Placental transfer of N-acetylcysteine following human maternal acetaminophen toxicity

Fifty years of paracetamol (acetaminophen) poisoning: the development of risk assessment and treatment 1973-2023 with particular focus on contributions published from Edinburgh and Denver

INTRODUCTION

Fifty years ago, basic scientific studies and the availability of assay methods made the assessment of risk in paracetamol (acetaminophen) poisoning possible. The use of the antidote acetylcysteine linked to new methods of risk assessment transformed the treatment of this poisoning. This review will describe the way in which risk assessment and treatments have developed over the last 50 years and highlight the remaining areas of uncertainty.

METHODS

A search of PubMed and its subsidiary databases revealed 1,166 references published in the period 1963-2023 using the combined terms "paracetamol", "poisoning", and "acetylcysteine". Focused searches then identified 170 papers dealing with risk assessment of paracetamol poisoning, 141 with adverse reactions to acetylcysteine and 114 describing different acetylcysteine regimens. To manage the extensive literature, we focused mainly on contributions made by the authors during their time in Edinburgh and Denver.

DOSE AND CONCENTRATION RESPONSE

The key relationship between paracetamol dose and toxicity risk was established in 1971 and led to the development of the Rumack-Matthew nomogram from data collected in Edinburgh.

MECHANISMS OF TOXICITY

A series of papers on the mechanisms of toxicity were published in 1973, and these showed that paracetamol hepatotoxicity was caused by the formation of a toxic intermediate epoxide metabolite normally detoxified by glutathione but which, in excess, was bound covalently to hepatic enzymes and proteins. An understanding of the relationship between the rate of paracetamol metabolism, paracetamol concentration, and toxic hazard in humans soon followed.

ANTIDOTE DEVELOPMENT AND EFFICACY IN PATIENTS

These discoveries were followed by the testing of a range of sulfhydryl-donors in animals and "at risk" patients. Acetylcysteine was developed as the lead intravenous antidote in the United Kingdom. The license holder in the United States refused to make an intravenous formulation. Thus, oral acetylcysteine became the antidote trialed in the United States National Multicenter Study. Intravenous acetylcysteine regimens used initially in the United Kingdom and subsequently in the United States used loading doses of 150 mg/kg over 15 minutes or one hour, 50 mg/kg over four hours, and 100 mg/kg over 16 hours. These regimens were associated with adverse drug reactions (nausea, vomiting and anaphylactoid reactions) and hence, treatment interruption. Newer dosing regimens now give loading doses more slowly. One, the Scottish and Newcastle Anti-emetic Pretreatment protocol, using an acetylcysteine regimen of 100 mg/kg over two hours followed by 200 mg/kg over 10 hours, has been widely adopted in the United Kingdom. A cohort comparison study suggests this regimen has comparable efficacy to standard regimens and offers opportunities for selective higher acetylcysteine dosing.

RISK ASSESSMENT AT PRESENTATION

No dose-ranging studies with acetylcysteine were done, and no placebo-controlled studies were performed. Thus, there is uncertainty regarding the optimal dose of acetylcysteine, particularly in patients ingesting very large overdoses of paracetamol. The choice of intervention concentration on the Rumack-Matthew nomogram has important consequences for the proportion of patients treated. The United States National Multicenter Study used a "treatment" line starting at 150 mg/L (992 µmol/L) at 4 hours post overdose, extending to 24 hours with a half-life of 4 hours, now standard there, and subsequently adopted in Australia and New Zealand. In the United Kingdom, the treatment line was initially 200 mg/L (1,323 µmol/L) at 4 hours (the Rumack-Matthew "risk" line). In 2012, the United Kingdom Medicines and Healthcare products Regulatory Agency lowered the treatment line to 100 mg/L (662 µmol/L) at 4 hours for all patients, increasing the number of patients admitted and treated at a high cost. Risk assessment is a key issue for ongoing study, particularly following the development of potential new antidotes that may act in those at greatest risk. The development of biomarkers to assess risk is ongoing but has yet to reach clinical trials.

CONCLUSION

Even after 50 years, there are still areas of uncertainty. These include appropriate acetylcysteine doses in patients who ingest different paracetamol doses or multiple (staggered) ingestions, early identification of at-risk patients, and optimal treatment of late presenters.

Cinnamon Oil Alleviates Acetaminophen-Induced Uterine Toxicity in Rats by Abrogation of Oxidative Stress, Apoptosis, and Inflammation

Paracetamol, or acetaminophen (APAP), is one of the first-line medications that is used for fever and pain. However, APAP can induce uterine toxicity when overused. The mode of action of APAP toxicity is due to the production of free radicals. The main goal of our study is to determine uterine toxicity from APAP overdose and the antioxidative activity of cinnamon oil (CO) in female rats. The effect of different doses of CO (50-200 mg/kg b.w.) was assessed in the uterus toxicity induced by APAP. Additionally, the imbalance in oxidative parameters, interleukins, and caspases was evaluated for the protective effects of CO. A single dose of APAP (2 g/kg b.w.) resulted in uterus toxicity, indicated by a significant increase in the level of lipid peroxidation (LPO), inflammatory interleukins cytokines (IL-1 and 6), expression of caspases 3 and 9, and a marked change in uterus tissue architecture evaluated by histopathology. Co-treatment of CO resulted in a significant amelioration of all the parameters such as LPO, interleukins IL-1β, IL-6, caspases 3 and 9 expression, and distortion of tissue architecture in a dose-dependent manner. Therefore, we can conclude that APAP-induced uterine injury due to oxidative stress can be restored by co-treatment with cinnamon oil (CO).

