Does the patient history predict hepatotoxicity after acute paracetamol overdose?

The abrogated role of premedication in the prevention of transfusion-associated adverse reactions in outpatients receiving leukocyte-reduced blood components

BACKGROUND AND OBJECTIVES

Although it remains controversial, premedication before transfusion is a common clinical practice to prevent transfusion-associated adverse reactions (TAARs) in Taiwan. Thus, we aimed to investigate whether premedication prevented outpatients from developing TAARs and whether an educational programme could improve the understanding of physicians related to the unnecessary use of premedication, and this could elicit changes in their prescribing activities without affecting the occurrence of TAARs.

MATERIALS AND METHODS

Clinical data from outpatients receiving transfusion therapy, including predisposing diseases, histories of transfusion and TAARs, premedication and the occurrence of TAARs in the period April 2017 to October 2018, were retrospectively obtained. The evidence-based transfusion programme implemented to educate physicians was started in January 2018.

RESULTS

A total of 5018 blood units were transfused to 803 outpatients, with 2493 transfusion events reported in the study interval. The most frequently transfused component was leukocyte-reduced packed red cells (n = 4338), followed by leukocyte-reduced apheresis platelets (n = 540) and other blood components. The overall premedication rate significantly decreased from 92.4% to 76.7% after the educational programme (p < 0.001). There was no remarkable change in the occurrence of TAARs per patient event between the periods before and after the educational programme (1.11% vs. 1.14%, p = 0.964). Besides, it was shown that the occurrence of TAARs was associated with the history of TAARs and inversely related to multiple transfusions, but not premedication.

CONCLUSION

Decreased premedication was not associated with increased incidence of TAARs in outpatients; these findings provide important evidence to support the need to revise clinical practices in the era of leukocyte-reduced blood products.

Evaluation of cut-off values in acute paracetamol overdose following the United Kingdom guidelines

Background

The United Kingdom guideline for acute paracetamol overdose has recommended the use of ‘100-treatment line’. Emergency medical centers in some developing countries lack the resources for timely reporting of paracetamol concentrations, hence treatment depends on reported dose. This study aimed to examine whether using an reported dose is safe to predict concentration above the 100-line.

Methods

Data were retrieved from two emergency medical centers retrospectively, between 2010 and 2017. The inclusion criteria were single acute paracetamol overdose, presentation within 15 h, and age ≥ 14 years. Multiple linear regression was performed to determine the effect of ingested dose on paracetamol concentration. Subgroups were created based on ingested dose, rate of concentration above 100-line were investigated.

Results

One hundred and seventy-two patients were enrolled in the primary analysis; median dose was 133.3 mg/kg and 46 (37.8%) had concentration above 100-line in the first test. Only dose per weight was moderately correlated with the first concentration (R² = 0.410, p < 0.001). In the ≤200 mg/kg ingestion group, 18 patients showed concentration above 100-line and 8 showed acute liver injury. The cut-off value of 150 mg/kg showed 82.6% sensitivity and 73.8% specificity to predict concentration above 100-line.

Conclusion

Where paracetamol concentration is not available and activated charcoal is readily used, following United Kingdom guideline, it is safe to use an ingested dose of > 150 mg/kg as the cut-off value for N-acetylcysteine treatment with risk stratification for hepatotoxicity if the patient is ≥14 years and visit the ED within 15 h after an acute paracetamol overdose.

Supplementary Information

The online version contains supplementary material available at 10.1186/s40360-021-00547-1.

Survey on Tunisian Dentists' Anti-Inflammatory Drugs' Prescription in Dental Practice

Dentists prescribe several types of drugs such as anti-inflammatory medicines in their practice in order to manage pain. An adequate knowledge of anti-inflammatory drugs' characteristics is mandatory for a reasonable prescription to ensure patients safety. The study aimed to describe dentists' anti-inflammatory drugs prescription in dental practice. Materials and Methods. This study was conducted on independent practice dentists working in the region of Tunis. A questionnaire was made on “Google forms” and sent to all of them via personal emails. The questionnaire included demographic data and 13 questions about anti-inflammatory medicines: indications and contraindications, the side effects, and their prescription in dental practice. Data analysis was performed on SPSS software version 20.0 (trial version), using the χ2 test for statistical analysis. Results. Two hundred dentists participated to the survey. The female gender was predominant (70%). More than half of the responders were recently graduated and working in their own dental offices. The present study showed that 60% of dentists rarely prescribe anti-inflammatory drugs. Ibuprofen was prescribed by 82% of the dentists. Next came dexamethasone acetate (68.2%). The most frequent indication was postoperative pain (65%). Gastric problem was found to be the most mentioned adverse effect (69%). Thus, 72% of the dentists prescribed proton pump inhibitors with AI. Conclusion. According to this study, dentists have a lack of knowledge and awareness about some contraindications, side effects, and drugs interactions. Thus, knowledge updating, practices assessment, and continuous education are always required to avoid drug iatrogenesis.

