Alcohol-acetaminophen syndrome. Even moderate social drinkers are at risk

Meat tenderization using acetaminophen (paracetamol/APAP): A review on deductive biochemical mechanisms, toxicological implications and strategies for mitigation

Meats consist of edible portions originating from domestic and wild animals. Meat's palatability and sensory accessibility largely depend on its tenderness to consumers. Although many factors influence meat tenderness, the cooking method cannot be neglected. Different chemical, mechanical, and natural means of meat tenderization have been considered healthy and safe for consumers. However, many households, food vendors, and bars in developing countries engage in the unhealthy use of acetaminophen (paracetamol/APAP) in meat tenderization due to the cost reduction it offers in the overall cooking process. Acetaminophen (paracetamol/APAP) is one of the most popular, relatively cheap, and ubiquitous over-the-counter drugs that induce serious toxicity challenges when misused. It is important to note that acetaminophen during cooking is hydrolyses into a toxic compound known as 4-aminophenol, which damages the liver and kidney and results in organ failure. Despite the reports on the increase in the use of acetaminophen for meat tenderizing in many web reports, there have not been any serious scientific publications on this subject. This study adopted classical/traditional methodology to review relevant literature retrieved from Scopus, PubMed, and ScienceDirect using relevant key terms (Acetaminophen, Toxicity, Meat tenderization, APAP, paracetamol, mechanisms) and Boolean operators (AND and OR). This paper provides in-depth information on the hazard and health implications of consuming acetaminophen tenderized meat via genetic and metabolic pathways deductions. Understanding these unsafe practices will promote awareness and mitigation strategies.

Acute and sub chronic toxicity studies with herbal pain relieving formula (Rhuleave-K™) in rats

Rhuleave-K™ is a proprietary combination of Curcuma longa extract, Boswellia serrata extract and black sesame seed oil. Acute toxicity was evaluated as per OECD guidelines 423. Rhuleave-K™ was fed at 2000 mg/kg to overnight fasted female rats. Clinical signs of abnormality and mortality was observed daily for 14 days. Sub-chronic toxicity was studied by feeding Rhuleave-K™ at 100, 500 and 1000 mg/kg/day to rats as per OECD guidelines 408. After 90 days feeding, heamatological and biochemical parameters were analyzed. Histopathology of all the major organs was also studied. In the acute toxicity study, there was no clinical sign of toxicity in any of the rat at maximum dose of 2000 mg/kg. The LD50 was computed as >2000 mg/kg in rats. The repeated dosing of Rhuleave-K™ at the maximum dose level of 1000 mg/kg for 90 days did not induce any observable toxic effects in rats, when compared to its corresponding control. The hematology and biochemistry profile of treated rats was similar to control animals and difference was non-significant (p > 0.05). The histopathology of major organs of all the control and treated animals was normal. In this study the NOAEL for Rhuleave-K™ was calculated as 1000 mg/kg daily in rats.

Potential deleterious effects of paracetamol dose regime used in Nigeria versus that of the United States of America

Paracetamol, also known as acetaminophen (N-acetyl-para-aminophenol, APAP) is the world's most used over-the-counter analgesic-antipyretic drug. Despite its good safety profile, acetaminophen can cause severe hepatotoxicity in overdose, and poisoning from paracetamol has become a major public health concern. Paracetamol is now the major cause of acute liver failure in the United States and Europe. This systematic review aims at examining the likelihood of paracetamol use in Nigeria causing more liver toxicity vis-à-vis the reduced maximum recommended daily adult dose of 3 g for the 500 mg tablet. Online searches were conducted in the databases of PubMed, Google Scholar and MEDLINE for publications using terms like "paracetamol toxicity," "acetaminophen and liver toxicity," "paracetamol and liver diseases in Nigeria," and other variants. Further search of related references in PubMed was carried out, and synthesis of all studies included in this review finalized. There were 94 studies that met the inclusion criteria. Evaluation of hepatic disorder was predicated mostly on a constellation of clinical features and limited clinical laboratory investigations. Determination of blood paracetamol concentration was rarely reported, thus excluding paracetamol poisoning as one of the likely causes of liver disorders in Nigeria. In Nigeria and elsewhere, several factors are known to increase paracetamol's predisposition to liver injury. They include: the over-the-counter status of paracetamol, use of fixed-dose combinations of paracetamol with other drugs, malnutrition, dose miscalculations, and chronic alcohol consumption. The tendency to exceed the new paracetamol maximum daily dose of 3 g in Nigeria may increase its risk for hepatotoxicity than observed in the United States of America known for emphasizing lower dose of the drug. In addition to recommending the new maximal daily paracetamol dose allowance, the historical maximum daily adult dose of 4 g should be de-emphasized in Nigeria.

