Management of Acetaminophen Poisoning in the US and Canada: A Consensus Statement.

Importance: The US and Canada currently have no formal published nationwide guidelines for specialists in poison information or emergency departments for the management of acetaminophen poisoning, resulting in significant variability in management. Objective: To develop consensus guidelines for the management of acetaminophen poisoning in the US and Canada. Evidence Review: Four clinical toxicology societies (America's Poison Centers, American Academy of Clinical Toxicology, American College of Medical Toxicology, and Canadian Association of Poison Control Centers) selected participants (n = 21). Led by a nonvoting chairperson using a modified Delphi method, the panel created a decision framework and determined the appropriate clinical management of a patient with acetaminophen poisoning. Unique to this effort was the collection of guidelines from most poison centers in addition to systematic collection and review of the medical literature. Comments from review by external organizations were incorporated before the guideline was finalized. The project began in March 2021 and ended in March 2023. Findings: The search retrieved 84 guidelines and 278 publications. The panel developed guidelines for emergency department management of single or repeated ingestion of acetaminophen. In addition, the panel addressed extended-release formulation, high-risk ingestion, coingestion of anticholinergics or opioids, age younger than 6 years, pregnancy, weight greater than 100 kg, and intravenous acetaminophen use. Differences from current US practice include defining acute ingestion as an ingestion presentation from 4 to 24 hours after overdose was initiated. A revised form of the Rumack-Matthew nomogram was developed. The term massive ingestion was replaced with the term high-risk ingestion and denoted by a specific nomogram line. Other recommendations include specific criteria for emergency department triage, laboratory evaluation and monitoring parameters, defining the role of gastrointestinal decontamination, detailed management of acetylcysteine treatment, associated adverse effects, and stopping criteria for acetylcysteine treatment, as well as criteria for consultation with a clinical toxicologist. Finally, specific treatment considerations, including acetylcysteine dosing, fomepizole administration, and considerations for extracorporeal elimination and transplant evaluation, were addressed. Conclusions and Relevance: This qualitative study provides a consensus statement on consistent evidence-based recommendations for medical, pharmacy, and nursing education and practice to optimize care of patients with acetaminophen poisoning.

Fifty years of paracetamol (acetaminophen) poisoning: the development of risk assessment and treatment 1973-2023 with particular focus on contributions published from Edinburgh and Denver.

