Overdose pattern and outcome in paracetamol-induced acute severe hepatotoxicity

Unveiling the molecular basis of paracetamol-induced hepatotoxicity: Interaction of N-acetyl-p-benzoquinone imine with mitochondrial succinate dehydrogenase

Background and aim

N-acetyl-p-benzoquinoneimine (NAPQI), a toxic byproduct of paracetamol (Acetaminophen, APAP), can accumulate and cause liver damage by depleting glutathione and forming protein adducts in the mitochondria. These adducts disrupt the respiratory chain, increasing superoxide production and reducing ATP. The goal of this study was to provide computational proof that succinate dehydrogenase (SDH), a subunit of complex II in the mitochondrial respiratory chain, is a favorable binding partner for NAPQI in this regard.

Method

Molecular docking, molecular dynamics simulation, protein-protein interaction networks (PPI), and KEGG metabolic pathway analysis were employed to identify binding characteristics, interaction partners, and their associations with metabolic pathways. A lipid membrane was added to the experimental apparatus to mimic the natural cellular environment of SDH. This modification made it possible to develop a context for investigating the role and interactions of SDH within a cellular ecosystem that was more realistic and biologically relevant.

Result

The molecular binding affinity score for APAP and NAPQI with SDH was predicted -6.5 and -6.7 kcal/mol, respectively. Furthermore, RMSD, RMSF, and Rog from the molecular dynamics simulations study revealed that NAPQI has slightly higher stability and compactness compared to APAP at 100 ns timeframe with mitochondrial SDH.

Conclusion

This study serves to predict the mechanistic process of paracetamol toxicity by using different computational approaches. In addition, this study will provide information about the drug target against APAP hepatotoxicity.

Barriers and facilitators to reducing paracetamol use in low back pain: A qualitative study

BACKGROUND

Paracetamol is widely used for low back pain (LBP), but research questions its efficacy and safety. Patient education booklets have been explored for promoting deprescribing, but barriers and facilitators specific to LBP deprescribing remain unexamined.

OBJECTIVE

To identify contextual factors facilitating and obstructing successful deprescribing of paracetamol for LBP after receiving an educational booklet.

STUDY DESIGN

This study is part of an uncontrolled cohort feasibility study (CEASE NOW) in the community, recruiting from Musculoskeletal Australia and painaustralia.

PATIENT SAMPLE

Twenty-four participants with acute, sub-acute, or chronic LBP, self-reporting paracetamol consumption, were included.

METHODS

Thematic content analysis was used to analyze qualitative data on barriers and facilitators. Data were categorized by deprescribing outcomes: i) successful deprescribing, ii) attempted but failed, or iii) no attempt. Semi-structured telephone interviews were conducted within one week after each participant completed the one-month follow-up.

RESULTS

Successful deprescribing was facilitated by supportive healthcare professionals, willingness, high self-efficacy, fear of future illness, and diverse strategies for deprescribing plans. Barriers included unsupportive healthcare professionals and fear of flare-ups. Participants not attempting deprescribing believed it unnecessary, perceived it as effortful, unquestioningly trusted healthcare professionals, and lacked risk awareness.

CONCLUSIONS

Support from healthcare professionals, patient willingness, perceived necessity, risk awareness, effort, and varied strategies influence deprescribing outcomes for LBP patients using paracetamol. Addressing these factors is crucial when designing interventions to promote safe and effective deprescribing in LBP management.

Caveolin-1 Alleviates Acetaminophen—Induced Hepatotoxicity in Alcoholic Fatty Liver Disease by Regulating the Ang II/EGFR/ERK Axis

Acetaminophen (APAP) is a widely used antipyretic analgesic which can lead to acute liver failure after overdoses. Chronic alcoholic fatty liver disease (AFLD) appears to enhance the risk and severity of APAP-induced liver injury, and the level of angiotensin II (Ang II) increased sharply at the same time. However, the underlying mechanisms remain unclear. Caveolin-1 (CAV1) has been proven to have a protective effect on AFLD. This study aimed to examine whether CAV1 can protect the APAP-induced hepatotoxicity of AFLD by affecting Ang II or its related targets. In vivo, the AFLD model was established according to the chronic-plus-binge ethanol model. Liver injury and hepatic lipid accumulation level were determined. The levels of Angiotensin converting enzyme 2 (ACE2), Ang II, CAV1, and other relevant proteins were evaluated by western blotting. In vitro, L02 cells were treated with alcohol and oleic acid mixture and APAP. CAV1 and ACE2 expression was downregulated in APAP-treated AFLD mice compared to APAP-treated mice. The overexpression of CAV1 in mice and L02 cells alleviated APAP-induced hepatotoxicity in AFLD and downregulated Ang II, p-EGFR/EGFR and P-ERK/ERK expression. Immunofluorescence experiments revealed interactions between CAV1, Ang II, and EGFR. The application of losartan (an Ang II receptor antagonist) and PD98059 (an ERK1/2 inhibitor) alleviated APAP-induced hepatotoxicity in AFLD. In conclusion, our findings verified that CAV1 alleviates APAP-aggravated hepatotoxicity in AFLD by downregulating the Ang II /EGFR/ERK axis, which could be a novel therapeutic target for its prevention or treatment.

Chemico-Pharmacological Screening of the Methanol Extract of Gynura nepalensis D.C. Deciphered Promising Antioxidant and Hepatoprotective Potentials: Evidenced from in vitro, in vivo, and Computer-Aided Studies

Gynura nepalensis D.C. (family: Asteraceae) has abundant uses in the alternative medicinal practice, and this species is commonly used in the treatment of diabetes, rheumatism, cuts or wounds, asthma, kidney stones, cough, urinary tract bleeding, gall bladder stones, hepatitis, diarrhea, hemorrhoids, constipation, vomiting, fertility problems, blood poisoning, septicemia, skin allergy, indigestion, high cholesterol levels, and so on. This study aims to investigate the hepatoprotective and antioxidant potential of the methanol extract of the Gynura nepalensis D.C. (GNME) along with chemical profiling with phytochemical screening. Moreover, prospective phytocompounds have been screened virtually to present the binding affinity of the bioactive components to the hepatic and oxidative receptors. In the hepatoprotective study, alanine transaminase (ALT), aspartate aminotransferase (AST), alkaline phosphatase (ALP), total protein (TP), and lipid peroxidation (LP) and total bilirubin (TB) have been assessed, and in the antioxidant study, the DPPH free radical scavenging, total antioxidant flavonoid, and phenolic contents were determined. Moreover, the molecular binding affinity of the bioactive component of the plant has been analyzed using PyRx AutoDock Vina, Chimera, and Discovery Studio software. The plant extract showed dose-dependent hepatoprotective potential (p < 0.05, 0.01, 0.001) as well as strong antioxidant properties. Moreover, hepatoprotective and antioxidant molecular docking studies revealed a result varying from −2.90 kcal/mol to −10.1 kcal/mol. 4,5-dicaffeoylquinic acid and chlorogenic acid revealed the highest binding affinity among the selected molecules. However, the plant showed portent antioxidant and hepatoprotective properties in the in vitro, in vivo, and in silico models, and it is presumed that the hepatoprotective properties of the plant extract have occurred due to the presence of the vast bioactive chemical compounds as well as their antioxidant properties. Therefore, advanced studies are recommended to elucidate the pharmacological properties of the plant extracts.

Urgent dental care use in the North East and Cumbria: predicting repeat attendance

Introduction Around one-third of the UK population are 'problem-orientated dental attenders', only seeking care when suffering with dental pain and often on a repeated basis to secondary care. Little is known about attendance in primary care. The aim here was to examine the period prevalence of repeat urgent care attenders and establish predictors of repeat attendance in primary care.

