Hemolysis and Hemolytic Uremic Syndrome following Five-fold N-Acetylcysteine Overdose

Protocol for a feasibility randomized controlled trial to evaluate the efficacy, safety and tolerability of N-acetylcysteine in reducing adverse drug reactions among adults treated for multidrug-resistant tuberculosis in Tanzania

BACKGROUND

Adverse drug reactions (ADRs) frequently occur in patients using second-line anti-tuberculosis medicine for treatment of multidrug resistant tuberculosis (MDR-TB). ADRs contribute to treatment interruptions which can compromise treatment response and risk acquired drug resistance to critical newer drugs such as bedaquiline, while severe ADRs carry considerable morbidity and mortality. N-acetylcysteine (NAC) has shown promise in reducing ADRs for medications related to TB in case series or randomized controlled trials in other medical conditions, yet evidence is lacking in MDR-TB patients. TB endemic settings have limited capacity to conduct clinical trials. We designed a proof-of-concept clinical trial primarily to explore the preliminary evidence on the protective effect of NAC among people treated for MDR-TB with second-line anti-TB medications.

METHODS

This is a proof-of-concept randomized open label clinical trial with 3 treatment arms including a control arm, an interventional arm of NAC 900 mg daily, and an interventional arm of NAC 900 mg twice-daily administered during the intensive phase of MDR-TB treatment. Patients initiating MDR-TB treatment will be enrolled at Kibong'oto National Center of Excellence for MDR-TB in the Kilimanjaro region of Tanzania. The minimum anticipated sample size is 66; with 22 participants in each arm. ADR monitoring will be performed at baseline and daily follow-up over 24 weeks including blood and urine specimen collection for hepatic and renal function and electrolyte abnormalities, and electrocardiogram. Sputum will be collected at baseline and monthly thereafter and cultured for mycobacteria as well as assayed for other molecular targets of Mycobacterium tuberculosis. Adverse drug events will be analysed over time using mixed effect models. Mean differences between arms in change of the ADRs from baseline (with 95% confidence intervals) will be derived from the fitted model.

DISCUSSION

Given that NAC promotes synthesis of glutathione, an intracellular antioxidant that combats the impact of oxidative stress, it may protect against medication induced oxidative damage in organs such as liver, pancreas, kidney, and cells of the immune system. This randomized controlled trial will determine if NAC leads to fewer ADRs, and if this protection is dose dependent. Fewer ADRs among patients treated with MDR-TB may significantly improve treatment outcomes for multidrug regimens that necessitate prolonged treatment durations. Conduct of this trial will set the needed infrastructure for clinical trials.

TRIAL REGISTRATION

PACTR202007736854169 Registered 03 July 2020.

Eculizumab in the Treatment of Acetylcysteine-Induced Atypical Hemolytic Uremic Syndrome

N-acetylcysteine overdose is almost exclusively an iatrogenic event. This rare complication can lead to hemolysis or atypical hemolytic uremic syndrome. A 53-year-old Caucasian male accidentally received a two-fold N-acetylcysteine overdose that resulted in a presentation compatible with the atypical hemolytic uremic syndrome. The patient required temporary hemodialysis sessions, and he received treatment with eculizumab. This case report is the first reported N-acetylcysteine-induced atypical hemolytic uremic syndrome successfully treated with eculizumab. Clinicians should be aware of N-acetylcysteine overdose and its possible hemolytic complications.

