Impact of new UK paracetamol overdose guidelines on patients presenting to the emergency department

Paracetamol is involved in a large proportion of overdoses that present to the Emergency Department (ED), either as lone or mixed overdoses. Non-treatment of toxic levels can lead to fulminant liver failure. This study is to determine the impact the new UK treatment guidelines will have on patients presenting with paracetamol overdose. A retrospective review was performed on all patients who had paracetamol levels done in the ED between September 2011 and August 2012. A total of 523 patients were identified, 95 (18%) of whom had detectable paracetamol levels. 74 patients from the 95 were evaluated. 18 (24%) patients were treated with N-acetylcysteine as per the then paracetamol overdose guidelines. Using the new guidelines would have resulted in 3 more patients being admitted. Our study shows that most patients who present following paracetamol overdose do not require treatment with N-acetylcysteine and suggests that the introduction of the new UK treatment guidelines is likely to result in only a small increase in the number of patients requiring treatment.

Acetaminophen Psi Nomogram: a sensitive and specific clinical tool to predict hepatotoxicity secondary to acute acetaminophen overdose

BACKGROUND

Acetaminophen Psi Parameter (APP) is a composite of acetaminophen (paracetamol) level and lag time before N-acetylcysteine (NAC) therapy. The APP is a significant predictor of hepatotoxicity secondary to acute acetaminophen overdose. Acetaminophen Psi Nomogram (APN) was invented as a graphic analog of the APP for use in predicting individual patient's risk of hepatotoxicity. Clinical accuracy of the APN has never been validated

OBJECTIVE

The authors are reporting the validity of APN in predicting hepatotoxicity secondary to acute acetaminophen overdose at Siriraj Hospital.

MATERIAL AND METHOD

This present study is a retrospective review of medical records of patients with acute acetaminophen overdose at Siriraj Hospital between January 2004 and June 2009. Each case was classified by APN into an appropriate risk group. The outcome of interest was hepatotoxicity. The validity of the APN is reported as sensitivity and specificity. Secondary outcomes include serum acetaminophen concentrations, delay to NAC therapy, and APP for each APN's risk group.

RESULTS

One hundred and sixty-one patients were enrolled Higher APN risk classifications are associated with a trend towards higher acetaminophen levels, longer delayed to NAC initiation, and larger APP. Twenty five patients (15.5%) developed hepatotoxicity. The number of patients who were above the APN's risk lines, 1% and 50% were 88 (54.7%) and 17 (10.6%), respectively, with corresponding sensitivities of 100.0% (95% CI 186.6, 100.0) and 40.0% (95% C121.2, 61.3). APN's risk lines 50% had specificity of 94.9% (95% CI 89.7, 97.9).

CONCLUSION

Acetaminophen Psi Nomogram is a sensitive and specific tool for prediction of hepatotoxicity secondary to acute acetaminophen overdose. By application of the APN, a significant proportion of patients may not require either further follow-up after the completion of NAC therapy or prolongation of NAC therapy. Patients in high APN's risk ranges may be treated and monitored more intensively with confidence.

Therapeutic dose of acetaminophen as a possible risk factor for acute kidney injury: learning from two healthy young adult cases

Acetaminophen overdose can lead to severe liver and kidney failure; however, the risk of therapeutic doses in healthy individuals causing acute kidney injury (AKI) is less clear. We herein describe the cases of two young adults with renal biopsy-proven acute tubular necrosis under a therapeutic dose of acetaminophen. The first patient exhibited mild reversible renal insufficiency, whereas, in the second case, the patient demonstrated a slightly increased serum creatinine level and enlarged kidneys and the administration of contrast media and antibiotics may have worsened the renal dysfunction, leading to the need for temporal hemodialysis. Physicians should be aware of the risk of acetaminophen causing AKI and avoid administering other nephrotoxic agents in such cases.

Paracetamol poisonings in the Czech and Slovak Republic and N-acetylcysteine treatment. Data analysis

OBJECTIVES

Paracetamol overdose belongs to frequent calls to Toxicological Information Centre (TIC) in the Czech Republic and to the National Toxicological Information Centre (NTIC) in Slovakia. The aim of the study was to evaluate outcomes and side effects of paracetamol overdose in both countries.

METHODS

Data concerning paracetamol poisoning extracted from TIC and NTIC databases 2000-2013 and discharge reports were analysed. Numbers and outcomes in patients presenting within 24 hours of a single paracetamol overdose were compared in relation to 3 paracetamol concentration bands (≤ 100 mg/l, 100-149 mg/l, and 150 mg/l).

