Acetaminophen Metabolites on Presentation Following an Acute Acetaminophen Overdose (ATOM-7)

Underlying mechanisms and treatment of acetaminophen‑induced liver injury (Review)

Acetaminophen (APAP) is safe at therapeutic doses; however, when ingested in excess, it accumulates in the liver and leads to severe hepatotoxicity, which in turn may trigger acute liver failure (ALF). This is known as APAP poisoning and is a major type of drug‑related liver injury. In the United States, APAP poisoning accounts for ≥50% of the total number of ALF cases, making it one of the most common triggers of ALF. According to the American Association for the Study of Liver Diseases, the incidence of APAP‑associated hepatotoxicity has increased over the past few decades; however, the mechanism underlying liver injury due to APAP poisoning has remained inconclusive. The present study aims to comprehensively review and summarize the latest research progress on the mechanism of APAP‑induced liver injury, and to provide scientific and effective guidance for the clinical treatment of APAP poisoning through in‑depth analysis of the metabolic pathways, toxicity‑producing mechanisms and possible protective mechanisms of APAP in the liver.

DIA-based quantitative proteomics explores the mechanism of amelioration of APAP-induced liver injury by anoectochilus roxburghii (Wall.) Lindl

Background

Drug-induced liver injury (DILI) is the most common cause of acute liver injury. Anoectochilus roxburghii (Wall.) Lindl. (AR) and its polysaccharide fractions (ARPs) have been shown to have effective therapeutic effects with minimal side effects on a wide range of diseases including hepatopathy. This study aims to determine the therapeutic effects of ARPs on acetaminophen (APAP)-induced liver injury and to explore the mechanistic pathways involved.

Methods

C57BL/6J male mice at 8 weeks were used to construct a model of APAP-induced liver injury. The acute hepatic injury was induced by oral administration of APAP (300 mg/kg) before 16 h fasting. For therapeutic experiment, mice were gavaged with the water extract of AR (AR.WE) or the purified ARPs before and after APAP administration. Biochemical analyses, ELISA analyses, H&E staining, RT-PCR, and Quantitative proteomic analysis were used to investigate the effects and mechanisms of AR on DILI.

Results

Both AR.WE. and the purified ARPs treatment reduced APAP-induced liver injury, decreased hepatic glutathione and TNF-α levels, alleviated oxidative stress and inflammation. Quantitative proteomic analysis revealed that ARPs downregulated the protein levels involved in apoptosis, inflammation, oxidative stress, necroptosis, while upregulated the protein levels involved in autophagy. These protective effects of ARPs are possibly related to the downregulation of vATPase activity and thus participating in the autophagic process and ferroptosis.

Conclusion

ARPs can protect mice against APAP-induced liver injury, alleviate oxidative stress and inflammation. Our study reveals a potential therapeutic effect for ARPs in protecting APAP-induced liver injury.

Clinical effects of acute lamotrigine overdose (ATOM-10)

INTRODUCTION

Lamotrigine overdose is not typically associated with severe toxicity. However, both severe toxicity and serotonin toxicity is occasionally reported following large ingestions. We aimed to investigate the clinical effects of lamotrigine overdose.

METHODS

This was a prospective observational study from July 2020-March 2024. Patients >14 years-old with acute lamotrigine overdose (≥2 g ingestion) were recruited from the Australian Toxicology Monitoring study or identified from three toxicology units. Data extracted included clinical features, lamotrigine concentrations, management, and outcomes.

RESULTS

Fifty-four patients were included, median age 29 years (IQR: 21-42 years), 37 (69%) were female. The median ingested dose was 4.8 g (IQR: 3.2-6.3 g) and 41 patients (76%) co-ingested other substances. The median maximum lamotrigine concentration was 18.5 mg/L (IQR: 12.4-25.0 mg/L) at a median time of 4.3 h (IQR: 3.2-10.8 h) post-ingestion. Clinical effects and their management included sedation in 44 (81%) with 29 patients (54%) endotracheally intubated, tachycardia in 39 (72%), hypotension in 21 (39%) with 15 (28%) receiving inotropes, and seizures in 11 (20%). Serotonin toxicity occurred in 23 (43%) patients with four having severe toxicity characterised by temperature >38.5 °C and/or rigidity treated with muscle paralysis. Higher peak lamotrigine concentrations were correlated with severe outcomes such as endotracheal intubation for coma (P <0.0001), patients with hypotension receiving inotropes (P = 0.0269) and patients developing seizures (P = 0.0002). Patients who co-ingested another serotonin agent (some in therapeutic doses) had a higher incidence of developing serotonin toxicity (22/33 [67%]) versus those who had not (1/21 [5%]); P <0.0001).

