Causality assessment in drug-induced liver injury using a structured expert opinion process: comparison to the Roussel-Uclaf causality assessment method

Features of Autoimmune Hepatitis in Patients With Drug-induced Liver Injury

BACKGROUND & AIMS

Drug-induced liver injury (DILI) has features similar to those of other liver diseases including autoimmune hepatitis (AIH). We aimed to characterize the clinical and autoimmune features of liver injury caused by nitrofurantoin, minocycline, methyldopa, or hydralazine.

METHODS

We analyzed data from 88 cases of DILI attributed to nitrofurantoin, minocycline, methyldopa, or hydralazine included in the Drug-Induced Liver Injury Network prospective study from 2004 through 2014. Sera were collected from patients at baseline and follow-up examination and tested for levels of immunoglobulin G (IgG), antibodies to nuclear antigen (ANA), smooth muscle (SMA), and soluble liver antigen (SLA). An autoimmune score was derived on the basis of increases in levels of IgG, ANA, SMA, and SLA (assigned values of 0, 1+, or 2+). AIH-associated HLA-DRB1*03:01 and HLA-DRB1*04:01 allele frequencies were compared with those of the general population (controls).

RESULTS

Of the 88 cases, 80 were women (91%), 74% had hepatocellular injury, and 25% had severe injury. At the onset of DILI, 39% of cases had increased levels of IgG, 72% had increased levels of ANA, 60% had increased levels of SMA, and none had increases in SLA. A phenotype of autoimmunity (autoimmune score ≥2) was observed in 82% of cases attributed to nitrofurantoin and 73% of cases attributed to minocycline (73%) but only 55% of cases attributed to methyldopa and 43% of cases attributed to hydralazine (P = .16 for nitrofurantoin and minocycline vs methyldopa and hydralazine). We observed a decrease in numbers of serum samples positive for ANA (P = .01) or SMA (P < .001) and in autoimmune scores (P < .001) between DILI onset and follow-up. Similar percentages of patients with DILI had HLA-DRB1*03:01 (15%) and HLA-DRB1*04:01 (9%) as controls (12% and 9%, respectively).

CONCLUSIONS

In analysis of data from the DILIN prospective study, we found that most cases of DILI attributed to nitrofurantoin or minocycline and about half of cases that were due to methyldopa and hydralazine have a phenotype of autoimmunity similar to AIH. These features decrease with recovery of the injury and are not associated with the typical HLA alleles found in patients with idiopathic AIH.

Research Advances on Hepatotoxicity of Herbal Medicines in China

In general, herbal medicines have been considered as safe by the general public, since they are naturally occurring and have been applied in treatment for over thousands of years. As the use of herbal medicine is rapidly increasing globally, the potential toxicity of herbal drugs, in particular drug-induced liver injury (DILI), has now become a serious medical issue. According to the literature, the authors analyzed and discussed the hepatotoxicity problem of Chinese herbal medicines (CHM), including global overview on herbal-induced liver injury (HILI), current research progress on toxic CHM, diagnosis and treatment of HILI, and modern approaches and technologies of study of hepatotoxicity. As to promote the recognition of HILI and tackle the issue, a guideline for the diagnosis and treatment of HILI has recently been drafted by Chinese scientists. As suggested by the guideline, the hepatotoxicity issue of CHM, as a matter of fact, is overestimated. Up to date, the investigation of hepatotoxicity of CHM is now booming with worldwide application of CHM. This review therefore provides useful information for investigating hepatotoxicity of herbal medicine and characterizing DILI caused by CHM. In addition, authors describe in which way further efforts should be made to study the rationale of CHM and liver injury.

Apixaban-induced liver injury

An 81-year-old woman with well-controlled hypertension presented to the emergency department with new-onset atrial fibrillation with rapid ventricular response. Treatment for atrial fibrillation was initiated, including rate control and anticoagulation with 5 mg of apixaban two times per day for primary stroke prophylaxis. Three days after initiation of apixaban, the patient noted new-onset abdominal pain, worsening shortness of breath and weakness. Laboratory results showed elevated liver enzymes. Workup for elevated transaminase did not reveal any underlying infectious or autoimmune process. Apixaban, a probable cause for the hepatocellular injury, was discontinued and replaced with intravenous unfractionated heparin to bridge anticoagulation with warfarin. The patient's symptoms resolved as her transaminases improved by discontinuation of apixaban. We illustrate this case of drug-induced hepatotoxicity secondary to treatment with apixaban. It is important for physicians to be aware of this rare adverse effect caused by a widely used novel oral anticoagulant.

Therapeutic efficacy of monthly subcutaneous injection of daclizumab in relapsing multiple sclerosis

Despite the availability of multiple disease-modifying therapies for relapsing multiple sclerosis (MS), there remains a need for highly efficacious targeted therapy with a favorable benefit-risk profile and attributes that encourage a high level of treatment adherence. Daclizumab is a humanized monoclonal antibody directed against CD25, the α subunit of the high-affinity interleukin 2 (IL-2) receptor, that reversibly modulates IL-2 signaling. Daclizumab treatment leads to antagonism of proinflammatory, activated T lymphocyte function and expansion of immunoregulatory CD56(bright) natural killer cells, and has the potential to, at least in part, rectify the imbalance between immune tolerance and autoimmunity in relapsing MS. The clinical pharmacology, efficacy, and safety of subcutaneous daclizumab have been evaluated extensively in a large clinical study program. In pivotal studies, daclizumab demonstrated superior efficacy in reducing clinical and radiologic measures of MS disease activity compared with placebo or intramuscular interferon beta-1a, a standard-of-care therapy for relapsing MS. The risk of hepatic disorders, cutaneous events, and infections was modestly increased. The monthly subcutaneous self-injection dosing regimen of daclizumab may be advantageous in maintaining patient adherence to treatment, which is important for optimal outcomes with MS disease-modifying therapy. Daclizumab has been approved in the US and in the European Union and represents an effective new treatment option for patients with relapsing forms of MS, and is currently under review by other regulatory agencies.

Severe Acute Hepatocellular Injury Attributed to OxyELITE Pro: A Case Series

BACKGROUND/AIM

Herbal and dietary supplement (HDS) hepatotoxicity is increasingly being reported in the USA. This case series describes the presenting clinical features and outcomes of seven patients with liver injury attributed to OxyELITE Pro enrolled in the Drug-Induced Liver Injury Network (DILIN) study.

METHODS

The 6-month outcomes of patients with hepatotoxicity attributed to OxyELITE Pro enrolled in the DILIN prospective registry between 2004 and 2015 are presented.