Downregulation of Glutathione-Mediated Detoxification Capacity by Binge Drinking Aggravates Acetaminophen-Induced Liver Injury through IRE1α ER Stress Signaling

Overdose of acetaminophen (APAP) can cause severe liver injury. Although alcohol is considered a risk factor for APAP toxicity, the mechanism underlying the interaction between alcohol and APAP remains unclear. Binge alcohol (5 g/kg every 12 h, 3 doses) reduced the concentration of cysteine and glutathione (GSH) and decreased expression of cystathionine β-synthase (CβS), cystathionine γ-lyase (CγL), and glutamate cysteine ligase catalytic subunit (GCLC) in the livers of male C57BL/6 mice. Furthermore, the levels of GSH S-transferase (GST) and GSH peroxidase (GPx) were decreased. To evaluate the effect of binge drinking on APAP-induced liver injury, 300 mg APAP was administered following alcohol binges. APAP in the binge group significantly amplified the serum ALT more than two fold and enhanced the pro-apoptotic proteins with a severe centrilobular necrosis compared to APAP alone. APAP treatment after alcohol binges caused lower levels of hepatic cysteine and GSH than APAP alone over 24 h, indicating that alcohol binges reduced GSH regenerating potential. Exposure to APAP after binge treatment significantly increased oxidative stress (lipid peroxidation) and endoplasmic reticulum (ER) stress (Grp78 and ATF6) markers at 6 h after treatment. Notably, the IRE1α/ASK1/MKK4/JNK pathway was activated, whereas CHOP expression was reduced by APAP administration in mice with pre-exposed alcohol binges compared with APAP alone. Thus, pretreatment with binge alcohol decreases GSH-mediated antioxidant capacity and contributes to augmentation of liver injury caused by subsequent APAP administration through differential ER stress signaling pathway.

The role of alcohol consumption on acetaminophen induced liver injury: Implications from a mathematical model

Acetaminophen (APAP) overdose is one of the predominant causes of drug induced acute liver injury in the U.S and U.K. Clinical studies show that ingestion of alcohol may increase the risk of APAP induced liver injury. Chronic alcoholism may potentiate APAP hepatotoxicity and this increased risk of APAP toxicity is observed when APAP is ingested even shortly after alcohol is cleared from the body. However, clinical reports also suggest that acute alcohol consumption may have a protective effect against hepatotoxicity by inhibiting microsomal acetaminophen oxidation and thereby reducing N-acetyl-p-benzoquinone imine (NAPQI) production. The aim of this study is to model this dual role of alcohol to determine how the timing of alcohol ingestion affects APAP metabolism and resulting liver injury and identify mechanisms of APAP induced liver injury. The mathematical model is developed to capture condition of a patient of single time APAP overdose who may be an acute or chronic alcohol user. The analysis suggests that the risk of APAP-induced hepatotoxicity is increased if APAP is ingested shortly after alcohol is cleared from the body in chronic alcohol users. A protective effect of acute consumption of alcohol is also observed in patients with APAP overdose. For example, simultaneous ingestion of alcohol and APAP overdose or alcohol intake after or before few hours of APAP overdose may result in less APAP-induced hepatotoxicity when compared to a single time APAP overdose. The rate of hepatocyte damage in APAP overdose patients depends on trade-off between induction and inhibition of CYP enzyme.

A Review of Bioinformatics Tools to Understand Acetaminophen-Alcohol Interaction

Background: Drug-ethanol interaction can result in hepatotoxicity. The liver is capable of metabolizing both acetaminophen and ethanol; however, severe acute or moderate chronic simultaneous exposure can cause cell and tissue damage. Therapeutic doses can become harmful if gene activity is altered via competition for metabolic pathways. Simultaneous intake of ethanol and acetaminophen results in overactive CYP2E1 and depletion of glutathione, leaving NAPQI to build up in the liver. NAPQI is a hepatotoxic substance typically neutralized by glutathione. Methods: Bioinformatics tools including PharmGKB, Chemical Annotation Retrieval Toolkit, Transcriptome Analysis Console 4.0 (TAC), wikipathways, STRING, and Ingenuity Pathway Analysis (IPA) were used to explore interactive metabolic pathways of ethanol-acetaminophen exposure as a proof of concept for assessing drug-drug or drug-alcohol interactions. Results: As the ethanol-acetaminophen comparison indicates, bioinformatics tools may be used to understand interactive pathways following exposure to ethanol and acetaminophen, with potential extrapolation to other drug-drug/drug-ethanol interactions. Conclusions: Direct interactive effects were not able to be confirmed through this bioinformatics study due to the lack of existing ethanol-acetaminophen simultaneous exposure data. This work suggests that a battery of software applications should be used to assess interactive effects.