Daytime versus Night Time Intentional Drug Overdose: The Outcome is Different

Introduction

In drug overdose, it is generally perceived that the dosage can predict the clinical outcome. Are the dosages of intentional drug overdosing the same between day and night? If so, are these overdoses followed by similar clinical outcomes? Answers to these two questions might affect resource allocation and clinical judgment. The present study was performed to establish whether daytime patients and night time patients report similar drug doses, and see which group of patients would have a higher incidence of severe outcomes.

Method

A retrospective observational study on intentional drug overdose was performed. The reported numbers of total tablets ingested and the incidences of major outcomes, in terms of death and intensive care unit admissions, were compared between daytime and night time.

Results

A total of 400 patients were included. The reported number of ingested tablets in daytime had no statistical difference with that at night time. The numbers of severe outcomes had no differences between the patients presenting to the emergency department at daytime or night time. Yet overdosing at night time was more likely associated with severe outcomes.

Conclusions

We advise a higher index of suspicion at the emergency department on the reliability of the dosages reported by patients who overdose during night time. The larger number of severe outcomes may also be related to more toxic drug exposures in the night time. More resources in the community could be allocated to self-harm prevention at night time.

Outcomes from massive paracetamol overdose: a retrospective observational study

LINKED ARTICLE

This article is commented on by Bateman DN and Dear JW. Should we treat very large paracetamol overdose differently? Br J Clin Pharmacol 2017; 83: 1163-5. https://doi.org/10.1111/bcp.13279 AIMS: Treatment of paracetamol (acetaminophen) overdose with acetylcysteine is standardized, with dose determined only by patient weight. The validity of this approach for massive overdoses has been questioned. We systematically compared outcomes in massive and non-massive overdoses, to guide whether alternative treatment strategies should be considered, and whether the ratio between measured timed paracetamol concentrations (APAP_pl ) and treatment nomogram thresholds at those time points (APAP_t ) provides a useful assessment tool.

METHODS

This is a retrospective observational study of all patients (n = 545) between 2005 and 2013 admitted to a tertiary care toxicology service with acute non-staggered paracetamol overdose. Massive overdoses were defined as extrapolated 4-h plasma paracetamol concentrations >250 mg l^-1 , or reported ingestions ≥30 g. Outcomes (liver injury, coagulopathy and kidney injury) were assessed in relation to reported dose and APAP_pl :APAP_t ratio (based on a treatment line through 100 mg l^-1 at 4 h), and time to acetylcysteine.

RESULTS

Ingestions of ≥30 g paracetamol correlated with higher peak serum aminotransferase (r = 0.212, P < 0.0001) and creatinine (r = 0.138, P = 0.002) concentrations. Acute liver injury, hepatotoxicity and coagulopathy were more frequent with APAP_pl :APAP_t  ≥ 3 with odds ratios (OR) and 95% confidence intervals (CI) of 9.19 (5.04-16.68), 35.95 (8.80-158.1) and 8.34 (4.43-15.84), respectively (P < 0.0001). Heightened risk persisted in patients receiving acetylcysteine within 8 h of overdose.

CONCLUSION

Patients presenting following massive paracetamol overdose are at higher risk of organ injury, even when acetylcysteine is administered early. Enhanced therapeutic strategies should be considered in those who have an APAP_pl :APAP_t  ≥ 3. Novel biomarkers of incipient liver injury and abbreviated acetylcysteine regimens require validation in this patient cohort.

Hepatitis E virus in patients with acute severe liver injury

AIM: To examine the incidence of hepatitis E (HepE) in individuals with acute liver injury severe enough to warrant treatment at a transplant unit.

METHODS: Hepatitis E virus (HEV) is an emerging pathogen in developed countries causing severe illness, particularly in immunocompromised patients or those with underlying chronic liver disease. HepE infection is often under diagnosed, as clinicians can be reluctant to test patients who have not travelled to regions traditionally considered hyperendemic for HepE. There are few data regarding the significance of HEV in patients with very severe acute liver injury in developed countries. Eighty patients with acute severe liver injury attending the Scottish Liver Transplant unit were tested for HEV and anti-HEV IgG and IgM. Severe acute liver injury was defined as a sudden deterioration in liver function confirmed by abnormal liver function tests and coagulopathy or presence of hepatic encephalopathy. Eighty percent of these patients were diagnosed with paracetomol overdose. No patients had a history of chronic or decompensated chronic liver disease at time of sampling. IgG positive samples were quantified against the World Health Organization anti-HEV IgG standard. Samples were screened for HEV viral RNA by quantitative reverse transcription polymerase chain reaction.