Methods Data on urgent and emergency dental care attendances in primary dental care in the North East and Cumbria were analysed from 2013-2019. Variables included: patient sex; ten-year age band; lower super output area; and Index of Multiple Deprivation. Period prevalence was calculated and data were considered year by year to identify trends in attendances. Analysis was with descriptive statistics and predictors of repeat attendance were identified using logistic regression modelling.

Results Over the six-year period, there were 601,432 attendances for urgent primary dental care, equating to a period prevalence of 2.76% for the geographic population studied. In total, 16.15% of attendances were repeat attendances (period prevalence 0.45%) and predictors included being a woman and residence in deprived and rural areas. All urgent care attendances decreased over the six-year period, with one-off attendances beginning to increase again in 2019, while repeat attendances stabilised.

Conclusion Interventions to encourage regular dental attendances should be targeted at patients from the most deprived and rural areas of the North East and Cumbria; however, a decrease in repeat attendance was noted in these areas.

Predictors of being a repeat attender for urgent and emergency dental care included being a woman and living in the most deprived and rural areas of the North East and Cumbria.

Over a six-year period (2013-2019), the number of one-off urgent and emergency dental care attenders to primary care in the North East and Cumbria decreased before beginning to increase.

Over the same period, the number of repeat urgent and emergency dental care attenders to primary care in the North East and Cumbria decreased before stabilising.

Deprescribing paracetamol in pain conditions: A scoping review

OBJECTIVE

To examine evidence on deprescribing paracetamol in pain conditions and inform future strategies for paracetamol deprescription.

DESIGN

Scoping review.

PARTICIPANTS

Adults with pain conditions, taking paracetamol.

RESULTS

After two independent teams of reviewers screening for titles, abstracts, and then full texts, 16 original articles were included. Deprescribing strategies were grouped into 5 categories: (1) Pharmacological, (2) Psychological, (3) Physiological, (4) Policy, and (5) Combination. We found strategies were predominately consumer-focused, conducted in community settings and involved individuals experiencing musculoskeletal pain (such as low back pain and osteoarthritis). A total of twelve studies investigated interventions targeting dose reduction and four studies examined interventions focusing on discontinuation of paracetamol. The most common strategies used to deprescribe paracetamol in pain conditions were physiological strategies, followed by psychological strategies. All included studies demonstrated some level of effectiveness to deprescribe paracetamol in a pain conditions through dose reduction or discontinuation, although the effectiveness of deprescribing strategies were highly variable, ranging from the majority of participants discontinuing their paracetamol use, to less than 10% reducing their paracetamol use upon the latest follow-up.

CONCLUSIONS

There are clear opportunities for prospective trials to be designed more purposely and primarily focused to influence reduction and cessation of paracetamol for specific pain conditions where deprescription is appropriate.

Acetaminophen Poisoning

Acetaminophen is a common medication taken in deliberate self-poisoning and unintentional overdose. It is the commonest cause of severe acute liver injury in Western countries. The optimal management of most acetaminophen poisonings is usually straightforward. Patients who present early should be offered activated charcoal and those at risk of acute liver injury should receive acetylcysteine. This approach ensures survival in most. The acetaminophen nomogram is used to assess the need for treatment in acute immediate-release overdoses with a known time of ingestion. However, scenarios that require different management pathways include modified-release, large/massive, and repeated supratherapeutic ingestions.

Paracetamol poisoning: a population-based study from Iceland

OBJECTIVE

To examine the incidence and severity of paracetamol poisoning in a population-based cohort in Iceland. A previous study showed a decrease in the incidence during a financial crisis in Iceland, by approximately half (16/100,000 annually). The aims of the study were to assess the incidence and nature of paracetamol poisoning after economic recovery in Iceland and to compare intentional and accidental poisoning.

METHODS

Paracetamol serum concentrations were used to identify patients in this retrospective study from 2010-2017. A search was undertaken in laboratory databases for patients with serum paracetamol concentrations, which were grouped by <66 µmol/L (below detection limit) and ≥66 µmol/L. Medical records were reviewed and relevant laboratory and clinical information obtained to determine whether paracetamol poisoning had occurred.

RESULTS

Altogether 542 cases of paracetamol poisoning were identified. The mean annual incidence was 27/100,000 (range 22-33). Intentional poisoning was observed in 437/542 (81%) cases, most frequently among females 16-25 years of age. Males ≥65 years were more likely to overdose by accident, which was associated with worse outcomes. Twenty-five (4.6%) patients developed severe paracetamol-induced liver injury and coagulopathy. Overall, six (1.1%) cases were fatal in which paracetamol contributed to the cause of death, with accidental poisoning found in 67% (4/6).

CONCLUSIONS

The incidence of paracetamol poisoning has increased in recent years associated with economic recovery in Iceland. Most patients had favourable outcomes. Intentional overdose was most common in young females, whereas accidental overdose was more common in older males and more frequently associated with a fatal outcome.

Acute Liver Injury With Therapeutic Doses of Acetaminophen: A Prospective Study

BACKGROUND AND AIMS

Because of the extensive use of this drug, further evaluation of acute liver injury (ALI) with therapeutic doses of acetaminophen (APAP; ≤6 g/d) is required. We characterize ALI with therapeutic doses of APAP and determine the host factors associated with disease severity and the predictors of outcome.

APPROACH AND RESULTS

All patients admitted with severe APAP-related ALI in our center were included from 2002 to 2019, either attributable to therapeutic doses or overdose. ALI with therapeutic doses (ALITD) was defined as APAP intake <6 g/d. Overall, 311 of 400 patients with APAP-related ALI had overdose and 89 had taken therapeutic doses. The host factors associated with ALITD were fasting ≥1 day (47.5% of ALITD patients vs. 26% in overdose; P = 0.001), excess drinking (93.3% vs. 48.5%; P < 0.0001), and repeated APAP use (4 vs. 1 day; P < 0.0001). Patients with ALITD were older (44 vs. 30.7 years; P < 0.0001) and had more severe liver injury. In the overall population, the independent predictors of disease severity were older age, longer duration of APAP, and excess drinking. Thirty-day survival was lower in ALITD than in overdose (87.2 ± 3.6% vs. 94.6 ± 1.3%; P = 0.02). Age and the presence of at least one of the King's College Hospital criteria were independent predictors of 30-day survival whereas the pattern of drug intoxication, excess drinking, and bilirubin were not.

CONCLUSIONS

ALI with therapeutic doses of APAP is associated with more severe liver injury than overdose. It only occurs in patients with excess drinking and/or fasting. A warning should be issued about the repeated use of nontoxic doses of APAP in patients with those risk factors.

Toxicological Property of Acetaminophen: The Dark Side of a Safe Antipyretic/Analgesic Drug?

Acetaminophen (paracetamol, N-acetyl-p-aminophenol; APAP) is the most popular analgesic/antipyretic agent in the world. APAP has been regarded as a safer drug compared with non-steroidal anti-inflammatory drugs (NSAIDs) particularly in terms of lower risks of renal dysfunction, gastrointestinal injury, and asthma/bronchospasm induction, even in high-risk patients such as the elderly, children, and pregnant women. On the other hand, the recent increasing use of APAP has raised concerns about its toxicity. In this article, we review recent pharmacological and toxicological findings about APAP from basic, clinical, and epidemiological studies, including spontaneous drug adverse events reporting system, especially focusing on drug-induced asthma and pre-and post-natal closure of ductus arteriosus. Hepatotoxicity is the greatest fault of APAP and the most frequent cause of drug-induced acute liver failure in Western countries. However, its precise mechanism remains unclear and no effective cure beyond N-acetylcysteine has been developed. Recent animal and cellular studies have demonstrated that some cellular events, such as c-jun N-terminal kinase (JNK) pathway activation, endoplasmic reticulum (ER) stress, and mitochondrial oxidative stress may play important roles in the development of hepatitis. Herein, the molecular mechanisms of APAP hepatotoxicity are summarized. We also discuss the not-so-familiar "dark side" of APAP as an otherwise safe analgesic/antipyretic drug.

