Management of paracetamol overdose: current controversies

Two chromatographic methods for analyzing paracetamol in spiked human plasma with its toxic metabolite, N-acetyl parabenzoquinone imine and its antidote, N-acetyl-L-cysteine

Acetaminophen, also known as paracetamol (APAP), is a highly utilized pharmaceutical agent on a global scale, particularly in the field of pediatrics. Regrettably, an overdose of APAP, resulting from the predominant oxidation, has the potential to trigger acute liver injury. The study's goal was to find an easy, accurate, and selective way to measure APAP, N-acetyl para benzoquinone imine (NAPQI) (an APAP metabolite that is harmful), and N-acetyl-L-cysteine (NAC) (an antidote). Two different chromatographic methods were used. The HPTLC method, which used silica gel 60 F254 as a stationary phase and a developing liquid made up of methanol, ethyl acetate, and glacial acetic acid (8:2:0.2, v/v/v) and a UV detection at 254 nm. The HPLC method was developed using a mobile phase consisting of water, methanol, and formic acid in a proportion of (70:30:0.15, v/v/v). The stationary phase used in the approach was a C18 column. Analytes quantification was established utilizing a UV detector operating at a wavelength of 254 nm. The present methods make it possible to measure the amount of APAP in plasma samples. When it comes to pharmacokinetics or medication levels in children's plasma, for example, this may be also very helpful. The current methods can quantify NAPQI, which is helpful in figuring out drug concentrations in individuals with APAP intoxication diagnoses. Additionally, the current approaches can estimate NAC as an antidote; as a result, this study is a complete study because it can analyse drug, toxic metabolite, and antidote in one analytical run. Using the innovative blue applicability grade index software, which measures the practicality of procedures, both methodologies were compared with a reported methods. Additionally, the achievement of the eco-friendliness profile of the designed procedures was assessed. Both techniques passed the ICH validation tests.

Electrochemical methods for the determination of acetaminophen in biological matrices: A critical review in the clinical field

BACKGROUND

Paracetamol or acetaminophen (APAP), or acetaminophen, is a widely used medication for pain relief and fever reduction due to its analgesic and antipyretic properties. However, excessive APAP consumption can lead to severe hepatotoxicity and nephrotoxicity, posing overdose risks. Consequently, the development of analytical methods for an accurate and rapid detection of APAP in biological matrices is of great interest in the health-related fields. Electrochemical methods have emerged as efficient, cost-effective, and sensitive tools for APAP detection in biological samples. In the light of the reported insights, this review examines critically diverse electrochemical methods for PAR detection in different biological matrices, including serum, urine, oral fluid, and sweat.

RESULTS

The claimed benefits of chemically-modified electrodes towards the selective determination of paracetamol in such complex sample matrices are discussed. On the other hand, the possible use of unmodified carbon-based electrodes combined with flow methods is highlighted as an alternative that can find relevance in the analysis of biological fluids suspected of PAR overdose occurring in the forensic scenario. Furthermore, the details regarding the distinct techniques and working electrodes for APAP determination are presented, compared and discussed in separate sections for each biological sample (serum, urine, and oral fluid). Another aspect herein debated is the selective determination of APAP in the presence of electroactive drugs naturally found in biological samples, as uric acid, and ascorbic acid, are evaluated. In addition, we have discussed and emphasized the significance of matrix selection to ensure precise results, especially in potential overdose scenarios.

SIGNIFICANCE

This review article provides a critical discussion on the development of electroanalytical methods for biological fluids, with relevance to the fields of clinical analysis and forensics.

Quality Evaluation of Locally Manufactured Paracetamol Tablets in East Africa

Background: Paracetamol, also known as acetaminophen, is categorized as an analgesic and antipyretic medication and is available as over the counter (OTC) medication. It is commonly used in conditions associated with pain and fever. There is a tendency for community to prefer using imported paracetamol tablets from Europe and United States than from Asia and Africa worrying of the quality of the products. Safety, effectiveness, and efficacy of a medicine can be guaranteed when its quality is reliable; however, there is limited data on the quality of locally manufactured paracetamol tablets, thus necessitating this study. Aim: This study is aimed at assessing the quality of paracetamol tablets 500 mg manufactured by local companies by evaluating their physical parameters, assay results, and dissolution profiles. The compliance of these tablets with the specifications outlined in the British Pharmacopoeia (BP) was analyzed. Additionally, a comparative dissolution test was conducted to assess dissolution profile for innovator product and generics. Method: Five different brands from East African countries with 76 tablets from each brand were compared with the innovator product regarding weight variation, hardness, friability, assay, and dissolution test based on the BP specifications. Results and discussion: All samples of paracetamol tablets 500 mg from the local manufacturers in this study met the specifications set by the BP for physical parameters, including weight variation, friability, hardness, and disintegration tests. The weight variation test, directly related to drug content variation, demonstrated compliance within the acceptable deviation of 5%. Similarly, the assay test, which determines the concentration of the active pharmaceutical ingredient (API), confirmed that all samples complied with the acceptable concentration range of 90%-110% for paracetamol. The dissolution test, assessing the percentage release of the API within a specified time, demonstrated that at 15 min, two samples (diodol and enamol) exhibited lower concentration releases than the required 80%, indicating potential delays in their bioavailability and onset of action. Conclusion: To conclude, all samples had good quality and they can be used for their therapeutic purposes.