DISCUSSION

Severe toxicity was associated with higher peak lamotrigine concentrations. Serotonin toxicity was common in those who were exposed to another serotonergic agent.

CONCLUSION

Coma, seizures and hypotension following lamotrigine overdose appeared to be concentration dependent. Serotonin toxicity occurred in those who co-ingested another serotonergic agent and was unrelated to lamotrigine concentration.

Novel reduced heteropolyacid nanoparticles for effective treatment of drug-induced liver injury by manipulating reactive oxygen and nitrogen species and inflammatory signals

With the rapid advancements in biomedicine, the use of clinical drugs has surged sharply. However, potential hepatotoxicity limits drug exploitation and widespread usage, posing serious threats to patient health. Hepatotoxic drugs disrupt liver enzyme levels and cause refractory pathological damage, creating a challenge in the application of diverse first-line drugs. The activation and deterioration of reactive oxygen and nitrogen species (RONS) and inflammatory signals are key pathological mechanisms of drug-induced liver injury (DILI). Herein, a novel reduced heteropolyacid nanoparticle (RNP) has been developed, possessing high RONS-scavenging ability, strong anti-inflammatory activity, and excellent biosafety. These features enable it to swiftly restore the redox and immune balance of the liver. Intravenous administration of RNP effectively scavenged RONS storm, reversing liver oxidative stress and restoring normal mitochondrial membrane potential and function. Furthermore, by inhibiting c-Jun-N-terminal kinase phosphorylation, RNP facilitated the restoration of nuclear factor erythroid 2-related factor 2-mediated endogenous antioxidant signaling, ultimately rescuing the liver function and tissue morphology in acetaminophen-induced DILI mice. Crucially, the high biocompatible RNP exhibited superior efficacy in the DILI mouse model compared to the clinical antioxidant N-acetylcysteine. This targeted therapeutic approach, tailored to address the onset and progression of DILI, offers valuable new insights into controlling the condition and restoring liver structure and function.

Ecotoxicological effects of paracetamol on the biochemical and molecular responses of spinach (Spinacia oleracea L.)

The widespread use of pharmaceuticals, including paracetamol, has raised concerns about their impact on the environment and non-target species. The aim of this study was to investigate the biochemical and molecular responses of Spinacia oleracea (spinach) to high paracetamol concentrations in order to understand the plant's stress responses and underlying mechanisms. Under controlled conditions, spinach plants were exposed to different paracetamol concentrations (0, 50, 100, and 200 mg/L). The study evaluated the impact of paracetamol exposure on biochemical parameters such as oxidative stress markers (H2O2, MDA), activities of antioxidant enzymes (APX, CAT, GPOD, SOD), levels of non-enzymatic components (phenolics and flavonoids), and phytohormones (ABA, SA, and IAA). Furthermore, the study assessed molecular impacts by analyzing stress-related genetic variation and alterations in the gene expression of the antioxidant enzymes. Results showed that paracetamol exposure significantly increased oxidative stress in spinach, which was evident through the elevated H2O2 and MDA levels. However, the antioxidant defense mechanisms were activated to counteract this effect, as evidenced by increased activity of antioxidant enzymes and higher phenolics and flavonoid levels. Moreover, induction in the phytohormone levels indicated a stress response in paracetamol-treated plants compared to control plants. RAPD analysis revealed polymorphism indicating the DNA damage, and the Real-time qRT-PCR method showed significant upregulation of stress-responsive genes, highlighting the severe impact of paracetamol at the molecular level. The study concludes that high paracetamol concentrations pose a significant threat to spinach growth by affecting both biochemical and molecular processes. These findings underscore the need for strict environmental management practices to mitigate the possible impact of continuous release, accumulation, and long-term exposure of pharmaceutical contaminants to the environment and implement policies to reduce pharmaceutical pollutants to preserve ecological health and biodiversity.

