Causality assessment in drug-induced hepatotoxicity

Management of Pharmacologic Adverse Effects in Advanced Liver Disease

As a consequence of the altered hepatic architecture in advanced liver disease, drug metabolism is modified by changes in pharmacokinetic and pharmacodynamic properties, leading to the appearance of adverse effects and drug interactions and increasing the risk of over- or underdosing of medications. However, there are no tests that accurately determine the degree of impairment of liver metabolic function; therefore, general recommendations are established based on the degree of hepatic extraction, degree of hepatic metabolism, and degree of protein binding. Although the hepatic toxicity of some frequently used drugs, such as acetaminophen, is well known, many health care professionals are unaware or not fully aware of the deleterious effects that other drugs can have on patients with advanced liver injury, as is the case for nonsteroidal anti-inflammatory drugs. It is very important to increase awareness among both health care professionals and patients with advanced liver disease to limit the use of inappropriate drugs and prevent drug-induced liver injury.

Drug induced liver injury: an update

Drug induced liver injury (DILI) is a relatively rare hepatic condition in response to the use of medications, illegal drugs, herbal products or dietary supplements. It occurs in susceptible individuals through a combination of genetic and environmental risk factors believed to modify drug metabolism and/or excretion leading to a cascade of cellular events, including oxidative stress formation, apoptosis/necrosis, haptenization, immune response activation and a failure to adapt. The resultant liver damage can present with an array of phenotypes, which mimic almost every other liver disorder, and varies in severity from asymptomatic elevation of liver tests to fulminant hepatic failure. Despite recent research efforts specific biomarkers are not still available for routine use in clinical practice, which makes the diagnosis of DILI uncertain and relying on a high degree of awareness of this condition and the exclusion of other causes of liver disease. Diagnostic scales such as the CIOMS/RUCAM can support the causality assessment of a DILI suspicion, but need refinement as some criteria are not evidence-based. Prospective collection of well-vetted DILI cases in established DILI registries has allowed the identification and validation of a number of clinical variables, and to predict a more severe DILI outcome. DILI is also in need of properly designed clinical trials to evaluate the efficacy of new DILI treatments as well as older drugs such as ursodeoxycholic acid traditionally used to ameliorate cholestasis or corticosteroids now widely tried in the oncology field to manage the emergent type of hepatotoxicity related to immune checkpoint inhibitors.

Key Challenges and Opportunities Associated with the Use of In Vitro Models to Detect Human DILI: Integrated Risk Assessment and Mitigation Plans

Drug-induced liver injury (DILI) is a major cause of late-stage clinical drug attrition, market withdrawal, black-box warnings, and acute liver failure. Consequently, it has been an area of focus for toxicologists and clinicians for several decades. In spite of considerable efforts, limited improvements in DILI prediction have been made and efforts to improve existing preclinical models or develop new test systems remain a high priority. While prediction of intrinsic DILI has improved, identifying compounds with a risk for idiosyncratic DILI (iDILI) remains extremely challenging because of the lack of a clear mechanistic understanding and the multifactorial pathogenesis of idiosyncratic drug reactions. Well-defined clinical diagnostic criteria and risk factors are also missing. This paper summarizes key data interpretation challenges, practical considerations, model limitations, and the need for an integrated risk assessment. As demonstrated through selected initiatives to address other types of toxicities, opportunities exist however for improvement, especially through better concerted efforts at harmonization of current, emerging and novel in vitro systems or through the establishment of strategies for implementation of preclinical DILI models across the pharmaceutical industry. Perspectives on the incorporation of newer technologies and the value of precompetitive consortia to identify useful practices are also discussed.

Acute Liver Failure after Initiation of Rivaroxaban: A Case Report and Review of the Literature

CONTEXT

Rivaroxaban is a direct factor Xa inhibitor approved for the prevention of thromboembolism. Drug induced liver injury has been increasingly reported with rivaroxaban recently, but actual liver failure has not been reported.

CASE REPORT

We present a case report on the probable occurrence of acute liver failure with rivaroxaban therapy. An 89 year old woman with history of atrial fibrillation was hospitalized for biventricular congestive heart failure with passive congestion of liver, which responded to furosemide. She was discharged home on rivaroxaban for prevention of thrombo-embolism. Liver function tests upon discharge returned to almost normal range. One week later, she presented with abdominal pain and was found to have highly elevated liver enzymes, elevated bilirubin, and an abnormal coagulation profile. A day later, she developed hepatic encephalopathy, suggesting liver failure.

CONCLUSION

Liver enzymes declined rapidly with the discontinuation of all of her medications, however patient died because of multi-organ failure. The causality assessment in this patient was "probable" with rivaroxaban.

Herbal hepatotoxicity in traditional and modern medicine: actual key issues and new encouraging steps

Plants are natural producers of chemical substances, providing potential treatment of human ailments since ancient times. Some herbal chemicals in medicinal plants of traditional and modern medicine carry the risk of herb induced liver injury (HILI) with a severe or potentially lethal clinical course, and the requirement of a liver transplant. Discontinuation of herbal use is mandatory in time when HILI is first suspected as diagnosis. Although, herbal hepatotoxicity is of utmost clinical and regulatory importance, lack of a stringent causality assessment remains a major issue for patients with suspected HILI, while this problem is best overcome by the use of the hepatotoxicity specific CIOMS (Council for International Organizations of Medical Sciences) scale and the evaluation of unintentional reexposure test results. Sixty five different commonly used herbs, herbal drugs, and herbal supplements and 111 different herbs or herbal mixtures of the traditional Chinese medicine (TCM) are reported causative for liver disease, with levels of causality proof that appear rarely conclusive. Encouraging steps in the field of herbal hepatotoxicity focus on introducing analytical methods that identify cases of intrinsic hepatotoxicity caused by pyrrolizidine alkaloids, and on omics technologies, including genomics, proteomics, metabolomics, and assessing circulating micro-RNA in the serum of some patients with intrinsic hepatotoxicity. It remains to be established whether these new technologies can identify idiosyncratic HILI cases. To enhance its globalization, herbal medicine should universally be marketed as herbal drugs under strict regulatory surveillance in analogy to regulatory approved chemical drugs, proving a positive risk/benefit profile by enforcing evidence based clinical trials and excellent herbal drug quality.

Profiling cumulative proportional reporting ratios of drug-induced liver injury in the FDA Adverse Event Reporting System (FAERS) database

BACKGROUND

Early prediction and accurate characterization of risk for serious liver injury associated with newly marketed drugs remains an important challenge for clinicians, the pharmaceutical industry, and regulators. To date, a biomarker that specifically indicates exposure to a drug as the etiologic cause of liver injury has not been identified.