Effect of ethanol on lipid metabolism

Hepatic lipid metabolism is a series of complex processes that control influx and efflux of not only hepatic lipid pools, but also organismal pools. Lipid homeostasis is usually tightly controlled by expression, substrate supply, oxidation and secretion that keep hepatic lipid pools relatively constant. However, perturbations of any of these processes can lead to lipid accumulation in the liver. Although it is thought that these responses are hepatic arms of the 'thrifty genome', they are maladaptive in the context of chronic fatty liver diseases. Ethanol is likely unique among toxins, in that it perturbs almost all aspects of hepatic lipid metabolism. This complex response is due in part to the large metabolic demand placed on the organ by alcohol metabolism, but also appears to involve more nuanced changes in expression and substrate supply. The net effect is that steatosis is a rapid response to alcohol abuse. Although transient steatosis is largely an inert pathology, the chronicity of alcohol-related liver disease seems to require steatosis. Better and more specific understanding of the mechanisms by which alcohol causes steatosis may therefore translate into targeted therapies to treat alcohol-related liver disease and/or prevent its progression.

Are some people at increased risk of paracetamol-induced liver injury? A critical review of the literature

Purpose

Paracetamol is one of the world’s most commonly used drugs. In overdose, it is well established to be hepatotoxic. The aim of this review was to identify factors that have been, or actually are, associated with the development of liver injury after paracetamol exposure in humans.

Method

Google Scholar and PubMed were searched on various dates between December 2016 and March 2017. Papers identified had their references analysed for further studies that might be relevant.

Results

At the time of writing, there was little good quality clinical evidence—from studies of paracetamol overdose or therapeutic use—to suggest that any groups of people are relatively protected from, or are at greater risk of, liver injury. The factors that were historically used to indicate higher risk in the UK have no good quality clinical evidence to support their re-introduction into clinical practice. The safe (and still effective) oral dose of paracetamol in patients weighing less than 50 kg has not been established.

Conclusion

There is no patient group that is unequivocally at elevated risk of paracetamol-induced liver toxicity. We propose two clinical scenarios that warrant further research. Firstly, there is a need to establish whether the dose of paracetamol should be reduced in patients with low body weight. Secondly, if or when genomic information regarding individual patients becomes readily available to inform prescribing, we propose the contribution of the genome to paracetamol toxicity should be re-investigated with robustly designed studies. Such studies could enhance the safe use of one of the most frequently taken drugs.

Electronic supplementary material

The online version of this article (10.1007/s00228-017-2356-6) contains supplementary material, which is available to authorized users.

Drug Hepatotoxicity: Environmental Factors

Drug-induced liver injury presents as various forms of acute and chronic liver disease. There is wide geographic variation in the most commonly implicated agents. Smoking can induce cytochrome P450 enzymes but this does not necessarily translate into clinically relevant drug-induced liver injury. Excessive alcohol consumption is a clear risk factor for intrinsic hepatotoxicity from acetaminophen and may predispose to injury from antituberculosis medications. Understanding of the role of infection, proinflammatory states, disorders of coagulation, and the hepatic clock in predisposing patients to drug-induced liver injury is evolving. More study focusing specifically on environmental risk factors predisposing patients to drug-induced liver injury is needed.

Hypercoagulable State Due to Alcohol-Paracetamol Syndrome Producing Acute Limb Ischemia

The authors describe a man with alcohol-paracetamol syndrome and hepatic failure who presented with acute arterial thrombosis of the left limb. The patient has jaundice, increased serum transaminase levels, and significant coagulopathy, with elevated international normalized ratio and prolonged prothrombin time. A transient hypercoagulable state due to liver failure is documented, characterized by acquired deficiencies of antithrombin III, protein C, and protein S. Laboratory and molecular testing for inherited hypercoagulable disorders during the follow-up period is positive for increased levels of factor VIII. The patient undergoes successful thrombectomy and receives intensive symptomatic and causal treatment, resulting in complete recovery. The patient is discharged 20 days after admission on a regimen of acenocoumarol.

The Dilemma of Alcohol Use by Potential Living Liver Donors

Previous and current alcohol use by potential living liver donors presents ethical challenges for donor selection committees. Discussing these challenges, we offer guidelines for selection and management of these individuals. Donor safety and welfare should be the primary concern, thus relapse potential during the postdonation period for those with a history of alcohol dependence or abuse is of importance, especially because of the potentially severe consequences of mixing pain relievers (eg, acetaminophen) and alcohol during liver regeneration. Psychosocial and chemical dependency evaluations are critical for potential living donors as well as recipients.