Patterns and outcomes of paracetamol poisoning management in Hamad Medical Corporation, Qatar: A retrospective cohort study

We aimed to investigate the characteristics and clinical outcomes of paracetamol poisoning and paracetamol overdose in Qatar. This retrospective cohort study included patients admitted to the emergency department (ED). We included patients who presented with excessive paracetamol ingestion, between December 2018 and September 2019. The primary outcomes were describing the characteristics and outcomes of paracetamol overdose (from a suicidal overdose or accidental overdose, dose ≤ 150 mg/kg, when serum levels of <60 mmol/L) or dose ingested (≤75 mg/kg) with staggered ingestion poisoning due to suicidal attempt or accidental attempt, defined as the dose ingested (>150 mg/kg), acute ingestion, nomogram level more than the treatment line, or dose ingested (>75 mg/kg) with staggered ingestion, and assessing the management of excessive paracetamol ingestion. Secondary outcomes included evaluation of the time difference between ingestion and time of administration, hospitalization, and adverse drug events. Significant differences were detected between patients who presented with paracetamol overdose and those who presented with paracetamol toxicity. A total of 69 patients were analyzed, of whom 43 received paracetamol overdose (mean age 27.5 ± 11.1 years) and 26 had paracetamol poisoning (mean age 25 ± 6.22 years). Paracetamol poisoning was identified in 26% of the patients with a 24.3% history of psychiatric illness, compared to 18.6% with paracetamol overdose. More patients presented with paracetamol toxicity in the time between ingestion and obtaining serum levels compared to the overdose group. A significantly longer length of hospitalization was observed in the toxicity group. A significantly higher number of patients in the toxicity group received N-acetylcysteine (NAC). More hypotension and rashes were observed among those who received NAC in the toxicity group. Patients presenting to the ED due to paracetamol toxicity are not uncommon, and most cases occur in young adults, and few in patients with a history of psychiatric illness, suggesting that preventive approaches are highly required.

Liver Damage and microRNAs: An Update

One of the major organs in the body with multiple functions is the liver. It plays a central role in the transformation of macronutrients and clearance of chemicals and drugs. The serum biomarkers often used to indicate liver damage are not specifically for drug-induced liver injury (DILI) or liver injury caused by other xenobiotics, nor for viral infection. In this case, microRNAs (miRNAs) could play an exciting role as biomarkers of specific liver damage. In this review, we aimed to update the current literature on liver damage induced by drugs, as acute conditions and viral infections mediated by the hepatitis B virus (HBV) linked these two conditions to advanced research, with a focus on microRNAs as early biomarkers for liver damage. The undoubtable evidence that circulating miR-122 could be used as a human biomarker of DILI came from several studies in which a strong increase of it was linked with the status of liver function. In infancy, there is the possibility of an early miRNA detection for hepatitis B virus infection, but there are a lack of solid models for studying the HVB molecular mechanism of infection in detail, even if miRNAs do hold unrealized potential as biomarkers for early detection of hepatitis B virus infection mediated by HBV.

Over-the-counter analgesics during pregnancy: a comprehensive review of global prevalence and offspring safety

BACKGROUND

Analgesia during pregnancy is often necessary. Due to their widespread availability, many mothers opt to use over-the-counter (OTC) analgesics. Those analgesic compounds and their metabolites can readily cross the placenta and reach the developing foetus. Evidence for safety or associations with adverse health outcomes is conflicting, limiting definitive decision-making for healthcare professionals.

OBJECTIVE AND RATIONALE

This review provides a detailed and objective overview of research in this field. We consider the global prevalence of OTC analgesia during pregnancy, explain the current mechanistic understanding of how analgesic compounds cross the placenta and reach the foetus, and review current research on exposure associations with offspring health outcomes.

SEARCH METHODS

A comprehensive English language literature search was conducted using PubMed and Scopus databases. Different combinations of key search terms were used including 'over-the-counter/non-prescription analgesics', 'pregnancy', 'self-medication', 'paracetamol', 'acetaminophen', 'diclofenac', 'aspirin', 'ibuprofen', 'in utero exposure', 'placenta drug transport', 'placental transporters', 'placenta drug metabolism' and 'offspring outcomes'.

OUTCOMES

This article examines the evidence of foetal exposure to OTC analgesia, starting from different routes of exposure to evidence, or the lack thereof, linking maternal consumption to offspring ill health. There is a very high prevalence of maternal consumption of OTC analgesics globally, which is increasing sharply. The choice of analgesia selected by pregnant women differs across populations. Location was also observed to have an effect on prevalence of use, with more developed countries reporting the highest consumption rates. Some of the literature focuses on the association of in utero exposure at different pregnancy trimesters and the development of neurodevelopmental, cardiovascular, respiratory and reproductive defects. This is in contrast to other studies which report no associations.