INTRODUCTION: Fifty years ago, basic scientific studies and the availability of assay methods made the assessment of risk in paracetamol (acetaminophen) poisoning possible. The use of the antidote acetylcysteine linked to new methods of risk assessment transformed the treatment of this poisoning. This review will describe the way in which risk assessment and treatments have developed over the last 50 years and highlight the remaining areas of uncertainty. METHODS: A search of PubMed and its subsidiary databases revealed 1,166 references published in the period 1963-2023 using the combined terms "paracetamol", "poisoning", and "acetylcysteine". Focused searches then identified 170 papers dealing with risk assessment of paracetamol poisoning, 141 with adverse reactions to acetylcysteine and 114 describing different acetylcysteine regimens. To manage the extensive literature, we focused mainly on contributions made by the authors during their time in Edinburgh and Denver. DOSE AND CONCENTRATION RESPONSE: The key relationship between paracetamol dose and toxicity risk was established in 1971 and led to the development of the Rumack-Matthew nomogram from data collected in Edinburgh. MECHANISMS OF TOXICITY: A series of papers on the mechanisms of toxicity were published in 1973, and these showed that paracetamol hepatotoxicity was caused by the formation of a toxic intermediate epoxide metabolite normally detoxified by glutathione but which, in excess, was bound covalently to hepatic enzymes and proteins. An understanding of the relationship between the rate of paracetamol metabolism, paracetamol concentration, and toxic hazard in humans soon followed. ANTIDOTE DEVELOPMENT AND EFFICACY IN PATIENTS: These discoveries were followed by the testing of a range of sulfhydryl-donors in animals and "at risk" patients. Acetylcysteine was developed as the lead intravenous antidote in the United Kingdom. The license holder in the United States refused to make an intravenous formulation. Thus, oral acetylcysteine became the antidote trialed in the United States National Multicenter Study. Intravenous acetylcysteine regimens used initially in the United Kingdom and subsequently in the United States used loading doses of 150 mg/kg over 15 minutes or one hour, 50 mg/kg over four hours, and 100 mg/kg over 16 hours. These regimens were associated with adverse drug reactions (nausea, vomiting and anaphylactoid reactions) and hence, treatment interruption. Newer dosing regimens now give loading doses more slowly. One, the Scottish and Newcastle Anti-emetic Pretreatment protocol, using an acetylcysteine regimen of 100 mg/kg over two hours followed by 200 mg/kg over 10 hours, has been widely adopted in the United Kingdom. A cohort comparison study suggests this regimen has comparable efficacy to standard regimens and offers opportunities for selective higher acetylcysteine dosing. RISK ASSESSMENT AT PRESENTATION: No dose-ranging studies with acetylcysteine were done, and no placebo-controlled studies were performed. Thus, there is uncertainty regarding the optimal dose of acetylcysteine, particularly in patients ingesting very large overdoses of paracetamol. The choice of intervention concentration on the Rumack-Matthew nomogram has important consequences for the proportion of patients treated. The United States National Multicenter Study used a "treatment" line starting at 150 mg/L (992 µmol/L) at 4 hours post overdose, extending to 24 hours with a half-life of 4 hours, now standard there, and subsequently adopted in Australia and New Zealand. In the United Kingdom, the treatment line was initially 200 mg/L (1,323 µmol/L) at 4 hours (the Rumack-Matthew "risk" line). In 2012, the United Kingdom Medicines and Healthcare products Regulatory Agency lowered the treatment line to 100 mg/L (662 µmol/L) at 4 hours for all patients, increasing the number of patients admitted and treated at a high cost. Risk assessment is a key issue for ongoing study, particularly following the development of potential new antidotes that may act in those at greatest risk. The development of biomarkers to assess risk is ongoing but has yet to reach clinical trials. CONCLUSION: Even after 50 years, there are still areas of uncertainty. These include appropriate acetylcysteine doses in patients who ingest different paracetamol doses or multiple (staggered) ingestions, early identification of at-risk patients, and optimal treatment of late presenters.

The Roles of Antidotes in Emergency Situations.

Management of the acutely poisoned patient requires supportive care and timely administration of antidotes to minimize ongoing toxicity and mortality. New applications for old antidotes include utilization of methylene blue and hydroxocobalamin in vasoplegia. Fomepizole is also being evaluated as a potential adjunct in acetaminophen toxicity. Other advancements include individualized acetylcysteine dosing regimens for acetaminophen toxicity and carnitine supplementation in valproic acid toxicity. Additional antidote considerations include administration of lipid emulsion in lipophilic xenobiotic exposure not responsive to standard resuscitative modalities. These expert recommendations provide guidance for providers caring for the acutely poisoned patient.

Prescription opioid treatment for non-cancer pain and initiation of injection drug use: large retrospective cohort study.

OBJECTIVE: To assess the association between long term prescription opioid treatment medically dispensed for non-cancer pain and the initiation of injection drug use (IDU) among individuals without a history of substance use. DESIGN: Retrospective cohort study. SETTING: Large administrative data source (containing information for about 1.7 million individuals tested for hepatitis C virus or HIV in British Columbia, Canada) with linkage to administrative health databases, including dispensations from community pharmacies. PARTICIPANTS: Individuals age 11-65 years and without a history of substance use (except alcohol) at baseline. MAIN OUTCOME MEASURES: Episodes of prescription opioid use for non-cancer pain were identified based on drugs dispensed between 2000 and 2015. Episodes were classified by the increasing length and intensity of opioid use (acute (lasting <90 episode days), episodic (lasting ≥90 episode days; with <90 days' drug supply and/or <50% episode intensity), and chronic (lasting ≥90 episode days; with ≥90 days' drug supply and ≥50% episode intensity)). People with a chronic episode were matched 1:1:1:1 on socioeconomic variables to those with episodic or acute episodes and to those who were opioid naive. IDU initiation was identified by a validated administrative algorithm with high specificity. Cox models weighted by inverse probability of treatment weights assessed the association between opioid use category (chronic, episodic, acute, opioid naive) and IDU initiation. RESULTS: 59 804 participants (14 951 people from each opioid use category) were included in the matched cohort, and followed for a median of 5.8 years. 1149 participants initiated IDU. Cumulative probability of IDU initiation at five years was highest for participants with chronic opioid use (4.0%), followed by those with episodic use (1.3%) and acute use (0.7%), and those who were opioid naive (0.4%). In the inverse probability of treatment weighted Cox model, risk of IDU initiation was 8.4 times higher for those with chronic opioid use versus those who were opioid naive (95% confidence interval 6.4 to 10.9). In a sensitivity analysis limited to individuals with a history of chronic pain, cumulative risk for those with chronic use (3.4% within five years) was lower than the primary results, but the relative risk was not (hazard ratio 9.7 (95% confidence interval 6.5 to 14.5)). IDU initiation was more frequent at higher opioid doses and younger ages. CONCLUSIONS: The rate of IDU initiation among individuals who received chronic prescription opioid treatment for non-cancer pain was infrequent overall (3-4% within five years) but about eight times higher than among opioid naive individuals. These findings could have implications for strategies to prevent IDU initiation, but should not be used as a reason to support involuntary tapering or discontinuation of long term prescription opioid treatment.