Peri-operative use of paracetamol

This article is a review of the peri-operative use of paracetamol. It reviews the pharmacology of paracetamol, highlighting new information about the mechanism of action, and examines its therapeutic use in the peri-operative period, focusing on efficacy, route of administration, and the use of a loading dose to improve early postoperative analgesia.

Does therapeutic use of acetaminophen cause acute liver failure?

STUDY OBJECTIVE

To compare the reported occurrence of liver failure in subjects in prospective trials with that in patients in retrospective reports after repeated use of therapeutic dosages of acetaminophen.

DESIGN

Systematic review of the medical literature.

DATA SOURCE

MEDLINE and EMBASE biomedical and pharmacologic databases.

SUBJECTS

Adults who received repeated dosing of acetaminophen 4 g/day or lower for at least 24 hours.

MEASUREMENTS AND MAIN RESULTS

Articles written in several languages were abstracted by trained personnel using a structured abstraction form. Data were categorized by methodology (prospective vs retrospective), acetaminophen dosage, and type of liver effect. A total of 791 articles were identified, which included 30,865 subjects in prospective studies and 9337 patients in retrospective reports. The prospective studies reported no cases of fulminant hepatic injury, liver transplantation, or death due to acetaminophen. Of the 30,865 subjects in these studies, 129 (0.4%) were identified who had a serum aminotransferase level that exceeded the upper limit of normal, including 61 subjects in randomized trials in which the proportion of serum aminotransferase level increase was the same as or less than that in the placebo group and 68 subjects in trials without a placebo group. In addition, 4263 (13.8%) received the maximum recommended therapeutic dosage (3.9-4 g/day). In the retrospective reports, 96 patients (1.0%) had a serum alanine aminotransferase level that exceeded the upper limit of normal, one (0.01%) underwent liver transplantation, and six (0.06%) died. Causality relationship of acetaminophen for each retrospective case was assessed with the Naranjo adverse drug reaction probability scale. The mean +/- SD Naranjo score for all 103 retrospective cases was 3.2 +/- 1.9, indicating a possible relationship between the increased aminotransferase levels and acetaminophen use. Some retrospective reports contained information suggesting that the patient had ingested an overdose despite a history of therapeutic use.

CONCLUSION

Prospective studies indicated that repeated use of a true therapeutic acetaminophen dosage may slightly increase the level of serum aminotransferase activity, but hepatic failure or death was not reported. Retrospective reports indicated a higher rate of increased serum aminotransferase levels, and several reported associated liver injury and death. The differing results and presence of evidence indicating inaccurate acetaminophen dosage information in some case reports suggests that these cases may be inadvertent overdoses, rather than true therapeutic dosages.

Pharmacy Review: Osteoarthritis: The Pharmacist's Perspective

A wide variety of treatment options are available for osteoarthritis pain relief. The pharmacist can serve as a source of information within his or her area of expertise, addressing controversies such as nonsteroidal antiinflammatory drugs versus acetaminophen, glucosamine-chondroitin, topical therapies, and herbals. Patients should be encouraged to use pain scales and diaries as they try different therapies.

Effect of reading additional safety information on planned use of over-the-counter analgesics

OBJECTIVES

This study was used to test the effect on planned safe use of over-the-counter (OTC) analgesics of adding information about the potential for nonsteroidal anti-inflammatory drug (NSAID) interaction with antihypertensive medications, the potential for interaction of alcohol and acetaminophen, and NSAID ceiling effects to the Federal Drug Administration's (FDA's) OTC analgesics pamphlet.

DESIGN

A randomized posttest-only double-blind experimental design was used to test an intervention with a comparison group reading the FDA pamphlet, and treatment group reading the pamphlet with added information.

SAMPLE

Participants included 137 adults.

INTERVENTION

Participants read the treatment or the comparison pamphlet.

RESULTS

Both groups responded with similar planned use of OTC analgesics. The majority were likely to read the label before taking an OTC analgesic, but were unlikely to give acetaminophen to a family member using antihypertensive medication.

CONCLUSIONS

Reading additional information about OTC analgesics resulted in no greater intention to safely use analgesics. Responses indicated reluctance to use OTC analgesics, and the potential need for increased health teaching regarding use of OTC analgesics with antihypertensive medication. Public health teaching should include the importance of treating pain and selecting the safest OTC analgesics for the clinical situation.