OBJECTIVES

Using cumulative proportional reporting ratios (PRRs), we investigated 'real-time' profiles of a set of pharmaceuticals, over the first 3 years of US marketing, for the signaling of clinically serious drug-induced liver injury (DILI) in a large spontaneous-reporting database.

METHODS

Using report counts of hepatic failure or clinically serious liver injury obtained from the FDA Adverse Events Reporting System (FAERS) database, PRRs of adverse drug event terms were calculated by division of counts of domestic reports of these events by counts of all serious adverse events for each of 13 selected drugs associated with a broad range of hepatotoxic risk (including three linked to only rare instances of clinically apparent liver injury) with reference to all other drugs in the database. Drug-specific cumulative PRRs were measured at successive intervals (calendar quarters) using cumulative tallies of FAERS reports to generate time-based profiles over the initial 3 years of US marketing.

RESULTS

In the set of drugs analyzed, those with no known hepatotoxic risk demonstrated time-based cumulative PRR profiles that approximate the background rates of hepatic failure and serious liver injury reported in the entire FAERS database. In contrast, those that were removed from marketing or subjected to marketing restrictions due to their potential to cause liver injury were associated with profiles of rapidly rising cumulative PRRs that were greater than 5 within the first 10 million domestic prescriptions or the first four quarters of US marketing. The systematic tracking and identification of rising PRRs for DILI associated with newly marketed pharmaceutical and biological agents is a valuable tool for identification of safety signals within the FAERS database.

LIMITATIONS

Disproportionality profiling of spontaneous reports in FAERS (e.g., cumulative PRR measurements), which signals an association between a recently marketed drug and liver injury, is not a method to quantitatively measure drug-related risk. Regulatory actions in response to emerging drug safety concerns often depend on an accurate assessment of risks using multiple sources of data and the consideration of overall benefits and risks of the agent. Causality must be determined through analysis of individual cases to exclude other etiologies of liver injury.

CONCLUSION

The FAERS database can be used to advance empiric hepatotoxicity time-trending reporting levels for newly marketed agents in order to rapidly identify recently launched potential hepatotoxic agents and initiate further evaluation.

Herbal hepatotoxicity: analysis of cases with initially reported positive re-exposure tests

BACKGROUND

Positive re-exposure tests are diagnostic hallmarks for hepatotoxicity.

OBJECTIVE

To test validity of positive re-exposures in herb induced liver injury.

METHODS

We searched Medline database for cases of herb induced liver injury with positive re-exposures and analysed 34 cases for positive re-exposure test criteria of baseline alanine aminotransferase< 5N before re-exposure, and re-exposure alanine aminotransferase ≥ 2× baseline alanine aminotransferase. Re-exposure test was negative, if baseline alanine aminotransferase< 5N combined with re-exposure alanine aminotransferase< 2× baseline alanine aminotransferase, or if baseline alanine aminotransferase≥ 5N regardless of the re-exposure alanine aminotransferase including no available re-exposure alanine aminotransferase result.

RESULTS

In 21/34 cases (61.8%), criteria for a positive re-exposure were fulfilled, with negative tests in 6/34 cases (17.6%) or uninterpretable ones in 7/34 cases (20.6%). Confirmed positive re-exposure tests established potential of herb induced liver injury for Aloe, Chaparral, Chinese herbal mixtures, Chinese Jin Bu Huan, Chinese Syo Saiko To, Germander, Greater Celandine, Green tea, Kava, Mistletoe, Polygonum multiflorum, and Senna, with up to 4 case reports per herb.

CONCLUSIONS

Among 34 cases of herb-induced liver injury with initially reported positive re-exposure tests, 61.8% of the cases actually fulfilled established test criteria and provided firm diagnoses of herb induced liver injury by various herbs.

Evaluation of database-derived pathway development for enabling biomarker discovery for hepatotoxicity

Current testing models for predicting drug-induced liver injury are inadequate, as they basically under-report human health risks. We present here an approach towards developing pathways based on hepatotoxicity-associated gene groups derived from two types of publicly accessible hepatotoxicity databases, in order to develop drug-induced liver injury biomarker profiles. One human liver ‘omics-based and four text-mining-based databases were explored for hepatotoxicity-associated gene lists. Over-representation analysis of these gene lists with a hepatotoxicant-exposed primary human hepatocytes data set showed that human liver ‘omics gene lists performed better than text-mining gene lists and the results of the latter differed strongly between databases. However, both types of databases contained gene lists demonstrating biomarker potential. Visualizing those in pathway format may aid in interpreting the biomolecular background. We conclude that exploiting existing and openly accessible databases in a dedicated manner seems promising in providing venues for translational research in toxicology and biomarker development.

Idiosyncratic drug hepatotoxicity: a 2008 update

Pharmaceutical preparations, and also herbal products and dietary supplements, are emerging contributors to severe forms of liver disease. Although acetaminophen intoxication is still the reason for many cases of drug-induced liver injury (DILI) in Western countries, the bulk of hepatic reactions to drugs are idiosyncratic. Only a small fraction of individuals exposed to a drug associated with liver injury will develop hepatotoxicity. Indeed, the rarity of this serious adverse event prevents its detection in clinical trials. The pathogenesis of idiosyncratic DILI is not well known because of a lack of reliable animal models, although it probably involves the metabolism of the drug and/or activation of the immune system. Different databases have described antibiotics, NSAIDs and anticonvulsants as the main group of drugs incriminated in DILI. Clinical presentation of DILI includes predominantly a hepatocellular type of damage, yet cholestatic and mixed types are also common; the determinants of the type of damage induced by a given drug are poorly understood. Analysis of pooled data has recently underlined the influence of older age in the cholestatic/mixed expression of liver injury, as well as the independent association of female gender, older age, aspartate aminotransferase levels with hepatocellular type of damage and high bilirubin levels with the risk of fulminant liver failure/death. In the long term (providing the patient survives the initial episode), persistent damage may occur in at least 6% of patients, with the cholestatic mixed type of damage more prone to becoming chronic, while in the hepatocellular pattern the severity is greater, with further likelihood of evolution to cirrhosis. Cardiovascular and CNS drugs are the main groups leading to chronic liver damage. The diagnosis of hepatotoxicity remains a difficult task owing to the lack of reliable markers for use in general clinical practice. Diagnostic algorithms may add consistency to clinical judgment by translating a suspicion into a quantitative score. Currently, the Council for International Organizations of Medical Sciences/Roussel Uclaf Causality Assessment Method instrument is considered the gold standard in causality assessment of hepatotoxicity, although there is probably room for improvement. Current efforts in collecting bona fide cases will make refinements of existing scales feasible. Efforts should also be directed towards the development of an abridged instrument for use in evaluating suspected drug-induced hepatotoxicity at the very beginning of the diagnosis and treatment process when clinical decisions need to be taken. The treatment of idiosyncratic DILI is largely supportive. Early suspicion and withdrawal of the offending agent is the most important therapeutic measure.