The Late-Stage Protective Effect of Mito-TEMPO against Acetaminophen-Induced Hepatotoxicity in Mouse and Three-Dimensional Cell Culture Models

An overdose of acetaminophen (APAP), the most common cause of acute liver injury, induces oxidative stress that subsequently causes mitochondrial impairment and hepatic necroptosis. N-acetyl-L-cysteine (NAC), the only recognized drug against APAP hepatotoxicity, is less effective the later it is administered. This study evaluated the protective effect of mitochondria-specific Mito-TEMPO (Mito-T) on APAP-induced acute liver injury in C57BL/6J male mice, and a three dimensional (3D)-cell culture model containing the human hepatoblastoma cell line HepG2. The administration of Mito-T (20 mg/kg, i.p.) 1 h after APAP (400 mg/kg, i.p.) injection markedly attenuated the APAP-induced elevated serum transaminase activity and hepatic necrosis. However, Mito-T treatment did not affect key factors in the development of APAP liver injury including the activation of c-jun N-terminal kinases (JNK), and expression of the transcription factor C/EBP homologous protein (CHOP) in the liver. However, Mito-T significantly reduced the APAP-induced increase in the hepatic oxidative stress marker, nitrotyrosine, and DNA fragmentation. Mito-T markedly attenuated cytotoxicity induced by APAP in the HepG2 3D-cell culture model. Moreover, liver regeneration after APAP hepatotoxicity was not affected by Mito-T, demonstrated by no changes in proliferating cell nuclear antigen formation. Therefore, Mito-T was hepatoprotective at the late-stage of APAP overdose in mice.

National Poison Center Calls Before vs After Availability of High-Dose Acetaminophen (Paracetamol) Tablets in Switzerland

IMPORTANCE

Acetaminophen (paracetamol) is among the most widely used pain medications worldwide; while safe within the therapeutic range, intake exceeding 4000 mg/d can lead to hepatotoxicity. Prior evidence suggests that limiting the availability of large quantities of acetaminophen is associated with decreased acetaminophen-related poisonings and mortality; in Switzerland, 500-mg tablets are available over-the-counter (OTC) and, as of October 2003, 1000-mg tablets are available with prescription.

OBJECTIVE

To evaluate the association of adding 1000-mg acetaminophen tablets to the Swiss market with utilization and poisonings.

DESIGN, SETTING, AND PARTICIPANTS

This cross-sectional study used a quasi-experimental interrupted time series analysis to evaluate 15 790 acetaminophen poison records from January 1, 2000, to December 31, 2018. All calls for acetaminophen-related poisonings identified from the National Swiss Poisons Centre and all sales for oral acetaminophen tablets (prescription and OTC) dispensed between January 2000 and December 2018 were included.

EXPOSURE

October 3, 2003 (Q4 2003), was defined as the intervention date, corresponding to the date of market entry for 1000-mg acetaminophen tablets in Switzerland.

MAIN OUTCOMES AND MEASURES

The primary outcome was the number of quarterly acetaminophen-related poison calls to the National Poison Centre. Additional outcomes included quarterly sales for acetaminophen and change in poisoning circumstances, stratified by preintervention and postintervention periods and by formulation (ie, 500-mg and 1000-mg tablets).

RESULTS

Between 2000 and 2018, 15 790 acetaminophen-related poisoning calls were identified, of which 10 628 (67.3%) were regarding women, and the mean (SD) age of patients was 25.2 (18.2) years. The interrupted time series analysis identified a significant increase in the slope for the number of reported poisonings following the intervention point, particularly for accidental circumstances (z score, -3.62; P < .001). In the preintervention period, 120 of 961 poisonings (15.3%) involved a dose greater than 10 000 mg, while for the postintervention period, 1140 of 5696 (30.6%) had a dose larger than 10 000 mg (P < .001). There was a rapid uptake in 1000-mg acetaminophen sales, while sales of the 500-mg tablet decreased slightly. Since 2012, a mean (SD) of 20.7 million (1.4 million) 1000-mg tablets were dispensed quarterly compared with 2.7 million (0.5 million) 500-mg tablets.

CONCLUSIONS AND RELEVANCE

This study found a significant increase in acetaminophen dispensing and acetaminophen-related poisonings in Switzerland following the approval of 1000-mg tablets in 2003. The availability of 1000-mg acetaminophen should be re-evaluated to minimize the potential for accidental poisonings.

Acetaminophen Oxidation and Inflammatory Markers - A Review of Hepatic Molecular Mechanisms and Preclinical Studies

Acetaminophen is a widely used analgesic for pain management, especially useful in chronic diseases, such as rheumatoid arthritis. However, easy access to this medicine has increased the occurrence of episodes of poisoning. Patients often develop severe liver damage, which may quickly lead to death. Consequently, numerous studies have been conducted to identify new biomarkers that allow the prediction of the degree of acetaminophen intoxication and thus intervene in a timely manner to save patients' lives. This review highlights the main mechanisms of the induction and progression of liver damage arising from acetaminophen poisoning. In addition, we have discussed the possibility of using new clinical biomarkers for detecting acetaminophen poisoning.

Acute Liver Failure Secondary to Drug-Induced Liver Injury

Drug-induced liver injury (DILI) is the most common cause of acute liver failure (ALF) in Western countries. Without liver transplantation, the mortality rate for ALF approaches greater than 80%. Acetaminophen-related ALF may be associated with a rapid progression but fortunately has a high chance for spontaneous survival compared with idiosyncratic DILI-related ALF. Several prognostic scoring systems for severe DILI have been developed to aid clinicians in selecting patients who require urgent liver transplantation. Patients who undergo liver transplantation for ALF are at risk for early graft loss and death and should be closely followed.

Silkworm pupa oil attenuates acetaminophen-induced acute liver injury by inhibiting oxidative stress-mediated NF-κB signaling

Acetaminophen (APAP) overdose causes severe hepatotoxicity and acute liver failure. The current study aims to investigate the protection effects of silkworm pupa oil (SPO) against acute hepatic injury in APAP-exposed Kunming mice. Our results showed that the liver index and the levels of serum alanine transaminase (ALT) and aspartate transaminase (AST) in mice subjected to APAP treatment were decreased by SPO. Supplement of SPO also restored hepatic histopathological alterations induced by APAP. The APAP-induced increase in proinflammatory cytokines, including TNF-α, IL-6, and IL-12, was reversed by SPO, which was mediated by the reduction of nuclear factor (NF)-κB p65 expression and the increase in the expression of IκB-α in liver tissue. Moreover, SPO inhibited APAP-triggered oxidative stress by decreasing MDA level and increasing the activities of SOD and GSH-Px. Collectively, SPO attenuated hepatic injury induced by APAP, which attributed to the suppression of oxidative stress-mediated NF-κB signaling. Our findings suggest that SPO supplementation may be potential strategy against acute hepatic injury.

Pathophysiology of Acute Liver Failure

Acute liver failure (ALF) is a rare syndrome resulting from an acute insult to the liver in patients without known underlying chronic liver disease. It is characterized by loss of synthetic function in the form of jaundice and coagulopathy and development of hepatic encephalopathy. Multiorgan failure (MOF) eventually develops, leading to death. Many different etiologies have been identified, with acetaminophen (APAP) overdose and viral hepatitis being the most common causes worldwide. The pathophysiology of ALF can be divided into cause-specific liver injury pathophysiologies and pathophysiology related to occurrence of secondary MOF. In terms of liver injury pathophysiology, APAP toxicity is the most well known. Secondary MOF is often a result of the initial massive proinflammatory response generating a systemic inflammatory response syndrome followed by a compensatory anti-inflammatory response leading to immune cell dysfunction and sepsis. As the liver is a tremendously important metabolic organ involved in energy metabolism, protein synthesis, fat metabolism, and glycemic control, multiple aspects of nutrition also need to be considered as part of the overall pathophysiology of ALF.