RESULTS

Six of the seven patients (86 %) presented in 2013 with symptoms of hepatitis and acute hepatocellular injury. The median duration of OxyELITE Pro use was 18 weeks (range 5-102 weeks). Median age was 36 years (range 28-62), 86 % were female, and 43 % were Asian. One patient had rash, none had eosinophilia, and three had antinuclear antibody reactivity. The median peak ALT was 2242 U/L, alkaline phosphatase 284 U/L and bilirubin 15.0 mg/dL. Six patients (86 %) were hospitalized, three developed acute liver failure and two underwent liver transplantation. DILIN causality scores for OxyELITE Pro were definite in 1, highly likely in 3, probable in 2, and possible in 1. Four of the five patients without liver transplant recovered completely within 6 months, while one patient had mild residual ALT elevations.

CONCLUSIONS

Seven cases of severe acute hepatocellular injury attributed to OxyELITE Pro are reported. These results reinforce the need to assess for HDS supplement use in patients presenting with unexplained acute hepatitis and point to the need for additional regulatory oversight of HDS products.

Monocyte-derived hepatocyte-like cells for causality assessment of idiosyncratic drug-induced liver injury

BACKGROUND

Idiosyncratic drug-induced liver injury (iDILI) is a frequent cause of acute liver injury and a serious problem in late stage drug-development. Its diagnosis is one of the most challenging in hepatology, since it is done by exclusion and relies on expert opinion. Until now no reliable in vitro test exists to support the diagnosis of iDILI. In some instances it is impossible to determine the causative drug in polymedicated patients.

AIM

To investigate if monocyte-derived hepatocyte-like (MH) cells might be a tool supporting clinical judgment for iDILI diagnosis and causality assessment.

METHODS

This prospective study included 54 patients with acute liver injury and intake of at least one drug. Thirty-one patients were diagnosed with iDILI based on causality likelihood. MH cells were generated from every patient and in vitro toxicity of the respective drugs was assessed by lactate-dehydrogenase release. The results from MH cells and RUCAM, the most widely used scoring system as methods to support clinical judgement were compared.

RESULTS

MH cells showed enhanced toxicity in 29 of the 31 patients with iDILI, similar to RUCAM score. MH cells exhibited negative results in the 23 non-DILI cases, whereas RUCAM indicated possible iDILI in six cases. Analysis of the comedications also showed superior specificity of MH cells. No MH cell toxicity of the drugs showing toxicity in patients with iDILI was observed in MH cells of healthy donors.

CONCLUSIONS

In this pilot study in vitro testing using MH cells derived from patients with acute liver injury was able to identify patients with iDILI with an excellent sensitivity and a higher specificity than RUCAM, the most widely used current causality assessment score. Therefore, MH cells could be useful to identify the causative drugs even in polymedicated patients by adding objective data to causality assessment.

TRIAL REGISTRATION NUMBER

NCT02353455.

Amoxicillin-Clavulanate-Induced Liver Injury

BACKGROUND AND AIMS

Amoxicillin-clavulanate (AC) is the most frequent cause of idiosyncratic drug-induced injury (DILI) in the US DILI Network (DILIN) registry. Here, we examined a large cohort of AC-DILI cases and compared features of AC-DILI to those of other drugs.

METHODS

Subjects with suspected DILI were enrolled prospectively, and cases were adjudicated as previously described. Clinical variables and outcomes of patients with AC-DILI were compared to the overall DILIN cohort and to DILI caused by other antimicrobials.

RESULTS

One hundred and seventeen subjects with AC-DILI were identified from the cohort (n = 1038) representing 11 % of all cases and 24 % of those due to antimicrobial agents (n = 479). Those with AC-DILI were older (60 vs. 48 years, P < 0.001). AC-DILI was more frequent in men than women (62 vs. 39 %) compared to the overall cohort (40 vs. 60 %, P < 0.001). The mean time to symptom onset was 31 days. The Tb, ALT, and ALP were 7 mg/dL, 478, and 325 U/L at onset. Nearly all liver biopsies showed prominent cholestatic features. Resolution of AC-DILI, defined by return of Tb to <2.5 mg/dL, occurred on average 55 days after the peak value. Three female subjects required liver transplantation, and none died due to DILI.

CONCLUSION

AC-DILI causes a moderately severe, mixed hepatocellular-cholestatic injury, particularly in older men, unlike DILI in general, which predominates in women. Although often protracted, eventual apparent recovery is typical, particularly for men and usually in women, but three women required liver transplantation.

Clinical Pattern of Tolvaptan-Associated Liver Injury in Subjects with Autosomal Dominant Polycystic Kidney Disease: Analysis of Clinical Trials Database

Introduction

Subjects with autosomal dominant polycystic kidney disease (ADPKD) who were taking tolvaptan experienced aminotransferase elevations more frequently than those on placebo in the TEMPO 3:4 (Tolvaptan Efficacy and Safety in Management of Autosomal Dominant Polycystic Kidney Disease and its Outcomes) clinical trial.

Methods

An independent, blinded, expert Hepatic Adjudication Committee re-examined data from TEMPO 3:4 and its open-label extension TEMPO 4:4, as well as from long-term (>14 months) non-ADPKD tolvaptan trials, using the 5-point Drug-Induced Liver Injury Network classification.

Results

In TEMPO 3:4, 1445 subjects were randomized 2:1 (tolvaptan vs. placebo) and 1441 had post-baseline assessments of hepatic injury. Sixteen patients on tolvaptan and one on placebo had significant aminotransferase elevations judged to be at least probably related to study drug. No association with dose or systemic exposure was found. Two of 957 subjects taking tolvaptan (0.2 %) and zero of 484 taking placebo met the definition of a Hy’s Law case. One additional Hy’s Law case was identified in a TEMPO 4:4 subject who had received placebo in the lead study. The onset of a hepatocellular injury occurred between 3 and 18 months after starting tolvaptan, with gradual resolution over the subsequent 1–4 months. None of the events were associated with liver failure or chronic liver injury/dysfunction. No imbalance in hepatic events was observed between tolvaptan and placebo in lower-dose clinical trials of patients with hyponatremia, heart failure, or cirrhosis.

Conclusions

Although hepatocellular injury following long-term tolvaptan treatment in ADPKD subjects was infrequent and reversible, the potential for serious irreversible injury exists. Regular monitoring of transaminase levels is warranted in this patient population.

Liver Function Test Abnormalities in Depressed Patients Treated with Antidepressants: A Real-World Systematic Observational Study in Psychiatric Settings

Background

Concerning the risk of antidepressant induced liver injury, it is not clear whether psychiatrists perform a liver function test (LFT) and whether an increase in aminotransferase levels should contraindicate antidepressant treatment.

