CI) (0.68-0.84)], any stroke (0.80, 0.73-0.88), systemic embolism (0.56, 0.34-0.93), and total mortality (0.89, 0.84-0.95). Safety outcomes also showed a lower risk of fatal, major, and intracranial bleeding but higher risk for gastrointestinal bleeding (GIB). Patients with acute VTE randomized to DOACs had comparable risk of recurrent VTE and death (OR 0.88, 95% CI 0.75-1.03), recurrent DVT (0.83, 0.66-1.05), recurrent non-fatal PE (0.97, 0.75-1.25), and total mortality (0.94, 0.79-1.12). Safety outcomes for DOACs showed a lower risk of major, fatal, and intracranial bleeding, but similar risk of GIB.

CONCLUSIONS

Patients receiving DOACs for NVAF had predominantly superior efficacy and safety. Patients who were treated with DOACs for acute VTE had non-inferior efficacy, but an overall superior safety profile.

The role of hepatic antioxidant capacity and hepatobiliary transporter in liver injury induced by isopsoralen in zebrafish larvae

Isopsoralen is the main component of the Chinese medicine psoralen, which has antitumour activity and can be used for the treatment of osteoporosis. However, the mechanism behind its hepatotoxicity has not yet been elucidated. In this study, the hepatotoxicity of isopsoralen was investigated using zebrafish. Isopsoralen treatment groups of 25, 50 and 100 μM were established. The mortality, liver morphology changes, levels of alanine aminotransferase (ALT) and aspartate aminotransferase (AST), liver histopathology and mRNA levels of liver injury–related genes in zebrafish larvae were measured. The results showed that isopsoralen resulted in the development of malformed zebrafish, dose-dependent increases in ALT and AST, decreased liver fluorescence and weakened fluorescence intensity. Histopathological examination showed that high-dose isopsoralen caused a large number of vacuolated structures in the larvae liver. The polymerase chain reaction results showed a significant decrease in the mRNA levels of genes related to antioxidant capacity ( lfabp, gstp2 and sod1) and drug transport ( mdr1, mrp1 and mrp2), indicating that isopsoralen significantly inhibited liver antioxidant capacity and drug efflux capacity in zebrafish larvae. Isopsoralen is hepatotoxic to zebrafish larvae via inhibition of drug transporter expression resulting in the accumulation of isopsoralen in the body and decreased antioxidant capacity, leading to liver injury.

Genetic Variations Associated with Anti-Tuberculosis Drug-Induced Liver Injury

Purpose of this Review

In order to combat the development of drug resistance, the clinical treatment of tuberculosis requires the combined use of several anti-tuberculosis (anti-TB) drugs, including isoniazid and rifampicin. Combinational treatment approaches are suggested by the World Health Organization (WHO) and are widely accepted throughout the world. Unfortunately, a major side effect of the treatment is the development of anti-tuberculosis drug-induced liver injury (AT-DILI). Many factors contribute to isoniazid- and rifampicin-mediated AT-DILI and genetic variations are among the most common factors. The purpose of this review is to provide information on genetic variations associated with isoniazid- and rifampicin-mediated AT-DILI.

Recent Findings

The genetic variations associated with AT-DILI have been identified in the genomic regions within or near genes encoding proteins in the following pathways: drug metabolizing enzymes (NAT2, CYP2E1, and GSTs), accumulation of bile acids, lipids, and heme metabolites (CYP7A1, BSEP, UGTs, and PXR), immune adaptation (HLAs and TNF-α), and oxidant challenge (TXNRD1, SOD1, BACH1, and MAFK).

Summary

The information summarized in this review considers the genetic bases of risk factors contributing to AT-DILI and provides information that may help for future studies. Some of the implicated genetic variations can be used in the design of genetic tests and serve as biomarkers for the prediction of isoniazid- and rifampicin-mediated AT-DILI risk in personalized medicine.