Paracetamol: new vistas of an old drug

Paracetamol (acetaminophen) is one of the most popular and widely used drugs for the treatment of pain and fever. It occupies a unique position among analgesic drugs. Unlike NSAIDs it is almost unanimously considered to have no antiinflammatory activity and does not produce gastrointestinal damage or untoward cardiorenal effects. Unlike opiates it is almost ineffective in intense pain and has no depressant effect on respiration. Although paracetamol has been used clinically for more than a century, its mode of action has been a mystery until about one year ago, when two independent groups (Zygmunt and colleagues and Bertolini and colleagues) produced experimental data unequivocally demonstrating that the analgesic effect of paracetamol is due to the indirect activation of cannabinoid CB(1) receptors. In brain and spinal cord, paracetamol, following deacetylation to its primary amine (p-aminophenol), is conjugated with arachidonic acid to form N-arachidonoylphenolamine, a compound already known (AM404) as an endogenous cannabinoid. The involved enzyme is fatty acid amide hydrolase. N-arachidonoylphenolamine is an agonist at TRPV1 receptors and an inhibitor of cellular anandamide uptake, which leads to increased levels of endogenous cannabinoids; moreover, it inhibits cyclooxygenases in the brain, albeit at concentrations that are probably not attainable with analgesic doses of paracetamol. CB(1) receptor antagonist, at a dose level that completely prevents the analgesic activity of a selective CB(1) receptor agonist, completely prevents the analgesic activity of paracetamol. Thus, paracetamol acts as a pro-drug, the active one being a cannabinoid. These findings finally explain the mechanism of action of paracetamol and the peculiarity of its effects, including the behavioral ones. Curiously, just when the first CB(1) agonists are being introduced for pain treatment, it comes out that an indirect cannabino-mimetic had been extensively used (and sometimes overused) for more than a century.

Estimates of acetaminophen (Paracetomal)-associated overdoses in the United States

OBJECTIVE

To estimate the number of acetaminophen-associated overdoses in the United States and identify possible risk factors for intervention.

METHODS

The investigators obtained estimates of acetaminophen-associated overdoses using different national databases. Two emergency room databases, a hospital discharge database, a national mortality file, and a poison surveillance database were used to identify cases. The FDA's spontaneous reporting system was searched to identify possible root causes for overdoses.

RESULTS

Analysis of national databases show that acetaminophen-associated overdoses account for about 56,000 emergency room visits and 26,000 hospitalizations yearly. Analysis of national mortality files shows 458 deaths occur each year from acetaminophen-associated overdoses; 100 of these are unintentional. The poison surveillance database showed near-doubling in the number of fatalities associated with acetaminophen from 98 in 1997 to 173 in 2001. AERS data describe a number of possible causes for unintentional acetaminophen-associated overdoses.

CONCLUSIONS

Each year a substantial numbers of Americans experience intentional and unintentional acetaminophen-associated overdoses that, in severe cases, lead to serious illness and possible death. This summary of a series of analyses highlights the need for strategies to reduce this public health burden.

Thermodynamically based profiling of drug metabolism and drug–drug metabolic interactions: A case study of acetaminophen and ethanol toxic interaction

Drug-drug metabolic interactions can result in unwanted side effects, including reduced drug efficacy and formation of toxic metabolic intermediates. In this work, thermodynamic constraints on non-equilibrium metabolite concentrations are used to reveal the biochemical interactions between the metabolic pathways of ethanol and acetaminophen (N-acetyl-p-aminophenol), two drugs known to interact unfavorably. It is known that many reactions of these pathways are coupled to the central energy metabolic reactions through a number of metabolites and the cellular redox potential. Based on these observations, a metabolic network model has been constructed and a database of thermodynamic properties for all participating metabolites and reactions has been compiled. Constraint-based computational analysis of the feasible metabolite concentrations reveals that the non-toxic pathways for APAP metabolism and the pathway for detoxifying N-acetyl-p-benzoquinoneimine (NAPQI) are inhibited by network interactions with ethanol metabolism. These results point to the potential utility of thermodynamically based profiling of metabolic network interactions in screening of drug candidates and analysis of potential toxicity.

Med-psych drug-drug interactions update. Antiretrovirals, part III: antiretrovirals and drugs of abuse

The third in a series reviewing the HIV/AIDS antiretroviral drugs, this report summarizes the interactions between antiretrovirals and common drugs of abuse. In an overview format for primary care physicians and psychiatrists, the metabolism and drug interactions in the context of antiretroviral therapy are presented for the following drugs of abuse: alcohol, benzodiazepines, cocaine, GHB (liquid X), ketamine (special K), LSD (acid), MDMA (Ecstasy), opiates, PCP (angel dust), and THC (marijuana).

