Acetaminophen overdose: a 48-hour intravenous N-acetylcysteine treatment protocol

Acetaminophen-related hepatotoxicity

Acetaminophen (APAP) is the leading worldwide cause of drug overdose and acute liver failure (ALF). Single overdose ingestion and therapeutic misadventure may cause hepatotoxicity. Several factors, such as concomitant alcohol use or abuse, concurrent medications, genetic factors, and nutritional status, can influence the susceptibility and severity of APAP hepatotoxicity. Early manifestations of APAP hepatotoxicity are nonspecific, but require prompt recognition by physicians. Patients with repeated overdose tend to present late, and in such hepatotoxicity may have already evolved. N-acetylcysteine is a very effective antidote when giving within 8 hours, and is also recommended after a presentation of hepatotoxicity and ALF. The prognosis of patients with APAP-induced ALF is better than other causes of ALF. Liver transplantation should be offered to those who are unlikely to survive.

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.

In vitro activity and durability of a combination of an antibiofilm and an antibiotic against vascular catheter colonization

Catheter-associated infections can cause severe complications and even death. Effective antimicrobial modification of catheters that can prevent device colonization has the potential of preventing clinical infection. We studied in vitro the antimicrobial activities of central venous catheters impregnated with N-acetylcysteine (NAC), an antibiofilm agent, and a broad-spectrum antibiotic against a range of important clinical pathogens. NAC-levofloxacin-impregnated (NACLEV) catheters were also evaluated for their antiadherence activity. NACLEV catheters produced the most active and durable antimicrobial effect against both Gram-positive and Gram-negative isolates and significantly reduced colonization (P < 0.0001) by all tested pathogens compared to control catheters. These in vitro results suggest that this antimicrobial combination can potentially be used to combat catheter colonization and catheter-associated infection.

Modeling drug- and chemical-induced hepatotoxicity with systems biology approaches

We provide an overview of computational systems biology approaches as applied to the study of chemical- and drug-induced toxicity. The concept of “toxicity pathways” is described in the context of the 2007 US National Academies of Science report, “Toxicity testing in the 21st Century: A Vision and A Strategy.” Pathway mapping and modeling based on network biology concepts are a key component of the vision laid out in this report for a more biologically based analysis of dose-response behavior and the safety of chemicals and drugs. We focus on toxicity of the liver (hepatotoxicity) – a complex phenotypic response with contributions from a number of different cell types and biological processes. We describe three case studies of complementary multi-scale computational modeling approaches to understand perturbation of toxicity pathways in the human liver as a result of exposure to environmental contaminants and specific drugs. One approach involves development of a spatial, multicellular “virtual tissue” model of the liver lobule that combines molecular circuits in individual hepatocytes with cell–cell interactions and blood-mediated transport of toxicants through hepatic sinusoids, to enable quantitative, mechanistic prediction of hepatic dose-response for activation of the aryl hydrocarbon receptor toxicity pathway. Simultaneously, methods are being developing to extract quantitative maps of intracellular signaling and transcriptional regulatory networks perturbed by environmental contaminants, using a combination of gene expression and genome-wide protein-DNA interaction data. A predictive physiological model (DILIsym™) to understand drug-induced liver injury (DILI), the most common adverse event leading to termination of clinical development programs and regulatory actions on drugs, is also described. The model initially focuses on reactive metabolite-induced DILI in response to administration of acetaminophen, and spans multiple biological scales.

Protective effects of goldenseal (Hydrastis canadensis L.) on acetaminophen-induced hepatotoxicity through inhibition of CYP2E1 in rats

Background:

Goldenseal (Hydrastis canadensis L.) inhibits various cytochrome P450 (CYP) isoforms such as CYP2C9, CYP2C19, CYP2D6, CYP2E1, and CYP3A in vitro. High doses of acetaminophen (APAP) generate the highly reactive intermediate, N-acetyl-p-benzoquinone imine (NAPQI), catalyzed mainly by CYP2E1. The aim of this study was to investigate the hepatoprotective effects of orally administrated goldenseal against APAP-induced acute liver failure (ALF) via inhibition of CYP2E1.

Materials and Methods:

Male Wistar rats were treated orally with goldenseal (300 and 1000 mg/kg) 2, 18, and 26 h before and 6 h after oral APAP (400 mg/kg) administration. Serum aspartate aminotransferase (AST) and alanine aminotransferase (ALT) activities as well as serum APAP concentration were evaluated.

Results:

Goldenseal extract inhibited CYP1A2, CYP2D6, CYP2E1, and CYP3A activity, and the inhibitory effect on CYP2E1 was the strongest (IC₅₀ 4.32 μg/mL). Treatment with goldenseal (300 mg/kg) significantly attenuated the APAP-induced increase in serum AST and ALT, and the hepatoprotective effect of goldenseal was stronger than that of silymarin (200 mg/kg). Moreover, serum APAP concentration was increased by goldenseal treatment, presumably as a result of the inhibitory effect of goldenseal on the metabolism of APAP to NAPQI.

Conclusion:

These results suggest that goldenseal ameliorates APAP-induced ALF and that this protection can likely be attributed to the inhibition of CYP2E1 activity, which generates the highly reactive intermediate of APAP.

An analysis of N-acetylcysteine treatment for acetaminophen overdose using a systems model of drug-induced liver injury

N-acetylcysteine (NAC) is the treatment of choice for acetaminophen poisoning; standard 72-h oral or 21-h intravenous protocols are most frequently used. There is controversy regarding which protocol is optimal and whether the full treatment course is always necessary. It would be challenging to address these questions in a clinical trial. We used DILIsym, a mechanistic simulation of drug-induced liver injury, to investigate optimal NAC treatment after a single acetaminophen overdose for an average patient and a sample population (n = 957). For patients presenting within 24 h of ingestion, we found that the oral NAC protocol preserves more hepatocytes than the 21-h intravenous protocol. In various modeled scenarios, we found that the 21-h NAC infusion is often too short, whereas the full 72-h oral course is often unnecessary. We found that there is generally a good correlation between the time taken to reach peak serum alanine aminotransferase (ALT) and the time taken to clear N-acetyl-p-benzoquinone imine (NAPQI) from the liver. We also found that the most frequently used treatment nomograms underestimate the risk for patients presenting within 8 h of overdose ingestion. V(max) for acetaminophen bioactivation to NAPQI was the most important variable in the model in determining interpatient differences in susceptibility. In conclusion, DILIsym predicts that the oral NAC treatment protocol, or an intravenous protocol with identical dosing, is superior to the 21-h intravenous protocol and ALT is the optimal available biomarker for discontinuation of the therapy. The modeling also suggests that modification of the current treatment nomograms should be considered.