Should high-dose N-acetylcysteine be given in cases of massive paracetamol overdoses: A narrative review

N-acetylcysteine (NAC) is regarded as an effective treatment of paracetamol overdoses. However, in cases of "massive" paracetamol overdoses, recent studies indicate that patients may not be sufficiently treated with the standard dose of NAC (300 mg/kg over 20-21 h). The subject is further complicated because "massive overdoses" and "high-risk" are defined differently; some studies use the ingested amount (e.g., >40 g), and some studies use blood concentrations of paracetamol and transaminases. This narrative review investigates whether high-dose NAC significantly decreases the risk of hepatotoxicity in patients with massive paracetamol overdoses. Three observational studies were analysed; one study with 373 patients found no significant difference (odds ratio [OR]: 1.27, 95% confidence interval [CI]: 0.49-3.29). One study with 79 patients found a significant difference (OR: 0.27, 95% CI: 0.08-0.94). The third study with 89 patients found a significant difference in hepatoxicity between the groups (p = 0.043). There are no solid evidence to support that treatment with high-dose NAC significantly reduces the rate of hepatotoxicity in patients presenting with massive paracetamol overdoses. Differences in inclusion criteria in the included studies make the studies incomparable. This paper shows that standardized inclusion is needed to determine whether a high-dose NAC regimen should be included in clinical practice.

The chemokine CXCL14 is a novel early prognostic biomarker for poor outcome in acetaminophen-induced acute liver failure

BACKGROUND AND AIMS

Patients with acetaminophen-induced acute liver failure are more likely to die while on the liver transplant waiting list than those with other causes of acute liver failure. Therefore, there is an urgent need for prognostic biomarkers that can predict the need for liver transplantation early after an acetaminophen overdose.

APPROACH AND RESULTS

We evaluated the prognostic potential of plasma chemokine C-X-C motif ligand 14 (CXCL14) concentrations in patients with acetaminophen (APAP) overdose (n=50) and found that CXCL14 is significantly higher in nonsurviving patients compared to survivors with acute liver failure ( p < 0.001). Logistic regression and AUROC analyses revealed that CXCL14 outperformed the MELD score, better discriminating between nonsurvivors and survivors. We validated these data in a separate cohort of samples obtained from the Acute Liver Failure Study Group (n = 80), where MELD and CXCL14 had similar AUC (0.778), but CXCL14 demonstrated higher specificity (81.2 vs. 52.6) and positive predictive value (82.4 vs. 65.4) for death or need for liver transplantation. Next, combining the patient cohorts and using a machine learning training/testing scheme to mimic the clinical scenario, we found that CXCL14 outperformed MELD based on AUC (0.821 vs. 0.787); however, combining MELD and CXCL14 yielded the best AUC (0.860).

CONCLUSIONS

We find in 2 independent cohorts of acetaminophen overdose patients that circulating CXCL14 concentration is a novel early prognostic biomarker for poor outcomes, which may aid in guiding decisions regarding patient management. Moreover, our findings reveal that CXCL14 performs best when measured soon after patient presentation to the clinic, highlighting its importance for early warning of poor prognosis.

Advances in the understanding of acetaminophen toxicity mechanisms: a clinical toxicology perspective

INTRODUCTION

Acetaminophen (paracetamol) is a commonly used analgesic and antipyretic agent, which is safe in therapeutic doses. Acetaminophen poisoning due to self-harm or repeated supratherapeutic ingestion is a common cause of acute liver injury. Acetylcysteine has been a mainstay of treatment for acetaminophen poisoning for decades and is efficacious if administered early. However, treatment failures occur if administered late, in 'massive' overdoses or in high-risk patients.

AREAS COVERED

This review provides an overview of the mechanisms of toxicity of acetaminophen poisoning (metabolic and oxidative phase) and how this relates to the assessment and treatment of the acetaminophen poisoned patient. The review focuses on how these advances offer further insight into the utility of novel biomarkers and the role of proposed adjunct treatments.

EXPERT OPINION

Advances in our understanding of acetaminophen toxicity have allowed the development of novel biomarkers and a better understanding of how adjunct treatments may prevent acetaminophen toxicity. Newly proposed adjunct treatments like fomepizole are being increasingly used without robust clinical trials. Novel biomarkers (not yet clinically available) may provide better assessment of these newly proposed adjunct treatments, particularly in clinical trials. These advances in our understanding of acetaminophen toxicity and liver injury hold promise for improved diagnosis and treatment.