N-Acetylcysteine for Preventing Acetaminophen-Induced Liver Injury: A Comprehensive Review

Aims: N-Acetylcysteine (NAC) is used as an antidote in acetaminophen (APAP) overdose to prevent and mitigate drug-induced liver injury (DILI). Our objective was to systematically review evidence of the use of NAC as a therapeutic option for APAP overdose and APAP-related DILI in order to define the optimal treatment schedule and timing to start treatment. Methods: Bibliographic databases (PubMed, Web of Science, Embase, and MEDLINE) were searched for retrospective and prospective cohort studies, case series, and clinical trials. The prespecified primary outcomes were DILI-related mortality, hepatotoxicity, and adverse events (AEs). Results: In total, 34 studies of NAC usage in APAP-related DILI cases with 19,580 patients were identified, of which 2,376 patients developed hepatotoxicities. The mortality rate across different studies ranged from 0 to 52%. Large variability of NAC regimens was found, i.e., intravenous (I.V.) (100-150 mg/kg) and oral (70-140 mg/kg), and length of treatment varied-12, 24, or 48 h for I.V. regimen and 72 h for oral administration. The timing of initiation of NAC treatment showed different results in terms of occurrence of hepatotoxicity and mortality; if started within 8 h and no more than 24 h from APAP overdose, either intravenously or orally, NAC administration was efficacious in terms of mortality. The most frequent AEs reported were anaphylactic reactions, followed by cutaneous AEs for the IV route and intestinal AEs for the oral one. Conclusion: NAC improves hepatotoxicity and reduces mortality. Timing of treatment, ranging from 8 to 24 h from APAP overdose, regardless of the regimen or route of administration, is important to prevent or minimize liver damage, particularly in children and in elderly and obese patients.

Prenatal Exposure to Acetaminophen and Childhood Asthmatic Symptoms in a Population-Based Cohort in Los Angeles, California

Acetaminophen is the most common over-the-counter pain and fever medication used by pregnant women. While European studies suggest acetaminophen exposure in pregnancy could affect childhood asthma development, findings are less consistent in other populations. We evaluated whether maternal prenatal acetaminophen use is associated with childhood asthmatic symptoms (asthma diagnosis, wheeze, dry cough) in a Los Angeles cohort of 1201 singleton births. We estimated risk ratio (RR) and 95% confidence interval (CI) for childhood asthmatic outcomes according to prenatal acetaminophen exposure. Effect modification by maternal race/ethnicity and psychosocial stress during pregnancy was evaluated. The risks for asthma diagnosis (RR = 1.39, 95% CI 0.96, 2.00), wheezing (RR = 1.25, 95% CI 1.01, 1.54) and dry cough (RR =1.35, 95% CI 1.06, 1.73) were higher in children born to mothers who ever used acetaminophen during pregnancy compared with non-users. Black/African American and Asian/Pacific Islander children showed a greater than two-fold risk for asthma diagnosis and wheezing associated with the exposure. High maternal psychosocial stress also modified the exposure-outcome relationships. Acetaminophen exposure during pregnancy was associated with childhood asthmatic symptoms among vulnerable subgroups in this cohort. A larger study that assessed prenatal acetaminophen exposure with other social/environmental stressors and clinically confirmed outcomes is needed.

Fetal Neuroprotective Strategies: Therapeutic Agents and Their Underlying Synaptic Pathways

Synaptic signaling is integral for proper brain function. During fetal development, exposure to inflammation or mild hypoxic-ischemic insult may lead to synaptic changes and neurological damage that impairs future brain function. Preterm neonates are most susceptible to these deleterious outcomes. Evaluating clinically used and novel fetal neuroprotective measures is essential for expanding treatment options to mitigate the short and long-term consequences of fetal brain injury. Magnesium sulfate is a clinical fetal neuroprotective agent utilized in cases of imminent preterm birth. By blocking N-methyl-D-aspartate receptors, magnesium sulfate reduces glutamatergic signaling, which alters calcium influx, leading to a decrease in excitotoxicity. Emerging evidence suggests that melatonin and N-acetyl-L-cysteine (NAC) may also serve as novel putative fetal neuroprotective candidates. Melatonin has important anti-inflammatory and antioxidant properties and is a known mediator of synaptic plasticity and neuronal generation. While NAC acts as an antioxidant and a precursor to glutathione, it also modulates the glutamate system. Glutamate excitotoxicity and dysregulation can induce perinatal preterm brain injury through damage to maturing oligodendrocytes and neurons. The improved drug efficacy and delivery of the dendrimer-bound NAC conjugate provides an opportunity for enhanced pharmacological intervention. Here, we review recent literature on the synaptic pathways underlying these therapeutic strategies, discuss the current gaps in knowledge, and propose future directions for the field of fetal neuroprotective agents.

Behavioral Problems at Age 11 Years After Prenatal and Postnatal Exposure to Acetaminophen: Parent-Reported and Self-Reported Outcomes

Several studies have reported associations between prenatal acetaminophen exposure and behavioral outcomes in young children. We aimed to evaluate the associations of prenatal and postnatal exposures to acetaminophen with behavioral problems in children at age 11 years, using behavioral measures reported by parents and children. We studied 40,934 mother-child pairs from the Danish National Birth Cohort enrolled during 1996-2002. Parent-reported and child-reported Strengths and Difficulties Questionnaire (SDQ) responses were collected during the 11-year follow-up. We estimated risk ratios for behavioral problems including total difficulties as well as internalizing or externalizing behaviors following prenatal (during pregnancy) or postnatal (within the first 18 months after birth) acetaminophen exposure. Parent-reported and child-reported SDQ scores were moderately correlated; higher for externalizing (r = 0.59) than internalizing (r = 0.49) behaviors. Prenatal acetaminophen exposure was associated with 10%-40% higher risks for total difficulties and internalizing and externalizing problems based on parent- or child-reported SDQ, with the association being stronger for greater cumulative weeks of acetaminophen use. Postnatal exposure was associated with 16%-19% higher risks for parent-reported internalizing behaviors, but the associations were weak or null for child-reported scores except for prosocial behavior. Our study corroborates published associations between prenatal exposures to acetaminophen and behavioral problems and extends the literature to early adolescence.