RESULTS: Four cases of hepatitis E were identified. Three of the four cases were only diagnosed on retrospective testing and were initially erroneously ascribed to drug-induced liver injury and decompensated chronic liver disease, with the cause of the decompensation uncertain. One case was caused by HEV genotype 1 in a traveller returning from Asia, the other three were autochthonous and diagnosed on retrospective testing. In two of these cases (where RNA was detected) HEV was found to be genotype 3, the most prevalent genotype in developed countries. Three patients survived, two of whom had been misdiagnosed as having drug induced liver injury. The fourth patient died from sepsis and liver failure precipitated as a result of hepatitis E infection and previously undiagnosed cirrhosis. Histopathology data to date is limited to mainly that seen for endemic HepE. All patients, with the exception of patient 1, demonstrated characteristics of HepE infection, as seen in previously described locally acquired cases.

CONCLUSION: In patients with acute severe liver injury, HEV testing should be part of the initial diagnostic investigation algorithm irrespective of suspected initial diagnosis, age or travel history.

Treating acetaminophen overdose: thresholds, costs and uncertainties

The United Kingdom's Medicines and Healthcare Products Regulatory Agency (MHRA) modified the indications for N-acetylcysteine therapy of acetaminophen (paracetamol) overdose in September 2012. The new treatment threshold line was lowered to 100 mg/L (662 μmol/L) for a 4 hours acetaminophen concentration from the previous 200 mg/L (1325 μmol/L). This decision has the potential to substantially increase overall costs associated with acetaminophen overdose with unclear benefits from a marginal increase in patients protected from hepatotoxicity, fulminant hepatic failure, death, or transplant. Changing the treatment threshold for acetaminophen overdose also implies that ingestion amounts previously thought not to require acetaminophen concentration measurements would need to be revised. As a result, more individuals will be sent to hospitals in order that everyone with a predicted 4 hours concentration above the 100 mg/L line will have concentrations measured and potentially be treated with N-acetylcysteine. Before others consider adopting this new treatment guideline, formal cost-effectiveness analyses need to be performed to define the appropriate thresholds for referral and treatment.

Low rates of hepatotoxicity among Asian patients with paracetamol overdose: a review of 1024 cases

Background

The metabolism of paracetamol in Asians is thought to differ from Westerners. Detailed clinical features of paracetamol -induced hepatotoxicity among Asians remains largely unreported.

Methods

A retrospective review of adult cases with paracetamol overdose over a five-year duration was performed in two of the largest public institutions in this country. Prevalence and predictive factors for hepatotoxicity were determined.

Results

Data on 1024 patients (median age 23 years, 82.0% female, ethnic groups: Malays 40.8%, Chinese 20.9% , Indian 33.2%) were obtained from January 2005 to December 2009. The median amount of paracetamol ingestion was 10.0 (IQR 5.0 - 15.0) g and the median serum paracetamol level was 274.80 (IQR 70.0 - 640.0) μmol/L at presentation. 75 (7.3%) patients developed hepatotoxicity. 23/ 55 (41.8%) patients who had ingested > 10 g of paracetamol and had a delayed (> 24 hour) administration of N-acetyl cystine (NAC) developed hepatotoxicity. No patients developed acute liver failure nor suffered any mortality (0%). Independent predictors for hepatotoxicity were identified as Malay (OR 2.22, 95% CI = 1.13-4.37) and Chinese (OR 3.26, 95% CI = 1.55-6.84) ethnicity, paracetamol dose > 10 g (OR 2.61, 95% CI = 1.53-4.46), prolonged duration of time from paracetamol ingestion to hospital presentation (> 24 hours OR 10.71, 95% CI = 3.46-33.15) and prolonged duration of time from paracetamol ingestion to NAC administration (> 24 hours OR 9.02, 95% CI = 2.97-27.45).

Conclusions

Paracetamol-induced hepatotoxicity rates in a multi-ethnic Asian population was low at 7.3%. Mortality and morbidity were non-existent despite high doses of paracetamol ingestion and delayed presentations to hospital.

