Delays during the administration of acetylcysteine for the treatment of paracetamol overdose

Investigation of the pharmacokinetic properties of synthetic heparan sulfate oligosaccharides

Heparan sulfate (HS) is a sulfated polysaccharide with a wide range of biological activities. There is an increasing interest in the development of structurally homogeneous HS oligosaccharides as therapeutics. However, the factors influencing the pharmacokinetic properties of HS-based therapeutics remain unknown. Here, we report the pharmacokinetic properties of a panel of dodecasaccharides (12-mers) with varying sulfation patterns in healthy mice and uncover the pharmacokinetic properties of an octadecasaccharide (18-mer) in acutely injured mice. In the 12-mer panel, 1 12-mer, known as dekaparin, is anticoagulant, and 3 12-mers are nonanticoagulant. The concentrations of 12-mers in plasma and urine were determined by the disaccharide analysis using liquid chromatography coupled with tandem mass spectrometry. We observed a striking difference between anticoagulant and nonanticoagulant oligosaccharides in the 12-mer panel, showing that anticoagulant dekaparin had a 4.6-fold to 8.6-fold slower clearance and 4.4-fold to 8-fold higher plasma exposure compared to nonanticoagulant 12-mers. We also observed that the clearance of HS oligosaccharides is impacted by disease. Using an antiinflammatory 18-mer, we discovered that the clearance of 18-mer is reduced 2.8-fold in a liver failure mouse model compared to healthy mice. Our results suggest that oligosaccharides are rapidly cleared renally if they have low interaction with circulating proteins. We observed that the clearance rate of oligosaccharides is inversely associated with the degree of binding to target proteins, which can vary in response to pathophysiological conditions. Our findings uncover a contributing factor for the plasma and renal clearance of oligosaccharides which will aid the development of HS-based therapeutics.

Comparison of Two-Bag Versus Three-Bag N-Acetylcysteine Regimens for Pediatric Acetaminophen Toxicity

BACKGROUND

Acetaminophen overdose is a leading cause of liver failure, and a leading cause of pediatric poisoning requiring hospital admission. The antidote, N-acetylcysteine (NAC), is traditionally administered as a three-bag intravenous infusion. Despite its efficacy, NAC is associated with high incidence of nonallergic anaphylactoid reactions (NAARs). Adult evidence demonstrates that alternative dosing regimens decrease NAARs and medication errors (MEs).

OBJECTIVES

To compare NAARs and MEs associated with two- versus three-bag NAC for acetaminophen overdose in a pediatric population.

METHODS

This is a retrospective observational cohort study comparing pediatric patients who received three- versus two-bag NAC for acetaminophen toxicity. The primary outcome was incidence of NAARs. Secondary outcomes were rates of MEs and relevant hospital outcomes (length of stay [LOS], intensive care unit (ICU) admission, liver transplant, death).

RESULTS

Two hundred forty-three patients met inclusion criteria (median age of 15 years): 150 (62%) three-bag NAC and 93 (38%) two-bag NAC. There was no difference in overall NAARs (p = 0.54). Fewer cutaneous NAARs were observed in the two-bag group, three-bag: 15 (10%), two-bag: 2 (2%), p = 0.02. MEs were significantly decreased with the two-bag regimen, three-bag: 59 (39%), two-bag: 21 (23%), p = 0.01. No statistical differences were observed in LOS, ICU admissions, transplant, or death.

CONCLUSION AND RELEVANCE

A significant decrease in cutaneous NAARs and MEs was observed in pediatric patients by combining the first two bags of the traditional three-bag NAC regimen. In pediatric populations, a two-bag NAC regimen for acetaminophen overdose may improve medication tolerance and safety.

A two-bag acetylcysteine regimen is associated with shorter delays and interruptions in the treatment of paracetamol overdose

BACKGROUND

The three-bag intravenous (IV) acetylcysteine regimen for paracetamol overdose is associated with frequent and long delays during treatment. This has not been previously studied in regard to the two-bag regimen.

AIMS

Our primary aim was to compare the cumulative duration of delays during IV acetylcysteine infusion between the three-bag and two-bag regimens. Secondary aims were to compare the frequency of delays and to identify causes for delay.