WIDER IMPLICATIONS

The high prevalence and the challenges of reporting exact consumption rates make OTC analgesia during pregnancy a pressing reproductive health issue globally. Even though some healthcare policy-making authorities have declared the consumption of some OTC analgesics for most stages of pregnancy to be safe, such decisions are often based on partial review of literature. Our comprehensive review of current evidence highlights that important knowledge gaps still exist. Those areas require further research in order to provide pregnant mothers with clear guidance with regard to OTC analgesic use during pregnancy.

Mucoactive Agents in the Therapy of Upper Respiratory Airways Infections: Fair to Describe Them Just as Mucoactive?

Background

Upper and lower respiratory tract infections are common conditions for which medical advice is sought, and their management relies on the use of prescription and over-the-counter (OTC) medicines. Ambroxol, bromhexine, carbocysteine, erdosteine, N-acetyl cysteine (NAC), and sobrerol are mucoactive agents for which clinical trials have been conducted, have been awarded well-established status by regulatory authorities, and are available as OTC or prescription products.

Objective

To briefly review the evidence-based efficacy and safety of these substances in the therapy of upper respiratory airways infections.

Methods

We conducted searches in MEDLINE and other databases for clinical trials and reviews done on the efficacy and safety of ambroxol, bromhexine, carbocysteine, erdosteine, NAC, and sobrerol.

Results

Clinical trials have shown that these mucolytics have an important place in the relief of cough symptoms by easing the elimination of mucus. All drugs have shown comparable efficacy in the symptomatic treatment of productive cough, with some shared characteristics and some specific features.

Conclusions and relevance

All mucolytics reviewed have a good safety profile, although some precautions should be taken when using ambroxol and bromhexine, and the use of NAC and carbocysteine should be monitored in special patient groups. Overall, however, the available evidence from randomised, controlled, and observational trials, as well as pragmatic, real-life experience, suggests that these products are useful in the therapy of upper respiratory airways infections, including bronchitis, sinusitis, and rhinosinusitis.

Effects of the Usage of l-Cysteine (l-Cys) on Human Health

This review summarizes recent knowledge about the use of the amino acid l-Cysteine (l-Cys) through diet, nutritional supplements or drugs with the aim to improve human health or treat certain diseases. Three databases (PubMed, Scopus, and Web of Science) and different keywords have been used to create a database of documents published between 1950 and 2017 in scientific journals in English or Spanish. A total of 60,885 primary publications were ultimately selected to compile accurate information about the use of l-Cys in medicine and nutritional therapies and to identify the reported benefits of l-Cys on human health. The number of publications about the use of l-Cys for these purposes has increased significantly during the last two decades. This increase seems to be closely related to the rise of nutraceutical industries and personalized medicine. The main evidence reporting benefits of l-Cys usage is summarized. However, the lack of accurate information and studies based on clinical trials hampers consensus among authors. Thus, the debate about the role and effectiveness of supplements/drugs containing l-Cys is still open.

A Study on the Medication Errors in the Administration of N-Acetylcysteine for Paracetamol Overdose Patients in Malaysia

Introduction

N-Acetylcysteine (NAC) has been used to treat paracetamol overdose for four decades. But the administration of NAC regimens is complicated. Therefore, medication errors are an ongoing issue in the acute-care setting and directly impact the safety of patients.

Objective

To evaluate the rate of NAC-related medication errors during the management of paracetamol overdose at a teaching hospital in Malaysia.

Methods

This clinical audit study was performed retrospectively between June 2008 and June 2011. Patients who presented to the adult emergency department with paracetamol overdose and had received at least the loading dose of intravenous NAC were eligible. Children below the age of 12 years old were not included. Also, patients displaying chronic excessive paracetamol usage or recurrent paracetamol overdose were excluded. We determined the type and frequency of medication errors during intravenous NAC administration.

Results

The study population ranged from 13 to 87 years old (mean age: 25.06; median: 23) and was predominantly female. The overall prevalence of intravenous NAC-related medication errors was found to be 84.3%. Moreover, the following frequencies were observed based on error type: 5.9% wrong dose, 37.3% incorrect infusion rate, 8.5% interruption during treatment, and 66.5% unnecessary administration.

Conclusion

We observe a surprisingly high prevalence of medication errors related to the administration of intravenous NAC. Thus, this emerging issue needs be addressed in order to ensure patient safety as well as to prevent unnecessary hospital admissions and/or burdening treatment costs. (Hong Kong j.emerg.med. 2014;21: 361-367)

Case Report: Paracetamol Poisoning in a 2-Year-Old Child – from International Overview to the Role of the Hong Kong Poison Information Centre

We report a 2-year-old girl suffering from acute liver failure as a result of paracetamol poisoning. The child successfully recovered after intensive care. We performed literature search for the past decade and found that the pathophysiological response in the child was different from that of the adult. Despite paracetamol poisoning being one of the most common poisonings in the world, there is still no consensus in the treatment protocol. Hence the role of the Hong Kong Poison Information Centre is briefly discussed.

