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.

Metabolomic Evaluation of N-Acetyl-p-Benzoquinone Imine Protein Adduct Formation with Therapeutic Acetaminophen Administration: Sex-based Physiologic Differences.

BACKGROUND: Acetaminophen (APAP)-associated transaminase elevation, induced by N-acetyl-p-benzoquinone imine (NAPQI) protein adduction, remains an area of research interest. Distinct from known genetic, physiologic, and dosage associations dictating severity of hepatic injury, no known factors predict an absence of protein adduct formation at therapeutic APAP dosing. HYPOTHESIS: Sex-based physiology is predictive of APAP-induced protein adduct formation and differential metabolite expression at therapeutic doses. METHODS: This retrospective study interrogated serum samples collected for a prior study investigating fluctuations of alanine aminotransferase (ALT) over time with 4G daily APAP dosing for ≥ 16 days in subjects from Denver, Colorado. Subjects were grouped by adduct formation (n = 184) vs no adducts (n = 20). Samples were run on ultra-high-performance liquid chromatography mass spectrometry from study days 0, 7, 16, and 31. Significant metabolite expressions were identified using t-tests with false discovery rate correction (FDR), partial least squares discriminant, and ANOVA simultaneous comparison analyses. Demographic and clinical data were explored using t-tests with FDR (age, weight, BMI, ALT) and Chi-square (sex, ethnicity, race) analyses. RESULTS: In pre-treatment samples, relative quantitation caprylic acid was expressed ninefold higher and 6-carboxyhexanoate was expressed threefold lower in subjects who did not develop adducts. Lactate had greater expression in the no adducts group (p = 0.001). Using absolute quantitation, glutathione was expressed 2.6-fold greater among no adduct subjects. Odds of males developing NAPQI protein adducts at therapeutic APAP dosing were 5.91 times lower than females (95% CI = 2.3-14.9; p = 0.0001). CONCLUSION: Multiple metabolites were differentially expressed based on adduct group and sex. Metabolites were identified unique to adduct development independent of sex. At therapeutic APAP dosing, males were less likely to develop APAP protein adducts. Further research into lipid biosynthesis and metabolism may provide further insight into physiology associated with adduct production.

Association of Emergency Department Opioid Administration With Ongoing Opioid Use: A Retrospective Cohort Study of Patients With Back Pain.

OBJECTIVES: Opioids are commonly administered in the emergency department (ED) and prescribed for the treatment of back pain. It is important to understand the unintended consequences of this approach to inform treatment decisions and the consideration of alternative treatments. Recent evidence has shown that ED opioid prescriptions are associated with future opioid use. The objective of this study was to measure the association of opioid administration in the ED to patients treated for back pain with future opioid use. METHODS: This is a retrospective study of opioid-naïve adults discharged from the ED with a diagnosis of back pain. Patients were stratified by opioid therapy (none, ED administration only, prescription only, or ED administration + prescription). Relative risks of ongoing opioid use (filling >90-day supply in 180 days following ED visit as documented in the prescription drug monitoring program) were calculated for each opioid-therapy group and compared to the no-opioid group. RESULTS: We identified 24,487 opioid naïve back pain patients. The median age was 38 years, 55% were female, and 56% were non-Hispanic white. A total of 41% received no opioid, 10% were only administered an opioid in the ED, 18% only received a prescription, and 31% received an opioid in the ED + prescription. The adjusted relative risks of ongoing use compared to the no opioid group were as follows: ED only 1.9, prescription only 2.1, and ED + prescription 2.3. The increased risk persisted for other definitions of ongoing use and after adjustment for baseline pain scores. CONCLUSIONS: For opioid-naïve patients with back pain, both administration of an opioid in the ED and opioid prescriptions are associated with a doubling of the risk of ongoing opioid use compared to patients not treated with opioids. This supports the consideration of minimizing exposure to opioids while treating back pain in the ED.

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.

Assessment of toxicology knowledge in the fourth-year medical students: Three years of data.