METHODS

This was a retrospective cohort study of patients receiving IV acetylcysteine for the treatment of paracetamol overdose, conducted at three Australian emergency departments. A cohort of patients treated with the three-bag regimen from October 2009 to October 2013 was compared to patients treated with the two-bag regimen from February 2014 to May 2020. Start times of each infusion were sourced from medical records and delays were calculated by comparing actual infusion time against prescribed time. Evidence of adverse drug reactions - gastrointestinal reactions and cutaneous and systemic non-allergic anaphylactoid reactions (NAARs) - were also recorded.

RESULTS

The three-bag cohort included 271 cases and the two-bag cohort included 598 cases. Delays were significantly shorter in the two-bag cohort, compared to the three-bag cohort: median delay 35 min (IQR: 15, 70) vs 65 min (IQR: 40, 105), p < 0.01. Delays longer than 1 h were less frequent in the two-bag cohort: 31% vs 51%, p < 0.01. NAARs were associated with significantly longer delays in both cohorts and were more frequent in the three-bag cohort.

CONCLUSIONS

The two-bag regimen was associated with significantly fewer and shorter delays. NAARs, which were more frequent in the three-bag cohort, were associated with significantly longer delays.

A review of alternative intravenous acetylcysteine regimens for acetaminophen overdose

INTRODUCTION

Acetylcysteine is the standard treatment for preventing hepatotoxicity caused by acetaminophen overdose. Several novel approaches to the management of acetaminophen overdose have been suggested to improve patient safety by reducing adverse drug reactions and dosing errors. This article reviews these alternative treatment regimens and intends to offer a detailed assessment of the available options to assist providers in managing cases of acetaminophen overdose.

AREAS COVERED

This review article covers observational and experimental studies that assessed the efficacy and safety of alternative intravenous acetylcysteine regimens for acetaminophen overdose. A literature search was conducted using PubMed, ProQuest, and Scopus to identify the studies, which included results through April 2021. The assessment of alternative regimens consists of a discussion on the limitations and benefits, barriers to implementation, and important considerations for each regimen.

EXPERT OPINION

Several alternative regimens have been studied and implemented in various institutions. Many of these dosing regimens have supporting safety data but most lack robust data. A reduction in infusion-related side effects is an important outcome, but established efficacy, local poison center familiarity with the regimen, institutional resources, and patient-specific factors should be equally considered when deciding on implementing and using an alternative dosing strategy.

Investigation of the biological functions of heparan sulfate using a chemoenzymatic synthetic approach

Heparan sulfate (HS) is a highly sulfated polysaccharide playing essential physiological and pathophysiological roles in the animal kingdom. Heparin, a highly sulfated form of HS, is a widely used anticoagulant drug. Isolated from biological sources, both heparin and HS are polysaccharide mixtures with different sugar chain lengths and sulfation patterns. Structural heterogeneity of HS complicates the investigation of HS-related biological activities. The availability of structurally defined HS oligosaccharides is critical in understanding the contribution of saccharide structures to the functions. The chemoenzymatic synthetic approach is emerging as a cost-effective method to synthesize HS oligosaccharides. Structurally defined oligosaccharides are now widely available for biologists. This review summarizes our efforts in using this new synthetic method to develop new anticoagulant therapeutics and discover the role of HS to protect liver damage under pathological conditions. The synthetic method also allows us to prepare reference saccharide standards to improve structural analysis of HS.

Electronic-prescribing tools improve N-acetylcysteine prescription accuracy and timeliness for patients who present following a paracetamol overdose: A digital innovation quality-improvement project

Objectives

Prescription error rates and delays in treatment provision are high for N-acetylcysteine (NAC) when prescribed for paracetamol overdose (POD). We hypothesised that an electronic tool which proposed the complete NAC regimen would reduce prescription errors and improve the timeliness of NAC provision. Error rates and delays in the provision of NAC were assessed following POD, before and after the implementation of an electronic prescribing tool.

Methods

The NAC electronic prescribing tool proposed the three NAC infusions (dosed for weight) following entry of the patient's weight. All NAC prescriptions were reviewed during a three-month period prior to and after the tool's implementation. Error rates were divided into dose, infusion volume or infusion rate. Delays in NAC provision were identified using national Emergency Medicine guidelines.

