Severe drug-induced liver injury associated with prolonged use of linezolid

Clinical drug interactions between linezolid and other antibiotics: For adverse drug event monitoring

Detailed data on safety associated with drug-drug interactions (DDIs) between Linezolid (LZD) and other antibiotics are limited. The aim of this study was to investigate the safety signals related to these DDIs and to provide a reference for clinically related adverse drug event monitoring. Adverse event (AE) information from 1 January 2004 to 16 June 2022 of the target antibiotics including LZD using alone or in combination with LZD was extracted from the OpenVigil FDA data platform for safety signal analysis. The combined risk ratio model, reporting ratio method, Ω shrinkage measure model, and chi-square statistics model were used to analyze the safety signals related to DDIs. Meanwhile, we evaluated the correlation and the influence of sex and age between the drug(s) and the target AE detected. There were 18991 AEs related to LZD. There were 2293, 1726, 4449, 821, 2431, 1053, and 463 AE reports when LZD was combined with amikacin, voriconazole, meropenem, clarithromycin, levofloxacin, piperacillin-tazobactam, and azithromycin, respectively. Except for azithromycin, there were positive safety signals related to DDIs between LZD and these antibiotics. These DDIs might influence the incidence of 13, 16, 7, 7, 6, and 15 types of AEs, respectively, and is associated with higher reporting rates of AEs compared with use alone. Moreover, sex and age might influence the occurrence of AEs. We found that the combinations of LZD and other antibiotics are related to multiple AEs, such as hepatotoxicity, drug resistance and electrocardiogram QT prolonged, but further research is still required to investigate their underlying mechanisms. This study can provide a new reference for the safety monitoring of LZD combined with other antibiotics in clinical practice.

Hepatotoxicity of Antibiotics and Antifungals and Their Safe Use in Hepatic Impairment

Idiosyncratic drug-induced liver injury (DILI) is a rare and unpredictable form of hepatotoxicity. While its clinical course is usually benign, cases leading to liver transplantation or death can occur. Based on modern prospective registries, antimicrobials including antibiotics and antifungals are frequently implicated as common causes. Amoxicillin-clavulanate ranks as the most common cause for DILI in the Western World. Although the absolute risk of hepatotoxicity of these agents is low, as their usage is quite high, it is not uncommon for practitioners to encounter liver injury following the initiation of antibiotic or antifungal therapy. In this review article, mechanisms of hepatoxicity are presented. The adverse hepatic effects of well-established antibiotic and antifungal agents are described, including their frequency, severity, and pattern of injury and their HLA risks. We also review the drug labeling and prescription guidance from regulatory bodies, with a focus on individuals with hepatic impairment.

Influence of Antibiotics on Functionality and Viability of Liver Cells In Vitro

(1) Antibiotics are an important weapon in the fight against serious bacterial infections and are considered a common cause of drug-induced liver injury (DILI). The hepatotoxicity of many drugs, including antibiotics, is poorly analyzed in human in vitro models. (2) A standardized assay with a human hepatoma cell line was used to test the hepatotoxicity of various concentrations (Cmax, 5× Cmax, and 10× Cmax) of antibiotics. In an ICU, the most frequently prescribed antibiotics, ampicillin, cefepime, cefuroxime, levofloxacin, linezolid, meropenem, rifampicin, tigecycline, and vancomycin, were incubated with HepG2/C3A cells for 6 days. Cell viability (XTT assay, LDH release, and vitality), albumin synthesis, and cytochrome 1A2 activity were determined in cells. (3) In vitro, vancomycin, rifampicin, and tigecycline showed moderate hepatotoxic potential. The antibiotics ampicillin, cefepime, cefuroxime, levofloxacin, linezolid, and meropenem were associated with mild hepatotoxic reactions in test cells incubated with the testes Cmax concentration. Rifampicin and cefuroxime showed significantly negative effects on the viability of test cells. (4) Further in vitro studies and global pharmacovigilance reports should be conducted to reveal underlying mechanism of the hepatotoxic action of vancomycin, rifampicin, tigecycline, and cefuroxime, as well as the clinical relevance of these findings.

