Assessing the impact of a new medical toxicology service on the treatment of paracetamol overdose at a large tertiary care hospital.

BACKGROUND: Paracetamol overdose is the most common cause of acute liver failure in the United States. Administration of acetylcysteine is the standard of care for this intoxication. Laboratory values and clinical criteria are used to guide treatment duration, but decision-making is nuanced and often complex and difficult. The purpose of this study was to evaluate the effect of the introduction of a medical toxicology service on the rate of errors in the management of paracetamol overdose. METHODS: This was a single center, retrospective, cohort evaluation. Patients with suspected paracetamol overdose were divided into two groups: those attending in the 1 year period before and those in the 1 year after the introduction of the medical toxicology service. The primary outcome was the frequency of deviations from the established management of paracetamol intoxication, using international guidelines as a reference. RESULTS: Fifty-four patients were eligible for the study (20 pre-toxicology-service, 34 post-toxicology-service). The frequency of incorrect therapeutic decisions was significantly lower in the post-toxicology service implementation versus the pre-implementation group (P = 0.005). DISCUSSION: Our study suggests that a medical toxicology service reduces the incidence of management errors, including the number of missed acetylcysteine doses in patients with paracetamol overdose. The limitations include the retrospective study design and that the study was conducted at a single center, which may limit generalizability. CONCLUSIONS: The implementation of a medical toxicology service was associated with a decrease in the number of errors in the management of paracetamol overdose.

Comparing N-acetylcysteine and 4-methylpyrazole as antidotes for acetaminophen overdose.

Acetaminophen (APAP) overdose can cause hepatotoxicity and even liver failure. N-acetylcysteine (NAC) is still the only FDA-approved antidote against APAP overdose 40 years after its introduction. The standard oral or intravenous dosing regimen of NAC is highly effective for patients with moderate overdoses who present within 8 h of APAP ingestion. However, for late-presenting patients or after ingestion of very large overdoses, the efficacy of NAC is diminished. Thus, additional antidotes with an extended therapeutic window may be needed for these patients. Fomepizole (4-methylpyrazole), a clinically approved antidote against methanol and ethylene glycol poisoning, recently emerged as a promising candidate. In animal studies, fomepizole effectively prevented APAP-induced liver injury by inhibiting Cyp2E1 when treated early, and by inhibiting c-jun N-terminal kinase (JNK) and oxidant stress when treated after the metabolism phase. In addition, fomepizole treatment, unlike NAC, prevented APAP-induced kidney damage and promoted hepatic regeneration in mice. These mechanisms of protection (inhibition of Cyp2E1 and JNK) and an extended efficacy compared to NAC could be verified in primary human hepatocytes. Furthermore, the formation of oxidative metabolites was eliminated in healthy volunteers using the established treatment protocol for fomepizole in toxic alcohol and ethylene glycol poisoning. These mechanistic findings, together with the excellent safety profile after methanol and ethylene glycol poisoning and after an APAP overdose, suggest that fomepizole may be a promising antidote against APAP overdose that could be useful as adjunct treatment to NAC. Clinical trials to support this hypothesis are warranted.

A review of alternative intravenous acetylcysteine regimens for acetaminophen overdose.

INTRODUCTION: Acetylcysteine is the standard treatment for preventing hepatotoxicity caused by acetaminophen overdose. Several novel approaches to the management of acetaminophen overdose have been suggested to improve patient safety by reducing adverse drug reactions and dosing errors. This article reviews these alternative treatment regimens and intends to offer a detailed assessment of the available options to assist providers in managing cases of acetaminophen overdose. AREAS COVERED: This review article covers observational and experimental studies that assessed the efficacy and safety of alternative intravenous acetylcysteine regimens for acetaminophen overdose. A literature search was conducted using PubMed, ProQuest, and Scopus to identify the studies, which included results through April 2021. The assessment of alternative regimens consists of a discussion on the limitations and benefits, barriers to implementation, and important considerations for each regimen. EXPERT OPINION: Several alternative regimens have been studied and implemented in various institutions. Many of these dosing regimens have supporting safety data but most lack robust data. A reduction in infusion-related side effects is an important outcome, but established efficacy, local poison center familiarity with the regimen, institutional resources, and patient-specific factors should be equally considered when deciding on implementing and using an alternative dosing strategy.

Plasma procalcitonin may be an early predictor of liver injury in acetaminophen poisoning: A prospective cohort study.