A Multicenter and Randomized Controlled Trial of Bicyclol in the Treatment of Statin-Induced Liver Injury

BACKGROUND The aim of this study was to evaluate the efficacy and safety of bicyclol treatment in statin-induced liver injury. MATERIAL AND METHODS The study included 168 patients with liver injury caused by statins. Patients were randomized into two four-week treatment groups: bicyclol 25 mg three times daily or polyene phosphatidylcholine 456 mg three times daily as control. Serum biochemical indexes were compared before and after treatment. RESULTS Significant differences in alanine transaminase (ALT) levels among the three measurements before and after treatment in the two groups at different time points were observed (p<0.01). There was a significant difference (p<0.01) between two weeks and four weeks after treatment compared to the baseline period. There was a significant interaction (p=0.003) between the two groups and time factors. After two and four weeks of treatment, the ALT levels in the control group (68.20±26.31, 50.71±27.13 respectively) were higher compared to the ALT in the bicyclol group (49.33±21.39, 30.36±17.41 respectively) (p<0.01). After four weeks of treatment, the normalization rates of bicyclol and polyene phosphatidylcholine groups were 74.68% and 46.15%, respectively. The efficacy of bicyclol was significantly better than that of polyene phosphatidylcholine (p<0.05). The incidence of adverse reactions in the bicyclol and polyene phosphatidylcholine groups were 2.53% and 2.56%, respectively, with no statistically significant differences observed between the two groups (p>0.05). CONCLUSIONS These findings suggest that trends of ALT changes in the two groups were different, and the improvement of ALT was more obvious in the bicyclol group. Bicyclol is considered to be safe and effective in the treatment of statin-induced liver injury.

Antituberculosis Drug-Induced Adverse Events in the Liver, Kidneys, and Blood: Clinical Profiles and Pharmacogenetic Predictors

Antituberculosis drug‐induced adverse drug reactions (ATD‐ADRs) are increasing globally, and it is key to identify candidate ATD‐ADRs loci for clinical management. We prospectively enrolled 1,235 highly suspicious tuberculosis (TB) inpatients to investigate the profiles and genetic risk factors of ATD‐ADRs in the liver, kidneys, and blood. Overall, 644 subjects were eligible and genotyped for seven polymorphisms in drug‐metabolizing enzymes and transporter genes. Clinical follow‐up and blood analysis were performed regularly. We found that a notable rate of ATD‐ADRs (incidence: 16.5%, drug intervention rate: 10.4%), mainly involving hepatotoxicity (10.6%) and leukopenia (3.3%) in western China. CYP2D6 rs1135840 and NUDT15 rs116855232 increased the risks of hepatotoxicity and leukopenia with an odds ratio of 2.52 and 4.97, respectively. Both variants showed excellent negative predictive values (93.7% and 98.1%, respectively) but moderate sensitivities (72.7% and 52.4%, respectively). These data provide new insight into ATD‐ADRs in the Chinese population and may offer future leads for diagnosis and treatment.

Mitochondrial pathway-mediated apoptosis is associated with erlotinib-induced cytotoxicity in hepatic cells

For advanced non-small-cell lung cancer (NSCLC) with mutations to the epidermal growth factor receptor (EGFR), EGFR tyrosine kinase inhibitors, including erlotinib are indicated for the first-line treatment. Liver injury is one of the multiple adverse effects of erlotinib and may affect its safety. The present study investigated the mechanism of erlotinib-induced hepatotoxicity in vitro and provided experimental evidence for the screening of potential hepatoprotectors. Erlotinib induced dose-dependent cytotoxicity in human L-02 hepatic cells 72 h after treatment. In other experiments, L-02 cells were treated with erlotinib for 48 h and thereafter exhibited typical features of apoptosis. Erlotinib caused alterations to nuclear morphology, including chromatin condensation and karyopyknosis; it also increased the fraction of late apoptotic cells and regulated apoptotic protein levels, activating caspase-3 and cleaving of poly-ADP-ribose polymerase. Furthermore, 48 h exposure to erlotinib disturbed mitochondrial function by decreasing the ratio of B-cell lymphoma 2 (Bcl-2) to Bcl-associated X proteins and reducing mitochondrial membrane potential. The results of this in vitro study indicate that erlotinib-induced hepatotoxicity may occur through mitochondrial-pathway-mediated apoptosis.