An automated causality assessment algorithm to detect drug-induced liver injury in electronic medical record data

PURPOSE

The aim of this study was to develop an automated causality assessment algorithm to identify drug-induced liver injury.

METHODS

The Roussel Uclaf Causality Assessment Method (RUCAM) is an algorithm for determining the causal association between a drug and liver injury. In collaboration with hepatology experts, definitions were developed for the RUCAM criteria to operationalize an electronic RUCAM (eRUCAM). The eRUCAM was tested in a population of patients taking 14 drugs with a characteristic phenotype for liver injury. Quality assurance for programming specifications involved comparisons between scores generated by the eRUCAM, for probable and highly probable cases, and expert manual RUCAM (n = 20). Concordance between eRUCAM and manual RUCAM subscores and total score was tested using the Wilcoxon signed rank test.

RESULTS

Causality scores were the same for 6 of 20 patients (30%) by manual and eRUCAM algorithms. Analysis of subscores revealed ≥80% concordance between manual and eRUCAM for five of the seven criteria. In general, the total scores tended to be higher for the eRUCAM compared with the manual RUCAM. Programming issues were identified for criterion 5 'non-drug causes of liver injury' where significant differences existed between manual and eRUCAM scoring (p = 0.001). For criterion 5, identical scores occurred in 9 of 20 patients (45%), and manual review identified additional codes, timing criteria, and laboratory results for improving subsequent eRUCAM revisions.

CONCLUSION

The eRUCAM had generally good concordance with manual RUCAM scoring. These preliminary findings suggest that the eRUCAM algorithm is feasible and could have application in clinical practice and drug safety surveillance.

Herbalife hepatotoxicity: Evaluation of cases with positive reexposure tests

AIM

To analyze the validity of applied test criteria and causality assessment methods in assumed Herbalife hepatotoxicity with positive reexposure tests.

METHODS

We searched the Medline database for suspected cases of Herbalife hepatotoxicity and retrieved 53 cases including eight cases with a positive unintentional reexposure and a high causality level for Herbalife. First, analysis of these eight cases focused on the data quality of the positive reexposure cases, requiring a baseline value of alanine aminotransferase (ALT) < 5 upper limit of normal (N) before reexposure, with N as the upper limit of normal, and a doubling of the ALT value at reexposure as compared to the ALT value at baseline prior to reexposure. Second, reported methods to assess causality in the eight cases were evaluated, and then the liver specific Council for International Organizations of Medical Sciences (CIOMS) scale validated for hepatotoxicity cases was used for quantitative causality reevaluation. This scale consists of various specific elements with scores provided through the respective case data, and the sum of the scores yields a causality grading for each individual case of initially suspected hepatotoxicity.

RESULTS

Details of positive reexposure test conditions and their individual results were scattered in virtually all cases, since reexposures were unintentional and allowed only retrospective rather than prospective assessments. In 1/8 cases, criteria for a positive reexposure were fulfilled, whereas in the remaining cases the reexposure test was classified as negative (n = 1), or the data were considered as uninterpretable due to missing information to comply adequately with the criteria (n = 6). In virtually all assessed cases, liver unspecific causality assessment methods were applied rather than a liver specific method such as the CIOMS scale. Using this scale, causality gradings for Herbalife in these eight cases were probable (n = 1), unlikely (n = 4), and excluded (n = 3). Confounding variables included low data quality, alternative diagnoses, poor exclusion of important other causes, and comedication by drugs and herbs in 6/8 cases. More specifically, problems were evident in some cases regarding temporal association, daily doses, exact start and end dates of product use, actual data of laboratory parameters such as ALT, and exact dechallenge characteristics. Shortcomings included scattered exclusion of hepatitis A-C, cytomegalovirus and Epstein Barr virus infection with only globally presented or lacking parameters. Hepatitis E virus infection was considered in one single patient and found positive, infections by herpes simplex virus and varicella zoster virus were excluded in none.

CONCLUSION

Only one case fulfilled positive reexposure test criteria in initially assumed Herbalife hepatotoxicity, with lower CIOMS based causality gradings for the other cases than hitherto proposed.

Herbalife hepatotoxicity: Evaluation of cases with positive reexposure tests

AIM: To analyze the validity of applied test criteria and causality assessment methods in assumed Herbalife hepatotoxicity with positive reexposure tests.

METHODS: We searched the Medline database for suspected cases of Herbalife hepatotoxicity and retrieved 53 cases including eight cases with a positive unintentional reexposure and a high causality level for Herbalife. First, analysis of these eight cases focused on the data quality of the positive reexposure cases, requiring a baseline value of alanine aminotransferase (ALT) < 5 upper limit of normal (N) before reexposure, with N as the upper limit of normal, and a doubling of the ALT value at reexposure as compared to the ALT value at baseline prior to reexposure. Second, reported methods to assess causality in the eight cases were evaluated, and then the liver specific Council for International Organizations of Medical Sciences (CIOMS) scale validated for hepatotoxicity cases was used for quantitative causality reevaluation. This scale consists of various specific elements with scores provided through the respective case data, and the sum of the scores yields a causality grading for each individual case of initially suspected hepatotoxicity.

RESULTS: Details of positive reexposure test conditions and their individual results were scattered in virtually all cases, since reexposures were unintentional and allowed only retrospective rather than prospective assessments. In 1/8 cases, criteria for a positive reexposure were fulfilled, whereas in the remaining cases the reexposure test was classified as negative (n = 1), or the data were considered as uninterpretable due to missing information to comply adequately with the criteria (n = 6). In virtually all assessed cases, liver unspecific causality assessment methods were applied rather than a liver specific method such as the CIOMS scale. Using this scale, causality gradings for Herbalife in these eight cases were probable (n = 1), unlikely (n = 4), and excluded (n = 3). Confounding variables included low data quality, alternative diagnoses, poor exclusion of important other causes, and comedication by drugs and herbs in 6/8 cases. More specifically, problems were evident in some cases regarding temporal association, daily doses, exact start and end dates of product use, actual data of laboratory parameters such as ALT, and exact dechallenge characteristics. Shortcomings included scattered exclusion of hepatitis A-C, cytomegalovirus and Epstein Barr virus infection with only globally presented or lacking parameters. Hepatitis E virus infection was considered in one single patient and found positive, infections by herpes simplex virus and varicella zoster virus were excluded in none.