In Silico Exploration of the Potential Role of Acetaminophen and Pesticides in the Etiology of Autism Spectrum Disorder

Recent epidemiological studies suggest that prenatal exposure to acetaminophen (APAP) is associated with increased risk of Autism Spectrum Disorder (ASD), a neurodevelopmental disorder affecting 1 in 59 children in the US. Maternal and prenatal exposure to pesticides from food and environmental sources have also been implicated to affect fetal neurodevelopment. However, the underlying mechanisms for ASD are so far unknown, likely with complex and multifactorial etiology. The aim of this study was to explore the potential effects of APAP and pesticide exposure on development with regards to the etiology of ASD by highlighting common genes and biological pathways. Genes associated with APAP, pesticides, and ASD through human research were retrieved from molecular and biomedical literature databases. The interaction network of overlapping genetic associations was subjected to network topology analysis and functional annotation of the resulting clusters. These genes were over-represented in pathways and biological processes (FDR p < 0.05) related to apoptosis, metabolism of reactive oxygen species (ROS), and carbohydrate metabolism. Since these three biological processes are frequently implicated in ASD, our findings support the hypothesis that cell death processes and specific metabolic pathways, both of which appear to be targeted by APAP and pesticide exposure, may be involved in the etiology of ASD. This novel exposures-gene-disease database mining might inspire future work on understanding the biological underpinnings of various ASD risk factors.

N-Acetylcysteine treatment of neonatal acetaminophen toxicity caused by transplacental transfer - a case report

We describe a case of maternal acetaminophen toxicity leading to Caesarean section delivery of a pre-term neonate with acetaminophen-induced hepatic injury and encephalopathy at 33 weeks gestational age. Delayed treatment with N-acetylcysteine (NAC) was initiated in the baby 11 h after delivery, with eventual discharge of a healthy baby at 12 days of age. The baby was treated with a standard but extended duration NAC protocol. Post-operatively, liver biopsy of the mother demonstrated acetaminophen-induced hepatic injury overlying mild hepatic steatosis. This was also managed with NAC therapy leading to complete clinical resolution of acetaminophen induced hepatic injury and discharge on post-operative day 10. This case of delayed NAC therapy for the treatment of pre-term neonatal acetaminophen toxicity is one of very few reported in the literature and can be used as a guide in the management of subsequent cases.

The Role of Redox Dysregulation in the Effects of Prenatal Stress on Embryonic Interneuron Migration

Maternal stress during pregnancy is associated with increased risk of psychiatric disorders in offspring, but embryonic brain mechanisms disrupted by prenatal stress are not fully understood. Our lab has shown that prenatal stress delays inhibitory neural progenitor migration. Here, we investigated redox dysregulation as a mechanism for embryonic cortical interneuron migration delay, utilizing direct manipulation of pro- and antioxidants and a mouse model of maternal repetitive restraint stress starting on embryonic day 12. Time-lapse, live-imaging of migrating GAD67GFP+ interneurons showed that normal tangential migration of inhibitory progenitor cells was disrupted by the pro-oxidant, hydrogen peroxide. Interneuron migration was also delayed by in utero intracerebroventricular rotenone. Prenatal stress altered glutathione levels and induced changes in activity of antioxidant enzymes and expression of redox-related genes in the embryonic forebrain. Assessment of dihydroethidium (DHE) fluorescence after prenatal stress in ganglionic eminence (GE), the source of migrating interneurons, showed increased levels of DHE oxidation. Maternal antioxidants (N-acetylcysteine and astaxanthin) normalized DHE oxidation levels in GE and ameliorated the migration delay caused by prenatal stress. Through convergent redox manipula-tions, delayed interneuron migration after prenatal stress was found to critically involve redox dysregulation. Redox biology during prenatal periods may be a target for protecting brain development.

N-Acetylcysteine Resolves Placental Inflammatory-Vasculopathic Changes in Mice Consuming a High-Fat Diet

The mechanism by which poor maternal nutrition can affect the long-term health of offspring is poorly understood. In mice, we previously found that maternal high-fat diet (HFD) exposure results in reduced fetal growth regardless of maternal genotype. We tested our hypothesis that maternal HFD-induced inflammation contributes to metabolic disease susceptibility of the offspring via alterations in the placenta. The effect of maternal genotype, diet, and treatment with the anti-inflammatory compound N-acetylcysteine (NAC) on placental morphologic features was investigated. Placentas from wild-type dams maintained on a HFD but not those heterozygous (+/-) for Glut4 (Slc2a4) on the same diet had an increase in decidual inflammation and vasculopathy occurring together. NAC administration resulted in amelioration of HFD-induced decidual vasculopathy independent of offspring genotype and sex. Consistent with these morphologic improvements, placentas from HFD dams treated with NAC had decreased mRNA and immunostaining of IL-1β and monocyte chemoattractant protein-1, decreased mRNA of inflammatory genes, and increased mRNA of Vegfa. These results strongly suggest consumption of an HFD results in vascular changes in placenta reflected by alterations in expression of pivotal vascular developmental markers and inflammatory genes all of which are ameliorated by NAC. These placental changes play a key role in the increased programed metabolic disease of HFD-exposed offspring.

Prenatal Exposure to Acetaminophen and Overweight in Childhood

OBJECTIVE

Acetaminophen (paracetamol), a medication commonly used in pregnancy, has hormonal effects, as has been suggested in experimental studies. Developmental exposure to endocrine disruptors could predispose individuals to weight gain. This study evaluated the associations between prenatal acetaminophen exposure and overweight in childhood.

METHODS

A total of 30,127 (age 7) and 24,934 (age 11) children in the Danish National Birth Cohort born during 1996 to 2002 were studied. Mothers reported acetaminophen use in telephone interviews conducted during pregnancy, and children's BMI and waist circumference were reported by parents at 7 and 11 years. Differences for BMI z score and waist circumference were estimated, as well as risk ratios for overweight in girls and boys adjusting for indications of use and other confounders.