A cost effectiveness analysis of the preferred antidotes for acute paracetamol poisoning patients in Sri Lanka

Background

Acute paracetamol poisoning is a rapidly increasing problem in Sri Lanka. The antidotes are expensive and yet no health economic evaluation has been done on the therapy for acute paracetamol poisoning in the developing world. The aim of this study is to determine the cost effectiveness of using N-acetylcysteine over methionine in the management of acute paracetamol poisoning in Sri Lanka.

Methods

Economic analysis was applied using public healthcare system payer perspective.

Costs were obtained from a series of patients admitted to the National Hospital of Sri Lanka with a history of acute paracetamol overdose. Evidence on effectiveness was obtained from a systematic review of the literature. Death due to hepatotoxicity was used as the primary outcome of interest. Analysis and development of decision tree models was done using Tree Age Pro 2008.

Results

An affordable treatment threshold of Sri Lankan rupees 1,537,120/death prevented was set from the expected years of productive life gained and the average contribution to GDP. A cost-minimisation analysis was appropriate for patients presenting within 10 hours and methionine was the least costly antidote. For patients presenting 10-24 hours after poisoning, n-acetylcysteine was more effective and the incremental cost effectiveness ratio of Sri Lankan rupees 316,182/life saved was well under the threshold. One-way and multi-way sensitivity analysis also supported methionine for patients treated within 10 hours and n-acetylcysteine for patients treated within 10-24 hours as preferred antidotes.

Conclusions

Post ingestion time is an important determinant of preferred antidotal therapy for acute paracetamol poisoning patients in Sri Lanka. Using n-acetylcysteine in all patients is not cost effective. On economic grounds, methionine should become the preferred antidote for Sri Lankan patients treated within 10 hours of the acute ingestion and n-acetylcysteine should continue to be given to patients treated within 10-24 hours.

The clinical management of acetaminophen poisoning in a community hospital system: factors associated with hospital length of stay

Acetaminophen (APAP) overdose is the most common pharmaceutical poisoning. The objective of this study was to examine the management of patients admitted for treatment of APAP overdose. Factors impacting hospital length of stay (LOS) were of particular interest. This was a retrospective cohort study of patients admitted to Kaiser Permanente Northern California hospitals for APAP overdose from July 2003 through December 2007. Medical records were abstracted for patient demographic data, key factors of overdose, California Poison Control System (CPCS) contact, data regarding hospital course, transfer for liver transplantation, and death. Four hundred thirty-five patients were included. The mean hospital LOS was 66.5 h (95% CI 62.1, 71.0). Four patients (0.9%) died. Eight patients (1.8%) were transferred for liver transplantation, but all of these patients later recovered without transplant. Of 289 cases eligible for placement on the Rumack-Matthew nomogram (acute ingestion with known time of ingestion <24 h and normal liver enzymes), 161 (55.7%) had APAP levels above the "200" line and 77 (26.6%) fell below the "150" line. CPCS was contacted in 295 cases (67.8%). Mean LOS in cases with CPCS consultation was 61.9 h (95% CI 57.2, 66.5 h) versus 76.3 h (95% CI 66.6, 86.0 h) in those without. LOS in cases treated with IV NAC was 67.1 h (95% CI 57.7, 76.5 h) versus 66.4 h (95% CI 61.2, 71.5 h) in cases treated with oral NAC. Many patients admitted for APAP overdose had serum APAP levels below the minimum toxicity level. Use of IV NAC did not impact hospital LOS. CPCS consultation appeared to decrease mean hospital LOS.

Unexpected late rise in plasma acetaminophen concentrations with change in risk stratification in acute acetaminophen overdoses

BACKGROUND

The acetaminophen risk analysis nomogram is used to predict hepatotoxicity risk in acute acetaminophen overdose based on a single plasma acetaminophen concentration (PAC) measured between 4 and 24 h after ingestion. There are case reports of patients with acute overdoses of acetaminophen combination products in whom a toxic PAC occurred later after an initial non-toxic PAC at approximately 4 h.

OBJECTIVES

The objective was to describe patients who had an initial non-toxic PAC and a subsequent toxic PAC.

METHODS

A poison center's database was searched for records in which patients were administered N-acetylcysteine. Cases were included if they involved an acute overdose of an acetaminophen-containing product with at least 2 plottable PACs, the first of which was obtained at least 4 h after ingestion and was below the treatment line on the nomogram with a subsequent toxic PAC. Data were analyzed for doses, timed PACs, specific acetaminophen preparation, coingestants, activated charcoal administration, and clinical effects.

RESULTS

Twenty patients were included. Thirteen patients ingested combination products. All patients experienced vomiting, neurologic, or cardiovascular effects at presentation or before obtaining the second PAC. Two patients developed hepatotoxicity, one of which died from the complications of acetaminophen-induced hepatotoxicity.

CONCLUSION

The nomogram fails to predict toxicity based on a single PAC in a small subset of patients.