BACKGROUND AND AIMS: Acetaminophen is a common cause of poisoning and liver injury worldwide; however, patient stratification is suboptimal. We aimed to assess the contribution of admission plasma procalcitonin concentration (PCT) to better identify acetaminophen-poisoned patients likely to develop liver injury. METHODS: We conducted a prospective observational cohort study including all acetaminophen-poisoned patients requiring N-acetylcysteine admitted in a toxicological intensive care unit between 2012 and 2017. Multivariate analysis was performed using a Cox regression model to investigate factors associated with liver injury, defined as an increase in alanine aminotransferase (ALT) >100 IU/L. RESULTS: One hundred seventeen patients (age, 32 years (21-53), median [25th-75th percentiles]) were included after self-ingesting 16 g (9-30) acetaminophen and received N-acetylcysteine infusion administered within a median 6 h-delay (4-12) from exposure. Co-ingestions were reported in 77% of patients. Rumack-Matthew nomogram was non-interpretable in 47% cases. Liver injury occurred in 38 patients (32%) with a median peak ALT of 2020 IU/L (577-4248). In liver injury patients, admission PCT was significantly increased in comparison to patients without liver injury (21.5 ng/ml (3.2-44.9) versus 0.1 ng/ml (0-0.4), respectively, p < 0.01). The increase in PCT preceded the increase in ALT by 33 h (10-74). In a multivariate analysis, PCT > 1 ng/ml was significantly associated with liver injury (hazard ratio, 7.2 [95% confidence interval, 2.3-22.6; p < 0.001]). PCT (area under the receiver-operating characteristics curve, 0.91 [95%CI: 0.84-0.97]) predicted liver injury with sensitivity, specificity, negative, and positive predictive values of 0.92, 0.84, 0.96, and 0.73, respectively. CONCLUSION: PCT on admission is associated with liver injury in acetaminophen poisoning. PCT might be used as a predictive tool of liver injury to improve clinical decision-making.

Clinical outcome of massive acetaminophen overdose treated with standard-dose N-acetylcysteine.

BACKGROUND: Recent recognition of "massive" acetaminophen (APAP) overdoses has led to the question of whether standard dosing of N-acetylcysteine (NAC) is adequate to prevent hepatoxicity in these patients. The primary aim of this study was to evaluate the clinical outcome for patients with massive APAP overdose who received standard intravenous NAC dosing of 300 mg/kg over 21 h. METHODS: This was a single-center retrospective cohort study conducted by chart review of APAP overdoses reported to a regional poison center from 1 January 2010 to 31 December 2019. Massive APAP overdose was defined by single, acute overdose resulting in an APAP concentration exceeding 300 mcg/mL at 4 h post-ingestion. Standard univariate statistical analysis was conducted to describe the cohort, and a multivariate logistic model was utilized to calculate adjusted odds ratios for risk of hepatoxicity. RESULTS: 1425 cases of APAP overdose were reviewed. 104 cases met the inclusion criteria of massive APAP overdose. Overall, 79 cases (76%) had no acute liver injury or hepatotoxicity, and 25 (24%) developed hepatoxicity. Nine percent (n = 4) of cases receiving NAC within 8 h developed hepatotoxicity. Crude odds for hepatoxicity was 5.5-fold higher for cases who received NAC after 8 h. CONCLUSIONS: Standard NAC dosing received within 8 h prevented hepatoxicity in 91% (n = 40) of cases in our series of massive APAP overdoses. Additional data is needed to determine the clinical outcomes of massive APAP overdose using current intravenous NAC dosing.

A Case Report of a Severe, Unusually Delayed Anaphylactoid Reaction to Intravenous N-Acetylcysteine During Treatment of Acute Acetaminophen Toxicity in an Adolescent.