RESULTS

There were no consistent associations found for prenatal acetaminophen exposure and BMI z score or waist circumference in girls and boys at both ages. Prenatal acetaminophen exposure was associated with overweight in girls at age 11 (risk ratio 1.31, 95% CI: 1.10-1.56, if exposed in all three trimesters; P < 0.001 for cumulative weeks of exposure), but no association was found in boys.

CONCLUSIONS

There was no strong association between prenatal acetaminophen exposure and childhood BMI, but the findings on frequent prenatal exposure to acetaminophen and overweight in girls warrant further investigation.

[Combined therapy in neonatal hypoxic-ischaemic encephalopathy]

Neonatal hypoxic-ischaemic encephalopathy due to the lack of oxygen at birth can have severe neurological consequences, such as cerebral palsy, or even the death of the asphyxiated newborn. Hypothermia is currently the only therapy included in intensive care neonatal units. This shows a clinical benefit in neonates suffering from hypoxic-ischaemic encephalopathy, mainly because of its ability to decrease the accumulation of excitatory amino acids and its anti-inflammatory, antioxidant, and anti-apoptotic effects. However, hypothermia is not effective in half of the cases, making it necessary to search for new, or to optimize current therapies, with the aim on reducing asphyxia-derived neurological consequences, either as single treatments or in combination with cooling. Within current potential therapies, melatonin, allopurinol, and erythropoietin stand out among the others, with clinical trials on the way. While, stem cells, N-acetylcysteine and noble gases have obtained promising pre-clinical results. Melatonin produces a powerful antioxidant and anti-inflammatory effect, acting as free radical scavenger and regulating pro-inflammatory mediators. Through the inhibition of xanthine oxidase, allopurinol can decrease oxidative stress. Erythropoietin has cell death and neurogenesis as its main therapeutic targets. Keeping in mind the whole scenario of current therapies, management of neonates suffering from neonatal asphyxia could rely on the combination of one or some of these treatments, together with therapeutic hypothermia.

Acute Poisoning During Pregnancy: Observations from the Toxicology Investigators Consortium

Acute poisonings during pregnancy pose a particular challenge to health care providers because of the potential for an immediate life threat or possible life-long implications for both the mother and fetus, including teratogenicity of the poison or its antidote. We describe recent consequential exposures among pregnant women in the USA. We identified all poisoning cases involving pregnant women that were catalogued by the medical toxicology services across the 37 sites of the Toxicology Investigators Consortium (ToxIC) Registry of the American College of Medical Toxicology between January 2010 and December 2012. Of 17,529 exposure cases reported in the ToxIC Registry, 103 (0.6 %) involved pregnant women, 80 % of whom were symptomatic and about a quarter displayed a specific toxidrome. The majority of cases (n = 53; 51.5 %) involved intentional exposures, most commonly to pharmaceutical agents, followed by unintentional pharmaceutical exposures (10 %) and withdrawal syndromes (9 %). Non-opioid analgesics were the most common class of agents encountered (31 %), followed by sedative-hypnotics/muscle relaxants (18 %), opioids (17 %), anti-convulsants (10 %), and anti-depressants (10 %). Over a third of cases involved exposure to multiple substances, and 32 % involved exposure to more than one drug class. The most commonly administered antidotes were N-acetylcysteine (23 %), sodium bicarbonate (10 %), flumazenil (4 %), and physostigmine (4 %). About half of acute poisoning cases among pregnant women presenting for emergency care involved intentional exposures, mostly with over-the-counter analgesics and psychoactive medications. Clinicians should be cognizant of the unique circumstances, maternal and fetal risks, and management principles of the acutely poisoned pregnant woman.

Antenatal pharmacokinetics and placental transfer of N-acetylcysteine in chorioamnionitis for fetal neuroprotection

OBJECTIVE

To determine the pharmacokinetics (PK) and placental transfer of intravenous (i.v.) N-acetylcysteine (NAC) in mothers with a clinical diagnosis of chorioamnionitis (CA) and determine the PK of i.v. NAC in their infants.

STUDY DESIGN

In this prospective, double-blind study i.v. NAC 100 mg/kg/dose or saline was administered within 4 hours of CA diagnosis to pregnant women ≥24 weeks' gestation and then every 6 hours until delivery. Maternal PK and placental transfer were determined with maternal blood and matched maternal and cord venous blood. Neonatal PK estimates were determined from i.v. NAC (12.5-25 mg/kg/dose) administered every 12 hours for 5 doses. Noncompartmental analyses were performed for maternal and neonatal PK estimates.

RESULTS

Eleven mothers (5 preterm, 6 near-term) and 12 infants (1 set of twins) received NAC. Maternal clearance (CL) of NAC was faster than in nonpregnant adults, with a terminal elimination half-life of 1.2 ± 0.2 hours. The NAC cord to maternal ratio was 1.4 ± 0.8, suggesting rapid placental transfer and slower rate of fetal CL. Neonatal PK estimates for near-term compared with preterm infants showed a significantly shorter terminal elimination half-life (5.1 vs 7.5 hours, respectively) and greater CL (53.7 vs 45.0 mL/h/kg, respectively).

CONCLUSIONS

Maternal CL and placental transfer of NAC was rapid, with umbilical cord concentrations frequently exceeding maternal concentrations. The administration of NAC to mothers with CA achieves predictable NAC plasma concentrations in the fetus, indicating that antenatal neuroprotection may be possible for these newborns at high risk for neuroinflammation.

N-Acetylcysteine prevents congenital heart defects induced by pregestational diabetes

BACKGROUND

Pregestational diabetes is a major risk factor of congenital heart defects (CHDs). Glutathione is depleted and reactive oxygen species (ROS) production is elevated in diabetes. In the present study, we aimed to examine whether treatment with N-acetylcysteine (NAC), which increases glutathione synthesis and inhibits ROS production, prevents CHDs induced by pregestational diabetes.