Acute Renal Failure and Hemolytic Uremic Syndrome in Overdose With N-acetyl Cysteine After Acetaminophen Poisoning

Context: Acetylcysteine is an effective treatment for acetaminophen poisoning. The preparation and dose calculation of acetylcysteine is associated with medical errors. The prevalence of this error is 34% globally. Case report: A 15-year-old girl took an overdose of acetaminophen in a suicide attempt. Acetylcysteine intravenous was ordered. Due to the medication error by the nurse, she received a 10-fold overdose of intravenous acetylcysteine in both initial loading dose and maintenance dose, at first day. On the second day, the patient showed abdominal pain, nausea, vomiting, and elevated liver enzymes. Her hemoglobin, hematocrit, and platelet quickly decreased. Subsequently, she developed oliguria, anuria, and rising serum creatinine levels. The patient was diagnosed with uremic hemolytic syndrome. She underwent hemodialysis and was treated with plasmapheresis, blood transfusions, and platelets. Discussion: The effects of acetaminophen poisoning and acetylcysteine overdose may be much more severe and have a greater impact on patient survival than each poisoning alone. Timely and accurate treatment measures can help prevent long-term side effects.

A review of alternative intravenous acetylcysteine regimens for acetaminophen overdose

INTRODUCTION

Acetylcysteine is the standard treatment for preventing hepatotoxicity caused by acetaminophen overdose. Several novel approaches to the management of acetaminophen overdose have been suggested to improve patient safety by reducing adverse drug reactions and dosing errors. This article reviews these alternative treatment regimens and intends to offer a detailed assessment of the available options to assist providers in managing cases of acetaminophen overdose.

AREAS COVERED

This review article covers observational and experimental studies that assessed the efficacy and safety of alternative intravenous acetylcysteine regimens for acetaminophen overdose. A literature search was conducted using PubMed, ProQuest, and Scopus to identify the studies, which included results through April 2021. The assessment of alternative regimens consists of a discussion on the limitations and benefits, barriers to implementation, and important considerations for each regimen.

EXPERT OPINION

Several alternative regimens have been studied and implemented in various institutions. Many of these dosing regimens have supporting safety data but most lack robust data. A reduction in infusion-related side effects is an important outcome, but established efficacy, local poison center familiarity with the regimen, institutional resources, and patient-specific factors should be equally considered when deciding on implementing and using an alternative dosing strategy.

An assessment of the variation in the concentration of acetylcysteine in infusions for the treatment of paracetamol overdose

BACKGROUND

Intravenous acetylcysteine is the treatment of choice for paracetamol poisoning. A previous UK study in 2001 found that 39% of measured acetylcysteine infusion concentrations differed by >20% from anticipated concentrations. In 2012, the UK Commission on Human Medicines made recommendations for the management of paracetamol overdose, including provision of weight-based acetylcysteine dosing tables. The aim of this study was to assess variation in acetylcysteine concentrations in administered infusions following the introduction of this guidance.

METHODS

A 6-month single-centre prospective study was undertaken at a UK teaching hospital. After preparation, 5-ml samples were taken from the first, second and third/any subsequent acetylcysteine infusions. Acetylcysteine was measured in diluted (1:50) samples by high-performance liquid chromatography. Comparisons between measured and expected concentrations based on prescribed weight-based dose and volume were made for each infusion.

RESULTS

Ninety samples were collected. There was a variation of ≤10% in measured compared to expected concentration for 45 (50%) infusions, of 10-20% for 27 (30%) infusions, 20.1-50% for 14 (16%) infusions and >50% for four (4%) infusions. There was a median (interquartile range) variation in measured compared to expected concentration of -3.6 mg ml^-1 (-6.7 to -2.3) for the first infusion, +0.2 mg ml^-1 (-0.9 to +0.4) for the second infusion and -0.3 mg ml^-1 (-0.6 to +0.2) for third and fourth infusions.

CONCLUSION

There has been a moderate improvement in the variation in acetylcysteine dose administered by infusion. Further work is required to understand the continuing variation and consideration should be given to simplification of acetylcysteine regimes to decrease the risk of administration errors.