Drug-induced liver injury: recent advances in diagnosis and risk assessment

Idiosyncratic drug-induced liver injury (IDILI) is a rare but potentially severe adverse drug reaction that should be considered in patients who develop laboratory criteria for liver injury secondary to the administration of a potentially hepatotoxic drug. Although currently used liver parameters are sensitive in detecting DILI, they are neither specific nor able to predict the patient's subsequent clinical course. Genetic risk assessment is useful mainly due to its high negative predictive value, with several human leucocyte antigen alleles being associated with DILI. New emerging biomarkers which could be useful in assessing DILI include total keratin18 (K18) and caspase-cleaved keratin18 (ccK18), macrophage colony-stimulating factor receptor 1, high mobility group box 1 and microRNA-122. From the numerous in vitro test systems that are available, monocyte-derived hepatocytes generated from patients with DILI show promise in identifying the DILI-causing agent from among a panel of coprescribed drugs. Several computer-based algorithms are available that rely on cumulative scores of known risk factors such as the administered dose or potential liabilities such as mitochondrial toxicity, inhibition of the bile salt export pump or the formation of reactive metabolites. A novel DILI cluster score is being developed which predicts DILI from multiple complimentary cluster and classification models using absorption-distribution-metabolism-elimination-related as well as physicochemical properties, diverse substructural descriptors and known structural liabilities. The provision of more advanced scientific and regulatory guidance for liver safety assessment will depend on validating the new diagnostic markers in the ongoing DILI registries, biobanks and public-private partnerships.

CSH guidelines for the diagnosis and treatment of drug-induced liver injury

Drug-induced liver injury (DILI) is an important clinical problem, which has received more attention in recent decades. It can be induced by small chemical molecules, biological agents, traditional Chinese medicines (TCM), natural medicines (NM), health products (HP), and dietary supplements (DS). Idiosyncratic DILI is far more common than intrinsic DILI clinically and can be classified into hepatocellular injury, cholestatic injury, hepatocellular-cholestatic mixed injury, and vascular injury based on the types of injured target cells. The CSH guidelines summarized the epidemiology, pathogenesis, pathology, and clinical manifestation and gives 16 evidence-based recommendations on diagnosis, differential diagnosis, treatment, and prevention of DILI.

A synergistic effect of Cremophor and beta glucosylceramide to exert liver and sugar protection

Many commonly used drugs carry the potential to induce hepatotoxicity, and a large number of foods and beverages induce an increase in blood sugar levels. A change in lifestyle by omitting these compounds is not applicable in many circumstances. β-Glucosylceramide (GC) is a naturally occurring glycosphingolipid that exerts an effect on the immune system. Cremophor EL (CrEL) is a synthetic, nonionic surfactant that is used as a vehicle for the administration of water-insoluble compounds. The aim of the present study was to determine the synergistic effect of oral administration of the combination of GC and CrEL (GCC) when added to potential toxic substrates or to sugar-enriched compounds. Four groups of mice, treated with PBS, GC, CrEL, or GCC were studied in the concanavalin A immune-mediated hepatitis model, in the acetaminophen (APAP) toxicity model, and as additives to two types of sugar-enriched soda drinks. Both GC and CrEL exerted hepatoprotective effects in the ConA hepatitis and APAP toxicity models. Moreover, in both models, GCC exerted a synergistic effect in ameliorating liver damage as manifested by a significant decrease in the ALT serum levels. When added to two types of sugar-enriched sodas, GCC exerted a synergistic effect in ameliorating the increase in blood sugar levels. GCC exerts synergistic hepatoprotective and glucose-protective effects in models of liver damage and increased serum glucose. GCC can provide liver and sugar protection when co-administered with hepatotoxic drugs or sugar-enriched drinks.