Aim

To evaluate LFT availability, the prevalence of LFT abnormalities and the probable cause of an altered LFT in patients with a major depressive episode (MDE) requiring an antidepressant drug.

Methods

We studied LFT evaluation in a real world psychiatric setting, in a sample of 321 consecutive patients with a current major depressive episode (MDE) requiring an antidepressant drug treatment, but without current alcohol or drug dependence or unstable medical disease.

Results

An LFT is performed in 36.1% (116/321) of depressed patients. One fifth of antidepressant-treated patients who had an LFT evaluation had abnormal results. The most frequent causes of LFT abnormalities were: NAFLD (nonalcoholic fatty liver disease) (7/321; 2.1%), acute alcohol consumption (4/321; 1.2%), antidepressant-induced liver injury (3/321; 0.9%), hepatitis C virus infection (2/321; 0.6%) and heart failure (1/321; 0.3%). The cause of LFT abnormalities was unknown in 32% of patients (8/25) due to the absence of etiological investigations.

Conclusion

These results demonstrate that an LFT is infrequently performed by psychiatrists in depressed patients requiring an antidepressant drug. Baseline LFT assessment and observations during the first six months of antidepressant treatment may be useful for detection of patients with pre-existing liver disease such as NAFLD, and early identification of cases of antidepressant-induced liver injury. An increase in aminotransferase levels may be related to an underlying liver disease, but does not contraindicate antidepressant treatment.

Causes, Features, and Outcomes of Drug-Induced Liver Injury in 69 Children from China

Background/Aims

Drug-induced liver injury (DILI) is a frequent cause of pediatric liver disease; however, the data on DILI are remarkably limited.

Methods

All 69 children hospitalized with DILI between January 2009 and December 2011 were retrospectively studied.

Results

A total of 37.7% of the children had medical histories of respiratory infection. The clinical injury patterns were as follows: hepatocellular 89.9%, cholestatic 2.9%, and mixed 7.2%. Liver biopsies from 55 children most frequently demonstrated chronic (47.3%) and acute (27.3%) hepatitis. Hypersensitivity features, namely, fever (31.9%), rash (21.7%), and eosinophilia (1.4%), were found. Twenty-four children (34.8%) developed chronic DILI. Antibiotics (26.1%) were the most common Western medicines (WMs) causing DILI, and the major implicated herbs were Ephedra sinica and Polygonum multiflorum. Compared with WM, the children whose injuries were caused by Chinese herbal medicine (CHM) showed a higher level of total bilirubin (1.4 mg/dL vs 16.6 mg/dL, p=0.004) and a longer prothrombin time (11.8 seconds vs 17.3 seconds, p=0.012), but they exhibited less chronic DILI (2/15 vs 18/39, p=0.031).

Conclusions

Most cases of DILI in children are caused by antibiotics or CHM used to treat respiratory infection and present with hepatocellular injury. Compared with WM, CHM is more likely to cause severe liver injury, but liver injury caused by CHM is curable.

Hepatotoxicity Associated with the Use of Anti-TNF-α Agents

Medications to inhibit the actions of tumour necrosis factor alpha have revolutionized the treatment of several pro-inflammatory autoimmune conditions. Despite their many benefits, several serious side effects exist and adverse reactions do occur from these medications. While many of the medications' potential adverse effects were anticipated and recognized in clinical trials prior to drug approval, several more rare adverse reactions were recorded in the literature as the popularity, availability and distribution of these medications grew. Of these potential adverse reactions, liver injury, although uncommon, has been observed in some patients. As case reports accrued over time and ultimately case series developed, the link became better established between this family of medicines and various patterns of liver injury. Interestingly, it appears that the majority of cases exhibit an autoimmune hepatitis profile both in serological markers of autoimmune liver disease and in classic autoimmune features seen on hepatic histopathology. Despite the growing evidence of this relationship, the pathogenesis of this reaction remains incompletely understood, but it appears to depend on characteristics of the medications and the genetic composition of the patients; it is likely more complicated than a simple medication class effect. Because of this still incomplete understanding and the infrequency of the occurrence, treatments have also been limited, although it is clear that most patients improve with cessation of the offending agent and, in certain cases, glucocorticoid use. However, more needs to be done in the future to unveil the underlying mechanisms of this adverse reaction.

Oral Azole Antifungal Medications and Risk of Acute Liver Injury, Overall and by Chronic Liver Disease Status

BACKGROUND

Reports on associations between azole antifungal medications and acute liver injury are inconsistent and have not been based on liver-related laboratory tests. We evaluated incidence rates of acute liver injury associated with oral azole antifungals.

METHODS

We conducted a cohort study among Kaiser Permanente Northern California members who initiated an oral azole antifungal in an outpatient setting during 2004-2010. We determined development of: (1) liver aminotransferases >200 U/L, (2) severe acute liver injury (coagulopathy with hyperbilirubinemia), and (3) acute liver failure. We calculated incidence rates of endpoints. Cox regression was used to determine whether chronic liver disease was a risk factor for outcomes.

RESULTS

Among 195,334 azole initiators (178,879 fluconazole; 14,296 ketoconazole; 1653 itraconazole; 478 voriconazole; 28 posaconazole), incidence rates (events/1000 person-years [95% confidence intervals (CIs)]) of liver aminotransferases >200 U/L were similarly low with fluconazole (13.0 [11.4-14.6]), ketoconazole (19.3 [13.8-26.3]), and itraconazole (24.5 [10.6-48.2]). Rates were higher with voriconazole (181.9 [112.6-278.0]) and posaconazole (191.1 [23.1-690.4]), but comparable. Severe acute liver injury was uncommon with fluconazole (2.0 [1.4-2.7]), ketoconazole (2.9 [1.1-6.3]), and itraconazole (0.0 [0.0-11.2]), but more frequent with voriconazole (16.7 [2.0-60.2]) and posaconazole (93.4 [2.4-520.6]). One patient developed acute liver failure due to ketoconazole. Pre-existing chronic liver disease increased risks of aminotransferases >200 U/L (hazard ratio 4.68 [95% CI, 3.68-5.94]) and severe acute liver injury (hazard ratio 5.62 [95% CI, 2.56-12.35]).

CONCLUSIONS

Rates of acute liver injury were similarly low for fluconazole, ketoconazole, and itraconazole. Events were more common among voriconazole and posaconazole users but were comparable. Pre-existing chronic liver disease increased risk of azole-induced liver injury.