CONCLUSION: Only one case fulfilled positive reexposure test criteria in initially assumed Herbalife hepatotoxicity, with lower CIOMS based causality gradings for the other cases than hitherto proposed.

Clinical and causality assessment in herbal hepatotoxicity

INTRODUCTION

Herbal hepatotoxicity represents a poorly understood, neglected and multifaceted disease with numerous confounding variables and missing established causality in the majority of cases. This review discusses overt shortcomings in its clinical and causality assessment and suggests improvements.

AREAS COVERED

A selective literature search of PubMed using the terms herbal hepatotoxicity, herb-induced liver injury, drug hepatotoxicity and drug-induced liver injury was performed to identify published case reports, spontaneous case reports, case series and review articles regarding hepatotoxicity due to herbs, herbal drugs and herbal dietary supplements. Covered areas focused on confounding variables related to the documentation of the herbal product and the clinical course, hepatotoxicity and reexposure criteria, temporal association, comedication and alternative causes with special attention to preexisting diseases of the liver, bile ducts and the pancreas. Of particular interest were recent discussions of approaches designed and validated for hepatotoxicity causality, such as the scale of CIOMS (Council for International Organizations of Medical Sciences).

EXPERT OPINION

The authors call for substantial improvements in data quality of herbal products and case characteristics and strongly recommend using the CIOMS scale to assess causality in suspected herbal hepatotoxicity.

Hepatic necrosis associated with drug-induced hypersensitivity syndrome

Drug-induced hypersensitivity syndrome (DIHS; also known as drug reaction with eosinophilia and systemic symptoms [DRESS]) is a life-threatening condition first described by Chaiken et al. in 1950. It is characterized by extensive mucocutaneous rash; fever; lymphadenopathy; hepatitis; hematological abnormalities; damage to several organs such as kidney, heart, lungs, and pancreas; and possible reactivation of human herpesvirus-6 (HHV-6) or other herpes virus. Rare and severe cases may present hepatic necrosis, and about 15% of them result in death or liver transplantation. A hallmark of this syndrome is the late onset of symptoms after the drug exposure. The most common culprit drugs are the aromatic anticonvulsants (in almost 30% of the cases) and the antibiotics (which in some series represent 20% of the cases). The authors report a case of a 41-year-old female who presented to the emergency department with erythroderma, acute hepatitis, acute pancreatitis and acute renal failure, and was then treated with corticosteroid after the diagnosis of DIHS/DRESS. A specific culprit drug could not confidently be determined due to the presence of multiple drugs used by the patient. The clinical and laboratory outcome was apparently satisfactory, but unexpectedly, on the sixth day of hospitalization, the patient complained of nonspecific malaise, drowsiness, which progressed in a few hours with signs and symptoms of hepatic failure, refractory shock, and death. The autopsy findings showed submassive hepatic necrosis, and the immediate cause of death was attributed to hepatic failure.

Predictive genetic testing for drug-induced liver injury: considerations of clinical utility

Genetic predisposition to drug-induced liver injury may be due to variation in both pharmacokinetic and pharmacodynamic pathways. Recent genome-wide association studies have identified, in the human leukocyte antigen (HLA) alleles, strong genetic factors that predispose to liver injury on exposure to any of several drugs. Although the genetic associations have provided mechanistic insights, none has been developed as a predictive test. Further work in this area, in combination with other "-omics" technologies, is needed to develop tests that are both clinically useful and cost-effective.

Effect of CYP3A4 inducer dexamethasone on hepatotoxicity of lapatinib: clinical and in vitro evidence

Concomitant usage of lapatinib, a cytochrome P450 (CYP) 3A4 substrate and dexamethasone, a CYP3A4 inducer, is a pharmacokinetic drug-drug interaction. This combination may increase the formation of reactive lapatinib metabolites, which is potentially hepatotoxic. This study aims to evaluate the clinical effect of dexamethasone on incidence of hepatotoxicity and to ascertain its in vitro role using a parallel cell culture model experimental setup. Clinical effects of dexamethasone on lapatinib-induced hepatotoxicity were evaluated in a nested case-control study based on 120 patient data obtained from our records. For the in vitro experiment, metabolically competent transforming growth factor α mouse hepatocytes (TAMH) were treated with lapatinib and viabilities were compared in the presence or absence of dexamethasone. After adjusting for confounders, patients receiving the combination were 4.57 times (95% CI 1.23-16.88, p = 0.02) more likely to develop hepatotoxicity and 3.48 times (95% CI 1.24-9.80, p = 0.02) more likely to develop a clinically important change in alanine aminotransferase than compared to the other group. Treatment of TAMH cells with lapatinib and dexamethasone caused a further reduction in viability, as compared to treatment with lapatinib alone. At 5 μM lapatinib, the introduction of dexamethasone 20 μM produced a 59% decline in viability. This is the first study to document a clinically important interaction between lapatinib and dexamethasone, which associates with an increased occurrence of hepatotoxicity. The in vitro findings have provided substantiating evidence and insights on the role of dexamethasone in lapatinib-induced hepatotoxicity.

Hepatic safety of antibiotics used in primary care

Antibiotics used by general practitioners frequently appear in adverse-event reports of drug-induced hepatotoxicity. Most cases are idiosyncratic (the adverse reaction cannot be predicted from the drug's pharmacological profile or from pre-clinical toxicology tests) and occur via an immunological reaction or in response to the presence of hepatotoxic metabolites. With the exception of trovafloxacin and telithromycin (now severely restricted), hepatotoxicity crude incidence remains globally low but variable. Thus, amoxicillin/clavulanate and co-trimoxazole, as well as flucloxacillin, cause hepatotoxic reactions at rates that make them visible in general practice (cases are often isolated, may have a delayed onset, sometimes appear only after cessation of therapy and can produce an array of hepatic lesions that mirror hepatobiliary disease, making causality often difficult to establish). Conversely, hepatotoxic reactions related to macrolides, tetracyclines and fluoroquinolones (in that order, from high to low) are much rarer, and are identifiable only through large-scale studies or worldwide pharmacovigilance reporting. For antibiotics specifically used for tuberculosis, adverse effects range from asymptomatic increases in liver enzymes to acute hepatitis and fulminant hepatic failure. Yet, it is difficult to single out individual drugs, as treatment always entails associations. Patients at risk are mainly those with previous experience of hepatotoxic reaction to antibiotics, the aged or those with impaired hepatic function in the absence of close monitoring, making it important to carefully balance potential risks with expected benefits in primary care. Pharmacogenetic testing using the new genome-wide association studies approach holds promise for better understanding the mechanism(s) underlying hepatotoxicity.