A quick inexpensive laboratory method in acute paracetamol poisoning could improve risk assessment, management and resource utilization

OBJECTIVES

Acute paracetamol poisoning is an emerging problem in Sri Lanka. Management guidelines recommend ingested dose and serum paracetamol concentrations to assess the risk. Our aim was to determine the usefulness of the patient's history of an ingested dose of >150 mg/kg and paracetamol concentration obtained by a simple colorimetric method to assess risk in patients with acute paracetamol poisoning.

MATERIALS AND METHODS

Serum paracetamol concentrations were determined in 100 patients with a history of paracetamol overdose using High Performance Liquid Chromatography (HPLC); (reference method). The results were compared to those obtained with a colorimetric method. The utility of risk assessment by reported dose ingested and colorimetric analysis were compared.

RESULTS

The area under the receiver operating characteristic curve for the history of ingested dose was 0.578 and there was no dose cut-off providing useful risk categorization. Both analytical methods had less than 5% intra- and inter-batch variation and were accurate on spiked samples. The time from blood collection to result was six times faster and ten times cheaper for colorimetry (30 minutes, US$2) than for HPLC (180 minutes, US$20). The correlation coefficient between the paracetamol levels by the two methods was 0.85. The agreement on clinical risk categorization on the standard nomogram was also good (Kappa = 0.62, sensitivity 81%, specificity 89%).

CONCLUSIONS

History of dose ingested alone greatly over-estimated the number of patients who need antidotes and it was a poor predictor of risk. Paracetamol concentrations by colorimetry are rapid and inexpensive. The use of these would greatly improve the assessment of risk and greatly reduce unnecessary expenditure on antidotes.

Comparative drug dose and drug combinations in patients that present to hospital due to self-poisoning

Self-poisoning is a common reason for acute presentation to hospital. Commonly involved drugs have been reported, but few data exist concerning the different combinations of agents or comparative doses ingested. The present study sought to better characterise the typical patterns of drug overdose that may present via the emergency department. Consecutive adults ≥16 years of age that presented to York Hospital owing to self-poisoning were studied for 2010-2011 inclusive. The primary outcome measure was reported dose, expressed as a multiple of the defined daily dose (DDD) to allow comparison between different agents. There were 1024 patients, including 622 women (60.7%), and median age was 32 years (range, 16 to 92 years). Overdose in men was associated with a higher overall quantity of drugs: arithmetic mean of 20 DDD multiples (95% CI, 15-26) versus 13 (11-15), p = 0.001. Overdose involved a single agent only in 538 patients (52.5%). The mean paracetamol dose was 4.0 (95% CI, 3.7-4.3) DDD multiples; the doses of antidepressants (19.4, 17.0-21.7, p < 0.0001) and benzodiazepines (18.0, 12.8-23.2, p < 0.0001) were comparatively higher. The types of agents involved in self-poisoning and common combinations of agents are characterised. Psychotropic medications were ingested in comparatively larger quantities than analgesic agents and had worse clinical outcome. Further work is required to understand the factors that determine the quantity of drug ingested in patients at risk of drug overdose so as to minimise the risk of significant toxicity.

Staggered overdose pattern and delay to hospital presentation are associated with adverse outcomes following paracetamol-induced hepatotoxicity

AIMS

Paracetamol (acetaminophen) poisoning remains the major cause of severe acute hepatotoxicity in the UK. In this large single centre cohort study we examined the clinical impact of staggered overdoses and delayed presentation following paracetamol overdose.

RESULTS

Between 1992 and 2008, 663 patients were admitted with paracetamol-induced severe liver injury, of whom 161 (24.3%) had taken a staggered overdose. Staggered overdose patients were significantly older and more likely to abuse alcohol than single time point overdose patients. Relief of pain (58.2%) was the commonest rationale for repeated supratherapeutic ingestion. Despite lower total ingested paracetamol doses and lower admission serum alanine aminotransferase concentrations, staggered overdose patients were more likely to be encephalopathic on admission, require renal replacement therapy or mechanical ventilation and had higher mortality rates compared with single time point overdoses (37.3% vs. 27.8%, P= 0.025), although this overdose pattern did not independently predict death. The King's College poor prognostic criteria had reduced sensitivity (77.6, 95% CI 70.8, 81.5) for this pattern of overdose. Of the 396/450 (88.0%) single time point overdoses in whom accurate timings could be obtained, 178 (44.9%) presented to medical services >24 h following overdose. Delayed presentation beyond 24 h post overdose was independently associated with death/liver transplantation (OR 2.25, 95% CI 1.23, 4.12, P= 0.009).

CONCLUSIONS

Both delayed presentation and staggered overdose pattern are associated with adverse outcomes following paracetamol overdose. These patients are at increased risk of developing multi-organ failure and should be considered for early transfer to specialist liver centres.