Selecting nonprescription analgesics

Worldwide, there has been an emerging patient demand for access to efficient drugs without consulting a doctor and obtaining a prescription. As a result, there has been an expanding movement of prescription-only drugs to over-the-counter (OTC) status. An increasing number of drugs are becoming available OTC, empowering patients to treat themselves. Where the principle of empowering individuals to treat themselves can fail is when consumers lack the knowledge to do so safely. This potentially applies to the self-selection of analgesic drugs by consumers. When used inappropriately, these drugs pose significant risks. The nonsteroidal antiinflammatory drugs (NSAIDs) are associated with many adverse reactions, interactions, and contraindications in a number of patient groups, even at OTC doses. In particular, in the elderly, the high incidence of cardiovascular and gastrointestinal disease, coupled with age-related decline in renal function and multiple medication use, all warrant extra caution with the use of NSAIDs and make paracetamol the simple analgesic drug of first choice. Despite the possibility of hepatotoxicity in overdose, paracetamol represents a better all-round option for most patients requiring OTC analgesic therapy.

Ethanol binging exacerbates sinusoidal endothelial and parenchymal injury elicited by acetaminophen

BACKGROUND/AIMS

The pathophysiology of binge drinking of ethanol and its potentiation of acetaminophen (APAP) toxicity has received very little attention. To evaluate if ethanol binging sensitizes hepatic sinusoidal endothelial cells (SEC) and liver to APAP toxicity.

METHODS

The histopathological responses to APAP were evaluated in the livers of mice gavaged with APAP alone, following a single, week-end type ethanol binge (4 g/kg every 12 h x 5 doses) or three weekly binges.

RESULTS

Six hours after APAP, 600 mg/kg elicited severe centrilobular necrosis together with hemorrhagic congestion and infiltration of erythrocytes into the Space of Disse through large gaps that had formed in SEC. There was no evidence of parenchymal injury at 2 h, but gaps already were formed through the cytoplasm of the SEC by coalescence of fenestrae. A single binge followed by 300 mg/kg APAP elicited SEC and parenchymal injury equivalent to 600 mg/kg APAP alone at 2 and 6 h. The responses were exacerbated following three binges. Lower glutathione levels in the liver were shown in ethanol-binged animals.

CONCLUSIONS

Ethanol binging increases APAP hepatotoxicity. SEC are an early target for APAP-induced injury and ethanol binging enhances the SEC injury prior to evidence of parenchymal cell injury.

Tolerability of Paracetamol

The excellent tolerability of therapeutic doses of paracetamol (acetaminophen) is a major factor in the very wide use of the drug. The major problem in the use of paracetamol is its hepatotoxicity after an overdose. Hepatotoxicity has also been reported after therapeutic doses, but critical analysis indicates that most patients with alleged toxicity from therapeutic doses have taken overdoses. Importantly, prospective studies indicate that therapeutic doses of paracetamol are an unlikely cause of hepatotoxicity in patients who ingest moderate to large amounts of alcohol. Controlled clinical trials have found that paracetamol is very well tolerated by the gastrointestinal tract. While variable results have been found in case control studies, most studies have shown no change or a small increase in the relative risk of perforations, ulcer or bleeding in the upper gastrointestinal tract. However, associations between the use of paracetamol and gastrointestinal toxicity, as well as with chronic renal disease and asthma, are very likely to reflect biases in some case control studies. In particular, such biases may be caused by the perceived high tolerability of paracetamol in these diseases. The consequent use of paracetamol in these diseases states then leads to an apparent association between paracetamol and the disease. Despite metabolism of paracetamol to reactive compounds, hypersensitivity reactions are rare, although urticaria occurs in occasional patients. Paracetamol appears to be well tolerated during pregnancy although prospective studies are required.

[The flavonoids effect against vinblastine, cyclophosphamide and paracetamol toxicity by inhibition of lipid-peroxydation and increasing liver glutathione concentration]