RESULTS

5397 inquiries concerning paracetamol were recorded in TIS and NTIC. Data from 196 discharge reports with plasma level were studied. Median age of the patients was 18 (0.2-86) years. Eight/196 (4.1%) patients developed side effects after N-acetylcysteine (NAC) administration. 120 cases fulfilled time criteria of the study and were divided into 3 groups, where 55.7%, 73.1% and 96.9% patients have been treated with NAC. Among these 120 patients, favourable outcome was seen in 100%, 100%, and 92.8%, respectively. One death due to suicidal attempt with plasma level 407 mg/l presenting at 20 hours has been recorded among 120 patients. No patient without NAC treatment died due to acute overdose and plasma concentration ≤ 150 mg/I at 4 hours.

CONCLUSIONS

These data support the opinion that NAC should not be used in patients with < 149 mg/l levels in absence of higher risk factors because of very low risk of hepatotoxicity on one side, and side effects on the other side.

Receptor interacting protein kinase 3 is a critical early mediator of acetaminophen-induced hepatocyte necrosis in mice

Acetaminophen (APAP) overdose is a major cause of hepatotoxicity and acute liver failure in the U.S., but the pathophysiology is incompletely understood. Despite evidence for apoptotic signaling, hepatic cell death after APAP is generally considered necrotic in mice and in humans. Recent findings suggest that the receptor interacting protein kinase 3 (RIP3) acts as a switch from apoptosis to necrosis (programmed necrosis). Thus, the aim of the current investigation was to determine if RIP3 is involved in APAP-induced liver cell death. APAP (200-300 mg/kg) caused glutathione depletion and protein adduct formation, oxidant stress, mitochondrial release of apoptosis inducing factor, and nuclear DNA fragmentation resulting in centrilobular necrosis in C57Bl/6J mice. Inhibiting RIP3 protein induction with antisense morpholinos in wild-type animals or using RIP3-deficient mice had no effect on protein adduct formation but attenuated all other parameters, including necrotic cell death, at 6 hours after APAP. In addition, cultured hepatocytes from RIP3-deficient mice showed reduced injury compared to wild-type cells after 24 hours. Interestingly, APAP-induced mitochondrial translocation of dynamin-related protein 1 (Drp1), the initiator of mitochondrial fission, was inhibited by reduced RIP3 protein expression and the Drp1 inhibitor MDIVI reduced APAP-induced cell death at 24 hours. All of these protective effects were lost after 24 hours in vivo or 48 hours in vitro.

CONCLUSION

RIP3 is an early mediator of APAP hepatotoxicity, involving modulation of mitochondrial dysfunction and oxidant stress. Controlling RIP3 expression could be a promising new approach to reduce APAP-induced liver injury, but requires complementary strategies to control mitochondrial dysfunction for long-term protection.

Comparative analysis of acute toxic poisoning in 2003 and 2011: analysis of 3 academic hospitals

Social factors may affect the available sources of toxic substances and causes of poisoning; and these factors may change over time. Additionally, understanding the characteristics of patients with acute toxic poisoning is important for treating such patients. Therefore, this study investigated the characteristics of patients with toxic poisoning. Patients visiting one of 3 hospitals in 2003 and 2011 were included in this study. Data on all patients who were admitted to the emergency departments with acute toxic poisoning were retrospectively obtained from medical records. Total 939 patients were analyzed. The average age of patients was 40.0 ± 20 yr, and 335 (36.9%) patients were men. Among the elements that did not change over time were the facts that suicide was the most common cause, that alcohol consumption was involved in roughly 1 of 4 cases, and that there were more women than men. Furthermore, acetaminophen and doxylamine remained the most common poisoning agents. In conclusion, the average patient age and psychotic drug poisoning has increased over time, and the use of lavage treatment has decreased.

Possible fatal acetaminophen intoxication with atypical clinical presentation

Acetaminophen or paracetamol, a commonly used over-the-counter analgesic, is known to elicit severe adverse reactions when taken in overdose, chronically at therapeutic dosage or, sporadically, following single assumptions of a therapeutic dose. Damage patterns including liver damage and, rarely, acute tubular necrosis or a fixed drug exanthema. We present a case of fatal acetaminophen toxicity with postmortem blood concentration 78 μg/mL and unusual clinical features, including a visually striking and massive epidermolysis and rhabdomyolysis, disseminated intravascular coagulation and myocardial ischemia. This case is compared with the most similar previous reports in terms of organ damage, clinical presentation, and cause of death. We conclude that a number of severe patterns of adverse effects to acetaminophen are emerging that were previously greatly underestimated, thus questioning the adequacy of the clinical spectrum traditionally associated with acetaminophen intoxication and leading to the need to review this spectrum and the associated diagnostic criteria.