Presentations Related to Acute Paracetamol Intoxication in an Urban Emergency Department in Switzerland

Aim

To investigate the characteristics of Emergency Department (ED) presentations due to acute paracetamol intoxication.

Methods

Retrospective observational study of patients presenting to the ED of Bern University Hospital between May 1, 2012, and October 31, 2018, due to a paracetamol overdose (defined as intake of >4 g/24 h). Cases were identified using the full-text search of the electronic patient database and were grouped into intentional (suicidal/parasuicidal) and unintentional intoxications (e.g., patient unaware of maximal daily dose).

Results

During the study period, 181 cases were included and 143 (79%) of those were intentional. Compared to the patients in the unintentional group, patients in the intentional group were more often female (85% vs 45%, p < 0.001) and younger (median age 23.0 vs 43.5 years, p < 0.001), more frequently suffered from psychiatric comorbidities (93%, (including 49% with borderline personality disorder) vs 24%, p < 0.001), and paracetamol was more often taken as a single dose (80% vs 13%, p < 0.001). Although the median daily ingested dose was lower in the unintentional than in the intentional group (8.2 g vs 12.9 g, p < 0.001), patients in the unintentional group presented later (29% vs 84% within 24 h of ingestion, p < 0.001), included more cases of acute liver failure (nine (24%) vs six (4%), p < 0.001), and were more often hospitalised (24% vs 52% treated as outpatients, p=0.002). There were no significant differences between the groups regarding drug-induced liver injury (seven cases (5%) in the intentional and one (3%) in the unintentional group) or fatalities (one in each group).

Conclusions

The majority of presentations due to paracetamol poisoning were intentional, most commonly in female patients with borderline personality disorder. Patients with unintentional paracetamol intoxication had worse outcomes with respect to acute liver failure and hospitalisation. Future preventive measures should raise awareness of paracetamol toxicity in the general population and encourage particular attention and frequent follow-ups when prescribing paracetamol for vulnerable groups.

Evaluation of mRNA expression of drug-metabolizing enzymes in acetaminophen-induced hepatotoxicity using a three-dimensional hepatocyte culture system

1. The expression and activity of drug-metabolizing enzymes are known to affect the pharmacokinetics of drugs metabolized in the liver. Here, we assessed the effect of acetaminophen (APAP)-induced hepatotoxicity on the mRNA expression of drug-metabolizing enzymes and elucidated the underlying mechanism using three-dimensional (3D) cultures of HepG2 cells.2. 3D culture cells enabled us to establish an in vitro model of APAP-induced hepatotoxicity which showed the increase in N-acetyl-p-benzoquinone imine production, reactive oxygen species (ROS) generation and cellular injury.3. In this 3D culture model, APAP treatment significantly increased the mRNA expression of drug-metabolizing enzymes (cytochrome P450 [CYP]3A4, CYP2E1 and UDP-glucuronosyltransferase 1A6) and their nuclear receptors (pregnane X receptor and constitutive androstane receptor) compared with untreated cells. Treatment with N-acetylcysteine, a therapeutic agent for APAP-induced hepatotoxicity, suppressed these increases. In addition, the mRNA expression of drug-metabolizing enzymes and nuclear receptors were elevated depending on the concentration of H₂O₂, one of ROS involved in the development of APAP-induced hepatotoxicity. The mRNA expression of nuclear receptors increased before that of drug-metabolizing enzymes.4. In conclusion, ROS may induce the mRNA expression of nuclear receptors and promote the transcription of drug-metabolizing enzymes in the in vitro model of APAP-induced hepatotoxicity.

Comparison of toxic responses to acetaminophen challenge in ICR mice originating from different sources

Acetaminophen (APAP) is the most common antipyretic analgesic worldwide. However, APAP overdose causes severe liver injury, especially centrilobular necrosis, in humans and experimental animals. At therapeutic dosage, APAP is mainly metabolized by sulfation and glucuronidation, and partly by cytochrome P450-mediated oxidation. However, APAP overdose results in production of excess reactive metabolite, N-acetyl-p-benzoquinone imine (NAPQI), by cytochromes P450; NAPQI overwhelms the level of glutathione (GSH), which could otherwise detoxify it. NAPQI binds covalently to proteins, leading to cell death. A number of studies aimed at the prevention and treatment of APAP-induced toxicity are underway. Rats are more resistant than mice to APAP hepatotoxicity, and thus mouse models are mainly used. In the present study, we compared the toxic responses induced by APAP overdose in the liver of ICR mice obtained from three different sources and evaluated the usability of the Korl:ICR stock established by the National Institute of Food and Drug Safety Evaluation in Korea. Administration of APAP (300 mg/kg) by intraperitoneal injection into male ICR mice enhanced CYP2E1 protein expression and depleted hepatic GSH level 2 h after treatment accompanied with significantly increased level of hepatic malondialdehyde, a product of lipid peroxidation. Regardless of the source of the mice, hepatotoxicity, as evidenced by activity of serum alanine aminotransferase, increased from 8 h and peaked at 24 h after APAP treatment. In summary, hepatotoxicity was induced after the onset of oxidative stress by overdose of APAP, and the response was the same over time among mice of different origins.

Acetaminophen is Undetectable in Plasma From More Than Half of Patients Believed to Have Acute Liver Failure Due to Overdose

BACKGROUND & AIMS

Evaluation of patients with acute liver injury (ALI) or acute liver failure (ALF) often includes measurement of plasma levels of acetaminophen, to determine exposure and/or toxicity. However, once liver injury has developed, acetaminophen might be undetectable in plasma. We investigated the association between level of acetaminophen measured and outcomes of patients designated as having ALF or ALI due to acetaminophen toxicity.

METHODS

We performed a retrospective analysis of data from 434 subjects in the Acute Liver Failure Study Group who met criteria for ALF (coagulopathy and hepatic encephalopathy within 26 weeks of the first symptoms, without pre-existing liver disease) or ALI (severe liver injury with coagulopathy but no encephalopathy) due to acetaminophen toxicity from January 1, 2010 through December 31, 2014. We collected data on patient demographics, biochemical features, reported acetaminophen use, N-acetylcysteine therapy, liver transplant, and outcomes. Descriptive statistics were used to assess patient demographics, clinical characteristics, and outcomes whereas differences in continuous variables between patients with vs without acetaminophen detection on admission were analyzed using the Wilcoxon rank-sum test. The primary aim was to determine the proportion of patients with detectable plasma levels of acetaminophen.

RESULTS

Acetaminophen was undetectable in serum samples from 227 patients (52%). There were no significant differences between groups of patients with detectable vs undetectable levels in demographic features, alcohol use, median levels of alanine aspartate, or use of N-acetylcysteine (given to 94.7% of patients with detectable acetaminophen vs 95.9% of those with undetectable acetaminophen; P=.63). We observed a significant difference in median dose taken between patients with detectable (29,500 mg; interquartile range, 15,000 mg-50,007 mg) vs no detectable parent compound (14,950 mg; interquartile range, 3960 mg-25,000) (P=.003). A lower proportion of patients with detectable plasma levels of acetaminophen (72.3%) survived without a liver transplant than of patients with undetectable levels (86.3%) in univariate analysis (P=.0006), although this was not significant in multivariable analysis (P=.12). Although most patients had unintentional overdoses, a higher proportion of patients with suicidal overdoses (43%) had detectable levels of acetaminophen than patients with accidental overdoses (29.3%; P=.01).

CONCLUSION

More than half of patients who present at the hospital with acetaminophen-induced ALI or ALF have undetectable levels of acetaminophen. Clinicians should not exclude acetaminophen toxicity because of undetectable levels or withhold N-acetylcysteine for patients with ALI or ALF when acetaminophen toxicity is suspected.