Cohort profile: development and characteristics of a retrospective cohort of individuals dispensed prescription opioids for non-cancer pain in British Columbia, Canada.

PURPOSE: Prescription opioids (POs) are widely prescribed for chronic non-cancer pain but are associated with several risks and limited long-term benefit. Large, linked data sources are needed to monitor their harmful effects. We developed and characterised a retrospective cohort of people dispensed POs. PARTICIPANTS: We used a large linked administrative database to create the Opioid Prescribing Evaluation and Research Activities cohort of individuals dispensed POs for non-cancer pain in British Columbia (BC), Canada (1996-2015). We created definitions to categorise episodes of PO use based on a review of the literature (acute, episodic, chronic), developed an algorithm for inferring clinical indication and assessed patterns of PO use across a range of characteristics. FINDINGS TO DATE: The current cohort includes 1.1 million individuals and 3.4 million PO episodes (estimated to capture 40%-50% of PO use in BC). The majority of episodes were acute (81%), with most prescribed for dental or surgical pain. Chronic use made up 3% of episodes but 88% of morphine equivalents (MEQ). Across the acute to episodic to chronic episode gradient, there was an increasing prevalence of higher potency POs (hydromorphone, oxycodone, fentanyl, morphine), long-acting formulations and chronic pain related indications (eg, back, neck, joint pain). Average daily dose (MEQ) was similar for acute/episodic but higher for chronic episodes. Approximately 7% of the cohort had a chronic episode and chronic pain was the characteristic most strongly associated with chronic PO use. Individuals initiating a chronic episode were also more likely to have higher social/material deprivation and previous experience with a mental health condition or a problem related to alcohol or opioid use. Overall, these findings suggest our episode definitions have face validity and also provide insight into characteristics of people initiating chronic PO therapy. FUTURE PLANS: The cohort will be refreshed every 2 years. Future analyses will explore the association between POs and adverse outcomes.

Kratom (Mitragyna Speciosa) Liver Injury: A Comprehensive Review.

Kratom (Mitragyna speciosa) leaves contain the mu opioid partial agonists mitragynine and 7-hydroxymitragynine. The US Drug Enforcement Agency considers it a 'drug of concern', and the US FDA is reviewing kratom, but there is a paucity of information regarding health effects. Liver injury is often cited as a potential health consequence, however the same few case reports are repeatedly referenced, without a broader context. Furthermore, reports have largely lacked standardized causality assessment methods. The objective is to evaluate causality in kratom liver injury, through a comprehensive scoping review of human cases, and by reviewing epidemiologic, animal, and mechanistic reports that relate to kratom liver injury. Hepatotoxicity causality was systematically examined using the Roussel Uclaf Causality Assessment Method (RUCAM) for case reports. Biopsy findings, potential pathophysiologic mechanisms, and management options are discussed. This review identified 26 case reports and abstracts, in addition to 7 cases reported from the Drug-Induced Liver Injury Network, 25 in FDA databases, and 27 in internet user forums. Latency periods to symptom onset had a median of 20.6 days and mean of 21 days (range 2-49). Common presenting signs and symptoms were abdominal discomfort, jaundice, pruritis, and dark urine. Histologic findings were predominantly cholestatic, although, biochemically, the condition was heterogenous or mixed; the median R ratio was 3.4 and the mean was 4.6 (range 0.24-10.4). Kratom likely causes liver injury based on the totality of low-quality human evidence, and, in the context of epidemiologic, animal, and mechanistic studies. It remains unclear which subgroups of users are at heightened risk.

