Fatal anaphylactoid reaction to N-acetylcysteine: caution in patients with asthma

Repurposing N-acetylcysteine for management of non-acetaminophen induced acute liver failure: an evidence scan from a global health perspective

Background

The World Health Organization (WHO)'s Essential Medicines List (EML) plays an important role in advocating for access to key treatments for conditions affecting people in all geographic settings. We applied our established drug repurposing methods to one EML agent, N-acetylcysteine (NAC), to identify additional uses of relevance to the global health community beyond its existing EML indication (acetaminophen toxicity).

Methods

We undertook a phenome-wide association study (PheWAS) of a variant in the glutathione synthetase (GSS) gene in approximately 35,000 patients to explore novel indications for use of NAC, which targets glutathione. We then evaluated the evidence regarding biologic plausibility, efficacy, and safety of NAC use in the new phenotype candidates.

Results

PheWAS of GSS variant R418Q revealed increased risk of several phenotypes related to non-acetaminophen induced acute liver failure (ALF), indicating that NAC may represent a therapeutic option for treating this condition. Evidence review identified practice guidelines, systematic reviews, clinical trials, retrospective cohorts and case series, and case reports. This evidence suggesting benefit of NAC use in this subset of ALF patients. The safety profile of NAC in this literature was also concordant with existing evidence on safety of this agent in acetaminophen-induced ALF.

Conclusions

This body of literature indicates efficacy and safety of NAC in non-acetaminophen induced ALF. Given the presence of NAC on the EML, this medication is likely to be available across a range of resource settings; promulgating its use in this novel subset of ALF can provide healthcare professionals and patients with a valuable and safe complement to supportive care for this disease.

Assessment of N-acetylcysteine use for acetaminophen overdose in the emergency department of a community teaching hospital: A pilot study

Introduction

N-acetylcysteine (NAC) is the first-line treatment for acetaminophen (APAP) overdose. However, using NAC inappropriately is associated with an increased risk of adverse effects as well as a substantial increase in hospitalization and healthcare costs. This study aims to assess NAC utilization for acute APAP overdose in the emergency department of a community teaching hospital in Saudi Arabia.

Methods

A retrospective chart review in which the patients initiated on an NAC secondary to acute APAP overdose at KSUMC during the period of June 2015 till November 2018 were included and assessed based on developed validated evident-based protocol for administering NAC for acute APAP ingestion.

Results

A total of 29 patients received NAC treatment for acute APAP overdose; 15 of which were adults, and 14 were pediatrics. Appropriate prescribing of NAC was observed in 14 (48.28%) patients, whereas NAC was inappropriately indicated for 15 (51.72%) patients; 9 of them were adults and 6 patients were pediatric. APAP-Ingestion <150 mg/kg (<200 mg/kg in children) was the most common reason for inappropriate use (n = 7, 46.67%) followed by administering NAC <4 hours post-APAP ingestion (n = 4, 26.67%).

Conclusion

Improper NAC administration appears to be a significant issue among patients with APAP overdose. The utilization of a protocol for the management of APAP overdose will reduce the unnecessary usage of NAC.

N-Acetylcysteine for Pediatric Obsessive-Compulsive Disorder: A Small Pilot Study

Background: Many children and adults with Obsessive-Compulsive Disorder (OCD) fail to respond to first-line pharmacological and behavioral treatments. Glutamate dysfunction may contribute to the development of OCD. N-acetylcysteine (NAC), a glutamate modulating drug, has shown to be a promising agent in adults with OCD. Methods: We conducted a double-blind, placebo-controlled clinical trial from July 2012 to January 2017. Children ages 8 to 17 years with OCD were assigned to receive NAC (up to 2700 mg/day) or the matching placebo for a period of 12 weeks. Children were required to be on stable psychiatric treatment (both medication and therapy) but were not required to be treatment-refractory. The primary outcome was OCD symptom severity as measured by the Children's Yale-Brown Obsessive-Compulsive Scale (CY-BOCS). We used linear mixed models to analyze the effect of NAC compared to placebo. Results: Due to poor recruitment and eventual expiration of the study medication, enrollment was stopped at 11 children out of a planned sample size of 40. Nonetheless, NAC was associated with significant reduction in CY-BOCS total score compared to placebo (Satterthwaite's test: t (37) = 2.36, p = 0.024) with effects separating from placebo beginning at week 8. Mean CY-BOCS total score decreased in the NAC group from 21.4 ± 4.65 at baseline to 14.4 ± 5.55 at week 12. In the placebo group, mean CY-BOCS total score remained unchanged (21.3 ± 4.65). In the NAC group, 1 out of 5 participants achieved >35% improvement in CY-BOCS total score, while none of the six patients in placebo group reached this improvement level. NAC and placebo were well tolerated. One mild adverse event was reported in each group. Conclusions: Our trial suggests that there may be some initial improvement in OCD symptom severity with NAC treatment. NAC was well tolerated in the study population. Future trials should employ multiple sites and have a larger study population to further confirm any benefits of NAC.

Acetylcysteine in paracetamol poisoning: a perspective of 45 years of use

Paracetamol poisoning was first reported in 1966. The development of antidotes followed within 10 years, and by 1980 acetylcysteine (NAC) was acknowledged as the optimal therapy available. This article examines the history of the development of NAC and recent developments in its use. We offer suggestions for improvements in the way NAC may be administered and outline new developments that should have major impacts on the way we manage paracetamol poisoning in the near future.