METHODS

Female mice were treated with streptozotocin (STZ) to induce pregestational diabetes prior to breeding with normal males to produce offspring. Some diabetic mice were treated with N-acetylcysteine (NAC) in drinking water from E0.5 to the end of gestation or harvesting of the embryos. CHDs were identified by histology. ROS levels, cell proliferation and gene expression in the fetal heart were analyzed.

RESULTS

Our data show that pregestational diabetes resulted in CHDs in 58% of the offspring, including ventricular septal defect (VSD), atrial septal defect (ASD), atrioventricular septal defects (AVSD), transposition of great arteries (TGA), double outlet right ventricle (DORV) and tetralogy of Fallot (TOF). Treatment with NAC in drinking water in pregestational diabetic mice completely eliminated the incidence of AVSD, TGA, TOF and significantly diminished the incidence of ASD and VSD. Furthermore, pregestational diabetes increased ROS, impaired cell proliferation, and altered Gata4, Gata5 and Vegf-a expression in the fetal heart of diabetic offspring, which were all prevented by NAC treatment.

CONCLUSIONS

Treatment with NAC increases GSH levels, decreases ROS levels in the fetal heart and prevents the development of CHDs in the offspring of pregestational diabetes. Our study suggests that NAC may have therapeutic potential in the prevention of CHDs induced by pregestational diabetes.

Acetaminophen and pregnancy: short- and long-term consequences for mother and child

Counter-intuitively, over-the-counter medication is commonly taken by pregnant women. In this context, acetaminophen (APAP, e.g. Paracetamol, Tylenol) is generally recommended by physicians to treat fever and pain during pregnancy. Thus, APAP ranks at the top of the list of medications taken prenatally. Insights on an increased risk for pregnancy complications such as miscarriage, stillbirth, preterm birth or fetal malformations upon APAP exposure are rather ambiguous. However, emerging evidence arising from human trials clearly reveals a significant correlation between APAP use during pregnancy and an increased risk for the development of asthma in children later in life. Pathways through which APAP increases this risk are still elusive. APAP can be liver toxic and since APAP appears to freely cross the placenta, therapeutic and certainly toxic doses could not only affect maternal, but also fetal hepatocytes. It is noteworthy that during fetal development, the liver transiently functions as the main hematopoietic organ. We here review the effect of APAP on metabolic and immunological parameters in pregnant women and on fetal development and immune ontogeny in order to delineate novel, putative and to date underrated pathways through which APAP use during pregnancy can impair maternal, fetal and long term children's health. We conclude that future studies are urgently needed to reconsider the safety and dosage of APAP during pregnancy and - based on the advances made in the field of reproduction as well as APAP metabolism - we propose pathways, which should be addressed in future research and clinical endeavors.

Neuroprotective treatment for perinatal asphyxia

BACKGROUND

Perinatal asphyxia can cause serious illness or death. By taking steps in the «latent phase», which occurs 6-24 hours after the hypoxic event, the neurological damage caused by perinatal asphyxia can be limited. We wish to present a selection of such measures that are either established treatment today or that appear promising.

METHOD

We searched in the Medline and Cochrane Library databases for options for treating perinatal asphyxia.

RESULTS

An overwhelming number of potential treatments were identified. From among them we selected 44 indexed, peer-reviewed original articles in English on strategies for neuroprotective treatment after perinatal asphyxia. The treatments target different cellular mechanisms that cause neurological damage following perinatal asphyxia. In randomised clinical trials, only hypothermia treatment has improved the long-term outcome for newborns with perinatal asphyxia. Xenon gas, erythropoeitin and allopurinol are undergoing clinical testing.

INTERPRETATION

The efficacy of xenon gas, erythropoeitin and allopurinol in combination with the established treatment form of hypothermia must be studied more closely. Antioxidants, stem cell treatment and DNA repair mechanisms can pave the way for new opportunities in the future.

Unintentional chronic acetaminophen poisoning during pregnancy resulting in liver transplantation

INTRODUCTION

Acetaminophen (APAP) is a widely used medication in pregnancy and is considered safe. Unfortunately, APAP is also among the most commonly reported agents implicated in overdoses during pregnancy. We present a unique case of a pregnant patient with fulminant hepatic failure resulting in a liver transplant from repeated supratherapeutic ingestions of APAP.

CASE REPORT

A 22 year pregnant female presented with abdominal pain and hepatotoxicity after taking supratherapeutic amounts of APAP to treat dental pain. The patient denied intentional or acute ingestion of APAP but did admit to taking approximately 8-9 grams of APAP per day for 10-14 days for dental pain. Other cause of hepatotoxicity, including acute fatty liver of pregnancy, were evaluated for and ruled out. She developed fulminant hepatic failure and required liver transplantation which was successful. The pregnancy remained viable through the operation but intrauterine fetal demise occurred 2 weeks later. An MRI of the fetus showed extensive peri-cerebral and intraventricular hemorrhage with extensive periventricular leukomalacia.

DISCUSSION

The degree of morbidity from repeated supratherapeutic ingestions of APAP seen in this case is rare and poorly described in a pregnant patient. There are no prior reports describing the need for liver transplant after repeated supratherapeutic ingestions of APAP during pregnancy. Along with the typical cause of hepatotoxicy several unique pregnancy-related causes also had to be evaluated for. This case highlights the significant morbidity that can occur with even unintentional APAP toxicity and the need to educate patients, especially pregnant patients, of the risk of excessive APAP use.

Antidotes for toxicological emergencies: a practical review

PURPOSE

Appropriate therapies for commonly encountered poisonings, medication overdoses, and other toxicological emergencies are reviewed, with discussion of pharmacists' role in ensuring their ready availability and proper use.

SUMMARY

Poisoning is the second leading cause of injury-related morbidity and mortality in the United States, with more than 2.4 million toxic exposures reported each year. Recently published national consensus guidelines recommend that hospitals providing emergency care routinely stock 24 antidotes for a wide range of toxicities, including toxic-alcohol poisoning, exposure to cyanide and other industrial agents, and intentional or unintentional overdoses of prescription medications (e.g., calcium-channel blockers, β-blockers, digoxin, isoniazid). Pharmacists can help reduce morbidity and mortality due to poisonings and overdoses by (1) recognizing the signs and symptoms of various types of toxic exposure, (2) guiding emergency room staff on the appropriate use of antidotes and supportive therapies, (3) helping to ensure appropriate monitoring of patients for antidote response and adverse effects, and (4) managing the procurement and stocking of antidotes to ensure their timely availability.