Reliability of the reported ingested dose of acetaminophen for predicting the risk of toxicity in acetaminophen overdose patients

PURPOSE

The present study examines the relationship between the dose of acetaminophen reported to have been ingested by patients and the occurrence of serum acetaminophen levels above the 'possible toxicity' line in patients presenting at the hospital after acetaminophen overdose. The prognostic value of patient-reported dosage cut-offs of 8, 10 and 12 g was determined.

METHODS

This retrospective cohort study included patients admitted to the emergency department or hospital within 24 hours of acetaminophen ingestion. Serum acetaminophen concentrations were considered to be the gold standard, and specificity, sensitivity and positive/negative predictive values were calculated from the reported ingested dose, to predict toxicity using the Rumack-Matthew nomogram (i.e. the 'possible toxicity' treatment line) and standard equations.

RESULTS

Of 305 patients identified, 291 met the study inclusion criteria, and 121 (41.6%) had serum acetaminophen concentrations above the 'possible toxicity' treatment line. The range of patient-reported acetaminophen ingested was 1-75 g, with 185 patients (63.6%) reporting ≥8 g. One hundred eighteen patients (97.5%) who reported ingesting ≥8 g had serum acetaminophen concentrations above the '150-line', compared with only three patients (2.5%) who reported ingesting <8 g (p < 0.001). The positive predictive value of a patient-reported dose ≥8 g for predicting serum acetaminophen concentrations above the 'possible toxicity' treatment line was 63.78%, with a negative predictive value of 97.17%. The sensitivity of patient-reported doses ≥8 g was high (97.52%) but with low specificity (60.59%). The sensitivity of patient-reported doses ≥10 g also was high (89.26%) with low specificity (65.29%), whereas the sensitivity of ≥12 g dose was low (61.16%) with high specificity (86.47%).

CONCLUSIONS

Patient-reported doses of acetaminophen are good risk indicators for acetaminophen overdose patients in Malaysia. Patient-reported ingestion of ≥8 g (as a cut-off dose) had a higher sensitivity than ≥10 g or ≥12 g. The results of this study have important implications for toxicity risk evaluations in areas with poor serum acetaminophen assay availability.

Does cytochrome P450 liver isoenzyme induction increase the risk of liver toxicity after paracetamol overdose?

Paracetamol (acetaminophen, N-acetyl-p-aminophenol, 4-hydroxyacetanilide) is the most common cause of acute liver failure in developed countries. There are a number of factors which potentially impact on the risk of an individual developing hepatotoxicity following an acute paracetamol overdose. These include the dose of paracetamol ingested, time to presentation, decreased liver glutathione, and induction of cytochrome P450 (CYP) isoenzymes responsible for the metabolism of paracetamol to its toxic metabolite N-acetyl-p-benzoquinoneimine (NAPQI). In this paper, we review the currently published literature to determine whether induction of relevant CYP isoenzymes is a risk factor for hepatotoxicity in patients with acute paracetamol overdose. Animal and human in vitro studies have shown that the CYP isoenzyme responsible for the majority of human biotransformation of paracetamol to NAPQI is CYP2E1 at both therapeutic and toxic doses of paracetamol. Current UK treatment guidelines suggest that patients who use a number of drugs therapeutically should be treated as “high-risk” after paracetamol overdose. However, based on our review of the available literature, it appears that the only drugs for which there is evidence of the potential for an increased risk of hepatotoxicity associated with paracetamol overdose are phenobarbital, primidone, isoniazid, and perhaps St John’s wort. There is no evidence that other drugs often quoted as increasing risk, such as carbamazepine, phenytoin, primidone, rifampicin, rifabutin, efavirenz, or nevirapine, should be considered risk factors for hepatotoxicity in patients presenting with acute paracetamol overdose.

The systemic inflammatory response syndrome and sequential organ failure assessment scores are effective triage markers following paracetamol (acetaminophen) overdose

BACKGROUND

The systemic inflammatory response syndrome (SIRS) and sequential organ failure assessment (SOFA) scores are widely used as prognostic markers in critical care settings and could improve triage of high-risk paracetamol (acetaminophen) overdose patients.

AIM

To evaluate the prognostic accuracy of the SIRS and SOFA scores following single time point paracetamol overdose.

METHODS

Analysis of 100 single time point paracetamol overdoses admitted to a tertiary liver centre, with subsequent prospective validation of identified thresholds. Individual laboratory samples were correlated with the corresponding clinical parameters in relation to time post-overdose, and the daily SOFA and SIRS scores calculated.