Brief report: Characterization of marijuana use in us college students by state marijuana legalization status as reported to an online survey.

BACKGROUND AND OBJECTIVE: US college student marijuana use is the highest since 1980. The objective was to investigate use characteristics among college students. METHODS: The RADARS® System College Survey Program surveyed individuals in a university, technical or online school. This was a secondary analysis of existing data. RESULTS: Seven thousand one hundred five students were enrolled, <30% of students' perceived marijuana use a health risk. Students in medical states were more likely to use marijuana compared to non-legal states. (p < .001) Smoking and edibles were common methods of use. CONCLUSIONS: Higher reports of college student use were observed in medical states without differences in risk perception. SCIENTIFIC SIGNIFICANCE: This study further demonstrates the public health impact of marijuana legalization by comparing college study use of marijuana by state legalization status, and demonstrating high rates of use of concentrated products. These findings should be factored when determining regulations and preventative measures when legalizing marijuana. (Am J Addict 2019;28:266-269).

Real-world misuse, abuse, and dependence of abuse-deterrent versus non-abuse-deterrent extended-release morphine in Medicaid non-cancer patients.

OBJECTIVE: Opioids with abuse-deterrent properties may reduce widespread abuse, misuse, and diversion of these products. This study aimed to quantify misuse, abuse, dependence, and health resource use of extended-release morphine sulfate with sequestered naltrexone hydrochloride (ER-MSN; EMBEDA®), compared with non-abuse-deterrent extended-release morphine (ERM) products in Medicaid non-cancer patients. METHODS: Administrative medical and pharmacy claims data were analyzed for 10 Medicaid states from 1 January 2015, to 30 June 2016. Patients were included if they received a prescription for ER-MSN or any oral, non-abuse-deterrent ERM. Index date was the date of first prescription for an ER-MSN or ERM. Abuse/dependence, non-fatal overdose, emergency department (ED) visits, and ED/inpatient readmissions were determined for each participant. An overall measure of misuse and abuse was also calculated. To account for differences in follow-up, all counts are expressed per 100 patient-years. RESULTS: There were 4,857 patients who received ER-MSN and 10,357 who received an ERM. The average age in the two cohorts was approximately 45 years old. From pre-index to follow-up, the number of patients per 100 patient-years with a diagnosis code indicating abuse or dependence increased by 0.91 (95% confidence interval [CI]: 0.85, 0.97) in the ER-MSN cohort and 2.23 (95% CI: 2.14, 2.32) in the ERM cohort. The number of patients per 100 patient-years with an opioid-related non-fatal overdose increased by 0.05 (95% CI: 0.04, 0.06) in the ER-MSN cohort compared with 0.11 (95% CI: 0.09, 0.13) in the ERM cohort. The opioid abuse overall composite score increased by 1.36 (95% CI: 1.24, 1.48) in the post-index period in the ER-MSN cohort compared to 3.21 (95% CI: 3.10, 3.32) in the ERM cohort. CONCLUSION: Misuse, abuse, and dependence events were numerically lower in patients receiving ER-MSN compared with those receiving ERM products.

Fewer adverse effects associated with a modified two-bag intravenous acetylcysteine protocol compared to traditional three-bag regimen in paracetamol overdose.

Context: The intravenous (IV) N-acetylcysteine (NAC) regimen used worldwide in paracetamol overdose is complex with three separate weight-based doses and is associated with a high incidence of adverse events including non-allergic anaphylactoid reactions (NAARs). In 2012, Denmark adopted the two-bag IV NAC regimen which combined the first two infusions of the three-bag regimen and kept the third infusion unchanged. We compared the safety and efficacy of the two-bag IV NAC regimen with the traditional Danish three-bag regimen. Methods: A medical chart review was conducted in three Danish medical centers from January 2012 through December 2014. Safety and efficacy data were compared for patients who received the traditional infusion protocol in Denmark or the 20-h two-bag IV regimen. Results: Four hundred and ninety-three cases received the two-bag regimen and 274 received the three-bag regimen. The overall incidence of NAARs was 9% with all being mild to moderate in intensity. Fewer subjects in the two-bag group (4%) developed NAARs compared to 17% in the three-bag group (p < .001). Overall, 31 patients (4%) developed hepatotoxicity. There was no apparent difference in hepatotoxicity rates between the groups and no deaths or liver transplants. Patients receiving the two-bag regimen had fewer interruptions or delays (5%) compared to the three-bag regimen cohort (12%). Overall, there were very few medication errors reported (1%). Conclusions: The incidence of NAARs was lower in patients receiving acetylcysteine in a two-bag regimen compared to the traditional Danish three-bag regimen without an apparent reduction in efficacy.