N,N'-Bis(2-mercaptoethyl)isophthalamide Binds Electrophilic Paracetamol Metabolites and Prevents Paracetamol-Induced Liver Toxicity

Paracetamol overdosing may cause liver injury including fulminant liver failure due to generation of the toxic metabolites, N-acetyl-p-benzoquinone imine (NAPQI) and p-benzoquinone (p-BQ). Herein, the chelating agent, N,N'-Bis(2-mercaptoethyl)isophthalamide (NBMI), was examined for its potential ability to entrap NAPQI and p-BQ and to prevent paracetamol-induced liver injury. Both NBMI and the conventional paracetamol antidote N-acetylcysteine (NAC) were investigated with regard to their abilities to scavenge the NAPQI and p-BQ in a Transient Receptor Potential Ankyrin 1-dependent screening assay. Stoichiometric evaluations indicated that NBMI was able to entrap these metabolites more efficiently than NAC. Furthermore, oral administration of either NBMI (680 mg/kg) or NAC (680 mg/kg) prevented the development of the characteristic liver necrosis and elevation of serum alanine aminotransferase in a mouse model for paracetamol-induced liver injury. In summary, these results show that NBMI is able to entrap the toxic metabolites NAPQI and p-BQ and to prevent paracetamol-induced liver injury in mice.

Anaphylactoid Reactions to Intravenous N-Acetylcysteine during Treatment for Acetaminophen Poisoning

BACKGROUND

Anaphylactoid reactions to intravenous (IV) N-acetylcysteine (NAC) are well-recognized adverse events during treatment for acetaminophen (APAP) poisoning. Uncertainty exists regarding their incidence, severity, risk factors, and management. We sought to determine the incidence, risk factors, and treatment of anaphylactoid reactions to IV NAC in a large, national cohort of patients admitted to hospital for acetaminophen overdose.

METHODS

This retrospective medical record review included all patients initiated on the 21-h IV NAC protocol for acetaminophen poisoning in 34 Canadian hospitals between February 1980 and November 2005. The primary outcome was any anaphylactoid reaction, defined as cutaneous (urticaria, pruritus, angioedema) or systemic (hypotension, respiratory symptoms). We examined the incidence, severity and timing of these reactions, and their association with patient and overdose characteristics using multivariable analysis.

RESULTS

An anaphylactoid reaction was documented in 528 (8.2%) of 6455 treatment courses, of which 398 (75.4%) were cutaneous. Five hundred four (95.4%) reactions occurred during the first 5 h. Of 403 patients administered any medication for these reactions, 371 (92%) received an antihistamine. Being female (adjusted OR 1.24 [95%CI 1.08, 1.42]) and having taken a single, acute overdose (1.24 [95%CI 1.10, 1.39]) were each associated with more severe reactions, whereas higher serum APAP concentrations were associated with fewer reactions (0.79 [95%CI 0.68, 0.92]).

CONCLUSION

Anaphylactoid reactions to the 21-h IV NAC protocol were uncommon and involved primarily cutaneous symptoms. While the protective effects of higher APAP concentrations are of interest in understanding the pathophysiology, none of the associations identified are strong enough to substantially alter the threshold for NAC initiation.

How Safe is Intravenous N-Acetylcysteine for the Treatment of Paracetamol Poisoning?

Objective

Paracetamol poisoning remains one of the most common and potentially lethal ingestions. N-acetylcysteine (NAC) has been proven to be a highly effective antidote. The aim of this study was to determine the rate of adverse drug reactions (ADR) to intravenous (IV) NAC. Our hypothesis was that IV NAC for the treatment of paracetamol toxicity has a low rate of adverse events.

Methods

This was an observational cohort study undertaken by explicit retrospective medical record review. It included patients who presented to the emergency department with paracetamol overdose over the ten-year period from July 1995 to June 2004. The primary outcome measure was the occurrence of an ADR during NAC administration. Adverse drug reactions were classified as minor (including flushing, urticaria, pruritus, bronchospasm, tachycardia, and non-ischaemic chest pain) and major (including hypotension, angio-oedema and death). Data analysis was by descriptive statistics and chi-square analysis using univariate analysis, Fisher's exact test and Mann-Whitney U-test. Inter-rater agreement was checked for 9% of the sample.

Results

There were 470 cases of paracetamol poisoning. Of these, 320 received IV NAC. Thirty-six (11%, 95% CI 8–15%) of these patients developed ADRs. There were two major ADRs, one hypotension and one angio-oedema (0.6%, 95% CI 0.02–2%). Two patients died during hospitalisation, but neither had an ADR to NAC. The most common ADRs were urticaria (20), flushing (15), bronchospasm (12), and pruritus (3). None of the variables analysed was a clinically significant predictor of increased ADR risk.

Conclusion

Adverse drug reactions after IV NAC infusion occur commonly, but most are minor. Treatment of paracetamol poisoning with IV NAC appears to be safe, however a large prospective study would be required to confirm this.

Characterisation and outcomes of adult patients with paracetamol overdose presenting to a tertiary hospital in Singapore

INTRODUCTION

Paracetamol is the most common pharmaceutical agent implicated in toxic exposure in Singapore. This study aimed to describe the characteristics of paracetamol overdose in the adult population managed at a tertiary healthcare facility in Singapore.

METHODS

Medical records of adult patients hospitalised with a diagnosis of paracetamol overdose at National University Hospital, Singapore, over a three-year period from January 2011 to December 2013 were retrospectively reviewed.

RESULTS

A total of 177 patients had paracetamol overdose. The median age was 25 years, with a significant female predominance (71.2%). Intentional ingestion accounted for the majority (76.8%) of cases. The median dose of paracetamol ingested was 10 (interquartile range 8-15) g. Among patients who reported ingesting more than 10 g, 46.5% perceived the overdose as non-lethal. N-acetylcysteine was administered in 76.3% of patients, among whom 24.4% experienced an anaphylactoid reaction. Of the 10 (5.6%) patients who had severe hepatotoxicity, 2 (1.1%) developed acute liver failure. Most patients had resolving transaminases at discharge and none required liver transplantation. The median length of hospitalisation was three days. There were no fatalities.