BACKGROUND: Pharmacology and toxicology are core content knowledge for physicians. Medical students should demonstrate understanding of general pharmacology and basic treatment of poisoning. The objective of this study was to measure the knowledge of the 4th-year medical students (MS4) on these topics over 3 years. METHODS: A multiple-choice exam (15 questions) was administered to MS4 students in spring of 2010, 2011, and 2012. Questions were developed by medical toxicologists to evaluate basic knowledge in three areas: pharmacologic effects (PE), treatment of poisoning (TOP), and pharmacokinetics (PK). The students were grouped by intended specialties into pharmacologic intense (anesthesia, emergency medicine, internal medicine, pediatrics, and psychiatry), less pharmacologic intense specialties (dermatology, OB/GYN, ophthalmology, pathology, physical medicine and rehabilitation, radiology, and surgery) and by completion of a pharmacology or toxicology elective. Mean group scores were compared using ANOVA. RESULTS: Totally 332 of 401 (83%) students completed the survey. Mean scores were stable over the three years, higher for students completing a toxicology rotation and for students entering a pharmacologically intense specialty. CONCLUSION: The external validity is limited to a single medical school with incomplete participation and content was limited by the survey length. Consistent results over the three-year period and correlation of performance with completing a toxicology rotation and intent to enter a pharmacology intensive specialty suggest this survey may correlate with toxicology knowledge. Implementation of required core courses focused on toxicology may improve core content knowledge in fourth year medical students.

Medication organizers (pill minders) increase the risk for unintentional pediatric ingestions.

OBJECTIVE: Medication organizers may help improve medication compliance; however, they may increase the risk of having an unintentional pediatric exposure. The objective of this study was to measure the association between a pediatric emergency department (ED) visit for an unintentional pharmaceutical ingestion and the use of a medication organizer in the household. METHODS: This was a cross-sectional case control study at a tertiary care children's hospital ED. Cases included subjects <6 years of age who were evaluated in the ED for an unintentional pharmaceutical ingestion. The control group presented to the ED for a non-injury complaint and was matched using age and sex. RESULTS: The unadjusted odds ratio (OR) of risk for unintentional pharmaceutical ingestion with use of a medication organizer was 2.0 (95% CI, 1.3, 2.9). After adjusting for the presence of prescription medications in the home, the OR of risk for ingestion remained statistically significant at 1.8 (95% CI, 1.1, 2.7). The child obtained the exposure medication from the medication organizer in 63% of cases where a medication organizer was present in the home. Cases were more likely to have knowledge of, and previous contact with poison control centers (PCC) than non-injury controls. Overall, a large number of caregivers (36%) did not have any knowledge of PCC. There were also differences in smoking and use of seat belts between cases and controls. CONCLUSIONS: The use of medication organizers may be a risk factor for unintentional pediatric pharmaceutical ingestions, even when controlling for the use of prescription medications in the home. Further research is needed to evaluate the specific role of medication organizers, and subsequently, improve prevention strategies.

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.

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.

Acetylcysteine for acetaminophen overdose in patients who weigh >100 kg.

N-Acetylcysteine (NAC) dosing for acetaminophen (APAP) overdose is weight based (150 mg/kg intravenous or 140-mg/kg oral loading dose) and, in the United States, the dosing protocol recommends using a maximum patient weight of 100 and 110 kg, respectively. Little clinical data describe the use of NAC for APAP poisoning in patients weighing >100 kg. The aim of this study was to describe the demographics, outcomes, and adverse event (AE) rates of patients weighing >100 kg treated with oral or IV NAC for APAP poisoning. Patients were identified from a multicenter retrospective NAC safety study for APAP overdose. We included patients with a recorded weight. Trained chart abstractors used a standardized form. Selected data included age, gender, weight, serum alanine transaminase, and aspartate transaminases, coingestants, NAC administration route, ingestion type, AEs, and outcome [hepatotoxicity (alanine transaminase > 1000 U/L), liver transplant, or death]. Descriptive statistics were used. Of 503 study patients, 37 (7.4%) had recorded weights >100 kg. The median (range) weight was 110 kg (101-160). The median (range) dosing for patients treated with oral NAC was 140 mg/kg (127-143 mg/kg) and 150 (108-168) mg/kg for IV NAC. Hepatotoxicity occurred in 12/36 (33.3%) patients. Death occurred in 4/36 (11.1%) patients. Thirteen NAC-related AEs occurred in 8 patients (1.6 per person). All AEs were related to NAC and were rated nonserious by the reviewer. Clinicians use an actual weight-based NAC dose rather than a maximum weight cutoff dose. Hepatotoxicity was common in our cohort. AEs were relatively common but not serious.