CONCLUSION

Pharmacists can play a key role in reducing poisoning and overdose injuries and deaths by assisting in the early recognition of toxic exposures and guiding emergency personnel on the proper storage, selection, and use of antidotal therapies.

Protective effect of N-acetylcysteine on liver damage during chronic intrauterine hypoxia in fetal guinea pig

Chronic exposure to hypoxia during pregnancy generates a stressed intrauterine environment that may lead to fetal organ damage. The objectives of the study are (1) to quantify the effect of chronic hypoxia in the generation of oxidative stress in fetal guinea pig liver and (2) to test the protective effect of antioxidant treatment in hypoxic fetal liver injury. Pregnant guinea pigs were exposed to either normoxia (NMX) or 10.5% O(2) (HPX, 14 days) prior to term (65 days) and orally administered N-acetylcysteine ([NAC] 10 days). Near-term anesthetized fetuses were excised and livers examined by histology and assayed for malondialdehyde (MDA) and DNA fragmentation. Chronic HPX increased erythroid precursors, MDA (NMX vs HPX; 1.26 ± 0.07 vs 1.78 ± 0.07 nmol/mg protein; P < .001, mean ± standard error of the mean [SEM]) and DNA fragmentation levels in fetal livers (0.069 ± 0.01 vs 0.11 ± 0.005 OD/mg protein; P < .01). N-acetylcysteine inhibited erythroid aggregation and reduced (P < .05) both MDA and DNA fragmentation of fetal HPX livers. Thus, chronic intrauterine hypoxia generates cell and nuclear damage in the fetal guinea pig liver. Maternal NAC inhibited the adverse effects of fetal liver damage suggestive of oxidative stress. The suppressive effect of maternal NAC may implicate the protective role of antioxidants in the prevention of liver injury in the hypoxic fetus.

[Poisonings in pregnancy]

Attempted suicides and poisonings in pregnancy are a challenge for health care professionals because of the unknown effects of the toxic agent and the antidote therapy on the unborn. In case of intoxication, the malformation risk is often overestimated. In contrast, pertinent data show that the risk is not very high as long as the drug is not known as a teratogen and the mother's health is not substantially impaired. This applies to suicide attempts with acetaminophen, iron-containing products, and multidrug overdoses with psychopharmaceuticals as well as snake and spider bites and the ingestion of poisonous mushrooms. It is of utmost importance that the pregnant patient receives the same detoxification and supportive therapy following pertinent guidelines as a non-pregnant patient. The fetus should be followed-up by ultrasound with special focus on its vital parameters, movement pattern, and normal growth and organ differentiation. As long as the maternal health status is not substantially impaired, there is no indication to discuss elective termination of pregnancy "for toxicological reasons".

Toxicology in the ICU: Part 2: specific toxins

This is the second of a three-part series that reviews the generalized care of poisoned patients in the ICU. This article focuses on specific agents grouped into categories, including analgesics, anticoagulants, cardiovascular drugs, dissociative agents, carbon monoxide, cyanide, methemoglobinemia, cholinergic agents, psychoactive medications, sedative-hypnotics, amphetamine-like drugs, toxic alcohols, and withdrawal states. The first article discussed the general approach to the toxicology patient, including laboratory testing; the third article will cover natural toxins.

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

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

Acetylcysteine for acetaminophen poisoning

A 25-year-old man presents to the emergency department with a toothache. During the evaluation, the physician determines that the patient has been taking large doses of over-the-counter acetaminophen along with an acetaminophen–hydrocodone product for the past 5 days. His daily dose of acetaminophen has been 12 g per day (maximum recommended dose, 4 g per day). He has no other medical problems and typically consumes two beers a day. The patient has no symptoms beyond his toothache, is not icteric, and has no hepatomegaly or right-upper-quadrant tenderness. His serum acetaminophen concentration 8 hours after the most recent dose is undetectable. His serum alanine aminotransferase concentration is 75 IU per liter, his serum bilirubin concentration is 1.2 mg per deciliter (20.5 μmol per liter), and his international normalized ratio (INR) is 1.1. The emergency department physician contacts the regional poison-control center, which recommends treatment with acetylcysteine.

N-acetylcysteine reduces lipopolysaccharide-sensitized hypoxic-ischemic brain injury

OBJECTIVE

Maternal inflammation/infection alone or in combination with birth asphyxia increases the risk for perinatal brain injury. Free radicals are implicated as major mediators of inflammation and hypoxia-ischemia (HI)-induced perinatal brain injury. This study evaluated the neuroprotective efficacy of a scavenging agent, N-acetylcysteine (NAC), in a clinically relevant model.

METHODS

Lipopolysaccharide (LPS)-sensitized HI brain injury was induced in 8-day-old neonatal rats. NAC was administered in multiple doses, and brain injury was evaluated at 7 days after HI.

RESULTS

NAC (200mg/kg) provided marked neuroprotection with up to 78% reduction of brain injury in the pre+post-HI treatment group and 41% in the early (0 hour) post-HI treatment group, which was much more pronounced protection than another free radical scavenger, melatonin. Protection by NAC was associated with the following factors: (1) reduced isoprostane activation and nitrotyrosine formation; (2) increased levels of the antioxidants glutathione, thioredoxin-2, and (3) inhibition of caspase-3, calpain, and caspase-1 activation.

INTERPRETATION

NAC provides substantial neuroprotection against brain injury in a model that combines infection/inflammation and HI. Protection by NAC was associated with improvement of the redox state and inhibition of apoptosis, suggesting that these events play critical roles in the development of lipopolysaccharide-sensitized HI brain injury.