Hepatotoxicity of Antimycotics Used for Invasive Fungal Infections: In Vitro Results

Purpose. Drug-induced liver injury (DILI) is the most common cause of liver injury and a serious clinical problem; antimycotics are involved in approximately 3% of all DILI cases. The hepatotoxicity of many drugs, including the antimycotics, is poorly screened in human models. Methods. In a standardized assay the cytotoxicity on hepatocytes of different concentrations (Cmax, 5x Cmax, and 10x Cmax) of the antimycotics used for systemic infections was tested. Anidulafungin (ANI), liposomal amphotericerin B (L-AmB), caspofungin (CASPO), fluconazole (FLUCO), and voriconazole (VORI) were incubated with HepG2/C3A cells. After incubation, the viability of cells (XTT test, LDH release, trypan blue staining), the synthesis of albumin, the cytochrome 1A2 activity, and the cell death (DNA fragmentation) were determined. Kruskal-Wallis and Mann-Whitney tests were used for statistical analyses. Results. L-AmB, ANI, and CASPO showed a mild hepatotoxicity in the Cmax concentrations. Higher concentrations of anidulafungin led to a severe impairment of hepatocyte viability and function. The azoles FLUCO and VORI had a higher hepatotoxic potential in all concentrations. Conclusion. Antimycotics, especially azoles, used for systemic infections should be given with caution in patient with liver insufficiency or liver failure or high risk for this; therefore, therapeutic drug monitoring should be used. Further studies with this approach are encouraged.

Genome-Wide Association Studies for Idiosyncratic Drug-Induced Hepatotoxicity: Looking Back-Looking Forward to Next-Generation Innovation

Idiosyncratic drug-induced hepatotoxicity is a formidable challenge for rational drug discovery and development, as well as the science of personalized medicine. There is evidence that hereditary factors, in part, contribute to drug toxicity. This expert analysis and review offer the insights gained, and the challenges ahead, for genome-wide association studies (GWASs) of idiosyncratic drug-induced hepatotoxicity. Published articles on genome-wide and subsequent replication studies were systematically searched in the PubMed electronic database. We found that the genetic risk variants that were identified genome-wide, and replication confirmed, are mainly related to polymorphisms in the human leukocyte antigen (HLA) region that include HLA-DQB1*06:02 for amoxicillin-clavulanate, HLA-B*57:01 for flucloxacillin, HLA-DRB1*15:01 for lumiracoxib, and HLA-DRB1*07:01 for lapatinib and ximelagatran-induced hepatotoxicity. Additionally, polymorphisms in ST6 β-galactosamide α-2, 6-sialyltranferase-1 (ST6GAL1), which plays a role in systemic inflammatory response, and variants in intron of family with sequence similarity-65 member-B (FAM65B) that play roles in liver inflammation displayed association with flucloxacillin and antituberculosis drug-induced hepatotoxicity, respectively. Taken together, these GWAS findings offer molecular leads on the central role that the immune system plays in idiosyncratic drug-induced hepatotoxicity. We conclude the expert review with a brief discussion of the salient challenges ahead. These include, for example, the need for discursive discovery paradigms that incorporate alternating GWASs and candidate gene studies, as well as the study of the environtome, the entire complement of environmental factors, including science and innovation policies that enact on global society and the human host, and by extension, on susceptibility for idiosyncratic drug-induced hepatotoxicity.

Patient-specific hepatocyte-like cells derived from induced pluripotent stem cells model pazopanib-mediated hepatotoxicity

Idiosyncratic drug-induced hepatotoxicity is a major cause of liver damage and drug pipeline failure, and is difficult to study as patient-specific features are not readily incorporated in traditional hepatotoxicity testing approaches using population pooled cell sources. Here we demonstrate the use of patient-specific hepatocyte-like cells (HLCs) derived from induced pluripotent stem cells for modeling idiosyncratic hepatotoxicity to pazopanib (PZ), a tyrosine kinase inhibitor drug associated with significant hepatotoxicity of unknown mechanistic basis. In vitro cytotoxicity assays confirmed that HLCs from patients with clinically identified hepatotoxicity were more sensitive to PZ-induced toxicity than other individuals, while a prototype hepatotoxin acetaminophen was similarly toxic to all HLCs studied. Transcriptional analyses showed that PZ induces oxidative stress (OS) in HLCs in general, but in HLCs from susceptible individuals, PZ causes relative disruption of iron metabolism and higher burden of OS. Our study establishes the first patient-specific HLC-based platform for idiosyncratic hepatotoxicity testing, incorporating multiple potential causative factors and permitting the correlation of transcriptomic and cellular responses to clinical phenotypes. Establishment of patient-specific HLCs with clinical phenotypes representing population variations will be valuable for pharmaceutical drug testing.