Fatal cesium chloride toxicity after alternative cancer treatment.

BACKGROUND: Cesium chloride (CsCl) is sold as a treatment for several types of cancers. The purported mechanism of action is alkalinization of relatively acidic neoplastic cells. The efficacy of CsCl has not been demonstrated in controlled experiments. Oral and intravenous CsCl use has been associated with seizures, cardiotoxicity, syncope, and death. Although intratumoral treatment with various antineoplastic agents is described, no cases of intratumoral cancer treatment with CsCl have been found in the medical literature. The case described here appears to be of the first reported patient with CsCl toxicity secondary to subcutaneous exposure after attempted intratumoral injection. CASE DETAILS: A 61-year-old woman presented in cardiac arrest 20 hours after injecting 9 mL of an oral CsCl preparation around a mass in her breast. She had been taking the CsCl orally for approximately 1 year to treat her breast mass. The patient had a headache and nausea for several hours after injection and then experienced ventricular tachycardia arrest at home. She received advanced cardiac life support care and multiple antiarrhythmic medications and underwent electrical cardioversion early in the course of the arrest. After stabilization, her electrocardiogram revealed QT interval prolongation to >700 milliseconds. Upon discovery of her CsCl exposure, she was treated with Prussian blue. Her initial whole blood cesium level was 100,000 µg/L (reference range <10 µg/L). Her QT prolongation resolved after several days, but she experienced no meaningful postarrest neurologic recovery and died at home less than a week after exposure. DISCUSSION: CsCl is sold as an alternative treatment for cancer. There is no demonstrable efficacy, and clear evidence shows life-threatening toxicity. Reported here is a case of fatal CsCl toxicity after attempted intratumoral injection.

Acetylcysteine therapy for acetaminophen poisoning.

Acetylcysteine has been used to treat acetaminophen overdose for nearly 50 years. While no placebo controlled trials have been conducted, the efficacy of acetylcysteine is accepted for the prevention of hepatic injury when administered early after acetaminophen overdose. Acetylcysteine can be administered as an infusion or oral solution. The duration of treatment varies from 21 to 72 hours, depending on the protocol. Acetylcysteine also prevents death when administered to patients with hepatic failure from acetaminophen.

Massive acetylcysteine overdose associated with cerebral edema and seizures.

CONTEXT: Acetylcysteine is a safe and effective treatment for the prevention of hepatic injury due to acetaminophen poisoning. While dosing errors are common, in most cases, overdoses produce minimal clinical effects. CASE REPORT: We describe a patient who received 150 g of IV acetylcysteine over 32 h when the clinician ordered the infusion doses be administered as an hourly dose (100 mg/kg/h) rather than administered over the infusion duration (100 mg/kg over 16 h). After approximately 28 h of receiving 100 mg/kg/h, the patient developed delirium, and seizures that progressed to cerebral edema, uncal herniation, and ultimately severe brain injury. No other cause for her symptoms was identified during an extensive workup. DISCUSSION: This case suggests that massive IV acetylcysteine overdose can cause cerebral dysfunction and life-threatening effects.

Acetaminophen-cysteine adducts during therapeutic dosing and following overdose.