Lower rate of preeclampsia after antioxidant supplementation in pregnant women with low antioxidant status

OBJECTIVE

To investigate maternal and neonatal outcomes after antioxidant supplementation relatively early in pregnancy (8 to 12 weeks) for pregnant women with low antioxidant status.

METHODS

A randomized, double-blind, placebo-controlled trial of daily antioxidant supplementation was performed on pregnant women screening positive for low antioxidant status at 8 to 12 weeks of gestation. Low antioxidant status was defined as a superoxidedismutase (SOD) level below 1102 U/g Hb or 164 U/mL. The supplementation group received the following antioxidants daily: vitamins A (1000 IU), B6 (2.2 mg), B12 (2.2 microg), C (200 mg), and E (400 IU), folic acid (400 microg), N-acetylcysteine (200 mg), Cu (2 mg), Zn (15 mg), Mn (0.5 mg), Fe (30 mg), calcium (800 mg), and selenium (100 microg). The control group received Fe (30 mg) and folic acid (400 microg). Maternal (preeclampsia, abortion, and hypertension) and perinatal outcomes were assessed.

RESULTS

In the supplementation group (29 subjects), we observed 2 cases of preeclampsia (6.8%, 1 mild and 1 severe), 1 of IUGR (birth weight 2300 g at 38 weeks), and 1 preterm delivery. In the control group (31 subjects), there were 8 abortions, 9 cases of preeclampsia (29%, 6 mild and 3 severe) with perinatal outcome: 3 preterm delivery cases and 1 IUGR (birth weight 2030 g at 39 weeks). Preeclampsia was significantly less frequent in the supplementation group when compared to the control group (2 vs. 9 cases, p = 0.043, OR = 0.18 [95% CI: 0.03, 0.92]). Finally we focused on the prediction of preeclampsia at 8 to 12 weeks. Combined sensitivity of markers of antioxidant status (SOD slutathione peroxidase, [GPx], and total anti-oxidant status [TAS]) was 33% (false-positive rate of 4.5%).

CONCLUSION

Antioxidant supplementation was associated with better maternal and perinatal outcome in pregnant women with low antioxidant status than control supplementation with iron and folate alone. In a selected population already screened positive for low SOD, preeclampsia can be detected in 33% of asymptomatic cases in the first trimester using SOD, GPx, and TAS. It seems feasible that panels of both biochemical and molecular markers may be clinically useful in the prediction of this disease.

Comparison of oral and i.v. acetylcysteine in the treatment of acetaminophen poisoning

PURPOSE

The efficacy, safety, and cost issues that should be considered when deciding on the appropriate route of acetylcysteine for the treatment of patients with acetaminophen poisoning are reviewed.

SUMMARY

Oral and i.v. acetylcysteine appear to be equally effective when given within 8-10 hours of acetaminophen overdose. Anaphylactoid reactions to i.v. acetylcysteine have generally been reported in 3-6% of acetaminophen-poisoned patients. Dosing errors and hyponatremia have occurred in pediatric patients receiving i.v. acetylcysteine. Several investigators found an increased rate of anaphylactoid reactions in patients treated with i.v. acetylcysteine whose pretreatment serum acetaminophen levels were nontoxic. Compounding i.v. acetylcysteine from the oral preparation is less expensive than using premade i.v. solution. State pharmacy laws dictate whether extemporaneous compounding of acetylcysteine from the oral formulation is allowed. Oral acetylcysteine administration has resulted in minimal anaphylactoid reactions and is safer than i.v. acetylcysteine. Oral therapy should preferentially be considered in patients with asthma or atopic histories. The most important factors to consider when selecting the route of acetylcysteine administration include individual susceptibility, the severity of acetaminophen toxicity, and the time interval between acetaminophen ingestion and initiation of acetylcysteine therapy.

CONCLUSION

Oral acetylcysteine administered within 8-10 hours of acetaminophen overdose prevents liver toxicity in the majority of patients who tolerate it and have no contraindications to therapy. I.V. acetylcysteine should be administered when patients are treated more than 10 hours postingestion of acetaminophen overdose or have underlying conditions preventing oral treatment. Anaphylactoid reactions are rare and occur more frequently in patients treated with the i.v. preparation.

Acetaminophen overdose in pregnancy

Acetaminophen (APAP) is the most common drug overdose in pregnancy. Available data regarding APAP overdose in pregnancy is limited to case reports and a small prospective case series. APAP has been demonstrated to cross the placenta and in toxic doses may harm the fetal and maternal hepatocytes. Fetal hepatocytes metabolize APAP into both active and toxic metabolites. These toxic metabolites may cause fetal hepatic necrosis. N-acetylcysteine (NAC) has also been demonstrated to cross the placenta and may bind toxic metabolites in both the mother and the fetus. Limited data suggest that the majority of morbidity and mortality from APAP overdose can be averted by initiation of NAC within the first 16 hours of ingestion and possibly even later. NAC may be safely administered during pregnancy and should be initiated early after APAP overdosage. The literature was reviewed through the use of OvidMEDLINE database, encompassing 1966 to the present. Searches were conducted using the key words acetaminophen, paracetamol, N-acetylcysteine, overdose, and hepatotoxicity. The search was further refined by selecting articles that contained these search words together with the key word pregnancy. Only English language papers were reviewed. Articles were selected on the basis of relevance to the topic. Pertinent citations found in the selected articles were also reviewed.

Exposure to 5-Bromo-2′-deoxyuridine induces oxidative stress and activator protein-1 DNA binding activity in the embryo

BACKGROUND

During organogenesis the embryo is highly sensitive to oxidative stress. We hypothesize that oxidative stress and activation of a redox-sensitive transcription factor, activator protein-1 (AP-1), are early indicators of embryonic stress in response to a teratogenic insult. 5-Bromo-2'-deoxyuridine (BrdU) was chosen as a model teratogen to test this hypothesis; BrdU is a thymidine analog that is incorporated into replicating DNA.