[Paracetamol overdose]

Acetaminophen is the most widely used analgesic-antipyretic and is available as an over-the-counter medication in many countries. Although generally safe at usual therapeutic doses, acetaminophen may cause hepatic toxicity in case of chronic or acute overuse and even at therapeutic doses in susceptible individuals. The aim of this article is to review the mechanisms of acetaminophen toxicity and to review the critical steps in the management of acute or chronic acetaminophen intoxication.

Assessment and management of paracetamol poisoning in adults

Paracetamol is a low cost, effective analgesic that is widely available in the UK. Paracetamol is the drug most commonly taken in overdose and can lead to acute liver failure, which can be fatal. This article focuses on the assessment and management of paracetamol poisoning in adults. It includes current UK guidelines on paracetamol poisoning, which changed in September 2012 following a review by the Commission on Human Medicines. It also discusses strategies to reduce incidence and severity of paracetamol poisoning, and outlines the metabolism of paracetamol at therapeutic doses and in overdose.

Missed paracetamol (acetaminophen) overdose due to confusion regarding drug names

Immediate management of drug overdose relies upon the patient account of what was ingested and how much. Paracetamol (acetaminophen) is involved in around 40% of intentional overdose episodes, and remains the leading cause of acute liver failure in many countries including the United Kingdom. In recent years, consumers have had increasing access to medications supplied by international retailers via the internet, which may have different proprietary or generic names than in the country of purchase. We describe a patient that presented to hospital after intentional overdose involving 'acetaminophen' purchased via the internet. The patient had difficulty recalling the drug name, which was inadvertently attributed to 'Advil', a proprietary non-steroidal anti-inflammatory drug. The error was later recognised when the drug packaging became available, but the diagnosis of paracetamol overdose and initiation of acetylcysteine antidote were delayed. This case illustrates the benefit of routinely measuring paracetamol concentrations in all patients with suspected poisoning, although this is not universally accepted in practice. Moreover, it highlights the importance of the internet as a source of medications for intentional overdose, and emphasises the need for harmonisation of international drug names to improve patient safety.

The predictive value of hospital admission serum alanine transaminase activity in patients treated for paracetamol overdose

BACKGROUND

Paracetamol is a major cause of poisoning. Treatment decisions are predominately based on the dose ingested and a timed blood paracetamol concentration because most patients present to hospital soon after overdose, before hepatotoxicity can be confirmed/excluded using serum alanine transaminase (ALT). Nonetheless, ALT is measured at hospital presentation; we investigated its value in predicting hepatotoxicity.

METHODS

From March 2011 to May 2012, patients admitted to the Royal Infirmary of Edinburgh for paracetamol overdose treatment were identified. We determined the value of admission ALT (below or above our upper limit of normal-50 IU/l) at predicting three endpoints: 1-doubling of ALT; 2-peak ALT >1000 IU/l; 3-peak international normalized ratio (INR) >2.

RESULTS

From 500 patients, 410 met the entry criteria; 264 presented within 8 h of overdose, 54 between 8 and 24 h, 53 after 24 h and 39 were staggered ingestions. Admission ALT was increased in 71. For endpoint 1 (ALT doubling), the positive predictive value (PPV) of admission ALT was 19% [95% confidence interval (CI) 12-30] with a negative predictive value (NPV) of 98% (95% CI 96-99); endpoint 2 (ALT >1000 IU/l: PPV 23% (95% CI 14-34) and NPV 100% (95% CI 99-100) and for endpoint 3 (INR >2): PPV 14% (95% CI 7-25) and NPV of 100% (95% CI 99-100). The NPV remained high when only late presenters were included.

CONCLUSION

Admission ALT within the normal range has a high NPV and could be used, alone or in combination with newer biomarkers, to identify lower risk patients at hospital presentation.

Therapeutic potential of Moringa oleifera extracts against acetaminophen-induced hepatotoxicity in rats

CONTEXT

Moringa oleifera Lam. (Moringaceae) is a rich source of essential minerals and antioxidants; it has been used in human and animal nutrition. The leaves and flowers are being used by the population with great dietary importance.