CONCLUSION

Paracetamol overdose occurred predominantly in young adults with intentional ingestion, suggesting that preventive measures targeted at promoting public awareness may not suffice. However, the perceived lack of lethality by many patients who ingested potentially toxic amounts of paracetamol reflects a certain knowledge gap. Healthcare providers should proactively educate consumers on the proper use of paracetamol and the consequences of its overdose.

The 100 most influential publications in paracetamol poisoning treatment: a bibliometric analysis of human studies

BACKGROUND

Analysis of the most influential publications within paracetamol poisoning treatment can be helpful in recognizing main and novel treatment issues within the field of toxicology. The current study was performed to recognize and describe the most highly cited articles related to paracetamol poisoning treatment.

METHODS

The 100 most highly cited articles in paracetamol poisoning treatment were identified from the Scopus database in November 2015. All eligible articles were read for basic information, including total number of citations, average citations per year, authors' names, journal name, impact factors, document types and countries of authors of publications.

RESULTS

The median number of citations was 75 (interquartile range 56-137). These publications were published between 1974 and 2013. The average number of years since publication was 17.6 years, and 45 of the publications were from the 2000s. A significant, modest positive correlation was found between years since publication and the number of citations among the top 100 cited articles (r = 0.316; p = 0.001). A total of 55 journals published these 100 most cited articles. Nine documents were published in Clinical Toxicology, whereas eight documents were published in Annals of Emergency Medicine. Citations per year since publication for the top 100 most-cited articles ranged from 1.5 to 42.6 and had a mean of 8.5 citations per year and a median of 5.9 with an interquartile range of 3.75-10.35. In relation to the origin of the research publications, they were from 8 countries. The USA had the largest number of articles, 47, followed by the UK and Australia with 38 and nine articles respectively.

CONCLUSIONS

This study is the first bibliometric assessment of the top 100 cited articles in toxicology literature. Interest in paracetamol poisoning as a serious clinical problem continues to grow. Research published in high-impact journals and from high income countries is most likely to be cited in published paracetamol research.

Antidote Use in the Critically Ill Poisoned Patient

The proper use of antidotes in the intensive care setting when combined with appropriate general supportive care may reduce the morbidity and mortality associated with severe poisonings. The more commonly used antidotes that may be encountered in the intensive care unit ( N-acetylcysteine, ethanol, fomepizole, physostigmine, naloxone, flumazenil, sodium bicarbonate, octreotide, pyridoxine, cyanide antidote kit, pralidoxime, atropine, digoxin immune Fab, glucagon, calcium gluconate and chloride, deferoxamine, phytonadione, botulism antitoxin, methylene blue, and Crotaline snake antivenom) are reviewed. Proper indications for their use and knowledge of the possible adverse effects accompanying antidotal therapy will allow the physician to appropriately manage the severely poisoned patient.

Reducing Hepatocyte Injury and Necrosis in Response to Paracetamol Using Noncoding RNAs

The liver performs multiple functions within the human body. It is composed of numerous cell types, which play important roles in organ physiology. Our study centers on the major metabolic cell type of the liver, the hepatocyte, and its susceptibility to damage during drug overdose. In these studies, hepatocytes were generated from a renewable and genetically defined resource. In vitro-derived hepatocytes were extensively profiled and exposed to varying levels of paracetamol and plasma isolated from liver-failure patients, with a view to identifying noncoding microRNAs that could reduce drug- or serum-induced hepatotoxicity. We identified a novel anti-microRNA, which reduced paracetamol-induced hepatotoxicity and glutathione depletion. Additionally, we identified a prosurvival role for anti-microRNA-324 following exposure to plasma collected from liver failure patients. We believe that these studies represent an important advance for the field, demonstrating the power of stem cell-derived systems to model human biology "in a dish" and identify novel noncoding microRNAs, which could be translated to the clinic in the future.

SIGNIFICANCE

The liver performs vital functions within the human body and is composed of numerous cell types. The major metabolic cell type of the liver, the hepatocyte, is susceptible to damage during drug overdose. In these studies, hepatocytes were generated from a renewable resource and exposed to varying levels of paracetamol, with a view to identifying interventions that could reduce or attenuate drug-induced liver toxicity. A novel noncoding RNA that reduced paracetamol-induced hepatocyte toxicity was identified. These findings may represent an important advance for the field.

Appropriateness in allergic respiratory diseases health care in Italy: definitions and organizational aspects

In a historical period in which sustainability of the National Health Service is mandatory because of the international economical situation, the limited available resources at national level and the tendency of passing from a “population medicine” model towards the concept of “individualized medicine”, the debate on appropriateness of medical and surgical procedures is of central importance. The choosing wisely campaign, started in United States in 2012 and then spread all over the world, tries to summarize which are the most inappropriate procedures for each medical and surgical speciality; as far as allergic respiratory diseases, the most relevant Italian societies and the American Academy defined the allergological procedures with the highest probability of inappropriateness. In Italy, a recent decree of the Ministry of Health defined a list of more than 200 procedures that will be considered as inappropriate in certain conditions; many of these procedures concern allergology, including allergic respiratory diseases. In this commentary we discuss the above mentioned decree and the concept of appropriateness in the field of allergic respiratory diseases, trying to figure out some practical considerations based on the current health resources available in the field of allergology in Italy.