Expert Consensus Guidelines for Stocking of Antidotes in Hospitals That Provide Emergency Care.

We provide recommendations for stocking of antidotes used in emergency departments (EDs). An expert panel representing diverse perspectives (clinical pharmacology, medical toxicology, critical care medicine, hematology/oncology, hospital pharmacy, emergency medicine, emergency medical services, pediatric emergency medicine, pediatric critical care medicine, poison centers, hospital administration, and public health) was formed to create recommendations for antidote stocking. Using a standardized summary of the medical literature, the primary reviewer for each antidote proposed guidelines for antidote stocking to the full panel. The panel used a formal iterative process to reach their recommendation for both the quantity of antidote that should be stocked and the acceptable timeframe for its delivery. The panel recommended consideration of 45 antidotes; 44 were recommended for stocking, of which 23 should be immediately available. In most hospitals, this timeframe requires that the antidote be stocked in a location that allows immediate availability. Another 14 antidotes were recommended for availability within 1 hour of the decision to administer, allowing the antidote to be stocked in the hospital pharmacy if the hospital has a mechanism for prompt delivery of antidotes. The panel recommended that each hospital perform a formal antidote hazard vulnerability assessment to determine its specific need for antidote stocking. Antidote administration is an important part of emergency care. These expert recommendations provide a tool for hospitals that offer emergency care to provide appropriate care of poisoned patients.

Serum Acetaminophen Protein Adduct Concentrations in Pediatric Emergency Department Patients.

OBJECTIVES: Acetaminophen toxicity is a common cause of pediatric liver failure. The diagnosis may be limited by the short window of detection of acetaminophen in serum. Recently acetaminophen protein adducts (APAP-CYS) have been used as a biomarker with a longer duration of detection. The objective of this study was to describe the serum concentrations of APAP-CYS in pediatric patients with and without reported therapeutic acetaminophen exposure. METHODS: A cross-sectional study of children age 1 to <12 years presenting to a pediatric emergency department. Subjects were stratified by recent acetaminophen use and had serum APAP-CYS measured using LC/MS. RESULTS: One hundred patients were enrolled. All of the patients whose caregivers denied acetaminophen exposure had nondetectable APAP-CYS. Fifty-two percent of subjects who were reported to have taken acetaminophen in the preceding 2 weeks had detectable serum APAP-CYS. The APAP-CYS concentrations were positively correlated with higher overall dose and more recent ingestion. CONCLUSIONS: APAP-CYS is detectable in the majority of children taking acetaminophen and not detected in the majority of children who are not exposed to acetaminophen.

Outcomes of Patients With Premature Discontinuation of the 21-h Intravenous N-Acetylcysteine Protocol After Acute Acetaminophen Overdose.

BACKGROUND: The minimum recommended treatment duration for i.v. N-acetylcysteine (NAC) after an acute, single acetaminophen (APAP) overdose is 21 h. Some have questioned whether shorter courses may be sufficient in carefully selected cases. OBJECTIVE: We sought to describe the incidence of hepatotoxicity in a cohort of acute APAP overdose patients who received <21 h of i.v. NAC for any reason. METHODS: We performed a secondary analysis of a large multicenter retrospective cohort of patients hospitalized for APAP poisoning. We selected patients with a potentially toxic serum APAP concentration measured between 4 and 24 h post ingestion, in whom i.v. NAC was initiated but discontinued before completing the full 21-h course. We further characterized outcomes in these patients as a function of two novel risk-prediction tools, the psi (ψ) parameter and APAP × aminotransferase (AT) product. The ψ parameter is an estimate of the cellular burden of injury based on the area under the concentration-time curve before treatment, and calculated with respect to the APAP concentration and time to initiation of NAC. RESULTS: Fifty-nine patients met inclusion criteria. Intravenous NAC was initiated a median of 11.3 h post ingestion and administered for a median of 11.0 h. Hepatotoxicity (aspartate aminotransferase [AST] or alanine aminotransferase [ALT] > 1,000 IU/L) occurred in one patient (1.7%; 95% confidence interval 0.04-9.1), and eight additional patients developed hepatic injury (AST or ALT > 100 IU/L). No fatalities occurred. A multiplication product of APAP and AT (APAP × AT) that falls below 10,000 µmol/L/IU-L, or pretreatment ψ < 5 mmol/L-h suggested a low risk of hepatic injury. CONCLUSIONS: In this retrospective analysis of patients treated with < 21 h of i.v. NAC for acute APAP overdose, the incidence of hepatotoxicity and coagulopathy was low, despite delays to NAC treatment.