N-Acetylcysteine, a glutathione precursor, reverts vascular dysfunction and endothelial epigenetic programming in intrauterine growth restricted guinea pigs

KEY POINTS

Intrauterine growth restriction (IUGR) is associated with vascular dysfunction, oxidative stress and signs of endothelial epigenetic programming of the umbilical vessels. There is no evidence that this epigenetic programming is occurring on systemic fetal arteries. In IUGR guinea pigs we studied the functional and epigenetic programming of endothelial nitric oxide synthase (eNOS) (Nos3 gene) in umbilical and systemic fetal arteries, addressing the role of oxidative stress in this process by maternal treatment with N-acetylcysteine (NAC) during the second half of gestation. The present study suggests that IUGR endothelial cells have common molecular markers of programming in umbilical and systemic arteries. Notably, maternal treatment with NAC restores fetal growth by increasing placental efficiency and reverting the functional and epigenetic programming of eNOS in arterial endothelium in IUGR guinea pigs.

ABSTRACT

In humans, intrauterine growth restriction (IUGR) is associated with vascular dysfunction, oxidative stress and signs of endothelial programming in umbilical vessels. We aimed to determine the effects of maternal antioxidant treatment with N-acetylcysteine (NAC) on fetal endothelial function and endothelial nitric oxide synthase (eNOS) programming in IUGR guinea pigs. IUGR was induced by implanting ameroid constrictors on uterine arteries of pregnant guinea pigs at mid gestation, half of the sows receiving NAC in the drinking water (from day 34 until term). Fetal biometry and placental vascular resistance were followed by ultrasound throughout gestation. At term, umbilical arteries and fetal aortae were isolated to assess endothelial function by wire-myography. Primary cultures of endothelial cells (ECs) from fetal aorta, femoral and umbilical arteries were used to determine eNOS mRNA levels by quantitative PCR and analyse DNA methylation in the Nos3 promoter by pyrosequencing. Doppler ultrasound measurements showed that NAC reduced placental vascular resistance in IUGR (P < 0.05) and recovered fetal weight (P < 0.05), increasing fetal-to-placental ratio at term (∼40%) (P < 0.001). In IUGR, NAC treatment restored eNOS-dependent relaxation in aorta and umbilical arteries (P < 0.05), normalizing eNOS mRNA levels in EC fetal and umbilical arteries (P < 0.05). IUGR-derived ECs had a decreased DNA methylation (∼30%) at CpG -170 (from the transcription start site) and this epigenetic signature was absent in NAC-treated fetuses (P < 0.001). These data show that IUGR-ECs have common molecular markers of eNOS programming in umbilical and systemic arteries and this effect is prevented by maternal treatment with antioxidants.

Human Ebola virus infection in West Africa: a review of available therapeutic agents that target different steps of the life cycle of Ebola virus

The recent outbreak of the human Zaire ebolavirus (EBOV) epidemic is spiraling out of control in West Africa. Human EBOV hemorrhagic fever has a case fatality rate of up to 90%. The EBOV is classified as a biosafety level 4 pathogen and is considered a category A agent of bioterrorism by Centers for Disease Control and Prevention, with no approved therapies and vaccines available for its treatment apart from supportive care. Although several promising therapeutic agents and vaccines against EBOV are undergoing the Phase I human trial, the current epidemic might be outpacing the speed at which drugs and vaccines can be produced. Like all viruses, the EBOV largely relies on host cell factors and physiological processes for its entry, replication, and egress. We have reviewed currently available therapeutic agents that have been shown to be effective in suppressing the proliferation of the EBOV in cell cultures or animal studies. Most of the therapeutic agents in this review are directed against non-mutable targets of the host, which is independent of viral mutation. These medications are approved by the Food and Drug Administration (FDA) for the treatment of other diseases. They are available and stockpileable for immediate use. They may also have a complementary role to those therapeutic agents under development that are directed against the mutable targets of the EBOV.

In vitro N-acetyl-L-cysteine promotes proliferation and suppresses interleukin-8 expression in adipose-derived stem cells

Adipose-derived stem cells (ADSCs) hold great promise for repair and regeneration of burn wounds by producing growth factors, but proinflammatory cytokines such as interleukin-8 (IL-8) released by ADSCs would potentially deepen the wound and inhibit healing. The reported research aimed to identify the effects of N-acetyl-L-cysteine (NAC) on the proliferation, death, and IL-8 production of ADSCs. In the presence or absence of NAC, ADSC proliferation was examined using a CCK-8 Kit, and cell death was evaluated by flow cytometry analysis. Subsequently, IL-8 mRNA expression was detected by reverse transcriptase-polymerase chain reaction and protein production by enzyme-linked immunoassay. Findings showed that cell proliferation in the NAC-treated group was a significant 1.53-fold greater than in the control group, that the apoptosis rate of ADSCs decreased by 55.4 % compared with the control group, and that the necrosis rate decreased by 48.8 %. Additionally, the IL-8 mRNA expression decreased to 46.2 ± 8.7 % that of the control group, and the IL-8 protein production decreased to 9.98 ± 0.57 %. The authors believe that NAC might be helpful in burn wound repair and regeneration by stimulating the proliferation of ADSCs, inhibiting cell death, and suppressing IL-8 production.