Effects of N-acetyl cysteine on renal functions evaluated by blood neutrophil gelatinase-associated lipocalin levels in geriatric patients undergoing coronary artery bypass grafting

Objective:

Recent conflicting studies on the renal effects of N-acetyl cysteine (NAC) after cardiac surgery have been published. The aim of this study was to evaluate the renal effects of NAC using neutrophil gelatinase-associated lipocalin (NGAL) blood levels in elderly patients undergoing coronary artery bypass grafting (CABG).

Methods:

This randomized, double-blinded, placebo-controlled study was conducted among geriatric patients (>65 years) scheduled to undergo CABG. A total of 60 consecutive patients were randomly assigned to 2 groups. The first group received I.V. NAC (n=30) and the second group received placebo (n=30) at induction of anesthesia and then for 20 h. NGAL values were determined and conventional renal function tests were performed. Statistical analysis was performed using SPSS 17.0 (IL, Chicago, USA). A p value of <0.05 was considered statistically significant

Results:

Plasma creatinine levels at 24 h postoperatively were significantly higher in the placebo group than in the NAC group (1.41±0.63 vs. 1.13±0.35; p<0.05). The mean serum NGAL levels at 3 h postoperatively were higher in the placebo group than in the NAC group (104.94±30.51 vs. 87.82±25.18; p<0.05). NGAL levels were similar between the groups at all other measurement time points. Plasma creatinine levels of ≥1.5 mg/dL or >25% of the baseline value at any time during the study period were observed in 27% of patients in the NAC group and 37% of patients in the placebo group; the difference was statistically significant (p<0.05).

Conclusion:

In the present study, we found that I.V. NAC infusion in elderly patients undergoing CABG reduced the incidence of acute kidney injury as determined by blood NGAL and creatinine levels.

A Review of the Toxicologic Implications of Obesity

The increasing prevalence of obesity in developed nations has far-reaching implications for medical toxicology. The management of obese patients is complicated by comorbid illnesses, changes in cardiovascular and respiratory physiology, alterations in pharmacokinetics, and a lack of studies to identify appropriate dosing for current therapeutics and antidotes. In this review article, we examine obesity-associated physiologic and pharmacokinetic changes that may increase the vulnerability of obese patients to overdose. Further research is needed to characterize the relationship between drug toxicity and obesity.

Evaluation of an Alternative Intravenous N-Acetylcysteine Regimen in Pediatric Patients

OBJECTIVE

Conventionally, intravenous N-acetylcysteine (IV-NAC) administration is a 3-bag regimen administered over the course of 21 hours, which increases the risk of reconstitution and administration errors. To minimize errors, an alternative IV-NAC regimen consists of a loading dose (150 mg/kg) followed by a maintenance infusion (15 mg/kg/hr) until termination criteria are met. The aim was to determine the clinical outcomes of an alternative IV-NAC regimen in pediatric patients.

METHODS

A retrospective review of pharmacy dispensing records and diagnostic codes at a pediatric hospital identified patients who received alternative IV-NAC dosing from March 1, 2008, to September 10, 2012, for acetaminophen overdoses. Exclusion criteria included chronic liver disease, initiation of oral or other IV-NAC regimens, and initiation of standard IV-NAC infusion prior to facility transfer. Clinical and laboratory data were abstracted from the electronic medical record. Descriptive statistics were utilized. Clinical outcomes and adverse drug reaction incidences were compared between the alternative and Food and Drug Administration (FDA)-approved IV-NAC regimens.

RESULTS

Fifty-nine patients (mean age 13.4 ± 4.3 years; range: 2 months-18 years) with acetaminophen overdoses were identified. Upon IV-NAC discontinuation, 45 patients had normal alanine transaminase (ALT) concentrations, while 14 patients' ALT concentrations remained elevated (median 140 units/L) but were trending downward. Two patients (3.4%) developed hepatotoxicity (aspartate transaminase/ALT > 1000 units/L). No patients developed hepatic failure, were listed for a liver transplant, were intubated, underwent hemodialysis, or died. Two patients (3.4%) developed anaphylactoid reactions. No known medication or administration errors occurred. Clinical outcome incidences of the studied endpoints with the alternative IV-NAC regimen are at the lower end of published incidence ranges compared to the FDA IV-NAC regimen for acetaminophen overdoses.

CONCLUSIONS

This alternative IV-NAC regimen appears to be effective and well tolerated among pediatric patients when compared to the FDA-approved regimen. It may also result in fewer reconstitution and administration errors, leading to improved patient safety.

Contrast-induced Nephropathy

Contrast-induced nephropathy (CIN) is a serious complication of angiographic procedures resulting from the administration of contrast media (CM). It is the third most common cause of hospital acquired acute renal injury and represents about 12% of the cases. CIN is defined as an elevation of serum creatinine (Scr) of more than 25% or ≥0.5 mg/dl (44 μmol/l) from baseline within 48 h. More sensitive markers of renal injury are desired, therefore, several biomarkers of tubular injury are under evaluation. Multiple risk factors may contribute to the development of CIN; these factors are divided into patient- and procedure-related factors. Treatment of CIN is mainly supportive, consisting mainly of careful fluid and electrolyte management, although dialysis may be required in some cases. The available treatment option makes prevention the corner stone of management. This article will review the recent evidence concerning CIN incidence, diagnosis, and prevention strategies as well as its treatment and prognostic implications.

Oral and Intravenous Acetylcysteine for Treatment of Acetaminophen Toxicity: A Systematic Review and Meta-analysis

INTRODUCTION

There are few reports summarizing the effectiveness of oral and intravenous (IV) acetylcysteine. We determined the proportion of acetaminophen poisoned patients who develop hepatotoxicity (serum transaminase > 1000 IU/L) when treated with oral and IV acetylcysteine.