INTRODUCTION: Anaphylactoid reactions are well-documented adverse events associated with the intravenous administration of N-acetylcysteine (NAC) in patients with acetaminophen overdose. Most reactions are mild, occurring within the first 1-5 hours of initiation. This report presents the case of an adolescent with a delayed, life-threatening anaphylactoid reaction 24.5 hours after starting NAC, where discontinuing NAC could have resulted in fulminant hepatic failure (FHF) and death. CASE REPORT: A 17-year-old previously healthy female presented with nausea, vomiting, and abdominal pain 10 hours after an acute acetaminophen ingestion. Her 11-hour serum acetaminophen concentration was above the treatment line (149 µg/mL), and she had elevated transaminases (AST = 202 U/L, ALT = 284 U/L). She was treated with intravenous NAC, which was suspended for 3 hours after she developed an apparent life-threatening anaphylactoid reaction with angioedema and respiratory distress 24.5 hours after treatment initiation. Given her high risk of progression to FHF, NAC was resumed at double the previous rate along with scheduled corticosteroids and antihistamines after resolution of her symptoms. Her AST increased to 10,927 U/L, and INR peaked at 3.6, but she had no further anaphylactoid symptoms. She was discharged in her normal state of health after 6 days. DISCUSSION: Discontinuing NAC in this case of severe, delayed anaphylactoid reaction could have resulted in FHF requiring liver transplant. The reason for her reaction is unclear but could be related to patient risk factors or medication error. Guidelines for reinitiation of NAC after development of delayed anaphylactoid reactions are not well-established.  Close observation beyond the first 1-5 hours of NAC administration is warranted.

Delayed peaks of acetaminophen in overdose patients with concomitant abdominal trauma.

OBJECTIVE: To present two cases of delayed acetaminophen absorption in abdominal trauma patients with concomitant acetaminophen overdose. CASES: Case 1. A 25-year-old female arrived to the emergency department with multiple stab wounds. She had ingested an unknown amount of acetaminophen and was then stabbed by her boyfriend in a suicide pact. Initial acetaminophen concentration was 211.7 mcg/mL and the patient was started on N-Acetylcysteine (NAC) therapy. She was found to have injuries and was taken for operative repair. Acetaminophen concentrations were down trending and nearly undetectable until 58 h post-presentation when concentrations began to rise again. CASE 2: A 41-year-old female ingested approximately 500 tablets of acetaminophen prior to jumping from a four-story building in a suicide attempt. She was found to have multiple traumatic injuries as well as an initial acetaminophen concentration of 225 mcg/mL and was started on NAC therapy. The patient underwent multiple interventions to treat her traumatic injuries. Despite receiving no acetaminophen while inpatient, the patient's acetaminophen concentrations peaked a second time on her third hospital day. CONCLUSIONS: In this case series, two patients with abdominal trauma and coexistent massive acetaminophen ingestions were described. Both cases demonstrated a delayed rise in serum acetaminophen concentrations and required extended NAC therapy.

Increased risk of acute liver failure by pain killer drugs in NAFLD: Focus on nuclear receptors and their coactivators.

Non-alcoholic fatty liver disease (NAFLD) is a global condition characterized by an accumulation of lipids in the hepatocytes. NAFLD ranges from simple steatosis, a reversible and relatively benign condition, to fibrosis with non-alcoholic steatohepatitis (NASH), potentially leading to cirrhosis and hepatocarcinoma. NAFLD can increase the susceptibility to severe liver injury with eventual acute liver failure induced by specific hepatotoxic drugs, including acetaminophen (APAP), which is commonly used as analgesic and antipyretic. Although several animal models have been used to clarify the predisposing role of hepatic steatosis to APAP intoxication, the exact mechanism is still not clear. Here, we shed a light into the association between NAFLD and APAP toxicity by examining the peculiar role of nuclear receptor peroxisome proliferator-activated receptor α (PPARα) and coactivator peroxisome proliferator-activated receptor gamma coactivator 1-ß (PGC-1ß) in driving fatty acid metabolism, inflammation and mitochondria redox balance. The knowledge of the mechanism that exposes patients with NAFLD to higher risk of acute liver failure by pain killer drug is the first step to eventually claim for a reduction of the maximal diurnal dose of APAP for subjects with liver steatosis.

Successful orthotopic liver transplantation in a patient with a positive SARS-CoV2 test and acute liver failure secondary to acetaminophen overdose.

SARS-CoV2, first described in December 2019, was declared a pandemic by the World Health Organization in March 2020. Various surgical and medical societies promptly published guidelines, based on expert opinion, on managing patients with COVID-19, with a consensus to postpone elective surgeries and procedures. We describe the case of an orthotopic liver transplantation (OLT) in a young female who presented with acute liver failure secondary to acetaminophen toxicity to manage abdominal pain and in the setting of a positive SARS-CoV2 test. Despite a positive test, she had no respiratory symptoms at time of presentation. The positive test was thought to be residual viral load. The patient had a very favorable outcome, likely related to multiple factors including her young age, lack of respiratory COVID-19 manifestations and plasma exchange peri-operatively. We recommend a full work-up for OLT in COVID-19 patients with uncomplicated disease according to standard of care, with careful interpretation of COVID-19 testing in patients presenting with conditions requiring urgent or emergent surgery as well as repeat testing even a few days after initial testing, as this could alter management.