LEVEL OF EVIDENCE II

This journal requires that authors assign a level of evidence to each article.

[Acute paracetamol overdose during pregnancy: a case report]

Severe but regressive toxic liver damage was observed in a 30-week pregnant woman due to acetaminophen poisoning. A cesarean section was performed 1 week later for suspected chorioamniotitis and the patient gave birth to an infant who only experienced complications of preterm birth. The lack of fetal liver damage following acute maternal paracetamol poisoning seems to be the rule, as shown by a review of the literature.

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

PURPOSE

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

METHODS

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

RESULTS

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

CONCLUSION

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

Relationship between serum acetaminophen concentration and N-acetylcysteine-induced adverse drug reactions

Intravenous N-acetylcysteine is usually regarded as a safe antidote. However, during the infusion of the loading dose, different types of adverse drug reactions (ADR) may occur. The objective of this study was to investigate the relation between the incidence of different types of ADR and serum acetaminophen concentration in patients presenting to the hospital with acetaminophen overdose. This is a retrospective study of patients admitted to the hospital for acute acetaminophen overdose over a period of 5 years (1 January 2004 to 31 December 2008). Parametric and non-parametric tests were used to test differences between groups depending on the normality of the data. SPSS 15 was used for data analysis. Of 305 patients with acetaminophen overdose, 146 (47.9%) were treated with intravenous N-acetylcysteine and 139 (45.6%) were included in this study. Different types of ADR were observed in 94 (67.6%) patients. Low serum acetaminophen concentrations were significantly associated with cutaneous anaphylactoid reactions but not other types of ADR. Low serum acetaminophen concentration was significantly associated with flushing (p < 0.001), rash (p < 0.001) and pruritus (p < 0.001). However, there were no significant differences in serum acetaminophen concentrations between patients with and without the following ADR: gastrointestinal reactions (p = 0.77), respiratory reactions (p = 0.96), central nervous reactions (p = 0.82) and cardiovascular reactions (p = 0.37). In conclusion, low serum acetaminophen concentrations were associated with higher cutaneous anaphylactoid reactions. Such high serum acetaminophen concentrations may be protective against N-acetylcysteine-induced cutaneous ADR.

N-acetylcysteine attenuates cerebral complications of non-acetaminophen-induced acute liver failure in mice: antioxidant and anti-inflammatory mechanisms

N-acetylcysteine (NAC) is an effective antidote to treat acetaminophen (APAP)-induced acute liver failure (ALF). NAC is hepatoprotective and prevents the neurological complications of ALF, namely hepatic encephalopathy and brain edema. The protective effect of NAC and its mechanisms of action in ALF due to other toxins, however, are still controversial. In the present study, we investigated the effects of NAC in relation to liver pathology, hepatic and cerebral glutathione, plasma ammonia concentrations, progression of encephalopathy, cerebral edema, and plasma proinflammatory cytokines in mice with ALF resulting from azoxymethane (AOM) hepatotoxicity, a well characterized model of toxic liver injury. Male C57BL/6 mice were treated with AOM (100 microg/g; i.p.) or saline and sacrificed at coma stage of encephalopathy in parallel with AOM mice administered NAC (1.2 g/kg; i.p.). AOM administration led to hepatic damage, significant increase in plasma transaminase activity, decreased hepatic glutathione levels and brain GSH/GSSG ratios as well as increased expression of plasma proinflammatory cytokines. NAC treatment of AOM mice led to reduced hepatic damage and improvement in neurological function, normalization of brain and hepatic glutathione levels as well as selective attenuation in expression of plasma proinflammatory cytokines. These findings demonstrate that the beneficial effects of NAC in experimental non-APAP-induced ALF involves both antioxidant and anti-inflammatory mechanisms.

Acetaminophen induced renal injury via oxidative stress and TNF-alpha production: therapeutic potential of arjunolic acid