The paracetamol and cyclophosphamid are metabolized in the liver by the cytochrome P450. The formed reactive intermediates are responsible of a hepatocyte depletion of the glutathion and a lipoperoxydation. the vinblastine is also a chemotherapeutic agent hepatotoxic and hematotoxic. Otherwise, flavonoïds are polyphenols substances of plant origin having some biological and anti-oxydative properties. However no information is available on their effects on glutathion and glutathion-s-transferases. In our research, we valued the effect of oral administration of flavonoids (diosmine and quercetine) under shape of propolis extract to 60 mg/kg daily during 14 days, on hematological and hepatic toxicity of a single dose of cyclophosphamide 80 mg/kg by intravenous way, vinblastine 2 mg/kg by intravenous way and the hepatic toxicity of the paracetamol managed by oral way to 200 mg/kg corresponding to 2/3 the DL50 at the rat female albinos wistar. We did a blood numeration, an assessment of serum activities of transaminases and alkali phosphatases as well as quantification of the glutathion and the malondialdehyde (MDA) in liver homogenats of rats treated. Analyses are done at regular intervals; 1, 3, 7 and 14 days after the administration of drugs. In the group of rats treated by the cyclophosphamid paracetamol alone we observed since the 1st day, an increase of lipid peroxide (MDA) of 120% and a downfall of hepatic glutathion including the group receiving the vinblastine (until 210% of reduction). In the same way a severe leucopenia and a thrombopenia (70% of reduction) are observed between the 3rd and the 14th day at rats treated by the chemotherapeutic agents alone (cyclophosphamide and vinblastine). The combination of flavonoids with drugs have clearly reduced the effect of drugs toxicity. Indeed, the aplasic observed with the vinblastine, as well as the leucopenia and thrombopenia of the cyclophosphamide are corrected entirely. In the same way, we noted a restoration of rates of peroxide and glutathion. Flavonoïds seem to act by activation of the turn over of the glutathion and enzymes stimulating particularly glutathion-s-transferases permitting the captation of the reactive metabolites of the studied drugs.

Paracetamol poisoning: Which nomogram should we use?

OBJECTIVES

To determine the type of paracetamol nomograms used in Australasian EDs. To review the literature to determine the evidence base for existing nomograms.

METHODS

A cross sectional descriptive study via postal survey of all Australasian EDs accredited for specialist emergency medicine training by the Australasian College for Emergency Medicine (ACEM). A literature review using Knowledge Finder search engine was employed.

RESULTS

The response rate was 87%. The most commonly used nomogram had a four-hour treatment level of 1300 mumol/L (69%). A total of 22% of respondents used a four-hour treatment level of 1000 mumol/L. Two departments (3%) treated all patients above the 660 mumol/L line. Eleven departments (15%) did not have a treatment line below 1300 mumol/L.

CONCLUSION

Practice varies in Australasian EDs. Patients with paracetamol levels below the 1300 mumol/L have been reported in the literature to develop hepatotoxicity, and deaths have been documented. N-acetylcysteine is extremely safe when used in the recommended dosages.

Acetaminophen hepatotoxicity

Unlike the bulk of medications, described in this fascicle, that cause liver injury in humans, acetaminophen is a non-prescription drug that can be purchased in drug stores and supermarkets without a physician's involvement. Death or severe injury is far more likely to occur with its use than with all the other medications considered in this study. Whereas attempts to control the quantity of drug ingested have been made in the United Kingdom and elsewhere in Europe, no comparable moves have taken place in the United States. The Food and Drug Administration claims to have concerns about the situation, however, but has yet to make an effort to more closely regulate the marketing and distribution of the drug. It is to be hoped that this will not be the case by the time the next issue of Drug Hepatotoxicity is scheduled for this series.

Fulminant liver disease

Fulminant liver disease, acute liver failure (ALF), is one of the most intriguing and challenging conditions in the entire field of internal medicine. ALF is defined as the onset of hepatic encephalopathy and coagulopathy in patients with no known underlying liver disease within 8 to 26 weeks of onset of illness. Many cases develop within a few days, dramatically transforming an otherwise healthy individual to a patient with a high risk for developing multi-organ failure and death.

Liver glutathione concentrations in dogs and cats with naturally occurring liver disease

OBJECTIVE

To determine total glutathione (GSH) and glutathione disulfide (GSSG) concentrations in liver tissues from dogs and cats with spontaneous liver disease.

SAMPLE POPULATION

Liver biopsy specimens from 63 dogs and 20 cats with liver disease and 12 healthy dogs and 15 healthy cats.

PROCEDURE

GSH was measured by use of an enzymatic method; GSSG was measured after 2-vinylpyridine extraction of reduced GSH. Concentrations were expressed by use of wet liver weight and concentration of tissue protein and DNA.