Results

108 NAC prescriptions were analysed for all adult patients admitted to the emergency department of a secondary care hospital in the UK between July-September 2017 and August-October 2018, respectively. There were no differences in the demographics of patients or the seniority of the prescribing clinician before or after the introduction of the electronic tool. The electronic prescribing tool was associated with a decrease in prescribing errors (25% to 0%, p < 0.0071) and an increase in the provision of NAC within recommended times (11.1% to 47.4%, p = 0.029).

Conclusions

An electronic prescribing tool improved prescription errors and the timeliness of NAC provision following POD. Further studies will determine the effect of this on length of stay and the benefit of wider implementation in other secondary care hospitals.

Design of anti-inflammatory heparan sulfate to protect against acetaminophen-induced acute liver failure

Acetaminophen/paracetamol (APAP) overdose is the leading cause of drug-induced acute liver failure (ALF) in the United States and Europe. The progression of the disease is attributed to sterile inflammation induced by the release of high mobility group box 1 (HMGB1) and the interaction with receptor for advanced glycation end products (RAGE). A specific, effective, and safe approach to neutralize the proinflammatory activity of HMGB1 is highly desirable. Here, we found that a heparan sulfate (HS) octadecasaccharide (18-mer-HP or hepatoprotective 18-mer) displays potent hepatoprotection by targeting the HMGB1/RAGE axis. Endogenous HS proteoglycan, syndecan-1, is shed in response to APAP overdose in mice and humans. Furthermore, purified syndecan-1, but not syndecan-1 core protein, binds to HMGB1, suggesting that HMGB1 binds to HS polysaccharide side chains of syndecan-1. Last, we compared the protection effect between 18-mer-HP and N-acetyl cysteine, which is the standard of care to treat APAP overdose. We demonstrated that 18-mer-HP administered 3 hours after a lethal dose of APAP is fully protective; however, the treatment of N-acetyl cysteine loses protection. Therefore, 18-mer-HP may offer a potential therapeutic advantage over N-acetyl cysteine for late-presenting patients. Synthetic HS provides a potential approach for the treatment of APAP-induced ALF.

Efficacy of a two bag acetylcysteine regimen to treat paracetamol overdose (2NAC study)

BACKGROUND

Previous studies of paracetamol overdose treatment show that a 2-bag, 20-h intravenous (IV) acetylcysteine regimen decreased the incidence of non-allergic anaphylactic reactions compared to the 3-bag, 21 h IV regimen, but have not examined efficacy of the 20-h 2 bag regimen.

METHODS

This was a multi-centre observational study of paracetamol overdose presentations treated with a 2-bag IV acetylcysteine regimen (200 mg/kg over 4 h, 100 mg/kg over 16 h) compared to a 3-bag regimen, performed from 2009 to 2019. Patients were referred from the emergency department to the inpatient toxicology units for continued management. For the primary non-inferiority analysis: subjects had single, acute ingestions, a serum paracetamol-concentration performed 4 to 8-h post-ingestion. The primary outcome was development of acute liver injury (ALI), defined as peak ALT>150 U/L; and > double admission baseline ALT (for presentations within 24 h post-overdose). Secondary outcomes included adverse reactions to acetylcysteine (cutaneous and systemic).

FINDING

Out of 6419 paracetamol overdoses, 2763 received acetylcysteine. For the primary analysis, 1003 received the 2-bag and 783 the 3-bag acetylcysteine regimen. When presentation bloods were performed 4 to 8-h post-overdose, 21 (3.1%) developed ALI with the 2-bag regimen vs 16 (2.9%) with the 3-bag regimen (Difference: 0.2%, 95%CI:-1.6 to 2.2). The incidence of hepatotoxicity was: 1.2% (n = 8) with the two-bag regimen and 1.6% (n = 9) with the three-bag regimen (Difference -0.4%, 95%CI -1.75, 0.91). When presentation bloods were performed 8 to 24-h post-overdose, 70 (21%) developed ALI with the 2-bag regimen vs 46 (23%) with the 3-bag regimen (Difference: -2%, 95%CI -9.12 to 5.36). There were significantly less cutaneous and systemic non-allergic anaphylactic reactions recorded after treatment with the two-bag than the three-bag regimen (1.3% [n = 17] and 7.1% [n = 65], Difference: -5.8%, 95%CI -7.6 to -4.0, p < 0.0001), respectively.