Acetaminophen (APAP) causes acute and chronic renal failure. The mechanisms leading to hepatic injury have been extensively studied, but the molecular mechanisms regarding APAP-induced nephro-toxicity are poorly defined. In earlier studies, we have demonstrated that arjunolic acid (AA) possesses protective roles against chemically induced organ pathophysiology. The purpose of the present study was to explore whether AA plays any protective role against APAP induced acute renal toxicity; and if so, what pathways it utilizes for the mechanism of its protective action. Exposure of rats with a nephro-toxic dose of APAP altered a number of biomarkers (like blood urea nitrogen and serum creatinine levels, etc.) related to renal oxidative stress, decreased antioxidant activity, elevated renal tumor necrosis factor-alpha and nitric oxide levels. AA treatment both pre- and post to APAP exposure protected the alteration of these biomarkers, compensated deficits in the antioxidant defense mechanisms, and suppressed lipid peroxidation in renal tissue. Investigating the inherent molecular signaling of this pathophysiology and its protection, we found that the mitochondrial pathway was not activated during APAP-induced cell death as no dissipation of mitochondrial membrane potential or release of cytochrome C was detected in the respective experiments. Our experimental evidence suggests that APAP-induced nephro-toxicity is a caspase-dependent process that involves activation of caspase-9 and caspase-3 in the absence of cytosolic cytochrome C release. These results provide evidence that inhibition of NO overproduction and maintenance of intracellular antioxidant status may play a pivotal role in the protective effects of AA against APAP-induced renal damage. AA represents a potential therapeutic option to protect renal tissue from the detrimental effects of acute acetaminophen overdose.

Acetaminophen hepatotoxicity and acute liver failure

Acetaminophen-induced hepatotoxicity is a common consequence of acetaminophen overdose and may lead to acute liver failure (ALF). Currently acetaminophen is the most common cause of ALF in both United States and United Kingdom, with a trend to increasing incidence in the United States. N-acetylcysteine is the most effective drug to prevent progression to liver failure with acetaminophen hepatotoxicity. Liver transplantation is the only definitive therapy that will significantly increase the chances of survival for advanced ALF. This communication reviews current information regarding causes and management of acetaminophen-induced hepatotoxicity and ALF.

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.

Drug-related hepatotoxicity and acute liver failure

Drug-induced acute liver failure (ALF) accounts for approximately 20% of ALF in children and a higher percentage of ALF in adults. Although most patients experience milder drug hepatotoxic reactions such as hepatitis, cholestasis, or asymptomatic enzyme elevation, it is important to recognize the potential for progression to ALF. The most common cause of drug-induced ALF in children is acetaminophen (15% of all ALF in children in the United Kingdom and the United States), whereas other drugs such as antituberculous and antiepileptic therapy account for 5%. The pathogenesis of liver injury includes direct hepatotoxicity and idiosyncratic reactions for most drugs, although for others the mechanism of injury is assumed on the basis of clinical presentation and hepatic histological findings. We review the adult and pediatric literature of drug-induced hepatotoxicity and ALF, with special attention to commonly used or offending medications, mechanism of the toxicity, clinical presentation, diagnosis, treatment, and prognosis. Although most of the available information is based on experience in adult patients, we have included that which is applicable to children, or we have cited pediatric examples. Enhanced awareness of the potential hepatotoxicity of commonly prescribed medications may minimize the frequency of serious hepatotoxicity and ALF in pediatric patients.

Synergistic action of sodium selenite and N-acetylcysteine in acetaminophen-induced liver damage

Acetaminophen (AAP) is a commonly used analgesic and antipyretic drug; however, when used in high doses, it causes fulminant hepatic necrosis in both humans and experimental animals. In this study, we investigated whether selenium (Se) and N-acetylcysteine (NAC), alone or in combination, are protective against AAP toxicity in mice. At the beginning of the experiment, blood samples were taken from 10 of 350 mice. Then, the remaining mice were randomly allocated into four groups, each consisting of 35 animals. The 1st group received a single administration of AAP by gavage at a dose of 600 mg/kg-bw, p.o. The 2nd group (AAP-Se) was treated with sodium selenite (0.5 mg Se/kg-bw, p.o.) one hour after ingestion of AAP. The 3rd group (AAP-NAC) ingested AAP, 1.5 h later followed by NAC (500 mg/kg-bw, p.o.). The 4th group (AAP-Se-NAC) was given sodium selenite and NAC, 1 and 1.5 h after administration of AAP, respectively. From each group, blood samples of seven mice for each time point were taken at 4, 8, 24, and 48 h after AAP toxicity. Serum alanine aminotransferase (ALT), aspartate aminotransferase (AST), lactate dehydrogenase (LDH) levels were measured. Compared with AAP group, the levels of ALT were lower after AAP ingestion in AAP-NAC, AAP-Se, and AAP-Se-NAC groups at the 8th hour. ALT, AST, and LDH levels in AAP-Se-NAC group were 50% of the levels of other groups starting form the 4th hour of toxicity. It is concluded that protection against AAP hepatotoxicity using a combination of Se and NAC is better than that found with either agent alone.

Effect of 3 g of intravenous paracetamol on post-operative analgesia, platelet function and liver enzymes in patients undergoing tonsillectomy under local anaesthesia

BACKGROUND

Paracetamol is often given as an adjunctive analgesic to reduce opioid-related adverse effects but its optimal dose is unknown. We studied the analgesic effect and safety of a single 3-g intravenous (i.v.) dose of paracetamol in adults.