Single-center experience with drug-induced liver injury from India: causes, outcome, prognosis, and predictors of mortality

OBJECTIVES

Although drug-induced liver injury (DILI) is rare, it may result in significant morbidity or death. The causes and outcome vary according to regions, with acetaminophen and complementary medicines common in the West and the Far East, respectively. This study evaluates the causes, outcomes, predictors, and models for 90-day mortality from DILI from India.

METHODS

Consecutive patients with DILI from 1997 to 2008 based on International Consensus Criteria from a medical college hospital setting were studied.

RESULTS

Of the 313 patients, 58% were males. Leading causes were a combination of four anti-tuberculous drugs (ATDs) (58%), anti-epileptics (11%), olanzapine (5.4%), and dapsone (5.4%). The overall 90-day mortality of 17.3% was significantly higher for ATD hepatitis (21.5%) vs. those without (11.4%) (P=0.02). The highest mortality was for leflunomide (75%). Seventy-eight percent of patients received more than one drug. Fulminant hepatic failure developed more commonly in females than in males (23% vs. 17%). Of the 66% of cases with jaundice and/or icterus, mortality was 26%. Multivariable models for mortality using a combination of encephalopathy, ascites, and bilirubin, or a combination of albumin, prothrombin time, and white blood cell count yielded a C-statistic of at least 0.86 by recursive partitioning and 0.92 by logistic regression. Model for end stage liver disease (MELD) scores of 38 and 46 yield probabilities of death of 0.90 (confidence interval (CI): 0.71-0.97) and 0.99 (CI: 0.90-1.00), respectively.

CONCLUSIONS

DILI results in significant overall mortality (17.3%). ATDs, anti-convulsants, sulphonamides, and olanzapine are the leading causes of DILI. Although common in males, more females developed fulminant hepatic failure. High-MELD score or a combination of ascites, encephalopathy, high bilirubin, prothrombin time, and leukocyte count are predictive of mortality.

[Acute toxic hepatitis due to drinking water]

Toxic-induced liver disease is uncommon, although the true proportion of cases of hepatotoxicity is unknown, as this entity is underdiagnosed and underreported. The main reasons why toxic-induced liver disease goes unnoticed is the lack of pathognomonic data and the lack of spontaneous reporting by doctors and pharmacists. In some cases, the toxic substance can leave its «signature» in the form of clinical semiology suggestive of an underlying toxic cause. We present a case of hepatotoxicity induced by drinking water (chlorinated), which produced a reactive metabolites syndrome (trihalomethanes from the reaction of chlorine with organic products). Although the clinical presentation was typical, the case posed a diagnostic challenge for the various professionals involved.

Regulatory causality evaluation methods applied in kava hepatotoxicity: are they appropriate?

Since 1998 liver injury has been assumed in some patients after the use of kava (Piper methysticum G. Forster) as an anxyolytic herbal extract, but the regulatory causality evaluation of these cases was a matter of international and scientific debate. This review critically analyzes the regulatory issues of causality assessments of patients with primarily suspected kava hepatotoxicity and suggests recommendations for minimizing regulatory risks when assessing causality in these and other related cases. The various regulatory causality approaches were based on liver unspecific assessments such as ad hoc evaluations, the WHO scale using the definitions of the WHO Collaborating Centre for International Drug Monitoring, and the Naranjo scale. Due to their liver unspecificity, however, these causality approaches are not suitable for assessing cases of primarily assumed liver related adverse reactions by drugs and herbs including kava. Major problems emerged trough the combination of regulatory inappropriate causality assessment methods with the poor data quality as presented by the regulatory agency when reassessment was done and the resulting data were heavily criticized worldwide within the scientific community. Conversely, causality of cases with primarily assumed kava hepatotoxicity is best assessed by structured, quantitative and liver specific causality algorithms such as the scale of the CIOMS (Council for International Organizations of Medical Sciences) or the main-test as its update. Future strategies should therefore focus on the implementation of structured, quantitative and liver specific causality assessment methods as regulatory standards to improve regulatory causality assessments for liver injury by drugs and herbs including kava.

Drugs associated with hepatotoxicity and their reporting frequency of liver adverse events in VigiBase: unified list based on international collaborative work

BACKGROUND

Challenges exist in the clinical diagnosis of drug-induced liver injury (DILI) and in obtaining information on hepatotoxicity in humans.

OBJECTIVE

(i) To develop a unified list that combines drugs incriminated in well vetted or adjudicated DILI cases from many recognized sources and drugs that have been subjected to serious regulatory actions due to hepatotoxicity; and (ii) to supplement the drug list with data on reporting frequencies of liver events in the WHO individual case safety report database (VigiBase).

DATA SOURCES AND EXTRACTION

(i) Drugs identified as causes of DILI at three major DILI registries; (ii) drugs identified as causes of drug-induced acute liver failure (ALF) in six different data sources, including major ALF registries and previously published ALF studies; and (iii) drugs identified as being subjected to serious governmental regulatory actions due to their hepatotoxicity in Europe or the US were collected. The reporting frequency of adverse events was determined using VigiBase, computed as Empirical Bayes Geometric Mean (EBGM) with 90% confidence interval for two customized terms, 'overall liver injury' and 'ALF'. EBGM of >or=2 was considered a disproportional increase in reporting frequency. The identified drugs were then characterized in terms of regional divergence, published case reports, serious regulatory actions, and reporting frequency of 'overall liver injury' and 'ALF' calculated from VigiBase.

DATA SYNTHESIS

After excluding herbs, supplements and alternative medicines, a total of 385 individual drugs were identified; 319 drugs were identified in the three DILI registries, 107 from the six ALF registries (or studies) and 47 drugs that were subjected to suspension or withdrawal in the US or Europe due to their hepatotoxicity. The identified drugs varied significantly between Spain, the US and Sweden. Of the 319 drugs identified in the DILI registries of adjudicated cases, 93.4% were found in published case reports, 1.9% were suspended or withdrawn due to hepatotoxicity and 25.7% were also identified in the ALF registries/studies. In VigiBase, 30.4% of the 319 drugs were associated with disproportionally higher reporting frequency of 'overall liver injury' and 83.1% were associated with at least one reported case of ALF.

CONCLUSIONS

This newly developed list of drugs associated with hepatotoxicity and the multifaceted analysis on hepatotoxicity will aid in causality assessment and clinical diagnosis of DILI and will provide a basis for further characterization of hepatotoxicity.

Black cohosh and suspected hepatotoxicity: inconsistencies, confounding variables, and prospective use of a diagnostic causality algorithm. A critical review

OBJECTIVE

The data of 69 cases of initially suspected black cohosh (BC)-induced liver disease were reviewed and analyzed to clarify whether BC hepatotoxicity really exists as a disease entity in these cases comparable to toxic liver disease being caused by various drugs and dietary supplements.