Detailed Molecular Mechanisms Involved in Drug-Induced Non-Alcoholic Fatty Liver Disease and Non-Alcoholic Steatohepatitis: An Update

Non-alcoholic fatty liver disease (NAFLD) and non-alcoholic steatohepatitis (NASH) are some of the biggest public health challenges due to their spread and increasing incidence around the world. NAFLD is characterized by intrahepatic lipid deposition, accompanied by dyslipidemia, hypertension, and insulin resistance, leading to more serious complications. Among the various causes, drug administration for the treatment of numerous kinds of diseases, such as antiarrhythmic and antihypertensive drugs, promotes the onset and progression of steatosis, causing drug-induced hepatic steatosis (DIHS). Here, we reviewed in detail the major classes of drugs that cause DIHS and the specific molecular mechanisms involved in these processes. Eight classes of drugs, among the most used for the treatment of common pathologies, were considered. The most diffused mechanism whereby drugs can induce NAFLD/NASH is interfering with mitochondrial activity, inhibiting fatty acid oxidation, but other pathways involved in lipid homeostasis are also affected. PubMed research was performed to obtain significant papers published up to November 2021. The key words included the class of drugs, or the specific compound, combined with steatosis, nonalcoholic steatohepatitis, fibrosis, fatty liver and hepatic lipid deposition. Additional information was found in the citations listed in other papers, when they were not displayed in the original search.

Treatment of Intracranial Infection Caused by Methicillin-Resistant Staphylococcus epidermidis with Linezolid Following Poor Outcome of Vancomycin Therapy: A Case Report and Literature Review

The pharmacokinetic/pharmacodynamic (PK/PD) parameter for evaluating the efficacy of vancomycin is now recommended to target an AUC/MIC (area under the curve, AUC; minimum inhibitory concentration, MIC) ratio of 400 to 600, and trough concentration should not be used as a substitute. We report a case of intracranial infection caused by methicillin-resistant Staphylococcus epidermidis (MRSE), which was sensitive to vancomycin (MIC=2µg/mL) and linezolid (MIC=4µg/mL). The trough concentration of vancomycin in serum was 18.3 µg/mL, and the vancomycin concentration in CSF was 5.0 µg/mL, all within normal range. However, the AUC/MIC ratio was calculated to be 125 mg·h·L^-1, unable to reach target AUC/MIC. Vancomycin was replaced with linezolid after 36 days of treatment due to poor outcome, and the patient was eventually cured. Further, 23 cases of intracranial methicillin-resistant Staphylococcus aureus (MRSA) or methicillin-resistant coagulase-negative Staphylococcus (MRCoNS) infections were reported, of which 1 case with MRSA had a vancomycin MIC of 1 µg/mL, while the remaining 22 cases had vancomycin MICs >1 µg/mL. The linezolid-containing regimen was used after drug susceptibility results or if the initial treatment failed, leading to recovery in 19 patients, microbial clearance in 3 patients, and treatment failure in 1 case. In conclusion, vancomycin dosing should be based on AUC-guided dosing and monitoring. When the vancomycin MIC of MRSA/MRCoNS is >1 µg/mL, the target AUC/MIC may not be achieved. In such cases, linezolid can effectively be considered as a good alternative to vancomycin.

Acute liver failure with thrombotic microangiopathy due to sodium valproate toxicity: A case report

BACKGROUND

Sodium valproate is widely used in the treatment of epilepsy in clinical practice. Most adverse reactions to sodium valproate are mild and reversible, while serious idiosyncratic side effects are becoming apparent, particularly hepatotoxicity. Herein, we report a case of fatal acute liver failure (ALF) with thrombotic microangiopathy (TMA) caused by treatment with sodium valproate in a patient following surgery for meningioma.

CASE SUMMARY

A 42-year-old man who received antiepileptic treatment with sodium valproate after surgery for meningioma exhibited extreme fatigue, severe jaundice accompanied by oliguria, soy sauce-colored urine, and ecchymosis. His postoperative laboratory values indicated a rapid decreased platelet count and hemoglobin level, severe liver and kidney dysfunction, and disturbance of the coagulation system. He was diagnosed with drug-induced liver failure combined with TMA. After plasma exchange combined with hemoperfusion, pulse therapy with high-dose methylprednisolone, and blood transfusion, his liver function deteriorated, and finally, he died.

CONCLUSION

ALF with TMA is a rare and fatal adverse reaction of sodium valproate which needs to be highly valued.