Acute hepatotoxicity associated with therapeutic doses of intravenous acetaminophen.

BACKGROUND: IV acetaminophen at 4 g per day is considered safe, producing no hepatic failure in more than 1400 cases. Oxidation of acetaminophen forms a reactive intermediate that binds to cellular proteins resulting in acetaminophen-protein adducts (APAP-CYS). Serum concentrations of APAP-CYS have been found to correlate with acetaminophen-induced hepatotoxicity. We report a case of hepatotoxicity associated with therapeutic doses of IV acetaminophen, with elevated serum APAP-CYS. CASE DETAILS: The patient was a 92-year-old, 68 kg woman without known hepatic disease or ethanol abuse. On hospital day 3 she underwent laparoscopic reduction of internal hernias under general anesthesia. Surgery was uncomplicated and postoperatively she was treated with subcutaneous heparin and IV acetaminophen, 1 g every 6 h for almost 4 days (total dose = 13 g). At the start of therapy, transaminases were normal. On hospital day 5, she was noted to have marked transaminase elevations (AST: 4698 IU/L; ALT: 3914 IU/L) with increases in INR (1.68), ammonia (60 mcg/dL), and total bilirubin (1.8 mg/dL). Serum acetaminophen concentration was 15.3 mcg/mL 26 h after her last dose. Acetaminophen was discontinued and IV acetylcysteine was given and continued at the second maintenance dose rate for a second 16-hour infusion, at which time transaminases, INR, ammonia and total bilirubin were all improving. The patient was discharged 2 days later. Serum APAP-CYS concentrations in serum samples obtained during her hospitalization were elevated (peak = 4.81 µM on hospital day 5; expected range for therapeutic dosing <1.1 µM). CASE DISCUSSION: We have identified a case of acute liver injury associated with therapeutic dosing of IV acetaminophen. The serum APAP-CYS concentrations are consistent with that seen in cases of hepatotoxicity following repeated supratherapeutic acetaminophen ingestion. Several factors that likely contributed to her susceptibility included advanced age, post-operative status, a likely catabolic state and multiple acetaminophen doses over several days. These uncommon circumstances limit the generalizability of risk. We believe the findings are most consistent with acetaminophen-induced liver injury. CONCLUSION: This case illustrates a potential hazard of IV acetaminophen and demonstrates the potential utility of APAP-CYS adducts in evaluating causality in acute liver injury.

Paracetamol (acetaminophen) protein adduct concentrations during therapeutic dosing.

BACKGROUND: Paracetamol protein adducts (PPA) are a biomarker of paracetamol exposure. PPA are quantified as paracetamol-cysteine (APAP-CYS), and concentrations above 1.1 µmol l(-1) have been suggested as a marker of paracetamol-induced hepatotoxicity. However, there is little information on the range of concentrations observed during prolonged therapeutic dosing. AIM: The aim of the present study was to describe the concentration of PPA in the serum of subjects taking therapeutic doses of paracetamol for at least 16 days. METHODS: Preplanned secondary aim of a prospective randomized controlled (placebo vs. 4g day(-1) paracetamol) trial. We measured subjects' serum PPA concentrations every 3 days for a minimum of 16 days. We also measured concentrations on study days 1-3 and 16-25 in subsets of patients. PPA were quantified as APAP-CYS after gel filtration and protein digestion using liquid chromatography/mass spectrometry. RESULTS: Ninety per cent of subjects had detectable PPA after five doses. Median APAP-CYS concentrations in paracetamol-treated subjects increased to a plateau of 0.1 µmol l(-1) on day 7, where they remained. The highest concentration measured was 1.1 µmol l(-1) and two subjects never had detectable PPA levels. PPA were detected in the serum of 78% of subjects 9 days after their final dose. CONCLUSIONS: PPA are detectable in the vast majority of subjects taking therapeutic doses of paracetamol. While most have concentrations well below the threshold associated with hepatotoxicity, concentrations may approach 1.1 µmol l(-1) in rare cases. Adducts are detectable after a few doses and can persist for over a week after dosing is stopped.

