Clinical course of repeated supratherapeutic ingestion of acetaminophen

Severe Acetaminophen Toxicity From the Use of Oxycodone-Acetaminophen With Normal Liver Function Tests and a Completely Asymptomatic Course of Hospitalization

Acetaminophen (N-acetyl-p-aminophenol, APAP), after being metabolized to toxic N-acetyl-p-benzoquinone imine, can cause irreversible hepatic necrosis. The mainstay of treatment includes N-acetylcysteine and fomepizole or liver transplant in patients who further deteriorate. Currently, many overdoses unintentionally occur in the setting of ingesting combined products that contain APAP. We report a rare case of a 60-year-old woman who presented with altered mental status and APAP toxicity in the setting of oxycodone-APAP overdose. She had a toxic serum APAP level on arrival. During hospitalization, her APAP level remained at the toxic level on the Rumack-Matthew nomogram. However, her liver function tests remained within normal limits, and she remained completely asymptomatic. To our best knowledge, this is the second case report with asymptomatic APAP toxicity and normal liver function tests. We will explore the effect of concomitant oxycodone ingestion on possibly delaying APAP absorption and thus resulting in a more favorable prognosis without hepatotoxicity.

Using a decision tree algorithm to distinguish between repeated supra-therapeutic and acute acetaminophen exposures

BACKGROUND

This study aimed to compare clinical and laboratory characteristics of supra-therapeutic (RSTI) and acute acetaminophen exposures using a predictive decision tree (DT) algorithm.

METHODS

We conducted a retrospective cohort study using the National Poison Data System (NPDS). All patients with RSTI acetaminophen exposure (n = 4,522) between January 2012 and December 2017 were included. Additionally, 4,522 randomly selected acute acetaminophen ingestion cases were included. After that, the DT machine learning algorithm was applied to differentiate acute acetaminophen exposure from supratherapeutic exposures.

RESULTS

The DT model had accuracy, precision, recall, and F1-scores of 0.75, respectively. Age was the most relevant variable in predicting the type of acetaminophen exposure, whether RSTI or acute. Serum aminotransferase concentrations, abdominal pain, drowsiness/lethargy, and nausea/vomiting were the other most important factors distinguishing between RST and acute acetaminophen exposure.

CONCLUSION

DT models can potentially aid in distinguishing between acute and RSTI of acetaminophen. Further validation is needed to assess the clinical utility of this model.

Paracetamol (acetaminophen) overdose and hepatotoxicity: mechanism, treatment, prevention measures, and estimates of burden of disease

INTRODUCTION

Paracetamol is one of the most used medicines worldwide and is the most common important poisoning in high-income countries. In overdose, paracetamol causes dose-dependent hepatotoxicity. Acetylcysteine is an effective antidote, however despite its use hepatotoxicity and many deaths still occur.

AREAS COVERED

This review summarizes paracetamol overdose and toxicity (including mechanisms, risk factors, risk assessment, and treatment). In addition, we summarize the epidemiology of paracetamol overdose worldwide. A literature search on PubMed for poisoning epidemiology and mortality from 1 January 2017 to 26 October 2022 was performed to estimate rates of paracetamol overdose, liver injury, and deaths worldwide.

EXPERT OPINION

Paracetamol is widely available and yet is substantially more toxic than other analgesics available without prescription. Where data were available, we estimate that paracetamol is involved in 6% of poisonings, 56% of severe acute liver injury and acute liver failure, and 7% of drug-induced liver injury. These estimates are limited by lack of available data from many countries, particularly in Asia, South America, and Africa. Harm reduction from paracetamol is possible through better identification of high-risk overdoses, and better treatment regimens. Large overdoses and those involving modified-release paracetamol are high-risk and can be targeted through legislative change.

Acetaminophen toxicity and overdose: current understanding and future directions for NAC dosing regimens

INTRODUCTION

Although N-acetyl-cysteine (NAC) has long been used for the treatment of acetaminophen poisoning/overdose, the optimal NAC dosing regimen for varying patterns or severity of the poisoning/overdose is still unknown.