INTERPRETATION

A two-bag intravenous acetylcysteine regimen was found to be non-inferior to the three-bag regimen with regards to efficacy in preventing acute liver injury for early presentations of paracetamol overdose. No important differences were seen for any other presentations. The two-bag regimen also decreased the incidence of both non-allergic anaphylactic reactions and gastrointestinal adverse events from acetylcysteine treatment.

FUNDING

AW is funded by a National Health and Medical Research Council (NHMRC) Early Career Fellowship ID 1159907. GI is funded by a NHMRC Senior Research Fellowship ID 1061041. The NHMRC had no role in the design, writing of this manuscript. The corresponding author (AW) had full access to all the data in the study and final responsibility for the decision to submit the manuscript for publication.

Accuracy of the paracetamol-aminotransferase product to predict hepatotoxicity in paracetamol overdose treated with a 2-bag acetylcysteine regimen

INTRODUCTION

Paracetamol concentration is a highly accurate risk predictor for hepatotoxicity following overdose with known time of ingestion. However, the paracetamol-aminotransferase multiplication product can be used as a risk predictor independent of timing or ingestion type. Validated in patients treated with the traditional, "three-bag" intravenous acetylcysteine regimen, we evaluated the accuracy of the multiplication product in paracetamol overdose treated with a two-bag acetylcysteine regimen.

METHODS

We examined consecutive patients treated with the two-bag regimen from five emergency departments over a two-year period. We assessed the predictive accuracy of initial multiplication product for the primary outcome of hepatotoxicity (peak alanine aminotransferase ≥1000IU/L), as well as for acute liver injury (ALI), defined peak alanine aminotransferase ≥2× baseline and above 50IU/L).

RESULTS

Of 447 paracetamol overdoses treated with the two-bag acetylcysteine regimen, 32 (7%) developed hepatotoxicity and 73 (16%) ALI. The pre-specified cut-off points of 1500 mg/L × IU/L (sensitivity 100% [95% CI 82%, 100%], specificity 62% [56%, 67%]) and 10,000 mg/L × IU/L (sensitivity 70% [47%, 87%], specificity of 97% [95%, 99%]) were highly accurate for predicting hepatotoxicity. There were few cases of hepatotoxicity irrespective of the product when acetylcysteine was administered within eight hours of overdose, when the product was largely determined by a high paracetamol concentration but normal aminotransferase.

CONCLUSIONS

The multiplication product accurately predicts hepatotoxicity when using a two-bag acetylcysteine regimen, especially in patients treated more than eight hours post-overdose. Further studies are needed to assess the product as a method to adjust for exposure severity when testing efficacy of modified acetylcysteine regimens.

Delays during the administration of acetylcysteine for the treatment of paracetamol overdose

BACKGROUND

The licensed intravenous acetylcysteine regimen for treating paracetamol overdose in most countries uses three separate infusions over 21 h. This complex regimen, requiring different infusion concentrations and rates, has been associated with administration errors. The aim of the present study was to assess the extent of administration delays occurring during this acetylcysteine regimen.

METHOD

A 6-month retrospective observational study was conducted at three English teaching hospitals with clinical toxicology services from October 2014. Patients aged 16 years and over, treated with intravenous acetylcysteine for paracetamol overdose, were included. The start times for infusions were recorded and the delays compared with the prescribed infusion times were calculated. Anaphylactoid reactions, intravenous cannula problems, overdose intent and smoking status were recorded to assess their contribution to delays.

RESULTS

From 263 cases identified, 198 met the study inclusion criteria. The median time between the start of infusions 1 and 3 was delayed from the intended 5 h by a median (interquartile range) of 90 (50-163) min, with 135 (68%) cases delayed by more than 1 h. Significantly longer delays were observed in patients with anaphylactoid reactions [median delay 267 (217-413) min, n = 8] and accidental/supratherapeutic overdose [median delay 170 (95-260) min, n = 29]. There were no significant differences between smokers and nonsmokers, or for patients with intravenous cannula problems.

CONCLUSION

Long delays were identified during the three-infusion acetylcysteine regimen for the treatment of paracetamol overdose. These were of clinical significance and could lead to periods of subtherapeutic plasma acetylcysteine concentrations and potentially avoidable hepatotoxicity, as well as delaying hospital discharge.