Hepatic failure despite early acetylcysteine following large acetaminophen-diphenhydramine overdose

We describe the case of a patient with massive acetaminophen-diphenhydramine overdose and a 4-hour serum acetaminophen concentration of 653 μg/mL. The patient was treated with acetylcysteine 5 hours after ingestion. Because of a persistently elevated serum acetaminophen level of 413 μg/mL 45 hours after ingestion, a medical toxicologist recommended that the patient be treated with a second bolus of acetylcysteine (150 mg/kg followed by 12.5 mg/kg per hour for 4 hours, then 6.25 mg/kg per hour). On hospital day 3, she developed hepatic failure despite early treatment. Her transaminase levels and hepatic synthetic function began to improve on hospital day 6, and acetylcysteine was discontinued on hospital day 10. In cases of massive acetaminophen overdose, standard acetylcysteine dosing may not be adequate. We suggest that elevated serum acetaminophen concentrations at the end of a standard 20-hour acetylcysteine infusion should be discussed with the local poison center.

N-acetylcysteine as a novel prophylactic treatment for ifosfamide-induced nephrotoxicity in children: translational pharmacokinetics

Ifosfamide (IFO), which is used in the treatment of pediatric solid tumors, causes high rates of nephrotoxicity. N-acetylcysteine (NAC), an antidote for acetaminophen overdose, has been shown to prevent IFO-induced renal cell death and nephrotoxicity in both LLCPK-1 cells and a rat model. To facilitate the use of NAC in preventing IFO-induced nephrotoxicity in children, the authors compared the systemic exposure to NAC in children treated for acetaminophen overdose to the systemic exposure of the therapeutically effective rat model. The mean systemic exposure in the rat model was 18.72 mM·h (range, 9.92-30.02 mM·h), compared to the mean systemic exposure found in treated children (14.48 mM·h; range, 6.22-32.96 mM·h). They also report 2 pediatric cases in which NAC-attenuated acute renal failure associated with IFO when given concurrently with their chemotherapy treatment. Systemic exposure to NAC measured in 1 of these cases was comparable to that in the children treated for acetaminophen overdose. These results corroborate NAC's potential to protect against IFO-induced nephrotoxicity in children when used in its clinically approved dose schedule and supports a clinical trial in children.

Using 0.45% saline solution and a modified dosing regimen for infusing N-acetylcysteine in children with paracetamol poisoning

INTRODUCTION

N-acetylcysteine (NAC) administration is recommended to all patients judged to be at risk of developing hepatotoxicity following paracetamol overdose. However, it has been shown that standard i.v. dosing can cause symptomatic hyponatraemia in children. We describe a case series using 0.45% NaCl plus 5% dextrose for infusing i.v. NAC in children with paracetamol poisoning.

CASE SERIES

A retrospective review of medical records of patients treated with NAC using 0.45% saline plus 5% dextrose, and a novel two-stage dosing regimen between January 2003 and July 2006 were undertaken.

RESULTS

A total of 40 patients (20 male and 20 female) who received NAC in 0.45% sodium chloride (NaCl) with 5% dextrose were identified. Mean age was 9 years 6 months (95% CI 4 years 4 months to 15 years 1 month) and the range 3 months to 17 years. All patients had NAC infused in a two-stage infusion regimen (150 mg/kg bolus over 1 h followed by a continuous infusion of 10 mg/kg/h for 20 h). The serum sodium was measured in all 40 patients with a mean of 140 (range of 133 to 152 mmol/L). Repeat sodium was measured in 35 cases, with a mean of 140 mmol/L (range from 134 to 149 mmol/L).

CONCLUSION

These findings support the use of saline-containing solutions to administer NAC as an alternative to 5% dextrose, and suggest that a two-stage infusion regimen should be further investigated with prospective studies.

Critical care management of patients before liver transplantation

The critical care management of patients before liver transplantation is aimed at optimizing hepatic and extrahepatic organ function before the transplant operation, with a goal to favorably influence perioperative and postoperative graft and patient outcomes. Critical illness in liver disease can present in the context of acute liver failure or acute on chronic liver failure. The differing pathophysiologic processes underlying these 2 types of liver failure necessitate specific approaches to their intensive care management. In their extreme presentations, both types of liver failure present as multiorgan system failure; and therefore, the critical care management of these entities requires a systematic multiorgan system approach to address hepatic and extrahepatic organ dysfunction. This review provides a multiorgan system-based description of critical care management of acute liver failure and acute on chronic liver failure before liver transplantation.

A multicenter comparison of the safety of oral versus intravenous acetylcysteine for treatment of acetaminophen overdose

Oral and intravenous (IV) N-acetylcysteine (NAC) are used for the treatment of acetaminophen poisoning. The objective of this multicenter study was to compare the safety of these two routes of administration.

METHODS

We conducted a multicenter chart review of all patients treated with NAC for acetaminophen poisoning. The primary safety outcome was the percentage of patients with NAC-related adverse events.

RESULTS

A total of 503 subjects were included in the safety analysis (306 IV-only, 145 oral-only, and 52 both routes). There were no serious adverse events related to NAC for either route. Nausea and vomiting were the most common related adverse events and were more common with oral treatment (23 vs. 9%). Anaphylactoid reactions were more common with IV administration (6 vs. 2%).

CONCLUSIONS

IV and oral NAC are generally mild adverse drug reactions.

Reliability of history of acetaminophen ingestion in intentional drug overdose patients

The objective of this study was to determine the reliability of denial of acetaminophen ingestion in intentional drug overdose patients. All intentional drug overdose patients admitted to an emergency department who were able to provide a history were included. A detailed history was obtained on names, timing and number of medications ingested, and serum acetaminophen was assayed. Multidrug ingestion was defined as the reporting of ≥2 medications. Patients were considered ‘reliable’ if they reported acetaminophen ingestion and had detectable acetaminophen levels or the other way around. Validity parameters of acetaminophen history were assessed by sensitivity, specificity and positive and negative predictive values. A total of 154 patients were included. History was significantly more reliable in patients who denied ingestion of acetaminophen (n = 107) compared with patients who reported it (n = 47; 95.3% vs 65.9%, respectively; p < 0.0001, 95% CI of the difference 17.5%—41.2%). No suicidal patient who denied both acetaminophen and multidrug ingestions had a detectable acetaminophen level (negative predictive value 1, 95% CI 0.93—1.0). It is suggested that denial of both acetaminophen and multidrug ingestions by intentional drug overdose patients after a thorough history taking can be considered reliable for acetaminophen history. In facilities with limited resources, these patients may not require routine acetaminophen screening.