Drug-Induced Liver Injury Network Causality Assessment: Criteria and Experience in the United States

Hepatotoxicity due to drugs, herbal or dietary supplements remains largely a clinical diagnosis based on meticulous history taking and exclusion of other causes of liver injury. In 2004, the U.S. Drug-Induced Liver Injury Network (DILIN) was created under the auspices of the U.S. National Institute of Diabetes and Digestive and Kidney Diseases with the aims of establishing a large registry of cases for clinical, epidemiological and mechanistic study. From inception, the DILIN has used an expert opinion process that incorporates consensus amongst three different DILIN hepatologists assigned to each case. It is the most well-established, well-described and vigorous expert opinion process for DILI to date, and yet it is an imperfect standard. This review will discuss the DILIN expert opinion process, its strengths and weaknesses, psychometric performance and future.

Current and future directions in the treatment and prevention of drug-induced liver injury: a systematic review

While the pace of discovery of new agents, mechanisms and risk factors involved in drug-induced liver injury (DILI) remains brisk, advances in the treatment of acute DILI seems slow by comparison. In general, the key to treating suspected DILI is to stop using the drug prior to developing irreversible liver failure. However, predicting when to stop is an inexact science, and commonly used ALT monitoring is an ineffective strategy outside of clinical trials. The only specific antidote for acute DILI remains N-acetylcysteine (NAC) for acetaminophen poisoning, although NAC is proving to be beneficial in some cases of non-acetaminophen DILI in adults. Corticosteroids can be effective for DILI associated with autoimmune or systemic hypersensitivity features. Ursodeoxycholic acid, silymarin and glycyrrhizin have been used to treat DILI for decades, but success remains anecdotal. Bile acid washout regimens using cholestyramine appear to be more evidenced based, in particular for leflunomide toxicity. For drug-induced acute liver failure, the use of liver support systems is still investigational in the United States and emergency liver transplant remains limited by its availability. Primary prevention appears to be the key to avoiding DILI and the need for acute treatment. Pharmacogenomics, including human leukocyte antigen genotyping and the discovery of specific DILI biomarkers offers significant promise for the future. This article describes and summarizes the numerous and diverse treatment and prevention modalities that are currently available to manage DILI.

The Art and Science of Diagnosing and Managing Drug-induced Liver Injury in 2015 and Beyond

Drug-induced liver injury (DILI) remains a leading reason why new compounds are dropped from further study or are the subject of product warnings and regulatory actions. Hy's Law of drug-induced hepatocellular jaundice causing a case-fatality rate or need for transplant of 10% or higher has been validated in several large national registries, including the ongoing, prospective U.S. Drug-Induced Liver Injury Network. It serves as the basis for stopping rules in clinical trials and in clinical practice. Because DILI can mimic all known causes of acute and chronic liver disease, establishing causality can be difficult. Histopathologic findings are often nonspecific and rarely, if ever, considered pathognomonic. A daily drug dose >50-100 mg is more likely to be hepatotoxic than does <10 mg, especially if the compound is highly lipophilic or undergoes extensive hepatic metabolism. The quest for a predictive biomarker to replace alanine aminotransferase is ongoing. Markers of necrosis and apoptosis such as microRNA-122 and keratin 18 may prove useful in identifying patients at risk for severe injury when they initially present with a suspected acetaminophen overdose. Although a number of drugs causing idiosyncratic DILI have HLA associations that may allow for pre-prescription testing to prevent hepatotoxicity, the cost and relatively low frequency of injury among affected patients limit the current usefulness of such genome-wide association studies. Alanine aminotransferase monitoring is often recommended but has rarely been shown to be an effective method to prevent serious DILI. Guidelines on the diagnosis and management of DILI have recently been published, although specific therapies remain limited. The LiverTox Web site has been introduced as an interactive online virtual textbook that makes the latest information on more than 650 agents available to clinicians, regulators, and drug developers alike.

Evidence chain-based causality identification in herb-induced liver injury: exemplification of a well-known liver-restorative herb Polygonum multiflorum

Herbal medicines have recently been recognized as the second most common cause of drug-induced liver injury (DILI) in the United States. However, reliable methods to identify the DILI causality of some herbs, such as Heshouwu (dried root of Polygonum multiflorum), remain lacking. In this study, a total of 12 307 inpatients with liver dysfunction and 147 literature-reported cases of Heshouwu DILI were screened. A general algorithm indicated that only 22.5% (9/40) and 30.6% (45/147) of all hospitalization and literature case reports, respectively, demonstrate the high probability of DILI causality of Heshouwu. By contrast, 95% (19/20) of all cases prospectively investigated by pharmacognosy, phytochemistry, and metabolomic tests exhibited highly probable causality, including a patient who was previously incorrectly attributed and a case that was excluded from Heshouwu causality by pharmacognostic evidence. Toxin (heavy metals, pesticides, and mycotoxins) contamination was also excluded from Heshouwu DILI causality. The objectivity of these screening methods for Heshouwu DILI diagnosis addresses safety concerns regarding stilbene-containing herbal medicines and dietary supplements.

Daclizumab HYP versus Interferon Beta-1a in Relapsing Multiple Sclerosis

BACKGROUND

Daclizumab high-yield process (HYP) is a humanized monoclonal antibody that binds to CD25 (alpha subunit of the interleukin-2 receptor) and modulates interleukin-2 signaling. Abnormalities in interleukin-2 signaling have been implicated in the pathogenesis of multiple sclerosis and other autoimmune disorders.

METHODS

We conducted a randomized, double-blind, active-controlled, phase 3 study involving 1841 patients with relapsing-remitting multiple sclerosis to compare daclizumab HYP, administered subcutaneously at a dose of 150 mg every 4 weeks, with interferon beta-1a, administered intramuscularly at a dose of 30 μg once weekly, for up to 144 weeks. The primary end point was the annualized relapse rate.

RESULTS

The annualized relapse rate was lower with daclizumab HYP than with interferon beta-1a (0.22 vs. 0.39; 45% lower rate with daclizumab HYP; P<0.001). The number of new or newly enlarged hyperintense lesions on T2-weighted magnetic resonance imaging (MRI) over a period of 96 weeks was lower with daclizumab HYP than with interferon beta-1a (4.3 vs. 9.4; 54% lower number of lesions with daclizumab HYP; P<0.001). At week 144, the estimated incidence of disability progression confirmed at 12 weeks was 16% with daclizumab HYP and 20% with interferon beta-1a (P=0.16). Serious adverse events, excluding relapse of multiple sclerosis, were reported in 15% of the patients in the daclizumab HYP group and in 10% of those in the interferon beta-1a group. Infections were more common in the daclizumab HYP group than in the interferon beta-1a group (in 65% vs. 57% of the patients, including serious infection in 4% vs. 2%), as were cutaneous events such as rash or eczema (in 37% vs. 19%, including serious events in 2% vs. <1%) and elevations in liver aminotransferase levels that were more than 5 times the upper limit of the normal range (in 6% vs. 3%).