RESULTS

A total of 74 (74%) patients developed the SIRS, which occurred significantly earlier in patients who died (n=21) compared with spontaneous survivors (n=53, P=0.05). The SIRS occurred in 70 (70%) patients by 96h post-overdose, with a 30% mortality rate; compared with 0% mortality in the 30 non-SIRS patients (P=0.001). Median SOFA scores were significantly higher in nonsurvivors at 48 (P=0.009), 72 (P<0.001), and 96h (P<0.001). A SOFA score >7 during the first 96h post-overdose predicted death/transplantation with a sensitivity of 95.0 (95% CI 78.5-99.1) and specificity of 70.5 (95% CI 66.3-71.6). A validation cohort of 38 single time point paracetamol overdoses confirmed the extremely high negative predictive value of both the SIRS and SOFA thresholds.

CONCLUSIONS

The absence of either a SOFA score >7 or a SIRS response during the first 96 h following paracetamol overdose could improve triage and reduce transfers of lower risk patients to tertiary liver centres.

Evaluation of a QT nomogram for risk assessment after antidepressant overdose

AIMS

A QT-heart rate nomogram has recently been proposed as a means of identifying patients at risk of torsades de pointes after antidepressant overdose, based on published cases of drug-induced torsades de pointes. The present study sought to examine the performance of the nomogram in patients who ingest an antidepressant overdose but do not develop arrhythmia.

METHODS

A retrospective case control study of patients presenting to hospital after overdose of citalopram, mirtazapine and venlafaxine was carried out. The primary outcome variable was QT higher than the nomogram, and was compared with occurrence of QT(c) (QT corrected by Bazett's formula) greater than ≥440 ms and QT(c) ≥500 ms, with comparison between drugs. Data are expressed as proportions in each group with 95% confidence intervals.

RESULTS

There were 858 electrocardiograms from 541 patients. QT was higher than the nomogram in 2.4% (1.4, 4.1%), whereas QT(c) was ≥440 ms in 23.1% (95% CI 19.8, 26.8%), and QT(c) was ≥500 ms in 1.1% (0.5, 2.5%). Citalopram overdose was more likely to be associated with QT higher than the nomogram compared with the other agents (difference 7.0%, 95% CI 2.9, 11.9%, P = 0.001) and more likely to be associated with QT(c) ≥440 ms (difference = 11.0%, 95% CI 2.6, 19.0%, P = 0.013).

CONCLUSIONS

The QT nomogram was associated with a lower false positive rate than widely accepted QT(c) criteria, and allowed detection of different effects of individual drugs. The nomogram offers potential advantages over QT(c) criteria and merits further investigation in a clinical setting.

Drug-induced liver injury: what was new in 2008?

BACKGROUND

Given the number of publications appearing annually regarding drug-induced liver injury (DILI), there remains a need to concisely summarize each year's new crop of case series and reports as well as the advances in mechanisms of liver injury and in the field of pharmacogenomics relating to DILI.

OBJECTIVE

To present an up-to-date review of the past year's most important clinical studies and reports of DILI, placing them into context of previous publications.

METHODS

A Medline search was conducted of all manuscripts appearing in the fields "hepatotoxicity" and "drug-induced liver injury" during the calendar year 2008. The most clinically relevant English language case reports and studies exploring mechanisms and risk factors for DILI were then chosen for review, and supplemented with older literature where appropriate.

CONCLUSIONS

As in past years, 2008 was replete with publications dealing with virtually all facets of DILI, including updated incidence and prevalence data, as well as the latest information regarding mechanisms of liver injury. Data from the first 300 patients in the National Institute of Health-sponsored DILI Network registry of > 100 non-acetaminophen causes were presented. Antimicrobials and CNS drugs were responsible for > 60% of cases, with herbals and dietary supplements being increasingly reported. Identification of genetic predispositions to DILI is coming of age with the FDA calling for the testing of human leukocyte antigen B(*)5701 before the use of abacavir to reduce the risk of hypersensitivity reactions. Several groups emphasized the pitfalls in utilizing Roussel Uclaf Causality Assessment Method and other causality assessment methodologies, and an updated review appeared on the use of potentially hepatotoxic medications in patients with underlying liver disease.

Limiting paracetamol pack size: has it worked in the UK?

INTRODUCTION

Paracetamol poisoning is a major health problem worldwide. Limitation of pack size is an approach increasingly advocated to reduce rates of suicide and serious self-harm from this agent. The United Kingdom adopted such a policy in 1998, restricting non-pharmacy sales to 8 g and pharmacy to pack sizes of 16 g.

METHODS

A literature review was conducted and commentary written on the impact of the change in the United Kingdom on a variety of indices of paracetamol overdose.