Liver Histology: Diagnostic and Prognostic Features

When patients with suspected drug-induced liver injury (DILI) undergo liver biopsy, the pathologist can provide a wealth of information on the morphologic changes. The most common histologic patterns of DILI include mimics of acute and chronic hepatitis as well as acute cholestasis, chronic cholestasis, and a mixed pattern that combines hepatitis with cholestasis. The pattern may suggest etiologies of injury or correlate with reported patterns of injury for specific agents. Biopsy may exonerate or indict particular drugs as causal agents of injury and provide specific information on severity of injury and specific types of changes related to various outcomes.

Safety implications of combined antiretroviral and anti-tuberculosis drugs

Introduction: Antiretroviral and anti-tuberculosis (TB) drugs are often co-administered in people living with HIV (PLWH). Early initiation of antiretroviral therapy (ART) during TB treatment improves survival in patients with advanced HIV disease. However, safety concerns related to clinically significant changes in drug exposure resulting from drug-drug interactions, development of overlapping toxicities and specific challenges related to co-administration during pregnancy represent barriers to successful combined treatment for HIV and TB.Areas covered: Pharmacokinetic interactions of different classes of ART when combined with anti-TB drugs used for sensitive-, drug-resistant (DR) and latent TB are discussed. Overlapping drug toxicities, implications of immune reconstitution inflammatory syndrome (IRIS), safety in pregnancy and research gaps are also explored.Expert opinion: New antiretroviral and anti-tuberculosis drugs have been recently introduced and international guidelines updated. A number of effective molecules and clinical data are now available to build treatment regimens for PLWH with latent or active TB. Adopting a systematic approach that also takes into account the need for individualized variations based on the available evidence is the key to successfully integrate ART and TB treatment and improve treatment outcomes.

A Case of Linezolid Toxicity Presenting as a Sepsis Mimic

Linezolid is an efficacious and well tolerated antimicrobial but can have serious adverse effects including myelo-suppression, serotonin syndrome, neuropathy, hypoglycemia, liver dysfunction, and lactic acidosis. The side effects are generally duration dependent; linezolid use is not recommended for more than 28 days. Case. A 59-year-old female presented with malaise, loss of appetite, and altered mentation. She had multiple medical comorbidities and required long-term anticoagulation with warfarin for venous thromboembolism. She had multiple medication allergies. Prior to admission, she was on linezolid for cellulitis of foot due to Methicillin-resistant Staphylococcus aureus (MRSA). On physical exam, she was drowsy and required endotracheal intubation for airway protection. Initial laboratory parameters showed lactic acidosis, thrombocytopenia, supra-therapeutic coagulation profile, low blood glucose, and transaminitis. Her altered mentation was due to hypoglycemia. The interaction with warfarin led to altered coagulation profile. She developed shock and vasopressors were initiated. Given her presentation, she was managed as severe sepsis. There were no active infectious foci attributing to decline of her clinical status. Linezolid was discontinued and she was managed with intravenous polymyxin B, aztreonam, and vancomycin. Her hemodynamic status improved within one day. She was extubated on Day 5 of her presentation. Her laboratory parameters showed gradual improvement over 12 days after discontinuation of linezolid. Retrospective evaluation revealed linezolid toxicity as possible cause of presentation. Linezolid toxicity can present as sepsis mimic and should be considered as a differential diagnosis while managing sepsis with other antimicrobial agents.

Alteration of mitochondrial DNA homeostasis in drug-induced liver injury

Mitochondrial DNA (mtDNA) encodes for 13 proteins involved in the oxidative phosphorylation (OXPHOS) process. In liver, genetic or acquired impairment of mtDNA homeostasis can reduce ATP output but also decrease fatty acid oxidation, thus leading to different hepatic lesions including massive necrosis and microvesicular steatosis. Hence, a severe impairment of mtDNA homeostasis can lead to liver failure and death. An increasing number of investigations report that some drugs can induce mitochondrial dysfunction and drug-induced liver injury (DILI) by altering mtDNA homeostasis. Some drugs such as ciprofloxacin, antiretroviral nucleoside reverse-transcriptase inhibitors and tacrine can inhibit hepatic mtDNA replication, thus inducing mtDNA depletion. Drug-induced reduced mtDNA levels can also be the consequence of reactive oxygen species-mediated oxidative damage to mtDNA, which triggers its degradation by mitochondrial nucleases. Such mechanism is suspected for acetaminophen and troglitazone. Other pharmaceuticals such as linezolid and tetracyclines can impair mtDNA translation, thus selectively reducing the synthesis of the 13 mtDNA-encoded proteins. Lastly, some drugs might alter the mtDNA methylation status but the pathophysiological consequences of such alteration are still unclear. Drug-induced impairment of mtDNA homeostasis is probably under-recognized since preclinical and post-marketing safety studies do not classically investigate mtDNA levels, mitochondrial protein synthesis and mtDNA oxidative damage.