CONCLUSIONS

Among patients with relapsing-remitting multiple sclerosis, daclizumab HYP showed efficacy superior to that of interferon beta-1a with regard to the annualized relapse rate and lesions, as assessed by means of MRI, but was not associated with a significantly lower risk of disability progression confirmed at 12 weeks. The rates of infection, rash, and abnormalities on liver-function testing were higher with daclizumab HYP than with interferon beta-1a. (Funded by Biogen and AbbVie Biotherapeutics; DECIDE ClinicalTrials.gov number, NCT01064401.).

Persistent liver biochemistry abnormalities are more common in older patients and those with cholestatic drug induced liver injury

OBJECTIVES

The long-term outcomes of patients with drug induced liver injury (DILI) are not well described. The aim of this study was to determine the frequency and severity of persistent liver biochemistry abnormalities in DILI patients followed over 2 years.

METHODS

Subjects with evidence of liver injury at 6 months after DILI onset were offered a month 12 and 24 study visit.

RESULTS

Amongst the 99 patients with definite, probable, or very likely DILI and available laboratory data at 12 months after DILI onset, 74 (75%) had persistent liver injury (persisters) defined as a serum aspartate aminotransferase (AST) or alanine aminotransferase (ALT) >1.5 × upper limit of normal (ULN) or an alkaline phosphatase >ULN, while 25 (25%) had resolved liver injury (resolvers). On multivariate analysis, month 12 persisters were significantly older (52.6 vs. 43.7 years, P=0.01) and more likely to have a cholestatic lab profile at DILI onset (54 vs. 20%, P<0.01) than resolvers. The month 12 persisters also had significantly poorer SF-36 physical summary scores at DILI onset and throughout follow-up compared with the resolvers (P<0.01). Amongst the 17 subjects with a liver biopsy obtained at a median of 387 days after DILI onset, 9 had chronic cholestasis, 3 had steatohepatitis, and 3 had chronic hepatitis.

CONCLUSIONS

In all, 75% of subjects with liver injury at 6 months after DILI onset have laboratory evidence of persistent liver injury during prolonged follow-up. Higher serum alkaline phosphatase levels at presentation and older patient age were independent predictors of persistent liver injury. Subjects with persistent liver injury at 12 months after DILI onset should be carefully monitored and assessed for liver disease progression.

Hepatitis E Virus Infection as a Possible Cause of Acute Liver Failure in Europe

BACKGROUND & AIMS

In Western countries, infection with the hepatitis E virus (HEV) is considered to be rare and imported from endemic regions. However, the prevalence of HEV infection has increased among adults in central Europe. HEV infection can cause acute liver failure (ALF), but there have been only a few confirmed cases of HEV-associated ALF in Europe. We investigated the number of cases of indeterminate ALF associated with HEV infection.

METHODS

We performed a retrospective analysis of 80 patients diagnosed with ALF or acute hepatitis at the University Hospital Essen in Germany from November 2006 through December 2013. Clinical data were collected from the hospital databases; archived sera were tested for IgG and IgM against HEV, as well as HEV RNA.

RESULTS

Sera from 12 patients (15%) tested positive for IgG against HEV IgG; 7 of these samples did not test positive for HEV IgM or HEV RNA. Sera from 64 patients (80%) did not test positive for IgG or IgM against HEV or HEV RNA. Sera from 8 patients (10%) tested positive for HEV RNA (only 4 of these were positive for HEV IgG) and had clinical findings to support acute HEV infection.

CONCLUSIONS

In a hospital in Germany, approximately 10% to 15% of patients with ALF had evidence for HEV infection. Serologic tests for IgG against HEV are insufficient to identify or exclude HEV infection; tests for HEV RNA also should be performed on patients with ALF of ambiguous etiology.

Drug-Induced Liver Injury

CONTEXT

Drug-induced liver injury (DILI) represents a diverse set of responses following exposure to any manufactured or naturally occurring chemical compound. Drug-induced liver injury is of major concern owing to the ever increasing number of compounds introduced into the market for treatment of various diseases as well as the increasing popularity of herbals, which lend themselves to self-medication but are not rigorously regulated.

OBJECTIVE

To provide an overview of the prevalence, classification, and diagnosis of DILI with emphasis on pathogenesis and the role of a liver biopsy. To focus on the most common, emerging, and herbal agents that cause DILI with emphasis on the histologic pattern of injury observed.

DATA SOURCES

A review of the literature was drawn from the PubMed (US National Library of Medicine) repository, textbooks, and online databases. All figures were taken from cases seen at our tertiary referral center, which is 1 of 12 participating sites in the National Institutes of Health-funded Drug-Induced Liver Injury Network.

CONCLUSIONS

Drug-induced liver injury due to prescription, over-the-counter, and herbal products is a major cause of liver disease in the United States and around the world. Diagnosis of DILI is challenging because there is no single clinical, laboratory, or histologic feature specific to DILI. Accurate diagnosis requires establishing a causal relationship with the suspected agent and excluding competing causes of liver injury. The liver biopsy is an essential component in the management of DILI by offering clues to the underlying pathogenesis, providing prognostic information, and guiding therapy.

Herbal medicine-related hepatotoxicity

Herbal medicine products represent a common therapeutic approach in the East and are gaining increasing popularity in Western countries. They are unjustifiably considered to be side-effect free; on the contrary, severe toxicity, including catastrophic hepatic injury has been reported in association with their use. Vigilance is required from both physicians and the general public. Physicians should always suspect herbal medicines when evaluating a patient with unexplained liver injury. Regulation standards for herbal products need to be reconsidered, so that the efficacy and safety of these products have been clearly demonstrated before they enter the markets.

Identification and Characterization of Cefazolin-Induced Liver Injury

BACKGROUND & AIMS

Cephalosporin antibiotics are popular because they have a broad spectrum of activity and are generally well tolerated; however, cephalosporin-induced liver injury is considered rare. We describe a new syndrome associated with a single intravenous dose of cefazolin and the clinical features of cephalosporin-induced liver injury.

METHODS

The Drug-Induced Liver Injury (DILI) Network collected detailed clinical data on 1212 patients with DILI between 2004 and 2012. We analyzed data from 41 patients in whom cephalosporins were implicated as primary agents of liver disease; 33 formally were adjudicated as having cephalosporin-induced DILI.

