Retrospective evaluation of repeated supratherapeutic ingestion (RSTI) of paracetamol

Paracetamol Dosing Errors in People Aged 12 Years and Over: An Analysis of Over 14,000 Cases Reported to an Australian Poisons Information Centre

INTRODUCTION

Paracetamol dosing errors can cause acute liver injury, with potentially toxic doses only slightly above the therapeutic range. This study aimed to characterise unintentional paracetamol overdose reported to an Australian poisons centre, including time trends, demographics, types of dosing errors, and outcomes.

METHODS

Records regarding paracetamol dosing errors for individuals aged ≥12 years were extracted from the New South Wales Poisons Information Centre database, January 2017 to June 2023. Data from 2021 underwent an in-depth screening of free text case notes to examine: dose, duration, products involved, reasons for ingestion and outcomes including hospitalisation, treatment, liver transplantations and deaths. Where possible, complete outcome data were obtained from medical records of New South Wales hospitalised cases in 2021.

RESULTS

There were 14,380 exposures due to paracetamol dosing errors (predominantly self-administered, median age 43 years, 62.6% female), with an average yearly increase of 2.5% (95% CI 1.6-3.8%; p < 0.0001). The in-depth analysis of exposures recorded during 2021 revealed 1899 exposures (median age 46 years, 63.4% female) with 26.8% requiring hospitalisation. Immediate- and modified-release formulations were highly implicated. Multiple paracetamol-containing products were ingested in approximately 20% of exposures. Hospitalised exposures were associated with paracetamol use for dental pain and ingested higher doses for longer durations. Over half of those hospitalised (52%) were treated with the antidote (N-acetylcysteine), and 6% of exposures developed hepatotoxicity.

CONCLUSION

Paracetamol dosing errors continue to occur, with relatively high rates of hospitalisation and liver injury. Many hospitalisations involved use for dental pain. Possible preventative measures include ingredient name prominence and increased education on appropriate dosing.

The presence of abdominal pain associated with acetaminophen overdose does not predict severity of liver injury

AIM

Whilst it is known that abdominal pain is a common symptom in patients with acetaminophen overdose, its association with severity of liver injury has not been clearly defined. This study investigates the association between the symptom of abdominal pain on presentation to hospital and the degree of liver injury post-acetaminophen overdose.

METHODS

Admissions with acetaminophen poisoning, requiring treatment with acetylcysteine were identified and reviewed from a search of a large Australian tertiary hospital network from February 20th, 2014, to August 30th, 2018. Parameters such as presence of abdominal pain, time post-ingestion and peak ALT were collected. Single acute ingestions, staggered and repeated supratherapeutic ingestions were analysed.

RESULTS

539 cases were identified in the study period, 79% female, with mean age 25 (17-43) years. Patients presenting to the emergency department with abdominal pain post-acetaminophen overdose had a similar risk of developing hepatotoxicity or acute liver injury compared to patients without abdominal pain regardless of time to presentation. Patients presenting <8-h post-overdose with abdominal pain were as likely to develop hepatotoxicity (1/46, 2.2%) compared to those without abdominal pain (1/54 [1.9%]; OR = 1.18 [0.07 to 19.4]). Those presenting >8-h post-overdose with abdominal pain were as likely to develop hepatotoxicity (13/92, 14.1%) compared to those without abdominal pain (4/35 [11.4%]; OR = 1.28 [0.39 to 4.21]).

CONCLUSIONS

The presence of abdominal pain after acetaminophen overdose was not predictive of the development of liver injury in patients receiving acetylcysteine treatment. Further prospective studies are required to confirm this finding. The data that support the findings of this study are available on request from the corresponding author. The data are not publicly available due to privacy or ethical restrictions.

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.

Performance of the paracetamol-aminotransferase multiplication product in risk stratification after paracetamol (acetaminophen) poisoning: a systematic review and meta-analysis

BACKGROUND

Risk stratification in paracetamol (acetaminophen) poisoning is crucial because hepatotoxicity is common and can be mitigated with treatment. However, current risk stratification tools have limitations.

AIMS

We evaluated the diagnostic performance of the paracetamol concentration × aminotransferase multiplication product, for predicting hepatotoxicity after paracetamol overdose.

METHODS

Medline, Cochrane Library and Embase were searched for eligible papers. We used random effects models to obtain pooled estimates of the likelihood ratios and diagnostic odds ratios, from which sensitivity and specificity were computed. We assessed two commonly used cut-off values of paracetamol × aminotransferase, 1500 mg/L × IU/L and 10,000 mg/L × IU/L. Using the confusion matrices of these two cut-offs, area under the summary receiver operator characteristic curve and optimal cut-off values in different clinical scenarios were established.