Inactivation of Sirtuin2 protects mice from acetaminophen-induced liver injury: possible involvement of ER stress and S6K1 activation

Acetaminophen (APAP) overdose can cause hepatotoxicity by inducing mitochondrial damage and subsequent necrosis in hepatocytes. Sirtuin2 (Sirt2) is an NAD⁺-dependent deacetylase that regulates several biological processes, including hepatic gluconeogenesis, as well as inflammatory pathways. We show that APAP decreases the expression of Sirt2. Moreover, the ablation of Sirt2 attenuates APAP-induced liver injuries, such as oxidative stress and mitochondrial damage in hepatocytes. We found that Sirt2 deficiency alleviates the APAP-mediated endoplasmic reticulum (ER) stress and phosphorylation of the p70 ribosomal S6 kinase 1 (S6K1). Moreover, Sirt2 interacts with and deacetylates S6K1, followed by S6K1 phosphorylation induction. This study elucidates the molecular mechanisms underlying the protective role of Sirt2 inactivation in APAP-induced liver injuries.

Mechanistic identification of biofluid metabolite changes as markers of acetaminophen-induced liver toxicity in rats

Acetaminophen (APAP) is the most commonly used analgesic and antipyretic drug in the world. Yet, it poses a major risk of liver injury when taken in excess of the therapeutic dose. Current clinical markers do not detect the early onset of liver injury associated with excess APAP-information that is vital to reverse injury progression through available therapeutic interventions. Hence, several studies have used transcriptomics, proteomics, and metabolomics technologies, both independently and in combination, in an attempt to discover potential early markers of liver injury. However, the casual relationship between these observations and their relation to the APAP mechanism of liver toxicity are not clearly understood. Here, we used Sprague-Dawley rats orally gavaged with a single dose of 2 g/kg of APAP to collect tissue samples from the liver and kidney for transcriptomic analysis and plasma and urine samples for metabolomic analysis. We developed and used a multi-tissue, metabolism-based modeling approach to integrate these data, characterize the effect of excess APAP levels on liver metabolism, and identify a panel of plasma and urine metabolites that are associated with APAP-induced liver toxicity. Our analyses, which indicated that pathways involved in nucleotide-, lipid-, and amino acid-related metabolism in the liver were most strongly affected within 10 h following APAP treatment, identified a list of potential metabolites in these pathways that could serve as plausible markers of APAP-induced liver injury. Our approach identifies toxicant-induced changes in endogenous metabolism, is applicable to other toxicants based on transcriptomic data, and provides a mechanistic framework for interpreting metabolite alterations.

A prospective study of the incidence of drug-induced liver injury by the modern volatile anaesthetics sevoflurane and desflurane

BACKGROUND

Volatile anaesthetics are known to cause drug-induced liver injury, a hepatotoxic reaction characterised by antibodies to trifluoroacetylated lipid and protein adducts and cytochrome p450 2E1. The incidence of volatile anaesthetic drug-induced liver injury from older agents has been described, but modern agents have not been prospectively studied.

AIM

To determine prospectively the incidence of volatile anaesthetic drug-induced liver injury from sevoflurane and desflurane.

METHODS

Adult surgical patients with a predicted post-operative stay of at least 4 days were recruited. If volatile anaesthetic was administered, liver biochemistry was performed regularly. Medications, observations and other investigations were documented. Patients with abnormal liver biochemistry were classified as likely volatile anaesthetic drug-induced liver injury or not based on clinical assessment, Roussel Uclaf Causality Assessment Method score, and the absence of other likely pathology. Some patients were also tested for antibodies to both trifluoroacetylated lipid and protein adducts, and cytochrome p450 2E1.

RESULTS

A total of 209 patients were recruited, of which 121 were included for analysis. Post-operative liver biochemistry was abnormal in 62 patients (51.2%); further classified as not volatile anaesthetic drug-induced liver injury in 47 cases (38.8%), and likely volatile anaesthetic-drug induced liver injury in 15 cases (12.4%). Of the likely volatile anaesthetic drug-induced liver injury patients, only one had severe disease with alanine transaminase greater than five times the upper limit of normal, while four cases had moderate disease with alanine transaminase greater than three times the upper limit of normal. Thus, the incidence of clinically significant volatile anaesthetic drug-induced liver injury was 4.1%. No risk factors were identified.

CONCLUSIONS

Volatile anaesthetic drug-induced liver injury from modern agents seems to be as common (4.1%) as previously reported with older agents (3%), and may identify patients at risk of severe acute liver injury with subsequent re-exposure.

Availability of drug at convenient stores is not associated with an increased incidence of their poisoning

PURPOSE

In late 2012, South Korea revised the Pharmaceutical Affairs Act to make selected medications including acetaminophen, ibuprofen, and cold medications available in nonpharmacy outlets, including the 24-hour convenient stores (CVS). The objective of this study was to identify whether the characteristics and trend of self-poisonings associated with these medications were altered after the legislative change.

METHODS

A retrospective study was performed using national data from the Emergency Department (ED)-based Injury In-depth Surveillance database. The patients diagnosed with poisoning were sorted from 2011 to 2016 and included in the study. As the Act was implemented from 2013, the demographic characteristics and clinical outcomes were compared before and after January 2013. A piecewise regression analysis was performed to determine the association between the monthly use of acetaminophen, medication for cold, and nonsteroidal anti-inflammatory drugs (NSAIDs) and the incidence of total poisonings before and after the January 2013.

RESULTS

Among 1 536 277 patients included in the database, 17 523 patients diagnosed with poisoning were enrolled. After the legislative change, the etiology of poisoning did not change, although the frequency of hospitalization from ED was significantly increased. The monthly trend for poisoning due to acetaminophen, cold medications, and NSAIDs showed no significant slope change between before and after the legislative change. The proportional use of acetaminophen and cold medications was significantly decreased, while that of NSAIDs was unchanged before and after the legislative change.

CONCLUSIONS

The change in the Pharmaceutical Affairs Act was not associated with any change in the monthly frequency of medication-related poisoning.

Hypersensitivity Reactions in Serious Adverse Events Reported for Paracetamol in the EudraVigilance Database, 2007⁻2018

Paracetamol is a popular and easily available drug which is used world-wide as analgesic, antipyretic agent. Hypersensitivity reactions to this drug involve a wide range of symptoms of various importance for patient management. The EudraVigilance (EV) database serves as a system for monitoring adverse events (AE) due to drug intake. We retrospectively recorded AE reports for "paracetamol" reported from 1 January 2007 to 1 October 2018 which fulfilled the category of "serious" in EV. For further analysis the retrieved AE reports were selected according to the keywords corresponding to hypersensitivity symptoms. We included in the study 4589 AE reports with 9489 particular AEs. 24.2% of all the AE reports concerned children. The most often reported symptoms were "angioedema," "rash" and "urticaria" (each of them with a frequency of >10% in the AE reports). An important group of AEs were oedema reported as being located in the head, neck or respiratory tract. We recorded 58 AE reports with fatal outcomes, including 9 Stevens-Johnson syndrome/toxic epidermal necrolysis cases (SJS/TEN), 10 anaphylactic reactions, 21 cases of hepatic failure and a further 18 cases which occurred for other reasons. SJS/TEN, acute generalized exanthematous pustulosis and drug reaction with eosinophilia and systemic symptoms were reported 129, 42 and 25 times, respectively. Prodromes and symptoms of potentially life-threating SJS/TEN appeared in 286 of the AE reports. 380 AE reports pointed to a diagnosis of anaphylaxis. To improve patient safety, healthcare professionals, including pharmacists, can identify warning signs of severe hypersensitivity reactions to paracetamol.