METHODS

The cases comprised 11 published case reports and 58 spontaneous reports to national regulatory agencies. The analysis includes assessment of causality for BC, data quality of the presented cases, and their inconsistencies and confounding variables.

RESULTS

The assessed data raise serious doubts on the initial claims of causality for BC in these cases and provide clear evidence of their poor quality, especially when spontaneous reports are considered. There are major inconsistencies for the same patient regarding reported data. Moreover, the analysis of all cases disclosed confounding variables. These include poor case data quality, uncertainty of BC product, quality, and identification, undisclosed indication, insufficient adverse event definition, lack of temporal association and dechallenge, missing or inadequate evaluation of alcohol use, comedication, comorbidity, reexposure test, and alternative diagnoses.

CONCLUSIONS

The presented data do not support the concept of hepatotoxicity in a primarily suspected causal relationship to the use of BC and failure to provide a signal of safety concern, but further efforts have to be undertaken to dismiss or to substantiate the existence of BC hepatotoxicity as a special disease entity. The future strategy should be focused on prospective causality evaluations in patients diagnosed with suspected BC hepatotoxicity, using a structured, quantitative, and hepatotoxicity-specific causality assessment method.

Rechallenge in drug-induced liver injury: the attractive hazard

Progress in the understanding of drug-induced liver injury (DILI) is clearly hampered by the lack of specific markers of the disease. In this scenario, recrudescence of the liver injury upon re-exposure to the suspicious drug is considered the more reliable evidence of DILI. On-purpose re-exposure, however, entails both practical and ethical issues because the bulk of situations in clinical practice are non-immunoallergic DILI in which a provocation test frequently would give negative results. Besides, deliberate re-exposure with a drug that is not considered vital or essential is potentially harmful and, hence, hardly justified in DILI, and rechallenge is more commonly described in an unintentional basis. The causes, characteristics and consequences of rechallenge have been specifically addressed recently. For causality assessment, a positive rechallenge test carries the strong value, and is accordingly scored by clinical algorithms. Such clinical scales, however, reward drugs that are associated with a positive rechallenge response, but might be considered biased against those where re-administration fails to elicit a response or, more commonly, for which no rechallenge is attempted.

Kava hepatotoxicity: regulatory data selection and causality assessment

BACKGROUND

Kava hepatotoxicity in 20 patients from Germany has been debated worldwide following a regulatory ad hoc causality assessment and ban of kava, an anxiolytic herbal remedy obtained from the rhizome of Piper methysticum Forster.

AIMS

We assessed causality with a quantitative structured causality analysis in all 20 cases of patients with liver disease, presented by the German regulatory agency that assumed a causal relationship with the use of kava extracts.

METHODS

The quantitative scale of CIOMS (Council for International Organizations of Medical Sciences) in its updated form was employed for causality assessment and quality evaluation of the regulatory data presentation.

RESULTS

The regulatory information is scattered and selective, and items essential for causality assessment, such as exclusion of kava independent causes, were not, or only marginally, considered by the regulator. Quantitative causality assessment for kava was possible (n=2), unlikely (n=12), or excluded (n=6), showing no concordance with the regulatory ad hoc causality evaluation.

CONCLUSION

The regulatory data regarding kava hepatotoxicity is selective and of low quality, not supportive of the regulatory proposed causality; but instead, is an explanation of the overall causality discussions of kava hepatotoxicity. We are proposing that the regulatory agency reports data in full length and reevaluates causality.

Drug-induced liver injury: insights from genetic studies

Drug-induced liver injury (DILI) is an increasing health problem and a challenge for physicians, regulatory bodies and the pharmaceutical industry, not only because of its potential severity and elusive pathogenesis but also because it is often inaccurately diagnosed, commonly missed entirely and more often not reported. The general view is that idiosyncratic DILI, which is not predictable whether based on the pharmacology of the drug or on the dose administered, is determined by the presence in the recipient of variants in, or expression of, genes coding for key metabolic pathways and/or the immune response, and the interaction of these genetic variants with environmental variables. Furthermore, idiosyncratic DILI is an example of a complex-trait disease with two or more susceptibility loci, as reflected by the frequency of genetic variants in the population often being higher than the occurrence of significant liver injury. Polymorphisms of bioactivation/toxification pathways via the CYP450 enzymes (Phase I), detoxification reactions (Phase II) and excretion/transport (Phase III), together with immunological factors that might determine DILI are reviewed. Challenges such as gene-trait association studies and whole-genome studies, and future approaches to the study of DILI are explored. Better knowledge of the candidate genes involved could provide further insight for the prospective identification of susceptible patients at risk of developing drug-induced hepatotoxicity, development of new diagnostic tools and new treatment strategies with safer drugs.

[Anticonvulsant hypersensitivity syndrome: an entity to be remembered]

Anticonvulsant hypersensitivity syndrome is an unpredictable, potentially fatal drug reaction to aromatic anticonvulsants such as carbamazepine, phenytoin and phenobarbital. The hallmark features include fever, eosinophilia, rash and involvement of one or more internal organs. Clearly established diagnostic criteria and treatment guidelines are lacking. A high index of suspicion is required to identify this syndrome, allowing early withdrawal of the drug and avoiding re-exposure. We report an illustrative case of anticonvulsant hypersensitivity syndrome and review the published literature.

Kava hepatotoxicity: comparison of aqueous, ethanolic, acetonic kava extracts and kava-herbs mixtures

ETHNOPHARMACOLOGICAL RELEVANCE

Ethanolic and acetonic kava extracts have previously been causally related to rare hepatotoxicity observed in patients from Germany and Switzerland, but causality assessment was not performed in cases of patients having taken the traditional aqueous kava extracts of South Pacific islands or kava-herbs mixtures.

AIM OF THE STUDY

To study the possible hepatotoxicity of aqueous kava extracts of the South Pacific Islands.

MATERIALS AND METHODS

Causality of hepatotoxicity by aqueous kava extracts and kava-herbs mixtures was assessed, using the updated score of the quantitative CIOMS (Council for the International Organizations of Medical Sciences).

RESULTS

Causality was established in five patients from New Caledonia, Australia, the United States and Germany for aqueous kava extracts and kava-herbs mixtures. A comparison with 9 patients from Germany and Switzerland with established causality of hepatotoxicity by ethanolic and acetonic kava extracts reveals that the clinical picture in all 14 patients is similar, independently whether aqueous, ethanolic and acetonic kava extracts or kava-herbs mixtures were used.