A Pharmacology Perspective of Simultaneous Tuberculosis and Hepatitis C Treatment

Tuberculosis (TB) and hepatitis C virus (HCV) infection are both major public health problems. Despite high rates of co-infection there is scarce literature addressing the convergence of the two diseases. One particularly unexplored area is the potential for simultaneous treatment of TB and HCV which would allow for leveraging an extensive global TB treatment infrastructure to help scale up HCV treatment. We review the drug metabolism of anti-TB and HCV drugs and the known and potential drug-drug interactions between recommended HCV regimens and individual anti-TB drugs. Rifampin is the only anti-TB drug to have been formally studied for potential drug interactions with anti-HCV direct-acting antivirals (DAAs) and existing data precludes these combinations. However, based on known pathways of drug metabolism and enzyme effects, the combination of HCV DAA regimens with all other anti-TB drugs may be feasible. Pharmacokinetic studies are needed next to help move co treatment regimens forward for clinical use among patients coinfected with TB and HCV.

Biomarkers of Drug-Induced Liver Toxicity

Drug-induced liver injury (DILI) is a comprehensive phenomenon. The injury to the liver may occur as an unexpected and undesired reaction to a therapeutic dose of a drug (idiosyncratic reaction) or as an expected therapeutic effect of the direct (intrinsic) toxicity of a drug taken in a large enough dose to cause liver injury. The direct toxicity (type A) reactions represent an extension of the drug's therapeutic effect; they occur relatively frequently and are typically dose-related and frequency-of-exposure-related. By contrast, idiosyncratic reactions, or type B reactions, are unpredictable, occurring only in susceptible individuals, and are unrelated to the dose or frequency of exposure. DILI encompasses both acute and/or chronic hepatic lesions. The liver injury may be the only clinical manifestation of the adverse drug effect. Otherwise, it may be accompanied by injury to other organs, or by systemic manifestations. The liver injury may be observed in 1-8 days from taking the drug. DILI cases may result in the disapproval of a new drug or in the removal of a useful drug from the market by regulatory agencies. The purpose of this review is to provide guidance to facilitate the detection and assessment of hepatotoxicity induced by therapeutics that received market authorization. This review supports the safe and effective use of drugs by patients and guides laboratory medicine professional in determining the possible drug-induced liver damage.

The risk factors of linezolid-induced lactic acidosis: A case report and review

BACKGROUND

In recent years, linezolid is increasingly used in multidrug-resistant bacteria therapy. At the same time, linezolid-induced lactic acidosis has been continually reported as a serious side effect. Notably, to our knowledge, there are limited available literatures that evaluate risk factors for linezolid-induced lactic acidosis, and there is no highly reliable study on the relationship between linezolid-induced lactic acidosis and age or gender. However, clinicians need relevant information to advice on the use of linezolid. Therefore, we report on a case of life-threatening lactic acidosis after 3 doses of linezolid exposure and evaluate the risk factors of linezolid-induced lactic acidosis.

METHODS

Cases of linezolid-induced lactic acidosis reported in PubMed were searched. Several characteristics and data of case numbers and deaths were extracted for analysis.

RESULTS

A total of 35 articles including 47 cases were included in this study. Twelve patients (25.5%) died due to linezolid-induced lactic acidosis. At the cut-offs of 7, 14, and 28 days, the mortalities were 27.3%, 20%, and 27.3%. No statistically significant difference was observed according to age and gender. However, the proportion (27.7% and 29.8%) and mortality (30.8% and 35.7%) of male patients were much higher than females in both ≥65 and <65 years old groups (proportion: 15.2% and 23.9%; mortality: 14.3% and 18.2%).