Protective effects of Cinnamomum zeylanicum L. (Darchini) in acetaminophen-induced oxidative stress, hepatotoxicity and nephrotoxicity in mouse model

Cinnamomum zeylanicum, a widely used spice and flavor, is used in the treatment and prevention of many diseases. In the current study, Balb/c mice were pretreated with cinnamon bark aqueous extract (200 mg/kg/day i.g.) 14 days prior to intragastrically administer single toxic dose of acetaminophen (200 mg/kg). Blood samples were collected for analysis of biochemical and oxidative stress parameters and liver and kidney samples were collected for histopathological analysis. The results indicate that cinnamon aqueous extract exhibit a highly significant preventive potential by ameliorating APAP-induced elevated levels of serum alanine aminotransferase, aspartate aminotransferase, creatinine, urea and macroscopic and histological alterations in liver and kidney. Moreover, significant increase in total oxidant status and decrease in total antioxidant capacity accompanied by APAP exposure, were restored by cinnamon pretreatment. We found that prior administration of cinnamon prevented the toxic changes induced by acetaminophen as confirmed by histopathological examination, more possibly owing to its antioxidant potential. In conclusion, the pretreatment with cinnamon provide potential therapeutic applications in acute liver and kidney injury induced by APAP in experimental animal model and it could have therapeutic potential in oxidative stress associated diseases.

Classification and Epidemiologic Aspects of Acute Liver Failure

Acute liver failure is a rare condition with high short-term morbidity and mortality. The most widely accepted definition is an abnormality in coagulation with any degree of encephalopathy in a patient without cirrhosis and an illness duration of less than 26 weeks. Multiple classifications systems are currently in use to help categorize the condition. This article reviews the most commonly used systems. The epidemiologic aspects of the disease are also reviewed, including incidence, prevalence, demographics, geographic distribution, and racial and cultural factors and are discussed for the various subtypes of acute liver failure.

Acetaminophen (APAP or N-Acetyl-p-Aminophenol) and Acute Liver Failure

Acetaminophen (APAP) is the leading cause of acute liver failure (ALF), although the worldwide frequency is variable. APAP hepatotoxicity develops either following intentional overdose or unintentional ingestion (therapeutic misadventure) in the background of several factors, such as concomitant use of alcohol and certain medications that facilitate the formation of reactive and toxic metabolites. Spontaneous survival is more common in APAP-induced ALF compared with non-APAP etiologies. N-acetylcysteine is recommended for all patients with APAP-induced ALF and it reduces mortality. Liver transplantation should be offered early to those who are unlikely to survive based on described prognostic criteria.

Ethyl pyruvate attenuates acetaminophen-induced liver injury and prevents cellular injury induced by N-acetyl-p-benzoquinone imine

Acetaminophen, a common analgesic/antipyretic, is a frequent cause of acute liver failure in Western countries. The development of an effective cure against acetaminophen hepatotoxicity is crucial. Ethyl pyruvate, an ethyl ester derivative of pyruvic acid, has been identified as a possible candidate against acetaminophen hepatotoxicity in animal experiments. However, the mode of the hepatoprotective action of ethyl pyruvate remains unclear. We examined the hepatoprotective effect of ethyl pyruvate against hepatocyte injury and oxidative stress in a mouse model of acetaminophen hepatotoxicity. In addition, to examine whether ethyl pyruvate has direct hepatocellular protection against acetaminophen hepatotoxicity to counteract the influence of inflammatory cells, such as macrophages, we examined the effects of ethyl pyruvate on cellular injury induced by N-acetyl-p-benzoquinone imine, a toxic metabolite of acetaminophen, in a human hepatocyte cell line, HepG2 cells. Treatment with ethyl pyruvate significantly prevented increases in serum transaminase levels and hepatic centrilobular necrosis induced with an acetaminophen overdose in mice in a dose-dependent manner. Although hepatic DNA fragmentation induced by acetaminophen was also attenuated with ethyl pyruvate, nitrotyrosine formation was not inhibited. Ehyl pyruvate significantly attenuated mitochondria dehydrogenase inactivity induced by N-acetyl-p-benzoquinone imine in HepG2 cells. The attenuating effect was also observed in a rat hepatocyte cell line. Increases in annexin V and propidium iodide-stained cells induced by N-acetyl-p-benzoquinone imine were prevented with ethyl pyruvate in HepG2 cells. Pyruvic acid, a parent compound of ethyl pyruvate, tended to attenuate these changes. The results indicate that ethyl pyruvate has direct hepatocellular protection against N-acetyl-p-benzoquinone imine induced injury observed in acetaminophen overdose. The in vivo and in vitro results suggest that ethyl pyruvate attenuates acetaminophen-induced liver injury via, at least in part, its cellular protective potential.

Midostaurin: A Multiple Tyrosine Kinases Inhibitor in Acute Myeloid Leukemia and Systemic Mastocytosis

Midostaurin (PKC412, Rydapt^®) is an oral multiple tyrosine kinase inhibitor. Main targets are the kinase domain receptor, vascular endothelial-, platelet derived-, and fibroblast growth factor receptor, stem cell factor receptor c-KIT, as well as mutated and wild-type FLT3 kinases. Midostaurin was approved by the Food and Drug Administration (FDA) and the European Medical Agency (EMA) for acute myeloid leukemia with activating FLT3 mutations in combination with intensive induction and consolidation therapy as well as aggressive systemic mastocytosis (ASM), systemic mastocytosis with associated hematological neoplasm (SM-AHN) or mast cell leukemia (MCL). Several clinical trials are active or are planned to further investigate the role of midostaurin in myeloid malignancies and mastocytosis.

Acetaminophen (APAP) hepatotoxicity-Isn't it time for APAP to go away?

Acetaminophen (APAP) is the most commonly used drug for the treatment of pain and fever around the world. At the same time, APAP can cause dose-related hepatocellular necrosis, responsible for nearly 500 deaths annually in the United States (US) alone, as well as 100,000 calls to US Poison Control Centers, 50,000 emergency room visits and 10,000 hospitalisations per year. As an over-the-counter and prescription product (with opioids), APAP toxicity dwarfs all other prescription drugs as a cause of acute liver failure in the US and Europe, but it is not regulated in any significant way. In this review the ongoing controversy surrounding the proper role for this ubiquitous pain reliever: its history, pathogenesis, clinical challenges in recognition and management, and current regulatory status are highlighted. A new solution to a 50-year-old problem is proposed.

Midostaurin treatment in FLT3-mutated acute myeloid leukemia and systemic mastocytosis

INTRODUCTION

A number of tyrosine kinase inhibitors (TKIs) have been developed that inhibit the constitutively activated kinase activity caused by activating tyrosine kinase mutations, such as FLT3 or KIT, thus interrupting signaling pathways. Currently, midostaurin is the only approved TKI as monotherapy for aggressive systemic mastocytosis (SM), SM with associated hematological neoplasm, or mast cell leukemia displaying a KIT mutation as well as in combination with standard intensive chemotherapy for adult patients with newly diagnosed FLT3-mutated acute myeloid leukemia (AML). Areas covered: We provide a concise review of the pharmacology, tolerability and clinical efficacy of midostaurin and emerging new treatment options for ASM and FLT3-mutated AML. Expert commentary: Currently, midostaurin is the only approved TKI in aggressive SM, SM with associated hematological neoplasm, or mast cell leukemia inducing responses including complete remissions. With regard to AML, midostaurin is the first drug to receive regulatory approval in this indication in the molecularly defined subgroup of AML with FLT3 mutations. By introduction of this new standard in AML with FLT3 mutations, the bare has been raised for future approvals of next generation FLT3 inhibitors which will be based increasingly on head to head comparisons with midostaurin.

Student-selected component in the medical curriculum: investigations and psychiatric referral for paracetamol overdose in an accident and emergency department

BACKGROUND

A student-selected component (SSC) of the medical curriculum requires the student to be self-directed in locating and undertaking a placement in a clinical specialty of their choosing and completing a project. The clinical area for experience was an accident and emergency department, and our topic was a focused audit on the investigations and referral for paracetamol overdose. The purpose of this paper is twofold: to reflect on the education value to medical students of an SSC in a medical curriculum, and to highlight learning and understanding through completion of an audit.