CONCLUSIONS

Kava hepatotoxicity occurs also with traditional aqueous kava extracts of the South Pacific islands and thereby independently from ethanol or acetone as chemical solvents, suggesting that the toxicity is linked to the kava plant itself with a possibly low quality of the used kava cultivar or kava plant part rather than to chemical solvents.

The hospitalized patient with abnormal liver function tests

Evaluation of abnormal liver function tests (LFTs) in the hospitalized patient is typically more urgent than the outpatient setting. This process is best organized into four steps. The first step is to determine whether the abnormal LFTs are associated with the illness resulting in the admission to the hospital or preceded the present illness. The second is to determine the etiology of the underlying liver disease. The third step is to evaluate the severity of the liver dysfunction and determine if acute liver failure (ALF) or acute decompensation of chronic liver failure is present. The final step is to look for the presence of associated complications-either those of ALF or chronic liver failure as appropriate.

Causality assessment in hepatotoxicity by drugs and dietary supplements

Structured causality assessment of hepatotoxicity by drugs and dietary supplements (DDS) is a major clinical challenge, since temporal associations as the sole criteria for a valid evaluation are not acceptable. Initially, a clear intuition for an ad hoc evaluation is necessary, but only provisional, and must be followed by a diagnostic algorithm using a pretest, main test and post test. The evaluation is based on a variety of items such as latency period, course of alanine aminotransferase and alkaline phosphatase after DDS discontinuation, risk factors, co-medication, previous information on hepatotoxicity of the DDS, response to rechallenge, and exclusion of other diseases. It is essential that practising and hospital physicians as well as other key health professionals, such as pharmacists, gather all information required for a sound causality assessment, obviating major discussions by expert panels, manufacturers and health agencies in face of scanty and fragmentary data. Because pharmacogenetic alterations may trigger metabolic hepatotoxicity by a few DDS, levels in plasma and urine should be measured and may be helpful for diagnosis. Concomitant genotyping of cytochrome P450 and other enzymes may also be useful in future to minimize the risk of unwanted side-effects, including toxic liver disease elicited by DDS.

Kava hepatotoxicity: a clinical survey and critical analysis of 26 suspected cases

BACKGROUND/AIMS

Hepatotoxicity has been previously suspected by national regulatory agencies in 26 patients in causal relationship with the treatment by kava extracts commonly used as herbal anxiolytic drugs.

METHODS

A quantitative causality assessment was undertaken using the system of the Council for International Organizations of Medical Sciences, scale of objective probability scoring.

RESULTS

Causality was unassessable, unrelated, or excluded in 16 patients owing to lack of temporal association and causes independent of kava or comedicated drugs. Low Council for International Organizations of Medical Sciences scores additionally resulted in excluded or unlikely causality assessments (n=2), leaving a total of eight patients with various degrees of causality for kava +/- comedicated drugs. Only one out of these eight patients adhered to the regulatory recommendations regarding both daily dose (<or=120 mg kavapyrones) and duration of therapy (<or=3 months) and experienced toxic liver injury with a probable causality for kava. In six cases with kava overdose and/or increased duration of kava treatment causality for kava was possible (n=3) and for kava together with the comedicated drug(s) possible (n=2) or probable (n=1).

CONCLUSION

Kava taken as recommended is associated with rare hepatotoxicity, whereas overdose, prolonged treatment, and comedication may carry an increased risk.

Atomoxetine-induced hepatitis in a child

OBJECTIVE

To report a case of hepatitis associated with atomoxetine hydrochloride use and to describe the previously-unpublished severe cases of this syndrome.

CASE SUMMARY

An eight-year-old female with attention deficient hyperactive disorder (ADHD) was treated with atomoxetine hydrochloride. She complained of increased abdominal pain and occasional emesis; her transaminases and bilirubin were markedly elevated. She was admitted to a tertiary-care pediatric hospital and treated for drug-induced hepatitis. Atomoxetine was discontinued and supportive care was instituted. A liver biopsy showed hepatitis with moderate piecemeal necrosis. Clinical status and liver function tests improved over 13 days of hospitalization.

DISCUSSION

To our knowledge this is the first published severe case of atomoxetine-induced hepatitis. The International Organization of Medical Science Diagnostic Scale and the Adverse Drug Reaction Probability Scale by Naranjo et al. were applied to assess causality. Both scales indicated the association of atomoxetine and hepatitis as "probable;" a positive rechallenge would have made this association "definitive." This potential serious adverse reaction should be considered in children receiving atomoxetine therapy.

Assessment of drug-induced hepatotoxicity in clinical practice: a challenge for gastroenterologists

Currently, pharmaceutical preparations are serious contributors to liver disease; hepatotoxicity ranking as the most frequent cause for acute liver failure and post-commercialization regulatory decisions. The diagnosis of hepatotoxicity remains a difficult task because of the lack of reliable markers for use in general clinical practice. To incriminate any given drug in an episode of liver dysfunction is a step-by-step process that requires a high degree of suspicion, compatible chronology, awareness of the drug's hepatotoxic potential, the exclusion of alternative causes of liver damage and the ability to detect the presence of subtle data that favors a toxic etiology. This process is time-consuming and the final result is frequently inaccurate. Diagnostic algorithms may add consistency to the diagnostic process by translating the suspicion into a quantitative score. Such scales are useful since they provide a framework that emphasizes the features that merit attention in cases of suspected hepatic adverse reaction as well. Current efforts in collecting bona fide cases of drug-induced hepatotoxicity will make refinements of existing scales feasible. It is now relatively easy to accommodate relevant data within the scoring system and to delete low-impact items. Efforts should also be directed toward the development of an abridged instrument for use in evaluating suspected drug-induced hepatotoxicity at the very beginning of the diagnosis and treatment process when clinical decisions need to be made. The instrument chosen would enable a confident diagnosis to be made on admission of the patient and treatment to be fine-tuned as further information is collected.

Drug-induced liver injury in a Swedish University hospital out-patient hepatology clinic

BACKGROUND

Limited data exist on the proportion of drug-induced liver injury among out-patients seen in a hepatology clinic.

AIM

To determine the proportion of drug-induced liver injury cases, and identify the most important agents and the nature of the liver injury.

METHODS

A computerized diagnoses database in an out-patient hepatology clinic in a Swedish University hospital was analysed during the period 1995-2005. All suspected drug-induced liver injury cases were causality assessed with the International Consensus Criteria.