Idiosyncratic Drug-Induced Liver Injury (IDILI): Potential Mechanisms and Predictive Assays

Idiosyncratic drug-induced liver injury (IDILI) is a significant source of drug recall and acute liver failure (ALF) in the United States. While current drug development processes emphasize general toxicity and drug metabolizing enzyme- (DME-) mediated toxicity, it has been challenging to develop comprehensive models for assessing complete idiosyncratic potential. In this review, we describe the enzymes and proteins that contain polymorphisms believed to contribute to IDILI, including ones that affect phase I and phase II metabolism, antioxidant enzymes, drug transporters, inflammation, and human leukocyte antigen (HLA). We then describe the various assays that have been developed to detect individual reactions focusing on each of the mechanisms described in the background. Finally, we examine current trends in developing comprehensive models for examining these mechanisms. There is an urgent need to develop a panel of multiparametric assays for diagnosing individual toxicity potential.

Drug-induced Liver Injury Associated with Mosapride Citrate: A Report of Two Cases

We herein report two cases of drug-induced liver injury (DILI) due to mosapride. Case 1: A 78-year-old man was admitted with elevated transaminase levels. The cessation of mosapride led to the improvement of elevated liver enzyme levels. Case 2: A 54-year-old man was admitted with jaundice. Mosapride was discontinued immediately, and methylprednisolone was administered for acute liver failure. The patient's data showed improvement, and he was discharged on Day 32. In both cases, mosapride gave a positive response to a drug-induced lymphocyte stimulation test (DLST), and the patient's score based on the criteria for DILI was "highly probable".

Are Polymorphisms in Genes Relevant to Drug Disposition Predictors of Susceptibility to Drug-Induced Liver Injury?

Despite considerable progress in identifying specific HLA alleles as genetic risk factors for some forms of drug-induced liver injury, progress in understanding whether genetic polymorphisms relevant to drug disposition also contribute to risk for developing this serious toxicity has been more limited. Evidence from both candidate-gene case control studies and genome-wide association studies is now discussed. In the case of genes relevant to drug metabolism, polymorphisms in cytochromes P450, UDP-glucuronosyltransferases, N-acetyltransferases and glutathione S-transferases as risk factors for DILI are assessed. The relevance of ABC transporters to drug-induced liver injury is also considered, together with data showing associations of particular ABCB11, ABCB1 and ABCC2 polymorphisms with some forms of drug-induced liver injury. Very few of the associations with genes relevant to drug disposition that have been reported have been well replicated. Even apparently well-studied associations such as that between isoniazid liver injury and N-acetyltransferase 2 slow acetylators remain problematic, though it seems likely that polymorphisms in drug metabolism genes do contribute to risk for some specific drugs. A better understanding of genetic risk factors for drug-induced liver injury will require further genome-wide association studies with larger numbers of cases, especially for forms of drug-induced liver injury where HLA genotype does not appear to be a risk factor.

Profile of Acute Liver Failure from North-east India and Its Differences from other Parts of the Country

Background

Acute liver failure (ALF) is a critical illness with a large number of viral and nonviral causes. Clinical course and etiologies in the Asian countries are different from those reported from the Western world and mortality is high. There may even be intracountry variations in large countries like India, which have differing culture, ethnicity, and environment. Data from North-east part of India is lacking.

Materials and methods

Acute liver failure cases (>14 years of age) seen over a period of 8 years (n = 255) were studied at a Government Medical College in Assam for their etiological and other demographic profile. Viral serology was carried out and revalidated at a laboratory in New Delhi.