METHODS

Studies were double abstracted by trained researchers. We determined the proportions of patients who developed hepatotoxicity for each route using a random effects model. Studies were further stratified by early and late treatment.

RESULTS

We screened 4,416 abstracts; 16 articles, including 5,164 patients, were included in the meta-analysis. The overall rate of hepatotoxicity for the oral and IV routes were 12.6% and 13.2%, respectively. Treatment delays are associated with a higher rate of hepatotoxicity.

CONCLUSION

Studies report similar rates of hepatotoxicity for oral and IV acetylcysteine, but direct comparisons are lacking. While it is difficult to disentangle the effects of dose and duration from route, our findings suggest that the rates of hepatotoxicity are similar for oral and IV administration.

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.

Contrast-induced acute kidney injury and renal support for acute kidney injury: a KDIGO summary (Part 2)

Acute kidney injury (AKI) is a common and serious problem affecting millions and causing death and disability for many. In 2012, Kidney Disease: Improving Global Outcomes completed the first ever international multidisciplinary clinical practice guideline for AKI. The guideline is based on evidence review and appraisal, and covers AKI definition, risk assessment, evaluation, prevention, and treatment. Two topics, contrast-induced AKI and management of renal replacement therapy, deserve special attention because of the frequency in which they are encountered and the availability of evidence. Recommendations are based on systematic reviews of relevant trials. Appraisal of the quality of the evidence and the strength of recommendations followed the Grading of Recommendations Assessment, Development and Evaluation approach. Limitations of the evidence are discussed and a detailed rationale for each recommendation is provided. This review is an abridged version of the guideline and provides additional rationale and commentary for those recommendation statements that most directly impact the practice of critical care.

Fatal myocardial infarction associated with intravenous N-acetylcysteine error

Background

N-acetylcysteine is used to treat acetaminophen toxicity and is available in both intravenous and oral formulations. Our report describes a patient treated with intravenous N-acetylcysteine for acetaminophen toxicity who died after an anaphylactoid reaction following initiation of the infusion.

Objective

Clinicians should be aware of potential complications when deciding on which formulation of N-acetylcysteine to administer.

Case Report

A 53-year-old male presented with altered mental status after an overdose of acetaminophen/hydrocodone and carisoprodol. He had an acetaminophen level of 49 mcg/ml with an unknown time of ingestion. The patient was admitted to the intensive care unit (ICU) on a naloxone drip and was started on intravenous N-acetylcysteine (NAC) at the presumed dose of 150 mg/kg. Shortly after initiating the NAC infusion, the patient developed periorbital edema, skin rash, and hypotension. The infusion of N-acetylcysteine was immediately stopped and the patient required emergent intubation. Resuscitation was begun with intravenous fluids followed by the initiation of phenylephrine. He developed ST elevation in the inferior leads on his ECG. This evolved into an inferior myocardial infarction by ECG and cardiac enzymes. Echocardiogram showed global, severe hypokinesis with an ejection fraction of less than 20% in a patient with no pre-existing cardiac history. Despite aggressive support, he died approximately 17 hours after the initiation of intravenous NAC. Further investigation found a 10-fold formulation error in his NAC loading dose.

Conclusion

The intravenous formulation of NAC has a higher probability of significant adverse effects and complications not described with the oral formulation. Clinicians should be aware of these potential complications when deciding on which formulation to administer.

[Acute kidney injury: from concept to practice]

Definition and classification of acute renal failure evolved in recent years. The acronym "Acute Kidney Injury" replaces "Acute Renal Failure". The RIFLE classification spreads the AKI in three degrees of severity, and two degrees of disease duration. The group Acute Kidney Injury Network refines this classification into three stages, to improve the sensitivity in detecting moderate forms. The epidemiology of AKI remains imprecise. In the ICU, more than 30% of patients suffered from AKI, often in a context of multiple organs failure. In addition to serum creatinine and urine output, new biomarkers can be assessed. Their early detection should enable a clearer distinction between "acute tubular necrosis" and other causes of AKI, but also to distinguish patients at risk for pejorative evolution of renal function. The management of AKI based on an optimal resuscitation. The administration of loop diuretics or low dose dopamine showed no benefit. Hydration in prevention of the contrast-induced nephropathy is confirmed. The role of acetylcysteine must be determined. The ideal time to initiate a renal replacement therapy and the choice of the technique remain unresolved. The same goes for the dose of dialysis administered. A systematic application of an algorithm, such as proposed by Bagshow would make comparisons easier and the realisation of multicenter studies will help to clarify these points.

Effects of delay in infusion of N-acetylcysteine on appearance of adverse drug reactions after acetaminophen overdose: a retrospective study

PURPOSE

To investigate the relationship between different types of adverse drug reaction (ADR) and late time to N-acetylcysteine (NAC) infusion in patients presenting to the hospital with acetaminophen overdose.

METHODS

This is a retrospective study of patients admitted to the hospital for acute acetaminophen overdose over a period of 5 years (1 January 2004 to 31 December 2008). The primary outcome of interest was the relationship between ADR, if any, and late time to NAC infusion. Parametric and non-parametric tests were used to test differences between groups depending on the normality of the data. SPSS 15 was used for data analysis.

RESULTS

Of 305 patients with acetaminophen overdose, 146 (47.9%) were treated with intravenous NAC and 139 (45.6%) were included in this study. Different types of ADR were observed in 94 (67.6%) patients. Late time to NAC infusion was significantly associated with cutaneous anaphylactoid reactions when compared to patients without this type of ADR (p  <  0.001). However, there were no significant differences in time to NAC infusion between patients with and without the following ADR: gastrointestinal reactions (p = 0.11), respiratory reactions (p = 0.77), central nervous reactions (p = 0.64), and cardiovascular reactions (p = 0.63).