MATERIALS AND METHODS

An audit approach was applied. The aim of the project study was to investigate the level of compliance with best-practice guidelines for investigations and psychiatric referral in paracetamol overdose.

RESULTS

A total of 40 cases meeting the inclusion criteria were randomly selected. The sample had a mean age of 27 years, of whom 70.5% were female, and the ingested dose of paracetamol ranged from 0.864 to 80 g. Paracetamol abuse may present as intentional and unintentional overdose. In our study, 85% of cases were identified as intentional overdose and 76% had a history of psychiatric illness. Generally, medical management was compliant with guidelines, with some minor irregularities. The international normalized ratio was the most underperformed test.

CONCLUSION

Our choice of topic, paracetamol overdose, contributed to our understanding of the breadth of factors to be considered in the emergency medical management of a patient. In this regard, we had the benefit of understanding how the diagnostic and therapeutic factors, when applied in accordance with best-practice guidelines, work very effectively. The SSC impacted positively on our cognitive, personal, and professional development. In facilitating the student with choice, the SSC encouraged self-direction and proactivity. We gained experience in the discipline of research and acquired some skills in independent thinking and analysis.

EASL Clinical Practical Guidelines on the management of acute (fulminant) liver failure

The term acute liver failure (ALF) is frequently applied as a generic expression to describe patients presenting with or developing an acute episode of liver dysfunction. In the context of hepatological practice, however, ALF refers to a highly specific and rare syndrome, characterised by an acute abnormality of liver blood tests in an individual without underlying chronic liver disease. The disease process is associated with development of a coagulopathy of liver aetiology, and clinically apparent altered level of consciousness due to hepatic encephalopathy. Several important measures are immediately necessary when the patient presents for medical attention. These, as well as additional clinical procedures will be the subject of these clinical practice guidelines.

Acute liver failure in Scotland: changes in aetiology and outcomes over time (the Scottish Look-Back Study)

BACKGROUND

Acute liver failure is a rare and devastating clinical condition resulting from sudden loss of hepatic parenchyma and metabolic function. The Scottish Liver Transplant Unit (SLTU) offers specialist management and emergency liver transplantation to patients with acute liver failure from across Scotland.

AIM

To describe temporal changes in number of admissions, aetiology of acute liver failure, severity of disease at presentation and outcomes over a 22-year period.

METHODS

Retrospective analysis of the SLTU database, including all patients admitted with acute liver injury or acute liver failure between November 1992 and March 2014.

RESULTS

There has been no change in the number of patients presenting with acute liver injury or failure secondary to paracetamol overdose, but a reduction in the number of admissions with acute liver injury or failure secondary to non paracetamol causes. Over time, disease severity at presentation has not changed in the paracetamol cohort; those with a non paracetamol aetiology have latterly presented with milder hepatic encephalopathy. Spontaneous survival rates improved significantly over time for those patients with acute liver failure due to paracetamol and non paracetamol aetiologies. The most marked improvement in survival is observed in the sickest patients meeting Kings College Hospital poor prognostic criteria.

CONCLUSIONS

The number of admissions to the SLTU with acute liver failure is decreasing, due to reduced numbers of non paracetamol cases. Outcomes in this condition are improving, due to improvements in intensive care management and use of liver transplantation, and the increase in survival is most marked in patients meeting Kings College Hospital poor prognostic criteria.

Acetylcholinesterase Inhibitors for Alzheimer's Disease Treatment Ameliorate Acetaminophen-Induced Liver Injury in Mice via Central Cholinergic System Regulation

Acetaminophen (APAP) is widely used as an analgesic and antipyretic agent, but it may induce acute liver injury at high doses. Alzheimer's disease patients, while treated with acetylcholinesterase inhibitor (AChEI), may take APAP when they suffer from cold or pain. It is generally recognized that inhibiting acetylcholinesterase activity may also result in liver injury. To clarify whether AChEI could deteriorate or attenuate APAP hepatotoxicity, the effects of AChEI on APAP hepatotoxicity were investigated. Male C57BL/6J mice were administrated with the muscarinic acetylcholine receptor (mAChR) blocker atropine (Atr), or classic α7 nicotine acetylcholine receptor (α7nAChR) antagonist methyllycaconitine (MLA) 1 hour before administration of AChEIs-donepezil (4 mg/kg), rivastigmine (2 mg/kg), huperzine A (0.2 mg/kg), or neostigmine (0.15 mg/kg)-followed by APAP (300 mg/kg). Eight hours later, the mice were euthanized for histopathologic examination and biochemical assay. The results demonstrated that the tested AChEIs, excluding neostigmine, could attenuate APAP-induced liver injury, accompanied by reduced reactive oxygen species formation, adenosine triphosphate and cytochrome C loss, c-Jun N-terminal kinase 2 (JNK2) phosphorylation, and cytokines. However, Atr or MLA significantly weakened the protective effect of AChEI by affecting mitochondrial function or JNK2 phosphorylation and inflammation response. These results suggest that central mAChR and α7nAChR, which are activated by accumulated acetylcholine resulting from AChEI, were responsible for the protective effect of AChEIs on APAP-induced liver injury. This indicates that Alzheimer's patients treated with AChEI could take APAP, as AChEI is unlikely to deteriorate the hepatotoxicity of APAP.

Development and validation of a dynamic outcome prediction model for paracetamol-induced acute liver failure: a cohort study

BACKGROUND

Early, accurate prediction of survival is central to management of patients with paracetamol-induced acute liver failure to identify those needing emergency liver transplantation. Current prognostic tools are confounded by recent improvements in outcome independent of emergency liver transplantation, and constrained by static binary outcome prediction. We aimed to develop a simple prognostic tool to reflect current outcomes and generate a dynamic updated estimation of risk of death.

METHODS

Patients with paracetamol-induced acute liver failure managed at intensive care units in the UK (London, Birmingham, and Edinburgh) and Denmark (Copenhagen) were studied. We developed prognostic models, excluding patients who underwent transplantation, using Cox proportional hazards in a derivation dataset, and tested in initial and recent external validation datasets. Mortality was estimated in patients who had emergency liver transplantation. Model discrimination was assessed using area under receiver operating characteristic curve (AUROC) and calibration by root mean square error (RMSE). Admission (day 1) variables of age, Glasgow coma scale, arterial pH and lactate, creatinine, international normalised ratio (INR), and cardiovascular failure were used to derive an initial predictive model, with a second (day 2) model including additional changes in INR and lactate.

FINDINGS

We developed and validated new high-performance statistical models to support decision making in patients with paracetamol-induced acute liver failure. Applied to the derivation dataset (n=350), the AUROC for 30-day survival was 0·92 (95% CI 0·88-0·96) using the day 1 model and 0·93 (0·88-0·97) using the day 2 model. In the initial validation dataset (n=150), the AUROC for 30-day survival was 0·89 (0·84-0·95) using the day 1 model and 0·90 (0·85-0·95) using the day 2 model. Assessment of calibration using RMSE in prediction of 30-day survival gave values of 0·1642 for the day 1 model and 0·0626 for the day 2 model. In the external validation dataset (n=412), the AUROC for 30-day survival was 0·91 (0·87-0·94) using the day 1 model and 0·91 (0·88-0·95) using the day 2 model, and assessment of calibration using RMSE gave values of 0·079 for the day 1 model and 0·107 for the day 2 model. Applied to patients who underwent emergency liver transplantation (n=116), median predicted 30-day survival was 51% (95% CI 33-85).

INTERPRETATION

The models developed here show very good discrimination and calibration, confirmed in independent datasets, and suggest that many patients undergoing transplantation based on existing criteria might have survived with medical management alone. The role and indications for emergency liver transplantation in paracetamol-induced acute liver failure require re-evaluation.