Results

Majority of cases were <30 years of age. Commonest etiology was nonviral (non-ABCE). Amongst viral causes, hepatitis A and E were common, while hepatitis B virus (HBV) was rare. Unknown herbal medication use was very frequent in our cases with a significantly higher mortality. Mortality was highest in cases in 3rd decade of life. Statistically, international normalized ratio (INR) was the strongest predictor of death.

Conclusion

Unlike the rest of India, hepatitis virus is not the major cause of ALF in our part; hepatitis A being commoner than hepatitis E, and B is rare. Unknown herbal medications are major cause of mortality and is important medicosocial issue. Our study highlights the differences in the profile of ALF from other Indian and western studies, possibly due to sociocultural factors prevalent in this part.

How to cite this article

Das AK, Begum T, Kar P, Dutta A. Profile of Acute Liver Failure from North-east India and Its Differences from other Parts of the Country. Euroasian J Hepato-Gastroenterol 2016;6(2):111-115.

Evaluation of a novel PXR-knockout in HepaRG™ cells

The nuclear pregnane X receptor (PXR) regulates the expression of genes involved in the metabolism, hepatobiliary disposition, and toxicity of drugs and endogenous compounds. PXR is a promiscuous nuclear hormone receptor (NHR) with significant ligand and DNA‐binding crosstalk with the constitutive androstane receptor (CAR); hence, defining the precise role of PXR in gene regulation is challenging. Here, utilising a novel PXR‐knockout (KO) HepaRG cell line, real‐time PCR analysis was conducted to determine PXR involvement for a range of inducers. The selective PXR agonist rifampicin, a selective CAR activator, 6‐(4‐chlorophenyl)imidazo[2,1‐b][1,3]thiazole‐5‐carbaldehyde O‐(3,4‐dichlorobenzyl)oxime (CITCO), and dual activators of CAR and PXR including phenobarbital (PB) were analyzed. HepaRG control cells (5F clone) were responsive to prototypical inducers of CYP2B6 and CYP3A4. No response was observed in the PXR‐KO cells treated with rifampicin. Induction of CYP3A4 by PB, artemisinin, and phenytoin was also much reduced in PXR‐KO cells, while the response to CITCO was maintained. This finding is in agreement with the abolition of functional PXR expression. The apparent EC₅₀ values for PB were in agreement between the cell lines; however, CITCO was ~threefold (0.3 μmol/L vs. 1 μmol/L) lower in the PXR‐KO cells compared with the 5F cells for CYP2B6 induction. Results presented support the application of the novel PXR‐KO cells in the definitive assignment of PXR‐mediated CYP2B6 and CYP3A4 induction. Utilization of such cell lines will allow advancement in composing structure activity relationships rather than relying predominantly on pharmacological manipulations and provide in‐depth mechanistic evaluation.

Clinical characteristics of drug-induced liver injury and related risk factors

Drug-induced liver injury (DILI) is often undiagnosed or misdiagnosed clinically because of diagnostic difficulties caused by lack of laboratory-specific serological markers. In this study, we comprehensively assessed the clinical characteristics, laboratory indices, hepatotoxic drugs, risk factors and outcomes concerning DILI, and explored the similarities in mechanisms between Chinese and Western drug-induced DILI. Patients with a first diagnosis of DILI and a Roussel Uclaf Causality Assessment Method (RUCAM) score >3 points were enrolled for systematic retrospective study. Their clinical characteristics, clinical classification, risk factors, laboratory indices, hepatotoxic drugs and outcomes were analyzed. Cholestatic patients had the highest alkaline phosphatase (ALP) and prothrombin time activity (PTA) levels (P<0.05). Patients with medication time ≥30 days had significantly higher positive rate of autoantibodies than those with medication time <30 days. Odds ratio values for DILI-related factors such as hepatobiliary diseases, immune dysfunction, diabetes, hypertension, chronic alcohol consumption and age ≥45 years were 6.552, 6.130, 3.774, 2.801, 2.002 and 1.838, respectively. Pathogeneses of Chinese and Western drug-induced DILI may be substantially the same. DILI accompanied with autoantibody positivity may indicate severe liver injury outcome. Hepatobiliary diseases, diabetes and hypertension are likely to increase drug susceptibility, and more prone to cause liver injury.