Late extensive intravenous administration of N-acetylcysteine can reverse hepatic failure in acetaminophen overdose

Acetaminophen is a commonly used analgesic and has been shown to be a main cause of drug-induced liver failure. N-acetylcysteine (NAC) should be employed as the antidote in case of acetaminophen poisoning within the first 8-10 hours. Oral administration of NAC is universally recommended and due to the adverse effects, the intravenous administration of the agent is reserved for patients with oral intolerance and severe complications. We here report an 18-year-old man with severe liver failure due to a huge ingestion of acetaminophen, who was taken into the Loghman Hakim Hospital Poison Center 72 hours after attempted suicide. Regarding the poor prognostic clues as his level of consciousness and impaired liver functions, an extensive intravenous regimen of NAC was started. The patient survived the condition with an additional intravenous administration of NAC past the first 72 hours of treatment. We discuss that even in late phases of intoxication; high-dose intravenous NAC can serve a substantial improvement.

N-acetylcysteine prevents nitric oxide-induced chondrocyte apoptosis and cartilage degeneration in an experimental model of osteoarthritis

We investigated whether N-acetylcysteine (NAC), a precursor of glutathione, could protect rabbit articular chondrocytes against nitric oxide (NO)-induced apoptosis and could prevent cartilage destruction in an experimental model of osteoarthritis (OA) in rats. Isolated chondrocytes were treated with various concentrations of NAC (0-2 mM). Apoptosis was induced by 0.75 mM sodium nitroprusside (SNP) dehydrate, which produces NO. Cell viability was assessed by MTT assay, while apoptosis was evaluated by Hoechst 33342 and TUNEL staining. Intracellular reactive oxygen species (ROS) and glutathione levels were measured, and expression of p53 and caspase-3 were determined by Western blotting. To determine whether intraarticular injection of NAC prevents cartilage destruction in vivo, cartilage samples of an OA model were subjected to H&E, Safranin O, and TUNEL staining. NAC prevented NO-induced apoptosis, ROS overproduction, p53 up-regulation, and caspase-3 activation. The protective effects of NAC were significantly blocked by buthionine sulfoximine, a glutathione synthetase inhibitor, indicating that the apoptosis-preventing activity of NAC was mediated by glutathione. Using a rat model of experimentally induced OA, we found that NAC also significantly prevented cartilage destruction and chondrocyte apoptosis in vivo. These results indicate that NAC inhibits NO-induced apoptosis of chondrocytes through glutathione in vitro, and inhibits chondrocyte apoptosis and articular cartilage degeneration in vivo.

A retrospective evaluation of shortened-duration oral N-acetylcysteine for the treatment of acetaminophen poisoning

INTRODUCTION

The use of less than the traditional 72-hour course of oral N-acetylcysteine has been an alternative treatment option following potentially toxic acute and chronic acetaminophen ingestions felt to be at low risk of developing hepatotoxicity. While clinical experience with shortened treatment duration is extensive, there are few studies evaluating the effectiveness and extent to which these regimens may be used.

METHODS

A large statewide poison center database was reviewed for all acetaminophen exposures involving potentially toxic acute and chronic ingestions, in addition to those taking place at unknown times. Patients were identified who met laboratory criteria for early N-acetylcysteine (NAC) discontinuation (APAP>10 micro/mL, INR<or=1.3, and AST/ALT<or=60 IU) after a minimum of a 140-mg/kg oral NAC loading dose and 5 additional 70-mg/kg doses over 20 hours. A further search of the poison center database was conducted for individuals who received shortened-course (20-48 hours) oral NAC treatment who developed subsequent hepatotoxicity or death.

RESULTS

Of 3303 individuals with potentially toxic acetaminophen ingestions, 1932 met criteria for early NAC discontinuation. Mean treatment duration was 36.4+/-7.7 hours (acute=37.3+/-7.6 hours; chronic=34.8+/-7.4 hours; unknown=35.2+/-7.6 hours). The poison center database search identified no short-course eligible subjects who developed subsequent hepatotoxicity or death following<or=48 hours of oral NAC.

CONCLUSION

Treatment with shortened-course oral NAC in patients meeting criteria for early discontinuation may be an effective treatment option in a sizeable proportion of individuals with potentially toxic acetaminophen ingestions.

Paracetamol-induced hepatotoxicity: lack of enhancement of the hepatoprotective effect of N-acetylcysteine by sodium sulphate

The potential role of sodium sulphate in possible enhancement of the hepatoprotective action of N-acetylcysteine (NAC) in paracetamol (PCM) overdose was examined. The effects of sodium sulphate (200 mg/kg) in combination with NAC (400 mg/kg) administered intraperitoneally 2 h post-PCM dose, on mortality rate and plasma activities of aspartate aminotransferase (AST) and alanine aminotransferase (ALT) were investigated in mice 24 h after receiving a single oral dose of 400 mg/kg PCM. In addition, the effect on the mortality rate of PCM-treated animals of co-administering 400 mg/kg sodium sulphate with NAC (200 or 400 mg/kg) was also studied. NAC alone caused a marked reduction in the mortality rate of PCM-treated mice and a sharp drop in their plasma AST and ALT activities to near normal values. However, no additional reduction in plasma levels of AST and ALT was observed when sodium sulphate was co-administered with NAC. Similarly, sodium sulphate (200 mg/kg) administered alone to PCM-treated mice had no effect on the high mortality rate or the elevation in plasma AST and ALT activities observed in these animals. Furthermore, increasing the dose of sodium sulphate to 400 mg/kg did not influence the mortality rate. It is therefore concluded that sodium sulphate neither protects against paracetamol-induced hepatotoxicity nor enhances the hepatoprotective action of N-acetylcysteine.