RESULTS

Disorders included necroinflammatory liver diseases (24 dogs, 10 cats), extrahepatic bile duct obstruction (8 dogs, 3 cats), vacuolar hepatopathy (16 dogs), hepatic lipidosis (4 cats), portosystemic vascular anomalies (15 dogs), and hepatic lymphosarcoma (3 cats). Significantly higher liver GSH and protein concentrations and a lower tissue DNA concentration and ratio of reduced GSH-to-GSSG were found in healthy cats, compared with healthy dogs. Of 63 dogs and 20 cats with liver disease, 22 and 14 had low liver concentrations of GSH (micromol) per gram of tissue; 10 and 10 had low liver concentrations of GSH (nmol) per milligram of tissue protein; and 26 and 18 had low liver concentrations of GSH (nmol) per microgram of tissue DNA, respectively. Low liver tissue concentrations of GSH were found in cats with necroinflammatory liver disease and hepatic lipidosis. Low liver concentrations of GSH per microgram of tissue DNA were found in dogs with necroinflammatory liver disease and cats with necroinflammatory liver disease, extrahepatic bile duct occlusion, and hepatic lipidosis.

CONCLUSIONS AND CLINICAL RELEVANCE

Low GSH values are common in necroinflammatory liver disorders, extrahepatic bile duct occlusion, and feline hepatic lipidosis. Cats may have higher risk than dogs for low liver GSH concentrations.

S-adenosyl-L-methionine (SAMe) for the treatment of acetaminophen toxicity in a dog

An 8-month-old, spayed female Shetland sheepdog presented 48 hours after ingesting acetaminophen (1 gm/kg body weight). On presentation, the dog was laterally recumbent and hypovolemic. The dog had brown mucous membranes, severe Heinz-body hemolytic anemia, bleeding tendencies, and a red blood cell (RBC) glutathione (GSH) concentration that was 10% of reference values, despite a regenerative erythroid response. Treatment with s-adenosyl-l-methionine (SAMe) as a GSH donor successfully rescued this dog, despite the animal's late presentation after drug ingestion. A loading dose (40 mg/kg body weight) of a stable SAMe salt per os was followed by a maintenance dose (20 mg/kg body weight) sid for 7 days. Additional therapeutic interventions included an intravenous (i.v.) infusion of one unit of packed RBCs (on admission), i.v. fluid support (3 days), and famotidine (7 days) to reduce gastric acidity. Sequential assessment of RBC GSH concentrations and RBC morphology documented response to antidote administration within 72 hours. This case suggests that SAMe may provide a therapeutic option for treatment of acetaminophen toxicosis in dogs capable of retaining an orally administered antidote and maintaining adequate hepatic function for metabolism of SAMe to its thiol substrates.

Acute versus chronic alcohol consumption in acetaminophen-induced hepatotoxicity

The aim of this study was to determine by multivariate analysis how alcohol and other factors affect the clinical course and outcome in patients with acetaminophen (paracetamol) poisoning. A total of 645 consecutive patients admitted from 1994 to 2000 with single-dose acetaminophen poisoning were studied, giving special attention to alcohol history, time between overdose and intravenous N-acetylcysteine (NAC) treatment ("time to NAC"), and other data available at the time of admittance. Up until 72 hours after ingestion, time to NAC was the single most important independent risk factor. With a time to NAC less than 12 hours, the mortality rate was 0.42% (95% CI, 0.05-2.7). When time to NAC exceeded 12, 24, and 48 hours, the mortality rate increased to 6.1%, 13%, and 19%, respectively. Chronic alcohol abuse was an independent risk factor of mortality (odds ratio [OR], 3.52; 95% CI, 1.78-6.97). Acute alcohol ingestion was an independent protective factor regarding mortality in alcoholic patients (OR, 0.08; 95% CI, 0.01-0.66) but not in nonalcoholic patients (OR, 0.21; 95% CI, 0.03-1.67). Patient age and quantity of acetaminophen were independent risk factors. In conclusion, time to NAC was confirmed as the major risk factor in acetaminophen-induced hepatotoxicity and mortality. Chronic alcohol abuse was an independent risk factor that could be counteracted by concomitant acute alcohol ingestion. We suggest that patients with chronic alcoholism and suspected acetaminophen poisoning due to an increased risk of developing hepatotoxicity should be treated with NAC regardless of risk estimation.

Update: the clinical importance of acetaminophen hepatotoxicity in non-alcoholic and alcoholic subjects

Acetaminophen (paracetamol) is one of the most commonly used over-the-counter medications. Taken in doses greater than 150 mg/kg/day (>10 g), it usually causes acute liver failure. The authors review mainly the management of acetaminophen toxicity in both users and nonusers of alcohol. Chronic alcoholics are a special subgroup, who risk serious toxicity when taking acetaminophen, even in therapeutic doses. The acetaminophen-alcohol interaction is complex, because acute and chronic ethanol have opposite effects. This review also considers physiological and clinical changes, as well as the diagnosis and treatment of acetaminophen poisoning.