AREAS COVERED

Relevant literature was searched for in the MEDLINE (from 1964 until August 31^st, 2022), SCOPUS (from 2004 until August 31^st, 2022) and GOOGLE SCHOLAR (from 2004 until August 31^st, 2022) databases, without restriction in terms of publication date. The inclusion criteria were: original clinical studies reporting results, and studies investigating efficacy and safety of NAC dosing regimens in case(s) of overdose or poisoning with acetaminophen.

EXPERT OPINION

For a more effective treatment of acetaminophen poisoning in the future, it will be crucial to advance the technology of measuring acetaminophen, its metabolites and NAC in the serum, preferably with the point-of-care technique, so that in real time it can be continuously assessed whether it is necessary to administer NAC, and further to increase the dose of NAC and extend the duration of its administration, or not.

N-Acetylcysteine for Preventing Acetaminophen-Induced Liver Injury: A Comprehensive Review

Aims: N-Acetylcysteine (NAC) is used as an antidote in acetaminophen (APAP) overdose to prevent and mitigate drug-induced liver injury (DILI). Our objective was to systematically review evidence of the use of NAC as a therapeutic option for APAP overdose and APAP-related DILI in order to define the optimal treatment schedule and timing to start treatment.

Methods: Bibliographic databases (PubMed, Web of Science, Embase, and MEDLINE) were searched for retrospective and prospective cohort studies, case series, and clinical trials. The prespecified primary outcomes were DILI-related mortality, hepatotoxicity, and adverse events (AEs).

Results: In total, 34 studies of NAC usage in APAP-related DILI cases with 19,580 patients were identified, of which 2,376 patients developed hepatotoxicities. The mortality rate across different studies ranged from 0 to 52%. Large variability of NAC regimens was found, i.e., intravenous (I.V.) (100–150 mg/kg) and oral (70–140 mg/kg), and length of treatment varied—12, 24, or 48 h for I.V. regimen and 72 h for oral administration. The timing of initiation of NAC treatment showed different results in terms of occurrence of hepatotoxicity and mortality; if started within 8 h and no more than 24 h from APAP overdose, either intravenously or orally, NAC administration was efficacious in terms of mortality. The most frequent AEs reported were anaphylactic reactions, followed by cutaneous AEs for the IV route and intestinal AEs for the oral one.

Conclusion: NAC improves hepatotoxicity and reduces mortality. Timing of treatment, ranging from 8 to 24 h from APAP overdose, regardless of the regimen or route of administration, is important to prevent or minimize liver damage, particularly in children and in elderly and obese patients.

The Timing and Effects of Low-Dose Ethanol Treatment on Acetaminophen-Induced Liver Injury

Acetaminophen (APAP) overdose is the major cause of drug-induced liver injury and acute liver failure. Approximately 10% of APAP is metabolized by cytochrome P450 (CYP2E1) into toxic N-acetyl-p-benzoquinone imine (NAPQI). CYP2E1 also contributes to ethanol metabolism, especially during conditions of high blood ethanol concentration. Acute and chronic ethanol consumption appears to have opposite effects on APAP-induced liver injury. We determined the effects of different doses, pre- and post-treatment, and various schedules of ethanol exposure in APAP-induced liver injury. Treatment with ethanol (0.5 g/kg) after 1 h of APAP (300 mg/kg) administration decreased serum ALT levels, histopathological features, and inflammatory cell infiltration. Moreover, ethanol treatment 1 h after APAP treatment reduced APAP-induced liver injury compared with later administration. Interestingly, ethanol pretreatment did not provide any protective effect. Furthermore, ethanol treatment was associated with a significant decrease in ERK and AKT phosphorylation during the acute injury phase. Ethanol exposure also increased CYP2E1 expression and decreased PCNA expression during the liver regeneration phase.