Effect of N-acetylcysteine on the accuracy of the prothrombin time assay of plasma coagulation factor II+VII+X activity in subjects infused with the drug. Influence of time and temperature

OBJECTIVES

The prothrombin time (PT) assay of factor II+VII+X activity is an important predictor of liver damage in paracetamol poisoned patients. It complicates interpretation of results that the antidote, acetylcysteine (NAC) depresses this activity. The aim was to investigate if NAC influences the accuracy of the plasma PT assay.

MATERIALS AND METHODS

The accuracy of Nycotest PT was studied using plasma added NAC in vitro and plasma from subjects infused with NAC. The latter results were compared with those obtained by analysis of PT by CoaguChek S.

RESULTS

Therapeutic NAC concentrations added to plasma in vitro decreased factor II+VII+X activity at 37 degrees C in a time-dependent manner. This effect was quenched at temperatures <24 degrees C. Activity lost at 37 degrees C could partly be recovered by subsequent incubation at 5 or 20 degrees C. Incubation at 37 degrees C prior to assay led to a significant additional depression of factor II+VII+X activity in plasma from subjects infused with NAC during the first 3h of infusion indicating that it contained reactive NAC. The risk that this NAC interfered with the accuracy of the PT assay was considered minimal with samples stored below 24 degrees C. This was supported by similarity of results obtained by analysis of appropriately stored plasma and simultaneously drawn blood by CoaguChek S.

CONCLUSIONS

Residual reactive NAC does not interfere with the accuracy of the PT assay of plasma stored below 24 degrees C, but NAC-induced loss in activity at 37 degrees C may be partly recovered during subsequent storage below 24 degrees C.

Role of N-acetylcysteine in adults with non-acetaminophen-induced acute liver failure in a center without the facility of liver transplantation

PURPOSE

We aimed to study the role of N-acetylcysteine (NAC) in non-acetaminophen-induced acute liver failure (NAI-ALF).

METHODS

A total of 47 adult patients were prospectively enrolled with NAI-ALF (group 1 or NAC group) and oral NAC was given. The primary outcome was reduction in mortality with the use of NAC in NAI-ALF. The secondary outcomes were to evaluate safety of NAC and to assess factors predicting mortality. We compared these results with records of NAI-ALF patients admitted in our hospital from 2000 to 2003 (n = 44) who were not given NAC (group 2 or historical controls).

RESULTS

The two groups were comparable for the etiology of ALF, prothrombin time (PT), alanine aminotransferase, creatinine, albumin, etc. The mean age in group 1 was 27.7 ± 11.8 years and in group 2 37.5 ± 18.8 years (P = 0.004). Bilirubin was 20.63 ± 11.03 and 14.36 ± 8.90 mg/dl in groups 1 and 2, respectively (P = 0.004). There were 8 (17%) and 1 (2.3%) pregnant ALF women with acute hepatitis E virus (HEV) infection in groups 1 and 2, respectively (P = 0.031). All patients were given supportive care, including mechanical ventilation. A total of 34 (37.36%) patients survived; 22 (47%) in group 1 (NAC group) and 12 (27%) in group 2 (controls) (P = 0.05). On multivariable regression analysis, patients not given NAC (odds ratio [OR] = 10.3, 95% confidence interval [CI] = 1.6-65.7), along with age older than 40 years (OR = 10.3, 95% CI = 2.0-52.5), PT more than 50 s (OR = 15.4, 95% CI = 3.8-62.2), patients requiring mechanical ventilation (OR = 20.1, 95% CI = 3.1-130.2), and interval between jaundice and hepatic encephalopathy (OR = 5.0, 95% CI = 1.3-19.1) were independent predictors of mortality.

CONCLUSIONS

The use of NAC causes reduction in NAI-ALF mortality and its use was safe.

Management of acute liver failure

Acute liver failure (ALF) is a syndrome of diverse etiology, in which patients without previously recognized liver disease sustain a liver injury that results in rapid loss of hepatic function. Depending on the etiology and severity of the insult, some patients undergo rapid hepatic regeneration and spontaneously recover. However, nearly 60% of patients with ALF in the US require and undergo orthotopic liver transplantation or die. Management decisions made by clinicians who initially assess individuals with ALF can drastically affect these patients' outcomes. Even with optimal early management, however, many patients with ALF develop a cascade of complications often presaged by the systemic inflammatory response syndrome, which involves failure of nearly every organ system. We highlight advances in the intensive care management of patients with ALF that have contributed to a marked improvement in their overall survival over the past 20 years. These advances include therapies that limit the extent of liver injury and maximize the likelihood of spontaneous recovery and approaches to enable prevention, recognition and early treatment of complications that lead to multi-organ-system failure, the most common cause of death. Finally, we summarize the role of orthotopic liver transplantation in salvage of the most severely affected patients.

Comparison of the 20-hour intravenous and 72-hour oral acetylcysteine protocols for the treatment of acute acetaminophen poisoning

STUDY OBJECTIVE

To compare outcomes after acute acetaminophen poisoning in 2 large cohorts of patients treated with either the 20-hour intravenous or 72-hour oral acetylcysteine protocol.

METHODS

We conducted a retrospective cohort study with historical control comparing patients treated with one of 2 acetylcysteine regimens. Data for the 20-hour group were obtained from a medical record review of patients on whom the 20-hour intravenous protocol was initiated in Canadian hospitals from 1980 to 2005. The 72-hour group consisted of a historical cohort of patients treated in US hospitals with the 72-hour oral protocol from 1976 to 1985. The primary outcome was hepatotoxicity (aminotransferase levels >1,000 IU/L).