METHODS

One hundred and seven patients undergoing tonsillectomy under local anaesthesia were randomly allocated to receive i.v. 3 g of paracetamol, 75 mg of diclofenac or placebo prior to surgery. The consumption of post-operative morphine using a patient-controlled analgesia-device was quantified for 6 h. Platelet aggregation and the concentrations of paracetamol, liver aminotransferases, glutathione transferase alpha 1-1 (GSTA1-1) and thromboxane B(2) were measured.

RESULTS

During the first hours after surgery, both paracetamol and diclofenac reduced (P < 0.05) the consumption of morphine but had no effect thereafter. The values for the 6-h cumulative consumption of morphine in patients given paracetamol (18.7 +/- 13.8 mg), diclofenac (16.1 +/- 9.9 mg) and placebo (22.0 +/- 12.1 mg) did not differ. Paracetamol had no effect on platelet aggregation, which was impaired only by diclofenac in response to arachidonic acid (P < 0.005). Both paracetamol (P < 0.01) and diclofenac (P < 0.005) inhibited the release of thromboxane B(2) at 1 h but they did not affect serum aminotransferase and GSTA1-1 levels. One patient given paracetamol displayed a transient increase in GSTA1-1 and liver aminotransferases.

CONCLUSION

During the initial hours after tonsillectomy, the administration of 3 g of i.v. paracetamol and 75 mg of diclofenac reduced the consumption of morphine. Both drugs also reduced the release of thromboxane B(2) from activated platelets but only diclofenac had a negative effect on platelet aggregation. In sensitive individuals, large doses of paracetamol may disturb the hepatocellular integrity. We do not recommend the use of i.v. doses of paracetamol higher than 1 g.

Safety and tolerability of N-acetylcysteine in cocaine-dependent individuals

A double-blind placebo-controlled crossover Phase I trial was conducted to assess the safety and tolerability of N-Acetylcysteine (NAC) in healthy, cocaine-dependent humans. Thirteen participants attended a three-day hospitalization in which they received placebo or NAC. Subjects were crossed over to receive the opposite medication condition during a second three-day hospitalization, which occurred the following week. Across placebo and NAC conditions, only mild side effects were noted, and the number of subjects reporting side effects did not differ. There were trends for a greater reduction in withdrawal symptoms and craving within the NAC condition. These preliminary results suggest that NAC is well tolerated in healthy, cocaine-dependent individuals and may reduce cocaine-related withdrawal symptoms and craving.

Modeling inflammation-drug interactions in vitro: a rat Kupffer cell-hepatocyte coculture system

Xenobiotic-inflammation interactions lead to hepatotoxicity in vivo. Selected xenobiotic agents (acetaminophen, APAP; chlorpromazine, CPZ; allyl alcohol, AlOH; monocrotaline, MCT) for which this occurs were evaluated for ability to elicit the release of Kupffer cell (KC)-derived inflammatory mediators and to modulate lipopolysaccharide (LPS)-stimulated release of these mediators. Using KCs and hepatocytes (HPCs) isolated from rat, KC/HPC cocultures were treated with either LPS, xenobiotic, vehicle or a combination. Six hours later, the release of inflammatory mediators was assessed. LPS alone caused a concentration-dependent increase in TNF-alpha release but had no significant effect on the release of PGE(2). APAP by itself did not alter release of TNF-alpha, PGE(2), IL-10, Gro/KC or IFN-gamma; however, in the presence of LPS, APAP enhanced LPS-induced TNF-alpha and Gro/KC release. APAP also attenuated LPS-induced increases in IL-10 and MCP-1. CPZ alone caused a concentration-dependent increase in TNF-alpha release, which was approximately additive in the presence of LPS. AlOH alone did not affect TNF-alpha release, but decreased TNF-alpha production in the presence of LPS. AlOH increased PGE(2) production, and this effect was potentiated in the presence of LPS. MCT by itself did not affect release of TNF-alpha but increased the response to LPS. Neither MCT, LPS, nor the combination affected production of PGE(2). These results demonstrate that KC/HPC cocultures can be used to evaluate interactions of xenobiotics with LPS. Furthermore, data from these studies qualitatively mirror reported data from whole animal studies, suggesting that this model could be useful for predicting aspects of xenobiotic-inflammation interactions in vivo.

An update of N-acetylcysteine treatment for acute acetaminophen toxicity in children

PURPOSE OF REVIEW

Acetaminophen poisoning accounts for a disproportionate percentage of all toxic ingestions, and can be life-threatening. This article reviews the mechanism and presentation of acetaminophen toxicity, as well as its treatment, including current thinking and treatment recommendations.

RECENT FINDINGS

N-acetylcysteine acts to detoxify acetaminophen in several ways, but primarily by increasing the synthesis and availability of glutathione, which binds and inactivates the highly reactive and hepatotoxic acetaminophen metabolite N-acetyl-p-benzoquinoneimine. The US Food and Drug Administration has approved an intravenous formulation of N-acetylcysteine, thus allowing the treatment time to be decreased from the 72 hr most commonly used for the oral regimen, to only 20 hr. This comes after many years of accepted intravenous N-acetylcysteine use in Europe and Canada, and much controversy as to the superiority of both treatments. This review summarizes this controversy, and offers a framework to develop a safe treatment plan that has the optimal outcome for the patient, as well as reflecting knowledge of the potential caveats at work. It describes side effects of N-acetylcysteine treatment, as well as relative indications to choose one route of treatment over the other.