Adducts Post Acetaminophen Overdose Treated with a 12-Hour vs 20-Hour Acetylcysteine Infusion.

INTRODUCTION: Acetaminophen protein adducts in the circulation are a specific biomarker of acetaminophen oxidation, and may be a more sensitive measure of impending hepatic injury following overdose than alanine transaminase (ALT). We performed an exploratory analytical substudy of adducts during a clinical trial (NACSTOP) of abbreviated (12-hour) versus control (20-hour) acetylcysteine to identify any signal of diminished antidotal effectiveness with shortened therapy. METHODS: We measured adducts at 0, 12, and 20 hours from a convenience sample of subjects enrolled in the cluster-controlled NACSTOP trial evaluating a 12-hour ("abbreviated"; 200 mg/kg over 4 hours, 50 mg/kg over 8 hours) vs 20-hour acetylcysteine regimen ("control"; 200 mg/kg over 4 hours, 100 mg/kg over 16 hours). Adducts were assayed using high-performance liquid chromatography/mass spectrometry. RESULTS: Median ALT 20 hours after the initiation of acetylcysteine was 12 U/L (IQR 8,14) in the abbreviated 12-hour regimen group (N = 8), compared with the control group 16 U/L (IQR 11,21; N = 21) (p = 0.46). Adduct concentrations were similarly low in both groups: abbreviated [(0.005 µmol/L, IQR (0,0.14)] and control [(0.005 µmol/L, IQR (0,0.05)] (p = 0.61). CONCLUSIONS: There were minimal to no acetaminophen protein adducts detected. These findings further support discontinuing acetylcysteine when acetaminophen concentrations are low and liver function tests normal after 12 hours of treatment.

Two-bag intravenous N-acetylcysteine, antihistamine pretreatment and high plasma paracetamol levels are associated with a lower incidence of anaphylactoid reactions to N-acetylcysteine.

Context:N-acetylcysteine (NAC) is used worldwide to prevent liver injury after paracetamol overdoses. Anaphylactoid reactions to NAC occur frequently and often lead to treatment interruptions or discontinuations. In Denmark in 2013, the NAC treatment regimen was simplified from a three-bag to a two-bag NAC regimen. Factors of importance for the development of anaphylactoid reaction to this new regimen are poorly explored. Previous studies have suggested a protective effect of high plasma levels of paracetamol on the development of anaphylactoid reactions. Likewise, exposure to antihistamines prior to NAC treatment may protect against these reactions.Methods: This is a retrospective cohort study of patients treated with NAC and with at least one plasma paracetamol sample performed in the Capital Region of Denmark from 2010 to 2017. The primary outcome was the incidence of anaphylactoid reactions to NAC requiring intravenous treatment with antihistamines and/or glucocorticoids. Logistic regression analyses were carried out to identify the risk of developing an anaphylactoid reaction to NAC affected by influencing factors.Results: Of 4315 admissions included in the study, 259 (6.0%) developed an anaphylactoid reaction to NAC. The two-bag regimen (adjusted OR 0.44 [95%CI: 0.32-0.60]), increasing age (adjusted OR 0.84 [95%CI: 0.78-0.90] per 10-year increase) or children <10 years (adjusted OR 0.14 [95%CI: 0.04-0.36]) and antihistamine co-ingestion in overdose (adjusted OR 0.17 [95%CI: 0.02-0.64]) were associated with significantly fewer anaphylactoid reactions. High plasma paracetamol concentrations protected against development of anaphylactoid reactions during the two-bag regimen (adjusted OR 0.59 [95%CI: 0.47-0.71] and three-bag regimen 0.82 [95%CI: 0.72-0.94] per doubling of paracetamol concentration). The effect differed between the two regimens (p = .004 for interaction).Conclusion: In this retrospective cohort, a high peak plasma paracetamol concentration, age, antihistamine co-ingestion and use of the two-bag NAC regimen were associated with fewer anaphylactoid reactions to NAC.