RESULTS

Of the 4,048 patients analyzed, 2,086 were in the 20-hour group and 1,962 were in the 72-hour group. The incidence of hepatotoxicity was 13.9% in the 20-hour group and 15.8% in the 72-hour group (-1.9% absolute difference; 95% confidence interval [CI] -4.2 to 0.3). The relative risk of hepatotoxicity was lower in the 20-hour group when acetylcysteine was initiated within 12 hours of ingestion. The relative risk was lower in the 72-hour group when acetylcysteine was initiated later than 18 hours after ingestion. There was no significant risk difference between groups when acetylcysteine treatment was started 12 to 18 hours after ingestion. One patient in the 20-hour group received a liver transplant and died because of acetaminophen toxicity compared with no liver transplants and 3 deaths in the 72-hour group. Anaphylactoid reactions to intravenous acetylcysteine were reported in 148 of 2,086 patients (7.1%; 95% CI 6.1% to 8.3%). This study is limited by comparison of 2 separate data sets from different countries and study years.

CONCLUSION

The risk of hepatotoxicity differed between the 20-hour and 72-hour protocols according to the time to initiation of acetylcysteine. It favored the 20-hour protocol for patients presenting early and favored the 72-hour protocol for patients presenting late after acute acetaminophen overdose.

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.

Managing acute acetaminophen poisoning with oral versus intravenous N-acetylcysteine: a provider-perspective cost analysis

BACKGROUND

Acetaminophen (APAP) overdose, which can lead to hepatotoxicity, is the most commonly reported poisoning in the United States and has the highest rate of mortality, with more than 100,000 exposures and 300 deaths reported annually (1) . The treatment of choice, N-acetylcysteine (NAC), is effective in both oral (PO) and intravenous (IV) formulations. The main difference in therapies, other than administration route, is time to complete delivery--72 hours for PO NAC versus 21 hours for IV NAC, according to full prescribing information. This distinction is the primary basis for variation in management costs for hospitalized patients receiving these products.

OBJECTIVES

To quantify and compare full treatment costs from the provider perspective to manage acute APAP poisoning with either PO or IV NAC in a standard treatment regimen.

METHODS

A cost model was developed and populated with published data comprising probabilities of potential clinical outcomes and the costs of resources consumed during patient care.

RESULTS

For patients who present <10 hours post-ingestion, the estimated total cost of care with PO NAC in the treatment regimen is $5,817 (ICU patients) or $3,850, (ward patients) compared with $3,765 and $2,768 for similar care with IV NAC. Potential cost savings equal - $2,052 (-35%) or -$1,083 (-28%), respectively, in favor of IV NAC. Similar potential savings were estimated for patients presenting 10-24 hours post-ingestion.

CONCLUSION

IV NAC is the less costly therapeutic option for APAP poisonings, based on simulation modeling and retrospective data. The current economic evaluation is restricted by the absence of comparative data from head-to-head, matched-cohort studies and the limitations common to retrospective APAP toxicology datasets. Additional research could refine these results.

Hepatotoxicity despite early administration of intravenous N-acetylcysteine for acute acetaminophen overdose

OBJECTIVES

The objective was to evaluate the effectiveness of intravenous N-acetylcysteine (IV NAC; 300 mg/kg over 21 hours) in early acute acetaminophen (APAP) overdose patients.

METHODS

This observational case series included patients hospitalized between 2004 and 2007 for acute APAP overdoses and who were reported to a regional poison center. Inclusion criteria were plasma APAP concentrations on or above the treatment line on the Rumack-Matthew nomogram, administration of IV NAC within 8 hours of ingestion, and follow-up to known outcome. The hospital chart of each patient who received IV NAC for longer than the standard 21 hours was reviewed. Hepatotoxicity was defined as hepatic aminotransferase levels greater than 1,000 IU/L.

RESULTS

Seventy-seven patients met inclusion criteria and received at least 21 hours of IV NAC for an acute APAP overdose. Seven patients received antidotal therapy for greater than 21 hours. These patients tended to have ingested combination preparations, have very high initial plasma APAP concentrations, and had persistently elevated plasma concentrations during their hospital stay. Hepatotoxicity occurred in 4 patients (5.2%, 95% confidence interval [CI] = 0.2% to 10.1%), including 1 death and 1 liver transplantation.

CONCLUSIONS

Hepatotoxicity developed in 5.2% of cases, suggesting that the 21-hour IV NAC regimen is suboptimal in some patients. In addition to high initial plasma APAP concentrations, APAP product formulation and persistently elevated plasma APAP concentrations were identified as factors possibly associated with developing hepatotoxicity. The authors propose a tailored approach to the discontinuation of IV NAC and point out the need for reevaluation of optimal doses and duration of therapy.

Safety and effectiveness of acetadote for acetaminophen toxicity

BACKGROUND

Acetaminophen (APAP) toxicity is commonly encountered in the Emergency Department. Until 2004, treatment consisted of either oral N-acetylcysteine (NAC) or filtered oral NAC administered intravenously (i.v.). Intravenous acetylcysteine (Acetadote) is a new Food and Drug Administration-approved i.v. formulation of acetylcysteine manufactured by Cumberland Pharmaceuticals in Nashville, Tennessee. Little post-marketing data exists on the effectiveness and safety of i.v. acetylcysteine.

OBJECTIVES

We evaluated the clinical presentations and outcomes of patients treated with i.v. acetylcysteine for APAP toxicity.

METHODS

We performed a retrospective chart review of patients treated with i.v. acetylcysteine for APAP ingestion. The primary outcome measures were: adverse reactions to and effectiveness of i.v. acetylcysteine, as defined by elevation of transaminases, liver failure, renal failure, death, and hospital length of stay (LOS). Data collected included: comorbidities, allergies, intentionality, timing and dosing of i.v. acetylcysteine, hospital LOS, transaminases > 1000 IU/L, development of liver failure requiring transplant, development of renal failure requiring hemodialysis, death, and anaphylactoid reactions.