CONCLUSION

Late time to NAC infusion is a risk factor for developing cutaneous anaphylactoid reactions, suggesting, rather than proving, that early NAC infusion (≤ 8 hours) may be protective against this type of ADR.

Curcumin protects rats against acetaminophen-induced hepatorenal damages and shows synergistic activity with N-acetyl cysteine

Acetaminophen is one of the most popular analgesic and antipyretic drugs and its overdose, which can cause severe damage to liver and kidneys, is one of the most common reasons of emergency admissions. In this study we investigated the effects of curcumin, derived from plant Curcuma longa, on acetaminophen toxicity, and the possibility of combining therapy of curcumin and N-acetyl cysteine (NAC) to treat this toxicity. The experiments were conducted on 72 male Sprague-Dawley rats randomly divided into 12 groups. Control group was left without treatment, and the other groups were treated with different combinations of acetaminophen, curcumin and NAC. 15min after intraperitoneal injection, the blood level of curcumin was measured using HPLC. Blood levels of AST (aspartate aminotransferase), ALT (alanine aminotransferase), blood urea nitrogen and creatinine were determined 18 and 42h after acetaminophen injection. One week later, the left kidney and the caudate lobe of the liver were harvested to assay glutathione peroxidase, catalase and malondialdehyde. The right kidney and the remaining lobes of the liver were used for histopathology. Analysis of organ function and oxidation parameters showed that curcumin significantly reduced toxic effects of acetaminophen on the liver and kidneys in a dose-dependent manner and significantly potentiated the protective effects of NAC. These findings were confirmed by histopathology. It is concluded that curcumin can protect the liver and kidney from the damage caused by acetaminophen overdose. Moreover, curcumin has the potential to be used in a combination therapy with NAC, significantly decreasing the therapeutic dose of NAC and therefore its side-effects.

Adverse reactions associated with acetylcysteine

INTRODUCTION

Paracetamol (acetaminophen) is one of the most common agents deliberately ingested in self-poisoning episodes and a leading cause of acute liver failure in the western world. Acetylcysteine is widely acknowledged as the antidote of choice for paracetamol poisoning, but its use is not without risk. Adverse reactions, often leading to treatment delay, are frequently associated with both intravenous and oral acetylcysteine and are a common source of concern among treating physicians.

METHODS

A systematic literature review investigating the incidence, clinical features, and mechanisms of adverse effects associated with acetylcysteine.

RESULTS

A variety of adverse reactions to acetylcysteine have been described ranging from nausea to death, most of the latter due to incorrect dosing. The pattern of reactions differs with oral and intravenous dosing, but reported frequency is at least as high with oral as intravenous. The reactions to the intravenous preparation result in similar clinical features to true anaphylaxis, including rash, pruritus, angioedema, bronchospasm, and rarely hypotension, but are caused by nonimmunological mechanisms. The precise nature of this reaction remains unclear. Histamine now seems to be an important mediator of the response, and there is evidence of variability in patient susceptibility, with females, and those with a history of asthma or atopy are particularly susceptible. Quantity of paracetamol ingestion, measured through serum paracetamol concentration, is also important as higher paracetamol concentrations protect patients against anaphylactoid effects. Most anaphylactoid reactions occur at the start of acetylcysteine treatment when concentrations are highest. Acetylcysteine also affects clotting factor activity, and this affects the interpretation of minor disturbances in the International Normalized Ratio in the context of paracetamol overdose.

CONCLUSION

This review discusses the incidence, clinical features, underlying pathophysiological mechanisms, and treatment of adverse reactions to acetylcysteine and identifies particular "at-risk" patient groups. Given the commonality of adverse reactions associated with acetylcysteine, it is important to ensure that any adverse event does not preclude patients from receiving maximal hepatic protection, particularly in the context of significant paracetamol ingestion. Further work on mechanisms should allow specific therapies to be developed.

Acetylcysteine for acetaminophen poisoning

A 25-year-old man presents to the emergency department with a toothache. During the evaluation, the physician determines that the patient has been taking large doses of over-the-counter acetaminophen along with an acetaminophen–hydrocodone product for the past 5 days. His daily dose of acetaminophen has been 12 g per day (maximum recommended dose, 4 g per day). He has no other medical problems and typically consumes two beers a day. The patient has no symptoms beyond his toothache, is not icteric, and has no hepatomegaly or right-upper-quadrant tenderness. His serum acetaminophen concentration 8 hours after the most recent dose is undetectable. His serum alanine aminotransferase concentration is 75 IU per liter, his serum bilirubin concentration is 1.2 mg per deciliter (20.5 μmol per liter), and his international normalized ratio (INR) is 1.1. The emergency department physician contacts the regional poison-control center, which recommends treatment with acetylcysteine.

Clinical policy: critical issues in the management of patients presenting to the emergency department with acetaminophen overdose

This clinical policy focuses on critical issues concerning the management of patients presenting to the emergency department (ED) with acetaminophen overdose. The subcommittee reviewed the medical literature relevant to the questions posed. The critical questions are: 1. What are the indications for N-acetylcysteine (NAC) in the acetaminophen overdose patient with a known time of acute ingestion who can be risk stratified by th Rumack-Matthew nomogram? 2. What are the indications for NAC in the acetaminophen overdose patient who cannot be risk stratified by the Rumack-Matthew nomogram? Recommendations are provided on the basis of the strength of evidence of the literature. Level A recommendations represent patient management principles that reflect a high degree of clinical certainty; Level B recommendations represent patient management principles that reflect moderate clinical certainty; and Level C recommendations represent other patient management strategies that are based on preliminary, inconclusive, or conflicting evidence, or based on committee consensus. This guideline is intended for physicians working in EDs.