RESULTS

Nineteen patients developed clinically apparent DILI after a single intravenous dose of cefazolin. All patients developed self-limited liver injury 3 to 23 days after receiving cefazolin during surgery-often during a minor outpatient procedure. The latency period was 20 days. Clinical features included itching, jaundice, nausea, fever, and rash. Laboratory abnormalities included a mixed or cholestatic pattern of serum enzyme increases. We identified 14 more patients with DILI attributed to other cephalosporins (5 first-generation, 2 second-generation, 6 third-generation, and 1 fourth-generation agent). Although latency and injury patterns were similar for cefazolin and other cephalosporins, the other cephalosporins were associated with more severe courses of injury, including 2 deaths from liver failure.

CONCLUSIONS

DILI can develop after a single dose of cefazolin. It is characterized by a latency period of 1 to 3 weeks after exposure, a cholestatic biochemical pattern, and a self-limited moderate to severe clinical course. Other cephalosporins can cause a similar but more severe injury.

Evolution of the Food and Drug Administration approach to liver safety assessment for new drugs: current status and challenges

Prompted by approval in 1997 of troglitazone and bromfenac, two drugs that promptly began to show serious and sometimes fatal liver toxicity, we began at the Food and Drug Administration (FDA) a series of annual conferences in 1999 to consider issues of drug-induced liver injury (DILI). First inviting reviewers of new drug applications we opened the audiences in 2001 to pharmaceutical industry and academic consultants to industry and FDA, and slides shown at the meetings were posted on the internet to be available at the website of the American Association for the Study of Liver Diseases (AASLD)–go to (http://www.aasld.org/dili/Pages/default.aspx). Observations by Dr. Hyman J. Zimmerman that “drug-induced hepatocellular jaundice is a serious lesion” with possible mortality formed a basis for developing a computer program to plot peak serum values for alanine aminotransferase (ALT) and total bilirubin (TBL) in an x–y log–log graph for all subjects enrolled in clinical trials. This program had the capability to show the time course of all liver tests for individuals who had both hepatocellular injury and reduced whole liver function, plus clinical narratives to diagnose the severity and most likely cause of the abnormalities. We called the program eDISH (for evaluation of Drug-Induced Serious Hepatotoxicity), and began in 2004 to use it to assess DILI in clinical trial subjects. From 2008, comments made by the presenters at the conferences about their slides and ensuing discussions have been added to the website. All this has raised awareness of the problem, and since 1997, the FDA has not had to withdraw a single drug because of post-marketing hepatotoxicity. Many issues still remain to be resolved; among the most controversial is the best method to estimate likelihood that a given liver injury was actually caused by the drug in question. On November 9, 2012, a workshop was convened to discuss the best practices for the assessment of drug-induced liver injury (DILI) in clinical trials.

Liver Injury from Herbal, Dietary, and Weight Loss Supplements: a Review

Herbal and dietary supplement usage has increased steadily over the past several years in the United States. Among the non-bodybuilding herbal and dietary supplements, weight loss supplements were among the most common type of HDS implicated in liver injury. While drug induced liver injury is rare, its consequences are significant and on the rise. The purpose of this review is to highlight case reports of weight loss products such as Hydroxycut and OxyElite Pro as one form of HDS that have hepatotoxic potential and to characterize its clinical effects as well as pattern of liver injury. We also propose future strategies in the identification and study of potentially hepatotoxic compounds in an effort to outline a diagnostic approach for identifying any drug induced liver injury.

Population-representative incidence of drug-induced acute liver failure based on an analysis of an integrated health care system

BACKGROUND & AIMS

Medications are a major cause of acute liver failure (ALF) in the United States, but no population-based studies have evaluated the incidence of ALF from drug-induced liver injury. We aimed to determine the incidence and outcomes of drug-induced ALF in an integrated health care system that approximates a population-based cohort.

METHODS

We performed a retrospective cohort study using data from the Kaiser Permanente Northern California (KPNC) health care system between January 1, 2004, and December 31, 2010. We included all KPNC members age 18 years and older with 6 months or more of membership and hospitalization for potential ALF. The primary outcome was drug-induced ALF (defined as coagulopathy and hepatic encephalopathy without underlying chronic liver disease), determined by hepatologists who reviewed medical records of all KPNC members with inpatient diagnostic and laboratory criteria suggesting potential ALF.

RESULTS

Among 5,484,224 KPNC members between 2004 and 2010, 669 had inpatient diagnostic and laboratory criteria indicating potential ALF. After medical record review, 62 (9.3%) were categorized as having definite or possible ALF, and 32 (51.6%) had a drug-induced etiology (27 definite, 5 possible). Acetaminophen was implicated in 18 events (56.3%), dietary/herbal supplements in 6 events (18.8%), antimicrobials in 2 events (6.3%), and miscellaneous medications in 6 events (18.8%). One patient with acetaminophen-induced ALF died (5.6%; 0.06 events/1,000,000 person-years) compared with 3 patients with non-acetaminophen-induced ALF (21.4%; 0.18/1,000,000 person-years). Overall, 6 patients (18.8%) underwent liver transplantation, and 22 patients (68.8%) were discharged without transplantation. The incidence rates of any definite drug-induced ALF and acetaminophen-induced ALF were 1.61 events/1,000,000 person-years (95% confidence interval, 1.06-2.35) and 1.02 events/1,000,000 person-years (95% confidence interval, 0.59-1.63), respectively.

CONCLUSIONS

Drug-induced ALF is uncommon, but over-the-counter products and dietary/herbal supplements are its most common causes.

Comparative analysis of portal hepatic infiltrating leucocytes in acute drug-induced liver injury, idiopathic autoimmune and viral hepatitis

Drug-induced liver injury (DILI) is often caused by innate and adaptive host immune responses. Characterization of inflammatory infiltrates in the liver may improve understanding of the underlying pathogenesis of DILI. This study aimed to enumerate and characterize leucocytes infiltrating liver tissue from subjects with acute DILI (n = 32) versus non-DILI causes of acute liver injury (n = 25). Immunostains for CD11b/CD4 (Kupffer and T helper cells), CD3/CD20 (T and B cells) and CD8/CD56 [T cytotoxic and natural killer (NK) cells] were evaluated in biopsies from subjects with acute DILI, either immunoallergic (IAD) or autoimmune (AID) and idiopathic autoimmune (AIH) and viral hepatitis (VH) and correlated with clinical and pathological features. All biopsies showed numerous CD8(+) T cells and macrophages. DILI cases had significantly fewer B lymphocytes than AIH and VH and significantly fewer NK cells than VH. Prominent plasma cells were unusual in IAD (three of 10 cases), but were associated strongly with AIH (eight of nine) and also observed in most with AID (six of nine). They were also found in five of 10 cases with VH. Liver biopsies from subjects with DILI were characterized by low counts of mature B cells and NK cells in portal triads in contrast to VH. NK cells were found only in cases of VH, whereas AIH and VH both showed higher counts of B cells than DILI. Plasma cells were associated most strongly with AIH and less so with AID, but were uncommon in IAD.