CONCLUSION

The mortality of linezolid-induced lactic acidosis was relatively high. The duration of linezolid use and age might not be risk factors. Gender (specifically, male) might be related to the mortality of linezolid-induced lactic acidosis.

Do In Vitro Assays Predict Drug Candidate Idiosyncratic Drug-Induced Liver Injury Risk?

In vitro assays are commonly used during drug discovery to try to decrease the risk of idiosyncratic drug-induced liver injury (iDILI). But how effective are they at predicting risk? One of the most widely used methods evaluates cell cytotoxicity. Cytotoxicity assays that used cell lines that are very different from normal hepatocytes, and high concentrations of drug, were not very accurate at predicting idiosyncratic drug reaction risk. Even cytotoxicity assays that use more biologically normal cells resulted in many false-positive and false-negative results. Assays that quantify reactive metabolite formation, mitochondrial injury, and bile salt export pump (BSEP) inhibition have also been described. Although evidence suggests that reactive metabolite formation and BSEP inhibition can play a role in the mechanism of iDILI, these assays are not very accurate at predicting risk. In contrast, inhibition of the mitochondrial electron transport chain appears not to play an important role in the mechanism of iDILI, although other types of mitochondrial injury may do so. It is likely that there are many additional mechanisms by which drugs can cause iDILI. However, simply measuring more parameters is unlikely to provide better predictive assays unless those parameters are actually involved in the mechanism of iDILI. Hence, a better mechanistic understanding of iDILI is required; however, mechanistic studies of iDILI are very difficult. There is substantive evidence that most iDILI is immune mediated; therefore, the most accurate assays may involve those that determine immune responses to drugs. New methods to manipulate immune tolerance may greatly facilitate development of more suitable methods.

Drug-Induced Alterations of Mitochondrial DNA Homeostasis in Steatotic and Nonsteatotic HepaRG Cells

Although mitochondriotoxicity plays a major role in drug-induced hepatotoxicity, alteration of mitochondrial DNA (mtDNA) homeostasis has been described only with a few drugs. Because it requires long drug exposure, this mechanism of toxicity cannot be detected with investigations performed in isolated liver mitochondria or cultured cells exposed to drugs for several hours or a few days. Thus, a first aim of this study was to determine whether a 2-week treatment with nine hepatotoxic drugs could affect mtDNA homeostasis in HepaRG cells. Previous investigations with these drugs showed rapid toxicity on oxidative phosphorylation but did not address the possibility of delayed toxicity secondary to mtDNA homeostasis impairment. The maximal concentration used for each drug induced about 10% cytotoxicity. Two other drugs, zalcitabine and linezolid, were used as positive controls for their respective effects on mtDNA replication and translation. Another goal was to determine whether drug-induced mitochondriotoxicity could be modulated by lipid overload mimicking nonalcoholic fatty liver. Among the nine drugs, imipramine and ritonavir induced mitochondrial effects suggesting alteration of mtDNA translation. Ritonavir toxicity was stronger in nonsteatotic cells. None of the nine drugs decreased mtDNA levels. However, increased mtDNA was observed with five drugs, especially in nonsteatotic cells. The mtDNA levels could not be correlated with the expression of key factors involved in mitochondrial biogenesis, such as peroxisome proliferator-activated receptor-γ coactivator 1α (PGC1α), PGC1β, and AMP-activated protein kinase α-subunit. Hence, drug-induced impairment of mtDNA translation might not be rare, and increased mtDNA levels could be a frequent adaptive response to slight energy shortage. Nevertheless, this adaptation could be impaired by lipid overload.

Drug-induced liver injury due to antibiotics

Drug-induced liver injury (DILI) is an important differential diagnosis in patients with abnormal liver tests and normal hepatobiliary imaging. Of all known liver diseases, the diagnosis of DILI is probably one of the most difficult one to be established. In all major studies on DILI, antibiotics are the most common type of drugs that have been reported. The clinical phenotype of different types of antibiotics associated with liver injury is highly variable. Some widely used antibiotics such as amoxicillin-clavulanate have been shown to have a delayed onset on liver injury and recently cefazolin has been found to lead to liver injury 1-3 weeks after exposure of a single infusion. The other extreme is the nature of nitrofurantoin-induced liver injury, which can occur after a few years of treatment and lead to acute liver failure (ALF) or autoimmune-like reaction. Most patients with liver injury associated with use of antibiotics have a favorable prognosis. However, patients with jaundice have approximately 10% risk of death from liver failure and/or require liver transplantation. In rare instances, the hepatoxicity can lead to chronic injury and vanishing bile duct syndrome. Given, sometimes very severe consequences of the adverse liver reactions, it cannot be over emphasized that the indication for the different antibiotics should be evidence-based and symptoms and signs of liver injury from the drugs should lead to prompt cessation of therapy.