Effects of N-acetylcysteine against systemic and renal hemodynamic effects of endotoxin in healthy humans

OBJECTIVE

Systemic inflammation causes vasodilation and impairs the vascular response to catecholamines. There is evidence that altered vasoreactivity is associated with increased production of free radicals. We studied the influence of systemic doses of the antioxidant N-acetylcysteine on inflammatory cytokines and renal plasma flow and on the systemic pressor response to norepinephrine during experimental endotoxemia.

DESIGN

A double-blind, placebo-controlled crossover study.

SETTING

Medical University of Vienna, Clinical Pharmacology, Vienna General Hospital, AKH.

SUBJECTS

Eight healthy, male humans.

INTERVENTIONS

Intravenous administration of Escherichia coli endotoxin (lipopolysaccharide, 20 IU/kg) on two separate study days with concomitant intravenous infusion of placebo or N-acetylcysteine (150 mg/kg loading dose; 15 mg/kg/hr continuous infusion), respectively.

MEASUREMENTS AND MAIN RESULTS

Measurements of inflammatory cytokines, of renal plasma flow by the para-aminohippurate-clearance method, and of the systemic pressor response to norepinephrine were taken at baseline and after endotoxin. Lipopolysaccharide increased body temperature and plasma concentrations of tumor necrosis factor-alpha, which was mitigated during N-acetylcysteine infusions. Likewise, the lipopolysaccharide-induced increases in renal plasma flow and decreases in blood pressure were attenuated, and the hyporeactivity of pulse rate to norepinephrine 4 hrs after lipopolysaccharide was improved by N-acetylcysteine.

CONCLUSION

High doses of N-acetylcysteine might exert protective effects on systemic hemodynamics and on the reactivity to catecholamines in humans challenged by lipopolysaccharide. This action of the antioxidant N-acetylcysteine is paralleled by humoral anti-inflammatory mechanisms and may be useful in patients with systemic inflammation.

Inhibitory effects of N-acetylcysteine on the functional responses of human eosinophils in vitro

BACKGROUND

Oxidative stress appears to be relevant in the pathogenesis of inflammation in allergic diseases like bronchial asthma. Eosinophils are oxidant-sensitive cells considered as key effectors in allergic inflammation.

OBJECTIVE

The aim of this work was to study the effects of the clinically used antioxidant N-acetyl-L-cysteine (NAC) on the functional responses of human-isolated eosinophils.

METHODS

Human eosinophils were purified from the blood of healthy donors by a magnetic bead separation system. The effects of NAC were investigated on the generation of reactive oxygen species (chemiluminescence and flow cytometry), Ca(2+) signal (fluorimetry), intracellular glutathione (GSH; flow cytometry), p47(phox)-p67(phox) translocation (Western blot) and eosinophil cationic protein (ECP) release (radioimmunoassay).

RESULTS

NAC (0.1-1 mm) inhibited the extracellular generation of oxygen species induced by N-formyl-L-methionyl-L-leucyl-L-phenylalanine (fMLP) and eotaxin (in the presence of IL-5) with -logIC(50) values of 3.61+/-0.03 and 3.36+/-0.09, respectively. Also, the intracellular generation of hydrogen peroxide was virtually abolished by NAC (0.5-1 mm). NAC (1 mm) did not alter the fMLP-induced Ca(2+) signal but augmented the eosinophil content of reduced GSH and inhibited p47(phox)-p67(phox) translocation. NAC inhibited the release of ECP ( approximately 90% inhibition at 1 mm) from fMLP-activated eosinophils.

CONCLUSION

Inhibition by NAC of human eosinophil functions in vitro is potentially useful in the treatment of allergic inflammation.

Clinical policy: critical issues in the management of patients presenting to the emergency department with acetaminophen overdose

This clinical policy focuses on critical issues concerning the management of patients presenting to the emergency department (ED) with acetaminophen overdose. The subcommittee reviewed the medical literature relevant to the questions posed. The critical questions are: 1. What are the indications for N-acetylcysteine (NAC) in the acetaminophen overdose patient with a known time of acute ingestion who can be risk stratified by the Rumack-Matthew nomogram? 2. What are the indications for NAC in the acetaminophen overdose patient who cannot be risk stratified by the Rumack-Matthew nomogram? Recommendations are provided on the basis of the strength of evidence of the literature. Level A recommendations represent patient management principles that reflect a high degree of clinical certainty; Level B recommendations represent patient management principles that reflect moderate clinical certainty; and Level C recommendations represent other patient management strategies that are based on preliminary, inconclusive, or conflicting evidence, or based on committee consensus. This guideline is intended for physicians working in EDs.

Comparison of oral and i.v. acetylcysteine in the treatment of acetaminophen poisoning

PURPOSE

The efficacy, safety, and cost issues that should be considered when deciding on the appropriate route of acetylcysteine for the treatment of patients with acetaminophen poisoning are reviewed.