HLA-DQ B1*0201 and A1*0102 Alleles Are Not Responsible for Antituberculosis Drug-Induced Hepatotoxicity Risk in Spanish Population

Aims

To evaluate the role of human leukocyte antigen (HLA) class II DQB1*0201 and DQA1*0102 in the risk of antituberculosis drug (ATD)-induced hepatotoxicity (ATDH) in a cohort of tuberculosis patients of Caucasian origin from Spain.

Methods

Matched case-control study including active tuberculosis (TB) patients from Spain (Caucasian) treated with first-line ATD (Isoniazid, Rifampin, and Pyrazinamide). Presence or absence of HLA class II DQB1*0201 and DQA1*0102 alleles were compared between cases and controls.

Results

We included 110 TB patients, 55 ATDH cases, and 55 sex-matched controls. The analysis of the presence of HLA-DQB1*0201 and HLA-DQA*0102 did not show significative differences between both groups [presence of HLA-DQB1*0201 53.6% of the cases vs. 45.4% of the controls, OR: 1.63 95% CI (0.62–4.52) p = 0.38; presence of HLA-DQA*0102 7.5% of cases vs. 20% of controls, OR: 0.36 95% CI (0.08–1.23) p = 0.12]. After multivariate logistic regression analysis including in the model, other potential risk factors of hepatotoxicity HLA class II DQB1*0201 and DQA1*0102 alleles were not found significantly associated with the risk of development ATDH. We could not demonstrate an association between HLA-DQA1*0102 and HLA-DQB1*0201 with the risk of ATDH in this Caucasian population of Spanish origin.

Hepatic drug transporters: the journey so far

INTRODUCTION

The key role of transporter biology in both the manifestation and treatment of disease is now firmly established. Experiences of sub-optimal drug exposure due to drug-transporter interplay have supported incorporation of studies aimed at understanding the interactions between compounds and drug transporters much earlier in drug discovery. While drug transporters can impact the most pivotal pharmacokinetic parameter with respect to human dose and exposure projections, clearance, at a renal or hepatobiliary level, the latter will form the focus of this perspective.

AREAS COVERED

A synopsis of guidelines on which transporters to study together with an overview of the currently available toolkit is presented. A perspective on when to conduct studies with various hepatic transporters is also provided together with structural "alerts" which should prompt early investigation.

EXPERT OPINION

Great progress has been made in individual laboratories and via consortia to understand the role of drug transporters in disease, drug disposition, drug-drug interactions and toxicity. A systematic analysis of the value posed by the available approaches and an inter-lab comparison now seems warranted. The emerging ability to use physico-chemical properties to guide future screening cascades promises to revolutionise the efficiency of early drug discovery.

In vitro evaluation of hepatotoxic drugs in human hepatocytes from multiple donors: Identification of P450 activity as a potential risk factor for drug-induced liver injuries