Impaired protein adduct removal following repeat administration of subtoxic doses of acetaminophen enhances liver injury in fed mice

Acetaminophen (APAP) is a widely used analgesic and is safe at therapeutic doses. However, an overdose of APAP is hepatotoxic and accidental overdoses are increasingly common due to the presence of APAP in several combination medications. Formation of protein adducts (APAP-CYS) is central to APAP-induced liver injury and their removal by autophagy is an essential adaptive response after an acute overdose. Since the typical treatment for conditions such as chronic pain involves multiple doses of APAP over time, this study investigated APAP-induced liver injury after multiple subtoxic doses and examined the role of autophagy in responding to this regimen. Fed male C57BL/6J mice were administered repeated doses (75 mg/kg and 150 mg/kg) of APAP, followed by measurement of adducts within the liver, mitochondria, and in plasma, activation of the MAP kinase JNK, and markers of liver injury. The role of autophagy was investigated by treatment of mice with the autophagy inhibitor, leupeptin. Our data show that multiple treatments at the 150 mg/kg dose of APAP resulted in protein adduct formation in the liver and mitochondria, activation of JNK, and hepatocyte cell death, which was significantly exacerbated by inhibition of autophagy. While repeated dosing with the milder 75 mg/kg dose did not cause mitochondrial protein adduct formation, JNK activation, or liver injury, autophagy inhibition resulted in hepatocyte death even at this lower dose. These data illustrate the importance of adaptive responses such as autophagy in removing protein adducts and preventing liver injury, especially in clinically relevant situations involving repeated dosing with APAP.

Metabolomic analysis of acetaminophen induced subclinical liver injury

Introduction: This study examines the metabolomic profile in humans following acetaminophen (APAP) induced subclinical hepatoxicity in the presence and absence of propylene glycol (PG), a cytochrome P450 2E1 inhibitor.Methods: Plasma samples were collected during a previously performed randomized, cross-over trial where 21 subjects received APAP, four grams daily for two weeks in one arm and APAP, four grams daily with 20 mL PG in a second arm. Plasma collected at baseline and at day nine of each arm(time of peak elevation of liver function tests) underwent metabolomic analysis.Results: There were reduced phase two metabolites in subjects who displayed liver injury. There was also decreased sulfonation capacity in all subjects as well as in subjects displaying liver injury relative to subjects not displaying liver injury as evidenced by decreased sulfonation of hepatically derived steroids. There were decreased levels of acylcarnitines in subjects who displayed liver injury relative to subjects not displaying liver injury, indicating inhibition of mitochondrial fatty acid β-oxidation.Conclusions: Daily APAP dosing led to saturation of metabolic pathways and inhibition of mitochondrial function in subjects displaying subclinical liver injury.

Inhibition of CYP2E1 With Propylene Glycol Does Not Protect Against Hepatocellular Injury in Human Acetaminophen Daily-Dosing Model

Acetaminophen (APAP)-induced liver injury is initiated by metabolism of APAP by the cytochrome P-450 (CYP) system, primarily CYP2E1. We previously demonstrated CYP inhibition following administration of a liquid APAP formulation containing propylene glycol, a CYP2E1 inhibitor, and other excipients. This study was undertaken to determine if propylene glycol specifically inhibits production of CYP-derived metabolites and if propylene glycol reduces the rise in alanine aminotransferase (ALT) seen following prolonged APAP dosing. Human subjects were randomized to receive 4 g of APAP daily in one arm of the study or 4 g of APAP with 5 mL of 99% propylene glycol in the other arm, both for 14 days. After a washout period of at least 14 days, subjects were crossed over between arms. Outcomes were rise of ALT greater than 2 times baseline (responders) and proportion of randomly sampled CYP-derived metabolites relative to total metabolites produced. There was no difference in percentage of responders between treatment groups: 6 of 21 in the APAP group (29%) compared with 8 of 20 in the APAP + propylene glycol group (40%); chi-square, P = .59. For all subjects, the mean percentage of CYP-derived metabolites produced was 5.8% (APAP) versus 4.3% (APAP + propylene glycol); P = .018. This effect was solely attributable to the responders: the mean percentage of CYP metabolites of responders was 7.7% (APAP) versus 4.6% (APAP + propylene glycol), P = .050, whereas there was no difference for the nonresponders. Five subjects were responders in both arms (2% probability of random occurrence). Our data indicates that propylene glycol inhibits CYP2E1 metabolism of APAP in some subjects but does not effect hepatocellular indury at the dose given.