Pharmacokinetics of micafungin in patients with pre-existing liver dysfunction: A safe option for treating invasive fungal infections

In this prospective observational study performed in 12 hospitalized patients with proven or suspected invasive fungal infection treated for a mean of 14 days with micafungin (MCF), 8 of whom with pre-existing liver function impairment, plasma levels of MCF at steady state were not correlated with liver function tests at the beginning of treatment. Liver function remained stable or even improved in all patients, except in one in which MCF was discontinued due to liver toxicity.

Clinical and histologic features of azithromycin-induced liver injury

BACKGROUND & AIMS

Rare cases of azithromycin-induced hepatotoxicity have been reported, with variable clinical and histologic features. We characterized clinical features and outcomes of azithromycin-induced liver injury.

METHODS

We identified patients with azithromycin-induced liver injury from the Drug-Induced Liver Injury Network Prospective Study who had causality scores of definite, highly likely, or probable. Demographic, clinical, and laboratory data and 6-month outcomes were examined.

RESULTS

Eighteen patients (72% female; mean age, 37 y) had causality scores of definite (n = 1), highly likely (n = 9), or probable (n = 8). Common presenting symptoms were jaundice, abdominal pain, nausea, and/or pruritus. For 16 patients, abnormal results from liver tests were first detected 14 days after azithromycin cessation (range, 9-20 d). The median duration of azithromycin treatment was 4 days (range, 2-7 d). The pattern of injury was hepatocellular in 10 patients, cholestatic in 6 patients, and mixed in 2 patients. The mean peak level of alanine aminotransferase was 2127 IU/L, of alkaline phosphatase was 481 IU/L, and of total bilirubin was 9.2 mg/dL. Liver histology showed ductopenia and veno-occlusive changes in a few patients. Two individuals had severe hypersensitivity cutaneous reactions. After 6 months, 8 patients had recovered, 4 patients had chronic injury, 1 patient died, and 1 patient underwent liver transplantation (outcomes were unavailable for 4 patients). Two of the patients who died or underwent liver transplantation had underlying chronic liver disease.

CONCLUSIONS

Azithromycin-induced liver injury occurs within 1 to 3 weeks after azithromycin initiation and predominantly is hepatocellular in nature. Although most patients recover fully, severe cutaneous reactions, chronic injury, and serious complications leading to death or liver transplantation can occur (ClinicalTrials.gov identifier, NCT00345930).

Toward predictive models for drug-induced liver injury in humans: are we there yet?

Drug-induced liver injury (DILI) is a frequent cause for the termination of drug development programs and a leading reason of drug withdrawal from the marketplace. Unfortunately, the current preclinical testing strategies, including the regulatory-required animal toxicity studies or simple in vitro tests, are insufficiently powered to predict DILI in patients reliably. Notably, the limited predictive power of such testing strategies is mostly attributed to the complex nature of DILI, a poor understanding of its mechanism, a scarcity of human hepatotoxicity data and inadequate bioinformatics capabilities. With the advent of high-content screening assays, toxicogenomics and bioinformatics, multiple end points can be studied simultaneously to improve prediction of clinically relevant DILIs. This review focuses on the current state of efforts in developing predictive models from diverse data sources for potential use in detecting human hepatotoxicity, and also aims to provide perspectives on how to further improve DILI prediction.

Bayesian ROC curve estimation under verification bias

Receiver operating characteristic (ROC) curve has been widely used in medical science for its ability to measure the accuracy of diagnostic tests under the gold standard. However, in a complicated medical practice, a gold standard test can be invasive, expensive, and its result may not always be available for all the subjects under study. Thus, a gold standard test is implemented only when it is necessary and possible. This leads to the so-called 'verification bias', meaning that subjects with verified disease status (also called label) are not selected in a completely random fashion. In this paper, we propose a new Bayesian approach for estimating an ROC curve based on continuous data following the popular semiparametric binormal model in the presence of verification bias. By using a rank-based likelihood, and following Gibbs sampling techniques, we compute the posterior distribution of the binormal parameters intercept and slope, as well as the area under the curve by imputing the missing labels within Markov Chain Monte-Carlo iterations. Consistency of the resulting posterior under mild conditions is also established. We compare the new method with other comparable methods and conclude that our estimator performs well in terms of accuracy.

Liver injury is common among chronic abusers of ketamine

Abuse of ketamine leads to liver injury. We investigated the histopathologic and radiologic features of ketamine abusers with significant liver injury in a cross-sectional survey of 297 consecutive chronic abusers of ketamine with urinary tract dysfunction. Liver biopsy and magnetic resonance cholangiopancreatography were performed in patients with liver injury (concentrations of bilirubin, alkaline phosphatase, and/or alanine aminotransferase >2-fold the upper limit of normal). The prevalence of liver injury was 9.8% (all cases cholestatic). Bile duct injury was observed in all 7 patients assessed by liver biopsy. Two patients had bridging fibrosis despite their young age. Three of 6 patients who underwent magnetic resonance cholangiopancreatography examination were found to have prominent or dilated common bile ducts without obstructions or extrinsic compressions. Ketamine abuse therefore appears to lead to common bile duct dilatation, microscopic bile duct injury, and even significant liver fibrosis.

ACG Clinical Guideline: the diagnosis and management of idiosyncratic drug-induced liver injury

Idiosyncratic drug-induced liver injury (DILI) is a rare adverse drug reaction and it can lead to jaundice, liver failure, or even death. Antimicrobials and herbal and dietary supplements are among the most common therapeutic classes to cause DILI in the Western world. DILI is a diagnosis of exclusion and thus careful history taking and thorough work-up for competing etiologies are essential for its timely diagnosis. In this ACG Clinical Guideline, the authors present an evidence-based approach to diagnosis and management of DILI with special emphasis on DILI due to herbal and dietary supplements and DILI occurring in individuals with underlying liver disease.

Idiosyncratic drug-induced liver injury is associated with substantial morbidity and mortality within 6 months from onset

BACKGROUND & AIMS

Little is known about the incidence of drug-induced liver injury (DILI) and risk factors for adverse outcomes. We evaluated short-term outcomes of a large cohort of patients with DILI enrolled in an ongoing multicenter prospective study.

METHODS

Data were collected from 660 adults with definite, highly likely, or probable DILI. Regression methods were used to identify risk factors for early liver-related death or liver transplantation and chronic liver injury.