Prescription opioid exposures and adverse outcomes among older adults.

PURPOSE: A high prevalence of chronic pain and high rates of polypharmacy among older adults suggest that this age group may be particularly susceptible to unintentional misuse of prescription opioids. We examined recent trends in misuse of prescription opioids and associated medical outcomes among older-aged adults (60+ years) and compared the patterns with trends among younger-aged adults (20-59 years). METHODS: Linear regression trend analysis was used to analyze 57 681 misuse cases reported to participating US poison centers during 2006-2014. RESULTS: Population rates of misuse of prescription opioids were higher for older adults than for younger adults, and this disparity increased over time. Rates among the older ages increased each year, although the rate of increase slowed over time (p < 0.0001 for negative quadratic trend). In contrast, among the younger adults, there was a significant negative quadratic trend in population rates (p < 0.0001) with a rise in rates during 2006-2010 followed by a decline during 2011-2014. Rates of serious medical outcomes among the older ages followed an increasing linear trend (p < 0.0001); in contrast, rates among younger adults rose and fell during the period, with recent rates trending downward (p < 0.0001 for quadratic trend). CONCLUSIONS: Recent increases in rates of misuse of prescription opioids and associated unfavorable medical outcomes among older adults have important implications as the USA undergoes a rapid expansion of its elderly population. Copyright © 2015 John Wiley & Sons, Ltd.

Confirming the Causative Role of Acetaminophen in Indeterminate Acute Liver Failure Using Acetaminophen-Cysteine Adducts.

INTRODUCTION: Acetaminophen-cysteine adducts (APAP-CYS) are a serum biomarker of acetaminophen exposure, formed when the oxidative metabolite of acetaminophen binds to cysteine residues of hepatic proteins. APAP-CYS adducts become elevated in cases of acute liver failure following acetaminophen overdose and have been proposed as a diagnostic tool to identify acetaminophen-induced acute liver failure when standard testing is inconclusive. CASE REPORT: A 26-year-old female with history of unexplained, severe hepatitis presented with a second episode of severe hepatitis including coagulopathy and transaminase levels >10,000 U/L. The patient reported ingesting "only a couple" of acetaminophen tablets several days prior to her presentation. An acetaminophen concentration of 14 mcg/mL at presentation aroused suspicion that acetaminophen might have caused the patient's liver failure, despite her adamant denial of overdose. APAP-CYS adduct levels measured from serum obtained 4 days after her presentation and in two consecutive serum samples are reported alongside previously reported APAP-CYS levels. DISCUSSION: The patient's APAP-CYS adduct levels were consistent with those seen in acute liver injury due to acetaminophen toxicity, even up to 1 week following presentation, and allowed for confirmation of acetaminophen toxicity as the cause of the her hepatitis. Overall, this case demonstrates the real-time application of APAP-CYS adducts as a biomarker to diagnose acetaminophen toxicity in patients with indeterminate acute liver failure.

Quantification of a biomarker of acetaminophen protein adducts in human serum by high-performance liquid chromatography-electrospray ionization-tandem mass spectrometry: clinical and animal model applications.