FUNDING

Foundation for Liver Research.

Identifying adults at risk of paracetamol toxicity in the acute dental setting: development of a clinical algorithm

Paracetamol is widely used and effective for the management of dental pain in the UK. Acute dental pain is a recognised precipitant of unintentional paracetamol overdose and in a small but significant number of cases this results in hepatotoxicity. Patients' understanding of the risks of excess paracetamol ingestion remains poor and risk of over-medication before presentation is increased due to a variety of factors including dental anxiety and fragmented provision of dental emergency services. Early recognition of overdose is crucial to preventing significant hepatotoxicity and death. Dentists have a role to play in recognising unintentional overdose cases and directing patients timeously to appropriate medical care. Guidelines on the treatment of paracetamol toxicity are readily available but our data suggests some dental settings may present a weak link in the care pathway and overdose may not be readily recognised. We have developed an algorithm and training package targeted at dentists in the acute dental setting with the aim of improving recognition of paracetamol toxicity in adults and directing onward referral appropriately. This paper also revises the key pharmacokinetics and pharmacodynamics of paracetamol and is intended to raise awareness of issues of toxicity for dentists.

N-Acetyl cysteine does not prevent liver toxicity from chronic low-dose plus subacute high-dose paracetamol exposure in young or old mice

Paracetamol is an analgesic commonly used by people of all ages, which is well documented to cause severe hepatotoxicity with acute overexposures. The risk of hepatotoxicity from nonacute paracetamol exposures is less extensively studied, and this is the exposure most common in older adults. Evidence on the effectiveness of N-acetyl cysteine (NAC) for nonacute paracetamol exposures, in any age group, is lacking. This study aimed to examine the effect of long-term exposure to therapeutic doses of paracetamol and subacute paracetamol overexposure, in young and old mice, and to investigate whether NAC was effective at preventing paracetamol hepatotoxicity induced by these exposures. Young and old male C57BL/6 mice were fed a paracetamol-containing (1.33 g/kg food) or control diet for 6 weeks. Mice were then dosed orally eight times over 3 days with additional paracetamol (250 mg/kg) or saline, followed by either one or two doses of oral NAC (1200 mg/kg) or saline. Chronic low-dose paracetamol exposure did not cause hepatotoxicity in young or old mice, measured by serum alanine aminotransferase (ALT) elevation, and confirmed by histology and a DNA fragmentation assay. Subacute paracetamol exposure caused significant hepatotoxicity in young and old mice, measured by biochemistry (ALT) and histology. Neither a single nor double dose of NAC protected against this toxicity from subacute paracetamol in young or old mice. This finding has important clinical implications for treating toxicity due to different paracetamol exposure types in patients of all ages, and implies a need to develop new treatments for subacute paracetamol toxicity.

Role of endoplasmic reticulum stress in drug-induced toxicity

Drug‐induced toxicity is a key issue for public health because some side effects can be severe and life‐threatening. These adverse effects can also be a major concern for the pharmaceutical companies since significant toxicity can lead to the interruption of clinical trials, or the withdrawal of the incriminated drugs from the market. Recent studies suggested that endoplasmic reticulum (ER) stress could be an important event involved in drug liability, in addition to other key mechanisms such as mitochondrial dysfunction and oxidative stress. Indeed, drug‐induced ER stress could lead to several deleterious effects within cells and tissues including accumulation of lipids, cell death, cytolysis, and inflammation. After recalling important information regarding drug‐induced adverse reactions and ER stress in diverse pathophysiological situations, this review summarizes the main data pertaining to drug‐induced ER stress and its potential involvement in different adverse effects. Drugs presented in this review are for instance acetaminophen (APAP), arsenic trioxide and other anticancer drugs, diclofenac, and different antiretroviral compounds. We also included data on tunicamycin (an antibiotic not used in human medicine because of its toxicity) and thapsigargin (a toxic compound of the Mediterranean plant Thapsia garganica) since both molecules are commonly used as prototypical toxins to induce ER stress in cellular and animal models.

Acute Liver Failure Due to Acetaminophen Poisoning in Patients With Prior Weight Loss Surgery: A Case Series

GOALS

To identify an association between prior weight loss surgery (WLS) and acetaminophen-induced acute liver failure (ALF).

BACKGROUND

WLS, which has increased in proportion to the global rise of obesity, alters the absorption and metabolism of many drugs including acetaminophen (APAP) and may predispose to toxicity. No study has identified an association between prior WLS and APAP-ALF.

STUDY

We retrospectively reviewed a cohort of patients who presented to our center with ALF. We identified 101 patients who presented to our center with ALF between January 2009 and December 2011. All patients were prospectively enrolled into a database using consensus criteria. A history of WLS was obtained through a retrospective chart review.

RESULTS

Fifty-four patients (53.5%) had APAP-ALF and 47 (46.5%) had ALF caused by other etiologies. A prior history of WLS was present in 9 of the 54 patients with APAP-ALF versus 0 of the 47 with non-APAP-ALF (P=0.003). Patients with APAP-ALF and prior WLS did not have higher rates of factors commonly associated with APAP overdose, including depression, alcohol abuse, intent to cause self-harm, or use of APAP-narcotic combination drugs.

CONCLUSIONS

A history of WLS may predispose to hepatotoxicity and ALF caused by acetaminophen.

Acute liver failure

Acute liver failure (ALF) is a rare critical illness with high mortality whose successful management requires early recognition and effective initial management. Though it may result from a wide variety of causes, in the UK and much of the developed world most cases result from paracetamol-induced hepatotoxicity, and administration of antidotal N-acetyl cysteine at first recognition is key. Involvement of local critical care services should occur at an early stage for stabilisation, monitoring and supportive care with parallel discussion with specialist liver centres to identify those patients who may benefit from transfer. Prognostic criteria are applied to identify patients for emergency liver transplantation, and candidates for surgery are prioritised on waitlisting schemes. Outcomes now approach that of elective surgery. However, the majority of cases, and particularly those with paracetamol-induced disease, recover with supportive medical care alone. Overall outcomes for patients with ALF have improved dramatically over the last three decades, but mortality remains unacceptable and further advances in care are required.

Prenatal acetaminophen induces liver toxicity in dams, reduces fetal liver stem cells, and increases airway inflammation in adult offspring

BACKGROUND & AIMS

During pregnancy, acetaminophen is one of the very few medications recommended by physicians to treat fever or pain. Recent insights from epidemiological studies suggest an association between prenatal acetaminophen medication and an increased risk for development of asthma in children later in life. The underlying pathogenesis of such association is still unknown.

METHODS

We aimed to develop a mouse model to provide insights into the effect of prenatal acetaminophen on maternal, fetal and adult offspring's health. The toxic effect of acetaminophen was studied in mice on 1) maternal liver; mirrored by biomarkers of liver injury, centrilobular necrosis, and infiltration of granulocytes; 2) fetal liver; reflected by the frequency of hematopoietic stem cells, and 3) postnatal health; evaluated by the severity of allergic airway inflammation among offspring.

RESULTS

We observed an increased susceptibility towards acetaminophen-induced liver damage in pregnant mice compared to virgins. Moreover, hematopoietic stem cell frequency in fetal liver declined in response to acetaminophen. Furthermore, a greater severity of airway inflammation was observed in offspring of dams upon prenatal acetaminophen treatment, identified lung infiltration by leukocytes and eosinophil infiltration into the airways.

CONCLUSION

Our newly developed mouse model on prenatal use of acetaminophen reflects findings from epidemiological studies in humans. The availability of this model will allow improvement in our understanding of how acetaminophen-related hepatotoxicity is operational in pregnant individuals and how an increased risk for allergic diseases in response to prenatal acetaminophen is mediated. Such insights, once available, may change the recommendations for prenatal acetaminophen use.