RESULTS

Six studies comprising 5036 participants were included. In 4051 patients, using the cut-off of 1500 mg/L × IU/L, a diagnostic odds ratio of 31.90 (95%CI: 9.52-106.90), sensitivity of 0.98 (95%CI: 0.94-1.00) and specificity of 0.66 (95%CI: 0.49-0.89) were obtained. In 3983 patients, using the cut-off of 10,000 mg/L × IU/L, a diagnostic odds ratio of 99.34 (95%CI: 12.26-804.87), sensitivity of 0.65 (95%CI: 0.51-0.82) and specificity of 0.97 (95%CI: 0.95-1.00) were obtained. For staggered ingestions, the 1500 mg/L × IU/L cut-off yielded a diagnostic odds ratio of 69.53 (95%CI: 4.03-1199.75), sensitivity of 1.00 (95%CI: 0.87-1.00) and specificity of 0.74 (95%CI: 0.43-1.00). Next, using the 10,000 mg/L × IU/L cut-off in this scenario yielded a diagnostic odds ratio of 254.58 (95%CI: 11.12-5827.60), sensitivity of 0.79 (95%CI: 0.59-1.00) and specificity of 0.98 (95%CI: 0.94-1.00). The overall summary receiver operator characteristic curve was 0.91 (95%CI: 0.75-0.97), and the optimal cut-off value was 3840 mg/L × IU/L. The summary receiver operator characteristic curve in patients with staggered ingestions was 0.96 (95%CI: 0.85-0.99). The summary receiver operator characteristic curve in patients with staggered ingestions and whose paracetamol concentration was below the detectable limit of 10 mg/L at presentation was 0.97 (95%CI: 0.94-0.99).

CONCLUSION

In this first meta-analysis, paracetamol × aminotransferase demonstrates its use in prognosticating hepatotoxicity in patients with paracetamol poisoning. It complements the Rumack-Matthew nomogram as it has shown promise in addressing two key limitations of the nomogram: it is usable after more than 24 h between overdose and acetylcysteine treatment, and it is applicable in staggered ingestions.

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.

Acetaminophen Poisoning

Acetaminophen is a common medication taken in deliberate self-poisoning and unintentional overdose. It is the commonest cause of severe acute liver injury in Western countries. The optimal management of most acetaminophen poisonings is usually straightforward. Patients who present early should be offered activated charcoal and those at risk of acute liver injury should receive acetylcysteine. This approach ensures survival in most. The acetaminophen nomogram is used to assess the need for treatment in acute immediate-release overdoses with a known time of ingestion. However, scenarios that require different management pathways include modified-release, large/massive, and repeated supratherapeutic ingestions.

Paracetamol poisoning: a population-based study from Iceland

OBJECTIVE

To examine the incidence and severity of paracetamol poisoning in a population-based cohort in Iceland. A previous study showed a decrease in the incidence during a financial crisis in Iceland, by approximately half (16/100,000 annually). The aims of the study were to assess the incidence and nature of paracetamol poisoning after economic recovery in Iceland and to compare intentional and accidental poisoning.

METHODS

Paracetamol serum concentrations were used to identify patients in this retrospective study from 2010-2017. A search was undertaken in laboratory databases for patients with serum paracetamol concentrations, which were grouped by <66 µmol/L (below detection limit) and ≥66 µmol/L. Medical records were reviewed and relevant laboratory and clinical information obtained to determine whether paracetamol poisoning had occurred.

RESULTS

Altogether 542 cases of paracetamol poisoning were identified. The mean annual incidence was 27/100,000 (range 22-33). Intentional poisoning was observed in 437/542 (81%) cases, most frequently among females 16-25 years of age. Males ≥65 years were more likely to overdose by accident, which was associated with worse outcomes. Twenty-five (4.6%) patients developed severe paracetamol-induced liver injury and coagulopathy. Overall, six (1.1%) cases were fatal in which paracetamol contributed to the cause of death, with accidental poisoning found in 67% (4/6).

CONCLUSIONS

The incidence of paracetamol poisoning has increased in recent years associated with economic recovery in Iceland. Most patients had favourable outcomes. Intentional overdose was most common in young females, whereas accidental overdose was more common in older males and more frequently associated with a fatal outcome.