SUMMARY

Acetaminophen can lead to irreversible liver damage and even death in acute overdose. Outcome is related to the swiftness in which the antidote (N-acetylcysteine) is provided. In the United States, there are now available both the oral and intravenous forms of N-acetylcysteine, and pros and cons exist for each. With brisk and adequate treatment using either route, recovery can be complete, and liver function can be restored.

Adverse hepatic drug reactions: inflammatory episodes as consequence and contributor

Susceptibility to drug toxicity is influenced by a variety of factors, both genetic and environmental. The focus of this article is the evidence addressing the hypothesis that inflammation is both a result of and a susceptibility factor for drug toxicity, with an emphasis on liver as a target organ. Results of studies suggesting a role for inflammatory mediators in the hepatotoxicity caused by acetaminophen or ethanol are discussed. For several drugs, the evidence from animal models that concurrent inflammation increases injury is presented. In addition, the occurrence of adverse drug reactions in people with preexisting inflammatory diseases is considered. The special case of idiosyncratic drug reactions is discussed and the potential raised for development of animal models for this type of drug toxicity. The conclusion is that inflammatory factors should be considered as determinants of sensitivity to adverse drug reactions.

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Randomized, double-blind, placebo-controlled comparison of the analgesic efficacy of oxycodone 10 mg/acetaminophen 325 mg versus controlled-release oxycodone 20 mg in postsurgical pain

This randomized, controlled trial compared the analgesic efficacy and safety of the new oxycodone 10-mg/acetaminophen 325-mg formulation (Percocet) for the treatment of acute pain following oral surgery with double the dose of oxycodone alone (controlled-release [CR] oxycodone 20 mg [OxyContin]). A total of 150 male and female patients with > or = 2 full or partial bone-impacted mandibular molars, at least moderate persistent pain, and moderate trauma received a single dose of combination agent, CR oxycodone, or placebo following oral surgery and rated pain intensity and pain relief over the next 6 hours. The intent-to-treat population comprised 141 patients (55 on combination agent, 56 on oxycodone, and 30 on placebo). Combination agent and CR oxycodone were significantly superior to placebo for all efficacy measures. Combination agent was statistically superior to CR oxycodone in four of five outcome measures of pain intensity and pain relief (PPID, PPAR, SPID, and SPRID). It also provided a faster onset and 24% reduction in the number of patients reporting treatment-related adverse events compared with twice the dose of opioid alone. This new formulation offers the combination of two analgesic drugs with complementary mechanisms of action, which results in enhanced analgesia, an "opioid-sparing" effect, and an improved side effect and safety profile.

Opioid and non-opioid analgesics

Opioids are the most potent analgesics. Toxicity results either from effects mediated by variation in affinity and intrinsic efficacy at specific opioid receptors or, rarely, from a direct toxic effect of the drugs. For some adverse effects, opioids exhibit a 'dual pharmacology' whereby these effects are usually observed only in pain-free individuals, and are not seen in patients in pain. Paracetamol, although generally very safe in therapeutic doses, displays potentially fatal toxicity in overdose requiring specific treatment. Non-steroidal anti-inflammatory drugs (NSAIDs) are known to act by inhibiting COX-1 and COX-2 isoenzymes to various degrees. Toxicity arises primarily from undesired inhibition at these enzyme sites. Knowledge of the mechanism of action of these drugs is fundamental to the understanding of their potential for toxicity, the details of which are still emerging.

Approaches toward repeated supratherapeutic doses of paracetamol in children: a survey of medical directors of poison centres in North America and Europe

BACKGROUND

During the last few years there has been an increase in the number of reports of liver failure associated with prolonged paracetamol (acetaminophen) administration in children for therapeutic reasons.

OBJECTIVE

To describe the approach taken by medical directors of poison centres regarding the treatment of repeated supratherapeutic doses of paracetamol in children.

METHODS

Questionnaires mailed to the medical directors of 76 poison centres in North America and 48 poison centres in Europe asked respondents to comment on the management of a hypothetical case of a child who had received repeated doses of paracetamol at a daily dose of 90 mg/kg during a febrile illness and who presented to the emergency department with mildly elevated serum transaminase levels.

RESULTS

The response rate was 62% for North American centres and 44% for European centres. There was a wide range of answers regarding the maximal safe daily dose of paracetamol. For the case described, 71% of the respondents suggested measuring paracetamol serum concentration. Fifty-four percent suggested treating the patient with acetylcysteine and 35% suggested not treating the patient.

CONCLUSIONS

Our study showed that there is little agreement among medical directors of poison centres on the toxic threshold for chronic exposure to paracetamol in children and on how these cases should be managed.