Test systems in drug discovery for hazard identification and risk assessment of human drug-induced liver injury

INTRODUCTION

The liver is an important target for drug-induced toxicities. Early detection of hepatotoxic drugs requires use of well-characterized test systems, yet current knowledge, gaps and limitations of tests employed remains an important issue for drug development. Areas Covered: The current state of the science, understanding and application of test systems in use for the detection of drug-induced cytotoxicity, mitochondrial toxicity, cholestasis and inflammation is summarized. The test systems highlighted herein cover mostly in vitro and some in vivo models and endpoint measurements used in the assessment of small molecule toxic liabilities. Opportunities for research efforts in areas necessitating the development of specific tests and improved mechanistic understanding are highlighted. Expert Opinion: Use of in vitro test systems for safety optimization will remain a core activity in drug discovery. Substantial inroads have been made with a number of assays established for human Drug-induced Liver Injury. There nevertheless remain significant gaps with a need for improved in vitro tools and novel tests to address specific mechanisms of human Drug-Induced Liver Injury. Progress in these areas will necessitate not only models fit for application, but also mechanistic understanding of how chemical insult on the liver occurs in order to identify translational and quantifiable readouts for decision-making.

Linezolid-induced lactic acidosis: the thin line between bacterial and mitochondrial ribosomes

INTRODUCTION

Linezolid inhibits bacterial growth by targeting bacterial ribosomes and by interfering with bacterial protein synthesis. Lactic acidosis is a rare, but potentially lethal, side effect of linezolid. Areas covered: The pathogenesis of linezolid-induced lactic acidosis is reviewed with special emphasis on aspects relevant to the recognition, prevention and treatment of the syndrome. Expert opinion: Linezolid-induced lactic acidosis reflects the untoward interaction between the drug and mitochondrial ribosomes. The inhibition of mitochondrial protein synthesis diminishes the respiratory chain enzyme content and thus limits aerobic energy production. As a result, anaerobic glycolysis and lactate generation accelerate independently from tissue hypoxia. In the absence of any confirmatory test, linezolid-induced lactic acidosis should be suspected only after exclusion of other, more common, causes of lactic acidosis such as hypoxemia, anemia or low cardiac output. Normal-to-high whole-body oxygen delivery, high venous oxygen saturation and lack of response to interventions that effectively increase tissue oxygen provision all suggest a primary defect in oxygen use at the mitochondrial level. During prolonged therapy with linezolid, blood drug and lactate levels should be regularly monitored. The current standard-of-care treatment of linezolid-induced lactic acidosis consists of drug withdrawal to reverse mitochondrial intoxication and intercurrent life support.

Drug-induced Liver Injury: The Hepatic Pathologist's Approach

The evaluation of liver biopsies in suspected drug-induced liver injury (DILI) can be complex. The biopsy may be approached systematically, by identification of histologic lesions and then identification of the overall pattern of injury. Potential DILI must be separated from concomitant non-DILI liver disease. The findings can be analyzed with respect to the various prescription and nonprescription medications and dietary supplements under suspicion to provide a complete interpretation of the findings. The pathologic findings, the histologic differential diagnosis, and expert interpretation are part of a complete biopsy assessment and provide information that is of greatest value in patient management.

The histopathological evaluation of drug-induced liver injury

Drug-induced liver injury (DILI) presents unique challenges to the pathologist. It is not only an uncommon reason for liver biopsy, but the pathology of DILI is spread across the entire spectrum of hepatic injury patterns. It is important for the pathologist to suspect DILI when the histological changes are unusual or out of synchronicity with the patient's history. A systematic evaluation approach will yield the most information. It begins with the characterization of the general pattern of injury which, for most cases, will be found in a handful of necroinflammatory and cholestatic patterns. A careful assessment of the severity of injury across the various anatomic compartments will provide information on the probable natural history of the injury. Correlation of liver injury with the patient's medication history and clinical findings will help to narrow the differential diagnosis, particularly when it is recognized that most drugs have a limited range of histological findings and vary in their propensity to cause injury. This review provides an overview of the assessment of the liver biopsy and its use to confirm or exclude particular drugs as contributing to the patient's liver injury.