Determinants of hepatotoxicity after repeated supratherapeutic paracetamol ingestion: systematic review of reported cases

AIMS

To evaluate the role of reported daily dose, age and other risk factors, and to assess the value of quantifying serum transaminase activity and paracetamol (acetaminophen) concentration at initial assessment for identifying patients at risk of hepatotoxicity following repeated supratherapeutic paracetamol ingestion (RSPI).

METHODS

Systematic literature review with collation and analysis of individual-level data from reported cases of RSPI associated with liver damage.

RESULTS

In 199 cases meeting the selection criteria, severe liver damage (ALT/AST ≥1000 IU l(-1) , liver failure or death) was reported in 186 (93%) cases including 77/78 (99%) children aged ≤6 years. Liver failure occurred in 127 (64%) cases; of these 49 (39%) died. Maximum ingested daily paracetamol doses were above UK recommendations in 143 (72%) patients. US-Australasian thresholds for repeated supratherapeutic ingestions requiring intervention were not met in 71 (36%) cases; of these 35 (49%) developed liver failure and 10 (14%) died. No cases developing liver damage had paracetamol concentration < 20 mg l(-1) and a normal ALT/AST on initial presentation or when RSPI was first suspected, but both of these values were only available for 79 (40%) cases.

CONCLUSIONS

Severe liver damage is reported after RSPI in adults and children, sometimes involving reported doses below current thresholds for intervention. Paracetamol concentrations <20 mg l(-1) with normal serum ALT/AST activity on initial assessment suggests a low risk of subsequent liver damage. These findings are, however, limited by low patient numbers, publication bias and the accuracy of the histories in reported cases.

A case of moderate liver enzyme elevation after acute acetaminophen overdose despite undetectable acetaminophen level and normal initial liver enzymes

Liver function test (LFT) increase is an early sign of acetaminophen (APAP) toxicity. Typically, when an acute overdose patient is evaluated and has an initial undetectable APAP level and normal liver enzymes, the patient is not treated with N-acetylcysteine, and liver enzymes are not expected to increase later. We report a case of moderate LFT increase despite normal LFTs and an undetectable APAP level after delayed presentation of an APAP ingestion. A 22-year-old male with no medical history ingested 15-25 hydrocodone/APAP tablets (5 mg/500 mg). His suicide note and his bunkmate corroborated the overdose time. He arrived at the emergency department 16 hours after ingestion. At that time, his APAP level was <10 μg/mL, and his liver enzymes were normal [aspartate transaminase (AST) 31 U/L and alanine transaminase (ALT) 34 U/L]. Twenty-nine hours after ingestion, the psychiatry team obtained LFTs (AST 45, ALT 61). He had persistent nausea and diffuse abdominal pain. On repeat analysis, the APAP level at 36 hours was found to be <10 μg/mL, AST 150, and ALT 204. After 2 more days of increasing LFTs and persistent abdominal pain and nausea, the toxicology department was consulted, the patient was transferred to the medicine department, and intravenous N-acetylcysteine was started 66 hours after ingestion. He was treated for 16 hours and had a significant decline in LFTs and symptom resolution. His prothrombin time, bilirubin, lactate, creatinine, and mental status were normal throughout the admission. Other cases of LFT increase were excluded. Our case report illustrates that a moderate increase in liver transaminase may occur despite an initial undetectable APAP level and normal transaminases after a delayed presentation. In our case, no serious clinical effects were reported.

A review of acetaminophen poisoning

Acetaminophen poisoning remains one of the more common drugs taken in overdose with potentially fatal consequences. Early recognition and prompt treatment with N-acetylcysteine can prevent hepatic injury. With acute overdose, the Rumack-Matthew nomogram is a useful tool to assess risk and guide management. Equally common to acute overdose is the repeated use of excessive amounts of acetaminophen. Simultaneous ingestion of several different acetaminophen-containing products may result in excessive dosage. These patients also benefit from N-acetylcysteine. Standard courses of N-acetylcysteine may need to be extended in patients with persistently elevated plasma concentrations of acetaminophen or with signs of hepatic injury.