BACKGROUND: Acetaminophen-cysteine adducts (APAP-CYS) are a specific biomarker of acetaminophen exposure. APAP-CYS concentrations have been described in the setting of acute overdose, and a concentration >1.1 nmol/ml has been suggested as a marker of hepatic injury from acetaminophen overdose in patients with an ALT >1000 IU/L. However, the concentrations of APAP-CYS during therapeutic dosing, in cases of acetaminophen toxicity from repeated dosing and in cases of hepatic injury from non-acetaminophen hepatotoxins have not been well characterized. The objective of this study is to describe APAP-CYS concentrations in these clinical settings as well as to further characterize the concentrations observed following acetaminophen overdose. METHODS: Samples were collected during three clinical trials in which subjects received 4 g/day of acetaminophen and during an observational study of acetaminophen overdose patients. Trial 1 consisted of non-drinkers who received APAP for 10 days, Trial 2 consisted of moderate drinkers dosed for 10 days and Trial 3 included subjects who chronically abuse alcohol dosed for 5 days. Patients in the observational study were categorized by type of acetaminophen exposure (single or repeated). Serum APAP-CYS was measured using high pressure liquid chromatography with electrochemical detection. RESULTS: Trial 1 included 144 samples from 24 subjects; Trial 2 included 182 samples from 91 subjects and Trial 3 included 200 samples from 40 subjects. In addition, we collected samples from 19 subjects with acute acetaminophen ingestion, 7 subjects with repeated acetaminophen exposure and 4 subjects who ingested another hepatotoxin. The mean (SD) peak APAP-CYS concentrations for the Trials were: Trial 1- 0.4 (0.20) nmol/ml, Trial 2- 0.1 (0.09) nmol/ml and Trial 3- 0.3 (0.12) nmol/ml. APAP-CYS concentrations varied substantially among the patients with acetaminophen toxicity (0.10 to 27.3 nmol/ml). No subject had detectable APAP-CYS following exposure to a non-acetaminophen hepatotoxin. CONCLUSIONS: Lower concentrations of APAP-CYS are detectable after exposure to therapeutic doses of acetaminophen and higher concentrations are detected after acute acetaminophen overdose and in patients with acetaminophen toxicity following repeated exposure.

Hepatic failure despite early acetylcysteine following large acetaminophen-diphenhydramine overdose.

We describe the case of a patient with massive acetaminophen-diphenhydramine overdose and a 4-hour serum acetaminophen concentration of 653 µg/mL. The patient was treated with acetylcysteine 5 hours after ingestion. Because of a persistently elevated serum acetaminophen level of 413 µg/mL 45 hours after ingestion, a medical toxicologist recommended that the patient be treated with a second bolus of acetylcysteine (150 mg/kg followed by 12.5 mg/kg per hour for 4 hours, then 6.25 mg/kg per hour). On hospital day 3, she developed hepatic failure despite early treatment. Her transaminase levels and hepatic synthetic function began to improve on hospital day 6, and acetylcysteine was discontinued on hospital day 10. In cases of massive acetaminophen overdose, standard acetylcysteine dosing may not be adequate. We suggest that elevated serum acetaminophen concentrations at the end of a standard 20-hour acetylcysteine infusion should be discussed with the local poison center.

A multicenter comparison of the safety of oral versus intravenous acetylcysteine for treatment of acetaminophen overdose.

UNLABELLED: Oral and intravenous (IV) N-acetylcysteine (NAC) are used for the treatment of acetaminophen poisoning. The objective of this multicenter study was to compare the safety of these two routes of administration. METHODS: We conducted a multicenter chart review of all patients treated with NAC for acetaminophen poisoning. The primary safety outcome was the percentage of patients with NAC-related adverse events. RESULTS: A total of 503 subjects were included in the safety analysis (306 IV-only, 145 oral-only, and 52 both routes). There were no serious adverse events related to NAC for either route. Nausea and vomiting were the most common related adverse events and were more common with oral treatment (23 vs. 9%). Anaphylactoid reactions were more common with IV administration (6 vs. 2%). CONCLUSIONS: IV and oral NAC are generally mild adverse drug reactions.