Lactic Acidosis Induced by Linezolid Mimics Symptoms of an Acute Intracranial Bleed: A Case Report and Literature Review

Lactic acidosis is common and most often associated with disturbed acid-base balance. Rarely, it can be a life-threatening medication side effect. Hence, determining the etiology of lactic acidosis early in patients is paramount in choosing the correct therapeutic intervention. Although lactic acidosis as an adverse drug reaction of linezolid is a well-recognized and documented clinical entity, the occurrence of such mimicking an acute intracranial bleed has not been reported to our knowledge. The following case is presented as an example of such an occurrence. A 67-year-old woman presented to the emergency department for lethargy, nausea and syncope. The head CT did not demonstrate any bleeding or mass effect, but lab results were significant for elevated lactic acid. The patient recently underwent left total hip replacement surgery, which was complicated by a methicillin-resistant Staphylococcus aureus (MRSA) infection. She received 6 weeks of oral linezolid therapy. And upon learning that key part of her history, the linezolid was discontinued. Her lactic acid rapidly normalized and she was discharged home. Several publications demonstrate that linezolid induces lactic acidosis by disrupting crucial mitochondrial functions. It is essential that clinicians are aware that linezolid can cause lactic acidosis. And, the important reminder is that adverse drug reactions can often mimic common diseases. If it is not recognized early, ominous clinical consequences may occur. In conclusion, linezolid should be suspected and included in the differential diagnosis if lactic acidosis exists with an uncommon clinical picture.

Diagnosis and treatment of coinfection of pulmonary tuberculosis and chronic hepatitis B

Hepatitis B virus (HBV) and tuberculosis bacillus (TB) are leading causes of infectious diseases in China, leading to a range of life-threaten diseases including chronic hepatitis B (CHB), cirrhosis, hepatocellular carcinoma (HCC) and pulmonary tuberculosis (PTB). Due to the high prevalence of infection and increased number of cases, coinfection of HCC and PTB is becoming a new hot area. Differences between coinfection and single infection include the disease process, injuries, medication selection, curative effects, drug-resistance and side effects. In particular, the adverse effects of clinical prognosis, etiological treatment, anti-tuberculosis drug induced liver injury (ATLI) and multidrug-resistant pulmonary tuberculosis (MDR-TB) have became a new challenge for therapy. This review aims to summarize the incidence of infections, clinical observations, adversely effects and existing problems of treatment, the development of antituberculous and anti-HBV therapy and hepatitis protection. Additionally, a suggestion for improving therapeutic efficacy has been proposed as well.

Antibiotic induced liver injury: what about children?

Antimicrobial agents are important causes of drug-induced liver injury. They are responsible for about 45% of cases of drug hepatotoxicity. Hepatic damage mechanisms are intrinsic or idiosyncratic. Usually, antibiotics are responsible for idiosyncratic toxicity. This review summarizes the rate of incidence and clinical features of hepatotoxicity due to antibiotics and chemotherapics, with particular attention to data regarding paediatric population. Liver injury features have been systematically evaluated for the most commonly administered antibiotics and chemotherapics in adults, even though there is little information about other widely used compounds, as cephalosporine or clarithromycin, and about antibiotics active against multi-resistant bacteria, as carbapenems, vancomycin, clindamycin, and linezolid. By contrast, there is an abundance of case reports in paediatrics, but very few structured studies have been carried out in children. Children are an important class of antibiotic users, with specific metabolic characteristics, so more studies on them should be carried out.