RESULTS

Sixty-four patients met our study criteria. Overall, 16 (25%) patients developed transaminases > 1000 IU/L, 4 (6%) of them died and 2 (3%) received liver transplants. Of the 15 patients (23%) treated within 8 h, none died or developed liver or renal failure, and only 1 developed transient transaminase elevation > 1000 IU/L. In the patients treated outside of 8 h, the median LOS was 3 days, whereas the group treated within 8 h had a median LOS of only 1 day. Six (9%) patients developed anaphylactoid reactions, 2 of whom received the i.v. acetylcysteine bolus over 15 min. Five of these patients were treated pharmacologically and completed treatment, and one had treatment discontinued for undocumented reasons.

CONCLUSION

Intravenous acetylcysteine seemed to be a safe and effective formulation of N-acetylcysteine.

A New Predictor of Toxicity Following Acetaminophen Overdose Based on Pretreatment Exposure

INTRODUCTION

Despite extensive clinical experience, no dose-response curve exists for acetaminophen toxicity in man. The absence of accurate toxicodynamics has hampered efforts to optimize patient therapy and to identify risk modifiers following overdose. We set out to parameterize both the degree and duration of pretreatment exposure into a single, continuous measure of exposure, which will serve as the x-axis of an eventual dose-response curve.

METHODS

The model was constructed from pharmacokinetic first principles, using as inputs the vertical distance above the Rumack-Matthew nomogram line (expressed as the equivalent serum acetaminophen concentration 4 h after ingestion) and the delay to antidote therapy (tNAC). A no-effect dose ([APAP]threshold) and lag time (ti) were assumed.

RESULTS

The area under the serum acetaminophen concentration vs. time curve bounded by [APAP]threshold, ti and tNAC represents our proposed time-weighted measure of exposure. We demonstrate that this non-negative area estimates the cellular burden of toxic adducts formed following overdose. This measure is also easily calculated at patient presentation using clinical data and allows for both declining serum acetaminophen concentrations and variable delays to antidote therapy.

DISCUSSION

We describe a new, pharmacokinetically based measure of exposure following acute acetaminophen overdose treated with N-acetylcysteine. Using this measure should enhance the analysis of nonexperimental clinical data and permit more accurate characterization of acetaminophen toxicodynamics. Ultimately, this approach may facilitate progress on many of the long-standing controversies regarding acetaminophen toxicity in man.

Caring for the mother, concentrating on the fetus: intravenous N-acetylcysteine in pregnancy

Acetaminophen is one of the most common toxicities in pregnancy, thus providers should be aware of treatment options. We use a case presentation to demonstrate the successful use of a 20-hour protocol of intravenous N-acetylcysteine. A 26-year-old woman, gravid3para1102, at an estimated gestational age of 32 weeks 2 days presented with a reported ingestion of 9.75 g of acetaminophen 1.5 hours before arrival. The patient was treated with activated charcoal and intravenous N-acetylcysteine. After brief inpatient admission and management, the patient went on to deliver a full-term infant without further sequelae. Acetaminophen toxicity in pregnancy can be treated successfully with intravenous N-acetylcysteine if used in a timely manner with minimal adverse affects on the fetus and mother.

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.

Lower incidence of anaphylactoid reactions to N-acetylcysteine in patients with high acetaminophen concentrations after overdose

BACKGROUND

Mechanisms responsible for anaphylactoid reactions to N-acetylcysteine (NAC) are poorly understood, and acetaminophen itself may play an important role. The present study examined the relationship between serum acetaminophen concentrations and risk of anaphylactoid reactions.

METHODS

Prospective study of adverse reactions to NAC administered according to standardized clinical protocols in patients who present to hospital after acute acetaminophen overdose. Subgroups were defined by serum acetaminophen concentrations 0 to 100 mg/L, 101 to 150 mg/L, 151 to 200 mg/L, 201 to 300 mg/L, and >300 mg/L.

RESULTS

There were 362 patients, and anaphylactoid reactions occurred in 14.9%. Anaphylactoid reactions occurred less commonly in patients with high serum acetaminophen concentrations (p = 0.046 by Cochran-Armitage trend test) and high equivalent 4 h acetaminophen concentrations (p = 0.004).

DISCUSSION

High serum acetaminophen concentrations were associated with fewer anaphylactoid reactions, suggesting that these might in some way be protective. The biological basis needs further exploration so as to allow a better understanding of the mechanisms responsible for adverse reactions to NAC treatment.

The poisoned child in the pediatric intensive care unit

Acutely poisoned children remain a common problem facing pediatricians working in acute care medicine in the United States and worldwide. The management of such children continues to be challenging, and their care has evolved throughout the years. The concept of gastric decontamination in acute poisoning has significantly changed over the past 10 years, and many of the previously used techniques have been abandoned or fallen out of favor for lack of evidence to their benefit or unacceptable serious risks and side effects. Supportive care continues to be the cornerstone in managing most poisoned children. Only a few patients benefit from antidotes or specific interventions.

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.

Acute liver failure: Summary of a workshop

Acute liver failure (ALF) is a rare but challenging clinical syndrome with multiple causes; a specific etiology cannot be identified in 15% of adult and 50% of pediatric cases. The course of ALF is variable and the mortality rate is high. Liver transplantation is the only therapy of proven benefit, but the rapidity of progression and the variable course of ALF limit its use. Currently in the United States, spontaneous survival occurs in approximately 45%, liver transplantation in 25%, and death without transplantation in 30% of adults with ALF. Higher rates of spontaneous recovery (56%) and transplantation (31%) with lower rates of death (13%) occur in children. The outcome of ALF varies by etiology, favorable prognoses being found with acetaminophen overdose, hepatitis A, and ischemia (approximately 60% spontaneous survival), and poor prognoses with drug-induced ALF, hepatitis B, and indeterminate cases (approximately 25% spontaneous survival). Excellent intensive care is critical in management of patients with ALF. Nonspecific therapies are of unproven benefit. Future possible therapeutic approaches include N-acetylcysteine, hypothermia, liver assist devices, and hepatocyte transplantation. Advances in stem cell research may allow provision of cells for bioartificial liver support. ALF presents many challenging opportunities in both clinical and basic research.