OBJECTIVE

The present study was to investigate the therapeutic effects of the hydroethanolic extract of Moringa oleifera (MO) leaves and flowers against hepatotoxicity induced by acetaminophen (APAP) in rats.

MATERIALS AND METHODS

In the hepatoprotective study, either flowers or leaves of hydroethanolic extract (200 or 400 mg/kg bw through IP injection) were administered an hour after APAP administration. N-Acetylcysteine (NAC) was used as the positive control for this study. Liver and kidney function tests including lipid peroxidation levels were analyzed and histopathological changes of liver and kidney were also observed.

RESULTS

Acetaminophen-induced hepatotoxicity increased the activities of liver marker enzymes. Histologically, the liver was observed to have inflammation and bridging necrosis. Liver marker enzymes were significantly reduced when treated with flower and leaf extracts of MO in animals with APAP induced toxicity. In addition, there were no significant changes observed in clinical markers of kidney function. Histological observation on liver tissue from the rats treated with MO flower and leaf extract showed reduction in the severity of the liver damage.

DISCUSSION AND CONCLUSION

These results indicated the possible therapeutic action of flower and leaf extract from MO in protecting liver damage in rats given an over dosage of APAP.

Long term effect of reduced pack sizes of paracetamol on poisoning deaths and liver transplant activity in England and Wales: interrupted time series analyses

OBJECTIVE

To assess the long term effect of United Kingdom legislation introduced in September 1998 to restrict pack sizes of paracetamol on deaths from paracetamol poisoning and liver unit activity.

DESIGN

Interrupted time series analyses to assess mean quarterly changes from October 1998 to the end of 2009 relative to projected deaths without the legislation based on pre-legislation trends.

SETTING

Mortality (1993-2009) and liver unit activity (1995-2009) in England and Wales, using information from the Office for National Statistics and NHS Blood and Transplant, respectively.

PARTICIPANTS

Residents of England and Wales.

MAIN OUTCOME MEASURES

Suicide, deaths of undetermined intent, and accidental poisoning deaths involving single drug ingestion of paracetamol and paracetamol compounds in people aged 10 years and over, and liver unit registrations and transplantations for paracetamol induced hepatotoxicity.

RESULTS

Compared with the pre-legislation level, following the legislation there was an estimated average reduction of 17 (95% confidence interval -25 to -9) deaths per quarter in England and Wales involving paracetamol alone (with or without alcohol) that received suicide or undetermined verdicts. This decrease represented a 43% reduction or an estimated 765 fewer deaths over the 11&frac14; years after the legislation. A similar effect was found when accidental poisoning deaths were included, and when a conservative method of analysis was used. This decrease was largely unaltered after controlling for a non-significant reduction in deaths involving other methods of poisoning and also suicides by all methods. There was a 61% reduction in registrations for liver transplantation for paracetamol induced hepatotoxicity (-11 (-20 to -1) registrations per quarter). But no reduction was seen in actual transplantations (-3 (-12 to 6)), nor in registrations after a conservative method of analysis was used.

CONCLUSIONS

UK legislation to reduce pack sizes of paracetamol was followed by significant reductions in deaths due to paracetamol overdose, with some indication of fewer registrations for transplantation at liver units during the 11 years after the legislation. The continuing toll of deaths suggests, however, that further preventive measures should be sought.

[Intoxication or false-positive acetaminophen result of toxicological determinations? Two case reports]

The aim of this study was to show the diagnostic procedure used in the two cases with false-positive serum acetaminophen results in suspected acetaminophen poisoning. The determination of serum acetaminophen were carried out using a UV/VIS spectrophotometer (Specord 40 Analytik Jena), coupled with an analytic computer station WinASPECT. The employed method of determination was based on the acetaminophen reaction with sodium nitrite, which yields yellow colour of solution in the presence of sodium hydrate. The intensity of the yellow colour depends on the concentration of acetaminophen in serum. The relationship between absorbance and concentration was linear at concentrations in the range 50-600 microg/mL, with relative standard deviation of +/- 2.1% and detection limit of 30 microg/mL. To confirm or reject the doubtful results of colorimetric assays, the serums of patients were measured with high performance liquid chromatography with mass spectrometry detection and gas chromatography with mass spectrometry detection. The analysis of presented cases leads to a conclusion that acetaminophen results should be confirmed either by scanning urine for p-aminophenol presence (which is a routine procedure in our laboratory) or by using a different method of measuring acetaminophen serum levels.