RESULTS

Potential markers of effect identified included paracetamol sales, poisons information data, laboratory results, liver unit referrals, and hospital activity and mortality data. Initial reports suggested effects associated with the legislation, but longer term suicide trend analysis has not confirmed these early findings, which were confounded by population trends in self-harm.

CONCLUSION

Paracetamol pack size limitation as applied in the United Kingdom has not reduced paracetamol-related death. Reasons postulated for this failure include patient avoidance of the legislation's intentions, patient confusion, and ineffectiveness of the regulations as conceived and implemented.

Self-poisoning in older adults: patterns of drug ingestion and clinical outcomes

BACKGROUND AND AIMS

self-poisoning accounts for a substantial proportion of acute medical hospital presentations, but has been poorly characterised in older adults. This study sought to determine the agents ingested by older adults presenting to hospital after drug overdose, and to compare clinical outcomes to younger patients.

METHODS

a retrospective observational study of patients admitted via the emergency department due to drug overdose between 2004 and 2007.

RESULTS

during the study period, there were 8,059 admissions, including 4,632 women (57.5%). This included a subgroup of 361 patients (4.5%) who were >60 years of age. This subgroup was more likely to require hospital stay >1 night, odds ratio (95% confidence interval) = 4.3 (3.6-5.5, P < 0.0001), transfer to a critical care area = 3.8 (1.1-13.0, P = 0.0340) and had higher mortality = 4.8 (1.1-22.1, P = 0.0463). A higher proportion of older patients required transfer to a psychiatric unit (P < 0.0001) or to a general medical ward (P < 0.0001) than younger adults.

CONCLUSIONS

older adults that presented to hospital after drug overdose had ingested different drugs than younger patients, possibly due to different prescribing patterns, and had a poorer outcome. The use of drugs associated with significant toxicity should be avoided in older patients at risk of self-harm.

Predictive factors for generalized seizures after deliberate citalopram overdose

AIMS

Seizures are a recognized complication of citalopram overdose. The present study sought to establish risk factors for seizures in this high-risk patient group, including stated dose ingested, co-ingested drugs or ethanol, and electrolyte disturbances.

METHODS

A retrospective casenote review was carried out of patients who attended the Emergency Department due to citalopram overdose between January 2000 and July 2007 inclusive. Stepwise logistic regression analysis considered age, gender, stated citalopram dose, acute ethanol consumption, co-ingested drugs, administration of activated charcoal, and hyponatraemia.

RESULTS

There were 241 patients (177 women), and the median (interquartile range) stated citalopram dose was 300 mg (200 to 600 mg). Generalized seizures occurred in 18 patients (7.5%). Logistic regression analysis found co-ingested tricyclic antidepressants or venlafaxine predicted seizures with odds ratio = 15 (95% confidence interval 3, 75). In the absence of co-ingested drugs, the minimum citalopram dose associated with seizures was 400 mg. Odds ratio for seizures = 1.1 (95% confidence interval 1.0, 1.2) for every 100 mg increment in citalopram dose. Seizures were associated with a greater need for invasive ventilatory support, higher creatine kinase activity, and prolonged hospital stay.

CONCLUSIONS

Generalized seizures are an important manifestation of citalopram toxicity, and cannot be explained solely by electrolyte disturbances or co-ingestion of other drugs or ethanol. The strongest predictors of seizures in this patient series were ingestion of high citalopram dosages and co-ingestion of drugs capable of lowering seizure threshold.

Circulating microRNAs, potential biomarkers for drug-induced liver injury

Drug-induced liver injury is a frequent side effect of many drugs, constitutes a significant threat to patient health and has an enormous economic impact on health care expenditures. Numerous efforts have been made to identify reliable and predictive markers to detect the early signs of drug-induced injury to the liver, one of the most vulnerable organs in the body. These studies have, however, not delivered any more informative candidates than the serum aminotransferase markers that have been available for approximately 30 years. Using acetaminophen overdose-induced liver injury in the mouse as a model system, we have observed highly significant differences in the spectrum and levels of microRNAs in both liver tissues and in plasma between control and overdosed animals. Based on our survey of microRNA expression among normal tissues, some of the microRNAs, like messenger RNAs, display restricted tissue distributions. A number of elevated circulating microRNAs in plasma collected from acetaminophen-overdosed animals are highly expressed in the liver. We have demonstrated that specific microRNA species, such as mir-122 and mir-192, both are enriched in the liver tissue and exhibit dose- and exposure duration-dependent changes in the plasma that parallel serum aminotransferase levels and the histopathology of liver degeneration, but their changes can be detected significantly earlier. These findings suggest the potential of using specific circulating microRNAs as sensitive and informative biomarkers for drug-induced liver injury.