A possible risk factor for drug-induced hepatotoxicity is drug metabolizing enzyme activity, which is known to vary among individuals due to genetic (genetic polymorphism) and environmental factors (environmental pollutants, foods, and medications that are inhibitors or inducers of drug metabolizing enzymes). We hypothesize that hepatic cytochrome P450-dependent monooxygenase (CYP) activity is one of the key risk factors for drug induced liver injuries (DILI) in the human population, especially for drugs that are metabolically activated to cytotoxic/reactive metabolites. Human hepatocytes from 19 donors were evaluated for the activities of 8 major P450 isoforms: CYP1A2, CYP2B6, CYP2C8, CYP2C9, CYP2C19, CYP2D6, CYP2E1 and CYP3A4. Extensive individual variations were observed, consistent with what is known to be in the human population. As CYP3A4 is known to be one of the most important P450 isoforms for drug metabolism, studies were performed to evaluate the relationship between the in vitro cytotoxicity of hepatotoxic drugs and CYP3A4 activity. In a proof of concept study, hepatocytes from six donors (lots) representing the observed range of CYP3A4 activities were chosen for the evaluation of in vitro hepatotoxicity of four drugs known to be associated with acute liver failure: acetaminophen, cyclophosphamide, ketoconazole, and tamoxifen. The hepatocytes were cultured in collagen-coated plates and treated with the hepatotoxicants for approximately 24 h, followed by viability determination based on cellular adenosine triphosphate (ATP) contents. HH1023, the lot of hepatocytes with the highest CYP3A4 activity, was found to be the most sensitive to the cytotoxicity of all 4 hepatotoxic drugs, thereby suggesting that high CYP3A4 activity may be a risk factor. To further validate the relationship, a second study was performed with hepatocytes from 16 donors. In this study, the hepatocytes were quantified for CYP3A4 activity at the time of treatment. Results of the second study show confirm the correlation between with high CYP3A4 activity and sensitivity to hepatotoxic drugs. Our results with primary cultured hepatocytes from multiple donors support the hypothesis that elevated P450 activity may be a risk factor for drug-induced liver injuries.

Metabolic activation and analgesic effect of flupirtine in healthy subjects, influence of the polymorphic NAT2, UGT1A1 and GSTP1

AIMS

The rare association of flupirtine with liver injury is most likely caused by reactive quinone diimines and their oxidative formation may be influenced by the activities of N-acetyltransferases (NAT) that conjugate the less toxic metabolite D13223, and by glucuronosyltransferases (UGT) and glutathione S-transferases (GST) that generate stable terminal glucuronides and mercapturic acid derivatives, respectively. The influence of genetic polymorphisms of NAT2, UGT1A1 and GSTP1 on generation of the terminal mercapturic acid derivatives and analgesic effects was evaluated to identify potential genetic risk factors for hepatotoxicity of flupirtine.

METHODS

Metabolic disposition of flupirtine was measured after intravenous administration (100 mg), after swallowing an immediate-release (IR) tablet (100 mg) and after repeated administration of modified release (MR) tablets (400 mg once daily 8 days) in 36 selected healthy subjects. Analgesic effects were measured using pain models (delayed onset of muscle soreness, electric pain).

RESULTS

Flupirtine IR was rapidly but incompletely absorbed (∼ 72%). Repeated administration of flupirtine MR showed lower bioavailability (∼ 60%). Approximately 12% of bioavailable flupirtine IR and 8% of bioavailable flupiritine MR was eliminated as mercapturic acid derivatives into the urine independent of the UGT1A1, NAT2 and GSTP1 genotype. Carriers of variant GSTP1 alleles showed lower bioavailability but increased intestinal secretion of flupirtine and increased efficiency in experimental pain. Flupirtine was not a substrate for ABCB1 and ABCC2.

CONCLUSIONS

Formation of mercapturic acid derivatives is a major elimination route for flupirtine in man. However, the theoretically toxic pathway is not influenced by the frequent polymorphisms of UGT1A1, NAT2 and GSTP1.

Immunosuppressant therapy successfully improved regorafenib-induced severe hepatic injury in a patient with metastatic gastrointestinal stromal tumor: A case report

A 75-year-old man diagnosed with ileal gastrointestinal tumor with peritoneal dissemination was subjected to salvage treatment with regorafenib at 120 mg/day. Following the initiation of the treatment, liver dysfunction appeared on day 28, and continued to worsen despite termination of the treatment. Since no increase in the levels of serum immunoglobulins of the patient was observed, and negative results were obtained for the analysis of viral markers and autoantibodies, a diagnosis of regorafenib-induced hepatitis was suggested. In consequence, the patient received steroid pulse therapy and continuous administration of prednisolone, without sufficient improvement. Liver biopsy revealed interface hepatitis with prominent plasma cell infiltration, suggesting regorafenib-induced autoimmune hepatitis. The patient was then administered azathioprine and prednisolone, which improved the hepatic injury. The present case represents the first report of successful treatment of regorafenib-induced severe hepatic injury by the use of an immunosuppressant.