Intensive care of patients with acute liver failure: recommendations of the U.S. Acute Liver Failure Study Group

OBJECTIVE

To provide a uniform platform from which to study acute liver failure, the U.S. Acute Liver Failure Study Group has sought to standardize the management of patients with acute liver failure within participating centers.

METHODS

In areas where consensus could not be reached because of divergent practices and a paucity of studies in acute liver failure patients, additional information was gleaned from the intensive care literature and literature on the management of intracranial hypertension in non-acute liver failure patients. Experts in diverse fields were included in the development of a standard study-wide management protocol.

MEASUREMENTS AND MAIN RESULTS

Intracranial pressure monitoring is recommended in patients with advanced hepatic encephalopathy who are awaiting orthotopic liver transplantation. At an intracranial pressure of > or =25 mm Hg, osmotic therapy should be instituted with intravenous mannitol boluses. Patients with acute liver failure should be maintained in a mildly hyperosmotic state to minimize cerebral edema. Accordingly, serum sodium should be maintained at least within high normal limits, but hypertonic saline administered to 145-155 mmol/L may be considered in patients with intracranial hypertension refractory to mannitol. Data are insufficient to recommend further therapy in patients who fail osmotherapy, although the induction of moderate hypothermia appears to be promising as a bridge to orthotopic liver transplantation. Empirical broad-spectrum antibiotics should be administered to any patient with acute liver failure who develops signs of the systemic inflammatory response syndrome, or unexplained progression to higher grades of encephalopathy. Other recommendations encompassing specific hematologic, renal, pulmonary, and endocrine complications of acute liver failure patients are provided, including their management during and after orthotopic liver transplantation.

CONCLUSIONS

The present consensus details the intensive care management of patients with acute liver failure. Such guidelines may be useful not only for the management of individual patients with acute liver failure, but also to improve the uniformity of practices across academic centers for the purpose of collaborative studies.

N-acetylcysteine as a potential antidote and biomonitoring agent of methylmercury exposure

BACKGROUND

Many people, by means of consumption of seafood or other anthropogenic sources, are exposed to levels of methylmercury (MeHg) that are generally considered to be quite low, but that may nevertheless produce irreversible brain damage, particularly in unborn babies. The only way to prevent or ameliorate MeHg toxicity is to enhance its elimination from the body.

OBJECTIVES

Using N-acetylcysteine (NAC), we aimed to devise a monitoring protocol for early detection of acute exposure or relatively low MeHg levels in a rodent model, and to test whether NAC reduces MeHg levels in the developing embryo.

RESULTS

NAC produced a transient, dose-dependent acceleration of urinary MeHg excretion in rats of both sexes. Approximately 5% of various MeHg doses was excreted in urine 2 hr after injection of 1 mmol/kg NAC. In pregnant rats, NAC markedly reduced the body burden of MeHg, particularly in target tissues such as brain, placenta, and fetus. In contrast, NAC had no significant effect on urinary MeHg excretion in preweanling rats.

CONCLUSIONS

Because NAC causes a transient increase in urinary excretion of MeHg that is proportional to the body burden, it is promising as a biomonitoring agent for MeHg in adult animals. In view of this and because NAC is effective at enhancing MeHg excretion when given either orally or intravenously, can decrease brain and fetal levels of MeHg, has minimal side effects, and is widely available in clinical settings, NAC should be evaluated as a potential antidote and biomonitoring agent in humans.

Safety and efficacy of N-acetylcysteine in children with non-acetaminophen-induced acute liver failure

Acute liver failure (ALF) carries a high mortality in children. N-acetylcysteine (NAC), an antioxidant agent that replenishes mitochondrial and cytosolic glutathione stores, has been used in the treatment of late acetaminophen-induced ALF and non-acetaminophen-induced ALF. In our unit, NAC was introduced as additional treatment for non-acetaminophen-induced ALF in 1995. The aim of this study was to evaluate the safety and efficacy of NAC in children with ALF not caused by acetaminophen poisoning. A retrospective review of medical records of 170 children presenting with nonacetaminophen-induced ALF between 1989 and 2004 was undertaken. ALF was defined as either international normalized ratio of prothrombin time (INR) > 2 and abnormal liver function or INR >1.5 with encephalopathy and abnormal liver function. Children were divided into the following groups: Group 1 (1989-1994), standard care (n = 59; 34 [58%] male; median age 2.03 yr, range 0.003-15.8 yr); and Group 2 (1995-2004), standard care and NAC administration (n = 111; 57 [51%] male; median age 3.51 yr, range 0.005-17.4 yr). NAC was administered as a continuous infusion (100 mg/kg/24 hours) until INR < 1.4, death, or liver transplantation (LT). The median duration of NAC administration in Group 2 was 5 (range, 1-77) days. Complications were noted in 8 (10.8%) children: rash in 3, arrhythmia in 3, and dizziness and peripheral edema in 1. One child had an allergic reaction (bronchospasm) and NAC was stopped. A total of 41 (71%) children in Group 1 vs. 85 (77%) in Group 2 required admission to intensive care, P = not significant (ns). The length of intensive care stay was 6 (range, 1-58) days in Group 1 vs. 5 (range, 1-68) days in Group 2, P = ns and length of hospital stay was 25 (range, 1-264) days vs. 19 (range, 1-201) days, P = 0.05. The 10-yr actuarial survival was 50% in Group 1 compared to 75% in Group 2, P = 0.009. Survival with native liver occurred in 13 (22%) in Group 1 vs. 48 (43%) in Group 2, P = 0.005; 15 (25%) in Group 1 died without transplant vs. 21 (19%) in Group 2, P = ns; and LT was performed in 32 (54%) vs. 42 (38%), P = ns. Death after transplantation occurred in 15 (39%) in Group 1 vs. 8 (16%) in Group 2, P = 0.02. In conclusion, NAC is safe in non-acetaminophen-induced ALF. In this retrospective study NAC was associated with a shorter length of hospital stay, higher incidence of native liver recovery without transplantation, and better survival after transplantation.