The aims of this study were to develop, validate, and apply a high-performance liquid chromatography-electrospray ionization-tandem mass spectrometry (HPLC-ESI-MS/MS) method for quantification of protein-derived 3-(cystein-S-yl)-acetaminophen (APAP-Cys) in human serum. Formation of acetaminophen (APAP) protein adducts is thought to be a critical, early event in the development of APAP-induced hepatotoxicity, and quantification of these protein adducts in human serum represents a valuable tool for assessment of APAP exposure, metabolism, and toxicity. In the reported procedure, serum samples were first dialyzed or passed through gel filtration columns to remove APAP-Cys not covalently bound to proteins. Serum eluates were then subjected to enzymatic protease digestion to liberate protein-bound APAP-Cys. Norbuprenorphine-D3 was utilized as an internal standard (IS). APAP-Cys and IS were recovered from digested serum by protein precipitation with acetonitrile, and sample extracts were analyzed by HPLC-ESI-MS/MS. The method was validated by assessment of intra- and inter-assay accuracy and imprecision on two different analytical instrument platforms. APAP-Cys could be accurately quantified from 0.010 to 10µM, and intra- and inter-assay imprecision were <15% on both analytical instruments. APAP-Cys was stable in human serum for three freeze-thaw cycles and for 24h at ambient temperature. Extracted samples were stable when stored in refrigerated autosamplers for the typical duration of analysis or when stored at -20°C for six days. Results from process efficiency and matrix effect experiments indicated adequate recovery from human serum and insignificant ion suppression or enhancement. The utility and sensitivity of the reported procedure were illustrated by analysis of clinical samples collected from subjects taking chronic, therapeutic doses of APAP. Applicability to other biological matrices was also demonstrated by measurement of protein-derived APAP-Cys in plasma collected from APAP-treated mice, a common animal model of APAP-induced hepatotoxicity.

Trends in opioid analgesic abuse and mortality in the United States.

BACKGROUND: The use of prescription opioid medications has increased greatly in the United States during the past two decades; in 2010, there were 16,651 opioid-related deaths. In response, hundreds of federal, state, and local interventions have been implemented. We describe trends in the diversion and abuse of prescription opioid analgesics using data through 2013. METHODS: We used five programs from the Researched Abuse, Diversion, and Addiction-Related Surveillance (RADARS) System to describe trends between 2002 and 2013 in the diversion and abuse of all products and formulations of six prescription opioid analgesics: oxycodone, hydrocodone, hydromorphone, fentanyl, morphine, and tramadol. The programs gather data from drug-diversion investigators, poison centers, substance-abuse treatment centers, and college students. RESULTS: Prescriptions for opioid analgesics increased substantially from 2002 through 2010 in the United States but then decreased slightly from 2011 through 2013. In general, RADARS System programs reported large increases in the rates of opioid diversion and abuse from 2002 to 2010, but then the rates flattened or decreased from 2011 through 2013. The rate of opioid-related deaths rose and fell in a similar pattern. Reported nonmedical use did not change significantly among college students. CONCLUSIONS: Postmarketing surveillance indicates that the diversion and abuse of prescription opioid medications increased between 2002 and 2010 and plateaued or decreased between 2011 and 2013. These findings suggest that the United States may be making progress in controlling the abuse of opioid analgesics. (Funded by the Denver Health and Hospital Authority.).

Medically significant late bleeding after treated crotaline envenomation: a systematic review.

STUDY OBJECTIVE: We estimate the proportion of patients with crotaline snake envenomation who are treated with Crotalidae polyvalent immune Fab (ovine) antivenom and who develop medically significant late bleeding. METHODS: We performed a systematic review of all published cohort studies of North American crotaline snake envenomation patients treated with Fab antivenom. We searched PubMed, Ovid MEDLINE, and EMBASE from January 1, 1997, to April 30, 2012. Data were extracted by 2 trained researchers. Late bleeding was defined as bleeding that began or recurred after initial control of the envenomation syndrome. Medically significant late bleeding was defined a priori as late bleeding treated with RBC transfusion, vasoactive drug infusion, surgery, or rehospitalization or associated with a hemoglobin decrease of greater than or equal to 3 g/dL, hematocrit decrease of greater than or equal to 8%, disability, or death. Summary incidence and 95% confidence intervals (CIs) were calculated with a random-effects Poisson regression model. RESULTS: Nineteen unique cohort studies were identified. Four studies collected data prospectively, and in 9 studies, patients were followed actively after hospital discharge. A total of 1,017 subjects were enrolled in these cohort studies. Late bleeding was reported in 9 subjects (0.9%; 95% CI 0.4% to 2.2%), of whom 5 subjects (0.5%; 95% CI 0.1% to 1.7%) had medically significant late bleeding. Three patients received RBC transfusion; no deaths or permanent sequelae were reported. Estimates of risk may be affected by underreporting. CONCLUSION: Medically significant late bleeding appears to be uncommon in snakebite victims treated with Fab antivenom.