Updated guidelines for the management of paracetamol poisoning in Australia and New Zealand.

INTRODUCTION: Paracetamol is a common agent taken in deliberate self-poisoning and in accidental overdose in adults and children. Paracetamol poisoning is the commonest cause of severe acute liver injury. Since the publication of the previous guidelines in 2015, several studies have changed practice. A working group of experts in the area, with representation from all Poisons Information Centres of Australia and New Zealand, were brought together to produce an updated evidence-based guidance. MAIN RECOMMENDATIONS (UNCHANGED FROM PREVIOUS GUIDELINES): The optimal management of most patients with paracetamol overdose is usually straightforward. Patients who present early should be given activated charcoal. Patients at risk of hepatotoxicity should receive intravenous acetylcysteine. The paracetamol nomogram is used to assess the need for treatment in acute immediate release paracetamol ingestions with a known time of ingestion. Cases that require different management include modified release paracetamol overdoses, large or massive overdoses, accidental liquid ingestion in children, and repeated supratherapeutic ingestions. MAJOR CHANGES IN MANAGEMENT IN THE GUIDELINES: The new guidelines recommend a two-bag acetylcysteine infusion regimen (200 mg/kg over 4 h, then 100 mg/kg over 16 h). This has similar efficacy but significantly reduced adverse reactions compared with the previous three-bag regimen. Massive paracetamol overdoses that result in high paracetamol concentrations more than double the nomogram line should be managed with an increased dose of acetylcysteine. All potentially toxic modified release paracetamol ingestions (≥ 10 g or ≥ 200 mg/kg, whichever is less) should receive a full course of acetylcysteine. Patients ingesting ≥ 30 g or ≥ 500 mg/kg should receive increased doses of acetylcysteine.

Fomepizole as an Adjunctive Treatment in Severe Acetaminophen Toxicity.

A 33-year-old male presented to the emergency department with a chief complaint of abdominal pain after taking #50 500 mg acetaminophen tablets over the preceding two days. He was tachycardic and tachypneic, and the initial labs were notable for acetaminophen level, 337 mg/L; AST, 137 IU/L; ALT, 194 IU/L; ABG pH, 7.24; and lactate, 4.1 mmol/L. The patient was started on IV N-Acetylcysteine (NAC) as well as given a single dose of 15 mg/kg fomepizole. The patient did remarkably well, with a peak AST of 198 IU/L, peak ALT of 301 IU/L, and peak INR of 3.1. Biochemical and animal data support fomepizole having hepatoprotective effects in acetaminophen poisoning. To our knowledge, this is the first human case of an intentional dual NAC/fomepizole regimen for severe acetaminophen toxicity.

[Improved and harmonised laboratory analysis of paracetamol provides safer assessment of poisoning cases]. / Bättre labbanalys av paracetamol ger säkrare bedömning av förgiftningsfall - Bestämning av koncentrationen är grunden för rätt behandling.

Toxicological analysis is an important part of the acute treatment of various intoxications. Rapid laboratory responses are important for the patient to be assessed and treated correctly, and also to exclude poisoning and thus avoid unjustified and costly overtreatment. In Sweden, paracetamol (acetaminophen) is one of the most common pharmaceuticals in drug poisoning. Paracetamol overdose can cause severe liver damage unless treated early with the antidote acetylcysteine. A nation-wide initiative for improved laboratory measurement of paracetamol in plasma/serum samples has resulted in a marked reduction in the inter-laboratory coefficient of variation to generally below 10%. The introduction of a harmonized national reporting range for plasma/serum paracetamol covering at least 50-5 000 µmol/l was also recommended. This initiative will hopefully contribute to better healthcare from both a patient and health resource perspective in cases of paracetamol poisoning.

Current concepts in acute liver failure.

Acute liver failure (ALF) is a severe condition secondary to a myriad of causes associated with poor outcomes. The prompt diagnosis and identification of the aetiology allow the administration of specific treatments plus supportive strategies and to define the overall prognosis, the probability of developing complications and the need for liver transplantation. Pivotal issues are adequate monitoring and the institution of prophylactic strategies to reduce the risk of complications, such as progressive liver failure, cerebral oedema, renal failure, coagulopathies or infections. In this article, we review the main aspects of ALF, including the definition, diagnosis and complications. Also, we describe the standard-of-care strategies and recent advances in the treatment of ALF. Finally, we include our experience of care patients with ALF.