RESULTS

Patients' median age was 51.4 years; 59.5% were female and 59.1% required hospitalization. Within 6 months of DILI onset, 30 patients received liver transplants (4.5%; 95% confidence interval [CI], 3.0%-6.1%) and 32 died (5%; 95% CI, 3.2%-6.5%); 53% of the deaths were liver related. Asian race, absence of itching, lung disease, low serum albumin levels, low platelet counts, and high serum levels of alanine aminotransferase and total bilirubin at presentation were independent risk factors for reduced times to liver-related death or liver transplantation (C-statistic = 0.87). At 6 months after DILI onset, 18.9% of the 598 evaluable subjects had persistent liver damage. African-American race, higher serum levels of alkaline phosphatase, and prior heart disease or malignancy requiring treatment were independent risk factors for chronic DILI (C-statistic = 0.71).

CONCLUSIONS

Nearly 1 in 10 patients die or undergo liver transplantation within 6 months of DILI onset and nearly 1 in 5 of the remaining patients have evidence of persistent liver injury at 6 months. The profile of liver injury at presentation, initial severity, patient's race, and medical comorbidities are important determinants of the likelihood of death/transplantation or persistent liver injury within 6 months.

Herbs and liver injury: a clinical perspective

Despite a perception that herbal and dietary supplements are safe, devastating liver injury has been reported to result from their use. The difficulty in characterizing liver injury attributable to herbal and dietary supplements stems from the permissive regulatory environment, the complexity of marketed products, and underreporting by the patients who use them. Despite these limitations, researchers, clinicians, and regulators have increasing awareness of the need for study in this area.

Drug-drug interactions with oral anti-HCV agents and idiosyncratic hepatotoxicity in the liver transplant setting

Studies of boceprevir and telaprevir based antiviral therapy in liver transplant (LT) recipients with hepatitis C genotype 1 infection have demonstrated dramatic increases in tacrolimus, cyclosporine, and mTOR inhibitor exposure. In addition to empiric dose reductions, daily monitoring of immunosuppressant blood levels is required when initiating as well as discontinuing the protease inhibitors to maximize patient safety. Although improved suppression of HCV replication is anticipated, 20 to 40% of treated subjects have required early treatment discontinuation due to various adverse events including anemia (100%), infection (30%), nephrotoxicity (20%) and rejection (5 to 10%). Simeprevir and faldaprevir will likely have improved efficacy and safety profiles but potential drug interactions with other OATP1B1 substrates and unconjugated hyperbilirubinemia are expected. In contrast, sofosbuvir and daclatasvir based antiviral therapy are not expected to lead to clinically significant drug-drug interactions in LT recipients but confirmatory studies are needed. Liver transplant recipients may also be at increased risk of developing drug induced liver injury (DILI). Establishing a diagnosis of DILI in the transplant setting is very difficult with the variable latency, laboratory features and histopathological manifestations of hepatotoxicity associated with a given drug, the need to exclude competing causes of allograft injury, and the lack of an objective and verifiable confirmatory test. Nonetheless, a heightened awareness of the possibility of DILI is warranted in light of the large number of medications used in LT recipients and the potential adverse impact that DILI may have on patient outcomes.

Pathogenesis of idiosyncratic drug-induced liver injury and clinical perspectives

Idiosyncratic drug-induced liver injury (DILI) is a rare disease that develops independently of drug dose, route, or duration of administration. Furthermore, idiosyncratic DILI is not a single disease entity but rather a spectrum of rare diseases with varying clinical, histological, and laboratory features. The pathogenesis of DILI is not fully understood. Standardization of the DILI nomenclature and methods to assess causality, along with the information provided by the LiverTox Web site, will harmonize and accelerate research on DILI. Studies of new serum biomarkers such as glutamate dehydrogenase, high mobility group box protein 1, and microRNA-122 could provide information for use in diagnosis and prognosis and provide important insights into the mechanisms of the pathogenesis of DILI. Single nucleotide polymorphisms in the HLA region have been associated with idiosyncratic hepatotoxicity attributed to flucloxacillin, ximelagatran, lapatinib, and amoxicillin-clavulanate. However, genome-wide association studies of pooled cases have not associated any genetic factors with idiosyncratic DILI. Whole genome and whole exome sequencing analyses are under way to study cases of DILI attributed to a single medication. Serum proteomic, transcriptome, and metabolome as well as intestinal microbiome analyses will increase our understanding of the mechanisms of this disorder. Further improvements to in vitro and in vivo test systems should advance our understanding of the causes, risk factors, and mechanisms of idiosyncratic DILI.

Hepatobiliary transporters in drug-induced cholestasis: a perspective on the current identifying tools

INTRODUCTION

Impaired bile formation leads to the accumulation of cytotoxic bile salts in hepatocytes and, consequently, cholestasis and severe liver disease. Knowledge of the role of hepatobiliary transporters, especially the bile salt export pump (BSEP), in the pathogenesis of cholestasis is continuously increasing.

AREAS COVERED

This review provides an introduction into the role of these transport proteins in bile formation. It addresses the clinical relevance and pathophysiologic consequences of altered functions of these transporters by genetic mutations and drugs. In particular, the current practical aspects of identification and mitigation of drug candidates with liver liabilities employed during drug development, with an emphasis on preclinical screening for BSEP interaction, are discussed.

EXPERT OPINION

Within the potential pathogenetic mechanisms of acquired cholestasis, the inhibition of BSEP by drugs is well established. Interference of a new compound with BSEP transport activity should raise a warning sign to conduct follow-up experiments and to monitor liver function during clinical development. A combination of in vitro screening for transport interaction, in silico predicting models, and consideration of physicochemical and metabolic properties should lead to a more efficient screening of potential liver liability.

Detection of anti-isoniazid and anti-cytochrome P450 antibodies in patients with isoniazid-induced liver failure

Isoniazid (INH)-induced hepatotoxicity remains one of the most common causes of drug-induced idiosyncratic liver injury and liver failure. This form of liver injury is not believed to be immune-mediated because it is not usually associated with fever or rash, does not recur more rapidly on rechallenge, and previous studies have failed to identify anti-INH antibodies (Abs). In this study, we found Abs present in sera of 15 of 19 cases of INH-induced liver failure. Anti-INH Abs were present in 8 sera; 11 had anti-cytochrome P450 (CYP)2E1 Abs, 14 had Abs against CYP2E1 modified by INH, 14 had anti-CYP3A4 antibodies, and 10 had anti-CYP2C9 Abs. INH was found to form covalent adducts with CYP2E1, CYP3A4, and CYP2C9. None of these Abs were detected in sera from INH-treated controls without significant liver injury. The presence of a range of antidrug and autoAbs has been observed in other drug-induced liver injury that is presumed to be immune mediated.

CONCLUSION

These data provide strong evidence that INH induces an immune response that causes INH-induced liver injury.