SUMMARY

Oral and i.v. acetylcysteine appear to be equally effective when given within 8-10 hours of acetaminophen overdose. Anaphylactoid reactions to i.v. acetylcysteine have generally been reported in 3-6% of acetaminophen-poisoned patients. Dosing errors and hyponatremia have occurred in pediatric patients receiving i.v. acetylcysteine. Several investigators found an increased rate of anaphylactoid reactions in patients treated with i.v. acetylcysteine whose pretreatment serum acetaminophen levels were nontoxic. Compounding i.v. acetylcysteine from the oral preparation is less expensive than using premade i.v. solution. State pharmacy laws dictate whether extemporaneous compounding of acetylcysteine from the oral formulation is allowed. Oral acetylcysteine administration has resulted in minimal anaphylactoid reactions and is safer than i.v. acetylcysteine. Oral therapy should preferentially be considered in patients with asthma or atopic histories. The most important factors to consider when selecting the route of acetylcysteine administration include individual susceptibility, the severity of acetaminophen toxicity, and the time interval between acetaminophen ingestion and initiation of acetylcysteine therapy.

CONCLUSION

Oral acetylcysteine administered within 8-10 hours of acetaminophen overdose prevents liver toxicity in the majority of patients who tolerate it and have no contraindications to therapy. I.V. acetylcysteine should be administered when patients are treated more than 10 hours postingestion of acetaminophen overdose or have underlying conditions preventing oral treatment. Anaphylactoid reactions are rare and occur more frequently in patients treated with the i.v. preparation.

New and novel antidotes in pediatrics

Antidotal therapy can be lifesaving in the management of poisoned children. Although supportive care is sufficient in many cases, a specific antidote can significantly reduce morbidity and mortality in a number of poisoning scenarios, and so the pediatric emergency medicine practitioner must be familiar with its indications for use, dosage and administration, and contraindications. A number of new antidotes have emerged in recent years. This review discusses the pediatric uses and limitations of intravenous N-acetylcysteine, octreotide, crotaline Fab antivenom, fomepizole, atropine and pralidoxime autoinjectors and provides some brief discussion on newer antidotes for which data is only starting to emerge.

N-Acetylcysteine for the Prevention of Kidney Injury in Abdominal Aortic Surgery: A Randomized, Double-Blind, Placebo-Controlled Trial

In this prospective, randomized, placebo-controlled, double-blind trial we studied the effects of IV N-acetylcysteine for prevention of renal injury in patients undergoing abdominal aortic surgery. Seventy patients without previously documented renal dysfunction were randomly allocated to receive either N-acetylcysteine (150 mg/kg mixed in 250 mL of 5% dextrose infused in 20 min, followed by an infusion of 150 mg/kg in 250 mL of 5% dextrose over 24 h) or placebo. The infusion was started after the induction of anesthesia. The primary outcome measure was renal injury as measured by the increases in urinary N-acetyl-beta-d-glucosaminidase (NAG)/creatinine ratio (indicator of renal tubular injury) and urinary albumin/creatinine ratio (indicator of glomerular injury). Renal function was assessed by measuring plasma creatinine and serum cystatin C concentrations. The urinary NAG/creatinine ratio increased significantly from baseline to before crossclamp and remained increased on day 5 in both groups. The urinary albumin/creatinine ratio increased significantly from baseline to 6 h after declamping in the N-acetylcysteine group. However, the changes in the NAG/creatinine ratio and the albumin/creatinine ratio were not significantly different between the two groups. Plasma creatinine and serum cystatin C values remained unchanged during the study period in both groups. In conclusion, N-acetylcysteine did not offer any significant protection from renal injury during elective aortic operation in patients with normal preoperative renal function, and some degree of tubular injury seems to occur before aortic crossclamp.

Interventions for paracetamol (acetaminophen) overdose

BACKGROUND

Poisoning with paracetamol (acetaminophen) is a common cause of hepatotoxicity in the Western World. Inhibition of absorption, removal from the vascular system, antidotes, and liver transplantation are interventions for paracetamol poisoning.

OBJECTIVES

To assess the benefits and harms of interventions for paracetamol overdose.

SEARCH STRATEGY

We identified trials through electronic databases, manual searches of bibliographies and journals, authors of trials, and pharmaceutical companies until December 2005.

SELECTION CRITERIA

Randomised clinical trials and observational studies were included.

DATA COLLECTION AND ANALYSIS

The primary outcome measure was all-cause mortality plus liver transplantation. Secondary outcome measures were clinical symptoms, (eg, hepatic encephalopathy, fulminant hepatic failure), hepatotoxicity, adverse events, and plasma paracetamol concentration. We used Peto odds ratios and odds ratios with 95% confidence intervals (CI) for analysis of outcomes. Random- and fixed-effects meta-analyses were performed.

MAIN RESULTS

Ten small and low-methodological quality randomised trials, one quasi-randomised study, and 48 observational studies were identified. It was not possible to perform relevant meta-analyses of randomised trials that have addressed our outcome measures. Activated charcoal, gastric lavage, and ipecacuanha are able to reduce the absorption of paracetamol, but the clinical benefit is unclear. Of these, activated charcoal seems to have the best risk-benefit ratio. N-acetylcysteine seems preferable to placebo/supportive treatment, dimercaprol, and cysteamine, but N-acetylcysteine's superiority to methionine is unproven. It is not clear which N-acetylcysteine treatment protocol offers the best efficacy. No strong evidence supports other interventions for paracetamol overdose. N-acetylcysteine may reduce mortality in patients with fulminant hepatic failure (Peto OR 0.26, 95% CI 0.09 to 0.94, one trial). Liver transplantation has the potential to be life saving in fulminant hepatic failure, but refinement of selection criteria for transplantation and long-term outcome reporting are required.

AUTHORS' CONCLUSIONS

Our results highlight a paucity of randomised trials on interventions for paracetamol overdose. Activated charcoal seems the best choice to reduce absorption. N-acetylcysteine should be given to patients with overdose but the selection criteria are not clear. No N-acetylcysteine regime has been shown to be more effective than any other. It is a delicate balance when to proceed to liver transplantation, which may be life-saving for patients with poor prognosis.