N-acetylcysteine overdose after acetaminophen poisoning

N-acetylcysteine (NAC) is used widely and effectively in oral and intravenous forms as a specific antidote for acetaminophen poisoning. Here we report a rare case of iatrogenic NAC overdose following an error in preparation of the solution, and describe its clinical symptoms. Laboratory results and are presented and examined. A 23-year-old alert female patient weighing 65 kg presented to the emergency ward with weakness, lethargy, extreme fatigue, nausea, and dizziness. She had normal arterial blood gas and vital signs. An excessive dosage of NAC over a short period of time can lead to hemolysis, thrombocytopenia, and acute renal failure in patients with normal glucose-6-phosphate dehydrogenase, and finally to death. Considering the similarity between some of the clinical symptoms of acetaminophen overdose and NAC overdose, it is vitally important for the administration phases and checking of the patient’s symptoms to be carried out attentively and cautiously.

Misuse of the Naranjo Adverse Drug Reaction Probability Scale in toxicology

CONTEXT

When an adverse event occurs in an overdose patient, it may be difficult to determine whether the event was caused by the ingested drug or by medical therapy. Naranjo et al. developed a probability scale, the Naranjo Adverse Drug Reaction Probability Scale (Naranjo Scale), to assess the probability that a drug administered in therapeutic doses caused an adverse event thereby classifying the event as an adverse drug reaction (ADR). Although Naranjo et al. specifically excluded the application of this scale to adverse events in overdose patients, case reports demonstrate that authors continue to apply the Naranjo Scale to events in these patients.

OBJECTIVE

The World Health Organization defines an ADR as occurring only when drugs are administered in therapeutic doses. Yet ADRs continue to be reported in overdose patients. We sought to examine the use of the Naranjo scale in case reports of overdose patients to assess the potential consequences of that application.

METHODS

A Medline search via PubMed without language limits, through September 2012, using the search terms "Naranjo" and "overdose" or "poisoning" yielded 146 publications. Additional searches were performed to find articles with keywords of the Naranjo Scale development, current applications and validity of application in specific populations such as critically ill and overdose patients.

RESULTS

From the 146 publications, we identified 17 case reports or case series of overdose patients in which the Naranjo Scale was applied to a clinical complication to support a causal relationship between an administered drug and the clinical complication and thereby classify the clinical complication as an ADR. We also identified a recent publication in which the Naranjo Scale was applied to a new treatment modality (lipid emulsion) that is currently administered to overdose patients. Original publication of the Naranjo Scale and studies evaluating its use in critically ill patients or those with drug-induced disease were also retrieved.

CONCLUSION

Adverse events that occur in overdose patients are excluded from the definition of ADR. Yet in case reports or series of overdose patients, the Naranjo Scale has been applied to assess the probability an event was caused by the ingested drug or therapeutic modality. This application of the Naranjo Scale is not scientifically valid and may lead to erroneous conclusions. There is no evidence to support the application of the Naranjo scale to any events that occur in overdose patients.

Novel acetylcysteine regimens for treatment of paracetamol overdose

Paracetamol (acetaminophen) overdose remains the leading cause of death or transplantation due to acute liver failure in many parts of the world. Acetylcysteine has long been recognized as an effective antidote, via oral or intravenous administration, minimizing the risk and severity of acute liver injury if administered sufficiently early after a paracetamol overdose. Despite this, its mechanisms of action remain obscure, and there is uncertainty regarding the optimal dose and duration of treatment. The intravenous infusion protocol was originally developed as a three-step loading regimen; it causes very high early peak plasma concentrations of acetylcysteine whereas the later maintenance infusion is associated with much lower concentrations. This pharmacokinetic profile is associated with two particular concerns: a high rate of occurrence of adverse effects that occur after the initial loading infusion, and the possibility that the maintenance phase of treatment might deliver too low a dose of acetylcysteine for optimum protection against liver injury. Recently described novel administration regimens offer different rates of intravenous acetylcysteine administration in both the loading and maintenance phases. These alternative regimens appear to be well tolerated in small patient groups, but too few clinical data are available to evaluate their comparative efficacy in preventing paracetamol-induced liver injury.