Circulating microRNAs, potential biomarkers for drug-induced liver injury

Drug-induced liver injury is a frequent side effect of many drugs, constitutes a significant threat to patient health and has an enormous economic impact on health care expenditures. Numerous efforts have been made to identify reliable and predictive markers to detect the early signs of drug-induced injury to the liver, one of the most vulnerable organs in the body. These studies have, however, not delivered any more informative candidates than the serum aminotransferase markers that have been available for approximately 30 years. Using acetaminophen overdose-induced liver injury in the mouse as a model system, we have observed highly significant differences in the spectrum and levels of microRNAs in both liver tissues and in plasma between control and overdosed animals. Based on our survey of microRNA expression among normal tissues, some of the microRNAs, like messenger RNAs, display restricted tissue distributions. A number of elevated circulating microRNAs in plasma collected from acetaminophen-overdosed animals are highly expressed in the liver. We have demonstrated that specific microRNA species, such as mir-122 and mir-192, both are enriched in the liver tissue and exhibit dose- and exposure duration-dependent changes in the plasma that parallel serum aminotransferase levels and the histopathology of liver degeneration, but their changes can be detected significantly earlier. These findings suggest the potential of using specific circulating microRNAs as sensitive and informative biomarkers for drug-induced liver injury.

Circulating microRNAs, potential biomarkers for drug-induced liver injury

Drug-induced liver injury is a frequent side effect of many drugs, constitutes a significant threat to patient health and has an enormous economic impact on health care expenditures. Numerous efforts have been made to identify reliable and predictive markers to detect the early signs of drug-induced injury to the liver, one of the most vulnerable organs in the body. These studies have, however, not delivered any more informative candidates than the serum aminotransferase markers that have been available for approximately 30 years. Using acetaminophen overdose-induced liver injury in the mouse as a model system, we have observed highly significant differences in the spectrum and levels of microRNAs in both liver tissues and in plasma between control and overdosed animals. Based on our survey of microRNA expression among normal tissues, some of the microRNAs, like messenger RNAs, display restricted tissue distributions. A number of elevated circulating microRNAs in plasma collected from acetaminophen-overdosed animals are highly expressed in the liver. We have demonstrated that specific microRNA species, such as mir-122 and mir-192, both are enriched in the liver tissue and exhibit dose- and exposure duration-dependent changes in the plasma that parallel serum aminotransferase levels and the histopathology of liver degeneration, but their changes can be detected significantly earlier. These findings suggest the potential of using specific circulating microRNAs as sensitive and informative biomarkers for drug-induced liver injury.

Proteinuria is unrelated to the extent of acute acetaminophen overdose: a prospective clinical study

BACKGROUND

Acute renal failure is a recognized complication of acute acetaminophen overdose. Its detection depends on rising creatinine concentrations, which is an insensitive method. The present study examined whether proteinuria might correspond with the extent of acute acetaminophen exposure as a possible early marker of renal effects.

METHODS

A prospective case-control study included patients attending the emergency department within 24 hours of acetaminophen ingestion. A urine specimen was collected within 12 hours of hospital attendance for creatinine, albumin, and protein determination. Equivalent 4-hour acetaminophen concentrations were used to indicate drug exposure: mild if >100 g/L (>662 mmol/L), moderate if 100-200 g/L (662-1323 mmol/L), or severe if <200 g/L (<1323 mmol/L). Data are presented as median (interquartile range) and groups compared using Mann Whitney and chi-square tests.

RESULTS

Seventy patients were studied (17 men, 53 women), age 37 years (23-45 years). The stated acetaminophen dose was 15 g (8-20 g), and interval between ingestion and presentation was 4.6 hours (4.1-7.9 hours). Urinary albumin concentrations were 8 mg/L (0-12 mg/L) in the mild group, 12 mg/L (5-25 mg/L) in the moderate group, and 11 mg/L (6-22 mg/L) in the severe group. Total protein concentrations were 90 mg/L (50-183 mg/L), 70 mg/L (40 to 130 mg/L), and 110 mg/L (75-205 mg/L), respectively. The proportions of patients who had urine albumin:creatinine ratio >3 mg/mmol were 20.8%, 23.5%, and 21.2%, respectively. None of the patients developed acute renal failure.

CONCLUSIONS

No relationship was found between the extent of acute acetaminophen exposure and proteinuria. Further work is required to examine whether urinary protein excretion is altered in patients who subsequently develop acute renal failure following acetaminophen overdose.