Clinical update on linezolid in the treatment of Gram-positive bacterial infections

Gram-positive pathogens are a significant cause of morbidity and mortality in both community and health care settings. Glycopeptides have traditionally been the antibiotics of choice for multiresistant Gram-positive pathogens but there are problems with their use, including the emergence of glycopeptide-resistant strains, tissue penetration, and achieving and monitoring adequate serum levels. Newer antibiotics such as linezolid, a synthetic oxazolidinone, are available for the treatment of resistant Gram-positive bacteria. Linezolid is active against a wide range of Gram-positive bacteria and has been generally available for the treatment of Gram-positive infections since 2000. There are potential problems with linezolid use, including its bacteriostatic action and the relatively high incidence of reported adverse effects, particularly with long-term use. Long-term use may also be complicated by the development of resistance. However, linezolid has been shown to be clinically useful in the treatment of several serious infections where traditionally bacteriocidal agents have been required and many of its adverse effects are reversible on cessation. It has also been shown to be a cost-effective treatment option in several studies, with its high oral bioavailability allowing an early change from intravenous to oral formulations with consequent earlier patient discharge and lower inpatient costs.

Central role of mitochondria in drug-induced liver injury

A frequent mechanism for drug-induced liver injury (DILI) is the formation of reactive metabolites that trigger hepatitis through direct toxicity or immune reactions. Both events cause mitochondrial membrane disruption. Genetic or acquired factors predispose to metabolite-mediated hepatitis by increasing the formation of the reactive metabolite, decreasing its detoxification, or by the presence of critical human leukocyte antigen molecule(s). In other instances, the parent drug itself triggers mitochondrial membrane disruption or inhibits mitochondrial function through different mechanisms. Drugs can sequester coenzyme A or can inhibit mitochondrial β-oxidation enzymes, the transfer of electrons along the respiratory chain, or adenosine triphosphate (ATP) synthase. Drugs can also destroy mitochondrial DNA, inhibit its replication, decrease mitochondrial transcripts, or hamper mitochondrial protein synthesis. Quite often, a single drug has many different effects on mitochondrial function. A severe impairment of oxidative phosphorylation decreases hepatic ATP, leading to cell dysfunction or necrosis; it can also secondarily inhibit ß-oxidation, thus causing steatosis, and can also inhibit pyruvate catabolism, leading to lactic acidosis. A severe impairment of β-oxidation can cause a fatty liver; further, decreased gluconeogenesis and increased utilization of glucose to compensate for the inability to oxidize fatty acids, together with the mitochondrial toxicity of accumulated free fatty acids and lipid peroxidation products, may impair energy production, possibly leading to coma and death. Susceptibility to parent drug-mediated mitochondrial dysfunction can be increased by factors impairing the removal of the toxic parent compound or by the presence of other medical condition(s) impairing mitochondrial function. New drug molecules should be screened for possible mitochondrial effects.

New tuberculosis drugs on the horizon

Tuberculosis (TB) remains a major global health concern whose control has been exacerbated by HIV and the emergence of multidrug-resistant (MDR-TB) and extensively drug-resistant (XDR-TB) strains of Mycobacterium tuberculosis. The demand for new and faster acting TB drugs is thus greater than ever. In the past decade intensive efforts have been made to discover new leads for TB drug development using both target-based and cell-based approaches. Here, we describe the most promising anti-tubercular drug candidates that are in clinical development and introduce some nitro-aromatic compounds that inhibit a new target, DprE1, an essential enzyme involved in a crucial step in mycobacterial cell wall biosynthesis.

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.

Drug-induced liver injury: a summary of recent advances

INTRODUCTION

The knowledge base of drug-induced liver injury (DILI) continues to grow each year as additional drugs are identified as hepatotoxins. There is still a need to improve our ability to predict and diagnose DILI in the preclinical and post-approval settings.

AREAS COVERED

This article presents the new and updated DILI registries for 2010, including the latest information on the causes and outcomes of non-acetaminophen DILI cases in the US Acute Liver Failure Study Group database. As DILI is still largely a diagnosis of exclusion, it is appropriate that causality assessment instruments are again the subject of considerable discussion.

EXPERT OPINION

DILI research remains extremely active including studies aimed at being better able to identify causative agents, utilize potential biomarkers, predict who is at greatest risk of injury and manage outcomes. With respect to identifying DILI risk factors at the genetic level, the field is rapidly approaching the day where 'personalized medicine' (based on pharmacogenomics) will become a reality. A large single-center series from India reminds us that geography can influence the drugs responsible for liver injury; however, Hy's law remains universal. As our DILI knowledge continues to grow, it remains essential to keep abreast of the important changes reported each year.