RESULTS

A total of 1164 cases were seen for the first time during this period. Drug-induced liver injury with at least a possible causal relationship was found in 77 cases (6.6%), 38 (3.3%) of whom were referred for evaluation to the out-patient clinic whereas 3% had a follow-up after hospitalization of drug-induced liver injury. The median age was 58 years, 43 (56%) were females, a hepatocellular pattern was observed in 37 cases (48%), cholestatic in 31 (40%) and mixed in 12%. Antibiotics were the most common agents causing drug-induced liver injury followed by non-steroidal anti-inflammatory drugs, with diclofenac most often responsible for the drug-induced liver injury.

CONCLUSIONS

Drug-induced liver injury cases constituted 6% of all out-patients and 3% of referrals and occurred more often in women. Antibiotics and diclofenac were the most common causes of drug-induced liver injury among out-patients.

Allergic hepatitis induced by drugs

PURPOSE OF REVIEW

To examine recent advances in our understanding of how drugs can trigger a hypersensitivity reaction in the liver, how tolerance is lost, the mechanisms of damage to hepatocytes and the strategies towards a better assessment of an idiosyncratic drug liver reaction.

RECENT FINDINGS

Formation and presentation of drug-protein adducts, or a direct interaction with the major histocompatibility complex/T-cell receptor complex is a necessary but not sufficient stimulus to trigger a hypersensitivity reaction. Liver shows considerable tolerogenic potential towards drug adducts. Recent studies highlight allergic hepatitis as a loss of liver tolerance towards drug antigens, the mechanisms of which are beginning to be unravelled. Cell injury caused by the drug itself, a concomitant inflammatory process, or a coincidental stimulus probably represents the additional signal needed to initiate the allergic process.

SUMMARY

Drug-induced liver injury is of concern due to its unpredictable nature and serious clinical implications. Clinically, both hepatocellular injury and cholestasis can occur and most episodes have good clinical prognoses upon drug discontinuation. In a few cases, damage to the liver cells may continue in the form of an autoimmune hepatitis. The available diagnostic tools to confirm an immune-mediated hepatic injury are still very limited, and rely on the lymphocyte transformation test.

High concordance of drug-induced human hepatotoxicity with in vitro cytotoxicity measured in a novel cell-based model using high content screening

To develop and validate a practical, in vitro, cell-based model to assess human hepatotoxicity potential of drugs, we used the new technology of high content screening (HCS) and a novel combination of critical model features, including (1) use of live, human hepatocytes with drug metabolism capability, (2) preincubation of cells for 3 days with drugs at a range of concentrations up to at least 30 times the efficacious concentration or 100 microM, (3) measurement of multiple parameters that were (4) morphological and biochemical, (5) indicative of prelethal cytotoxic effects, (6) representative of different mechanisms of toxicity, (7) at the single cell level and (8) amenable to rapid throughput. HCS is based on automated epifluorescence microscopy and image analysis of cells in a microtiter plate format. The assay was applied to HepG2 human hepatocytes cultured in 96-well plates and loaded with four fluorescent dyes for: calcium (Fluo-4 AM), mitochondrial membrane potential (TMRM), DNA content (Hoechst 33,342) to determine nuclear area and cell number and plasma membrane permeability (TOTO-3). Assay results were compared with those from 7 conventional, in vitro cytotoxicity assays that were applied to 611 compounds and shown to have low sensitivity (<25%), although high specificity ( approximately 90%) for detection of toxic drugs. For 243 drugs with varying degrees of toxicity, the HCS, sublethal, cytotoxicity assay had a sensitivity of 93% and specificity of 98%. Drugs testing positive that did not cause hepatotoxicity produced other serious, human organ toxicities. For 201 positive assay results, 86% drugs affected cell number, 70% affected nuclear area and mitochondrial membrane potential and 45% affected membrane permeability and 41% intracellular calcium concentration. Cell number was the first parameter affected for 56% of these drugs, nuclear area for 34% and mitochondrial membrane potential for 29% and membrane permeability for 7% and intracellular calcium for 10%. Hormesis occurred for 48% of all drugs with positive response, for 26% of mitochondrial and 34% nuclear area changes and 12% of cell number changes. Pattern of change was dependent on the class of drug and mechanism of toxicity. The ratio of concentrations for in vitro cytotoxicity to maximal efficaciousness in humans was not different across groups (12+/-22). Human toxicity potential was detected with 80% sensitivity and 90% specificity at a concentration of 30x the maximal efficacious concentration or 100 microM when efficaciousness was not considered. We conclude that human hepatotoxicity is highly concordant with in vitro cytotoxicity in this novel model and as detected by HCS.

Comparison of potentially hepatotoxic drugs among major US drug compendia

BACKGROUND

Although a large number of drugs include warnings or listed adverse reactions that describe reports of associated hepatotoxicity, the hepatotoxic risk is documented with different definitions in major drug compendia.

OBJECTIVES

The purposes of this study were to compare inclusion of potentially hepatotoxic drugs, and analyze the ratings of hepatotoxic risk among major drug compendia.

METHODS

To assess the risk of drug-associated hepatotoxicity, we used current literature of epidemiological studies and developed a 4-level rating scale of hepatotoxic drugs: 3, clear literature evidence of life-threatening hepatotoxicity; 2, multiple case reports or significant liver injuries; 1, no significant liver damage has been reported; and 0, no information. All drugs were evaluated using the 5 major US drug compendia: American Hospital Formulary Service (AHFS), United States Pharmacopeia Drug Information (USPDI), Facts and Comparisons (F&C), Physicians' Desk Reference (PDR), and Clinical Pharmacology (CP). Average rating scores were calculated as the sum of each drug rating score divided by the total number of drugs. One-way analysis of variance and independent t tests were conducted to compare the difference among the rating scores.

RESULTS

In total, 175 different drugs and 3 therapeutic classes with hepatotoxic effects were identified in the compendia, including 59 antineoplastics, 28 anti-infectives, 17 nonsteroidal anti-inflammatory drugs, 17 antipsychotics or phenothiazine derivatives, 9 angiotensin-converting enzyme inhibitors, 6 anticonvulsants, 4 histamine-2 receptor antagonists, and other drugs. Average rating scores were 1.65 for AHFS, 1.10 for USPDI, 1.27 for F&C, 1.34 for PDR, and 1.61 for CP (F=7.93, P<.0001). The risk categories were significantly different among compendia in 4 therapeutic classes of antipsychotics and/or phenothiazines (F=3.471, P=.011), nonsteroidal anti-inflammatory drugs (F=7.866, P<.0001), antineoplastics (F=2.476, P=.044), anti-infectives (F=2.003, P=.098), and angiotensin-converting enzyme inhibitors (F=38.125, P<.0001).

CONCLUSIONS

Rating scores of hepatotoxicity were significantly different among drug compendia. The different compendium put different emphasis on hepatotoxicity severity. Comprehensive evaluations of hepatotoxic-related drugs provide critical information for health practitioners.