METHODS

Timed pregnant CD1 mice were given vehicle or BrdU (400, 600, 800, or 1000 mg of BrdU/kg of body weight) on gestation day 9 (GD 9). Oxidative stress, assessed as the ratio of glutathione disulfide (GSSG) to reduced glutathione (GSH), and AP-1 DNA binding activity (c-Fos- and c-Jun-dependent DNA binding) were measured in the maternal livers and embryos 0.5, 3, and 6 hr after treatment. External and skeletal malformations were assessed on GD 18. N-acetylcysteine, a glutathione precursor, was coadministered with BrdU to further explore the relationship between teratogenicity and redox homeostasis.

RESULTS

BrdU exposure produced a dose-dependent increase in skeletal malformations, which included polydactyly, and delayed ossification of the sternebrae and vertebrae. Exposure to teratogenic doses of BrdU depleted GSH concentrations and increased oxidative stress, as assessed by the GSSG:GSH ratio, in both maternal livers and embryos. While c-Jun DNA binding activity in embryos was not affected, c-Fos DNA binding activity was elevated significantly 3 hr after BrdU exposure. Coadministration of N-acetylcysteine decreased the skeletal malformations and AP-1 DNA binding activity induced by BrdU.

CONCLUSIONS

BrdU exposure induced an embryonic stress response manifested as an increase in oxidative stress and AP-1 DNA binding activity; these data support the hypothesis that disturbances in redox homeostasis mediate the response of the conceptus to a teratogenic insult.

Oral N-acetylcysteine administration does not stabilise the process of established severe preeclampsia

OBJECTIVE

To stabilise the disease process in women with early onset severe preeclampsia and/or HELLP syndrome by enhancing maternal antioxidants effects of glutathione.

STUDY DESIGN

In a randomised, double-blind, placebo-controlled trial, women with severe preeclampsia and/or HELLP syndrome received oral N-acetylcysteine. Primary outcome measures were disease stabilisation expressed as treatment-to-delivery interval and biochemical assessment of glutathione and parameters of oxidative stress. Secondary outcome measures were maternal complications, rate of caesarean section, stay at intensive care unit, postpartum hospital stay and neonatal morbidity and mortality. Analyses were done by intention-to-treat using Wilcoxon's two-sample test and regression analysis.

RESULTS

Median treatment-to-delivery interval was not significantly different between the N-acetylcysteine and placebo group. The whole blood and plasma levels of glutathione and other thiols were not affected by N-acetylcysteine administration, except for plasma homocysteine concentrations, which were lower in the N-acetylcysteine group. There were no differences found in maternal nor neonatal secondary outcome measures between both groups.

CONCLUSION

Oral N-acetylcysteine administration does not stabilise the disease process of early onset severe preeclampsia and/or HELLP syndrome.

N-acetylcysteine restores nitric oxide-mediated effects in the fetoplacental circulation of preeclamptic patients

OBJECTIVE

Preeclampsia is associated with an imbalance between oxidants and antioxidants, resulting in reduced effects of the endothelium-derived, relaxing-factor nitric oxide (NO). Antioxidants, like N-acetylcysteine (NAC), remove reactive oxygen species, resulting in an improvement of endothelial function. We aimed to investigate the effect of NAC on the NO-pathway in the human fetoplacental circulation in preeclampsia and control pregnancies.

STUDY DESIGN

The NO-pathway was investigated by use of the NO-synthase inhibitor L-NAME in an ex vivo cotyledon perfusion model.

RESULTS

At baseline, fetoplacental arterial pressure was comparable in preeclamptic pregnancies (n=8) and control pregnancies (n=8), and increased dose-dependently after L-NAME. The maximal L-NAME-induced rise in fetoplacental arterial pressure was attenuated in preeclamptic versus control pregnancies (20.8 +/- 2.0 mm Hg vs 36.7 +/- 3.5 mm Hg, P<.05). Addition of NAC increased the L-NAME-induced rise in fetoplacental arterial pressure to 36.4 +/- 3.4 mm Hg in preeclampsia pregnancies (P<.05) and to 49.2 +/- 2.6 mm Hg in control pregnancies (P<.05).

CONCLUSION

Preeclampsia is associated with a dysfunction of the NO-pathway. N-acetylcysteine increases NO-mediated effects in the fetoplacental circulation in preeclamptic placentas as well as in healthy control placentas.

Birth-related genomic and transcriptional changes in mouse lung

Birth is characterized by a sudden transition from the maternal-mediated respiration to the autonomous pulmonary respiration. Notwithstanding the importance of the involved functional and metabolic changes, little is known about possible DNA alterations occurring in the lung during the perinatal period. We comparatively evaluated genomic and transcriptional changes in the lung of fetuses and newborn Swiss albino mice, whose dams had either been untreated or treated with oral N-acetyl-L-cysteine (NAC) throughout the pregnancy period. In the less than 24h period elapsing between the end of fetal life and the start of post-natal life, nucleotide alterations occurred in mouse lung, as shown by a significant increase of both bulky DNA adducts and 8-hydroxy-2'-deoxyguanosine levels, detected by 32P post-labeling procedures. The frequency of micronuclei in peripheral blood erythrocytes was not significantly increased after birth. Multigene expression analysis of 746 selected genes, by cDNA arrays, showed that 33 of them (4.4%) were upregulated in the lung of newborn mice, as compared with fetuses. The overexpressed genes were mainly involved in protective mechanism as a response to oxidative changes, alterations of glutathione metabolism, cellular stress, and damage to DNA and proteins. The transplacental treatment with NAC totally prevented birth-related genomic alterations in lung DNA. NAC did not change the basal gene expression in mouse fetal lung, but attenuated the upregulation of most genes involved in oxidative stress, stress response, and DNA repair in the lung of newborn mice. In fact, only 13 genes (1.7%) were overexpressed in newborns from NAC-treated dams. It therefore appears that administration of NAC during pregnancy is beneficial not only to counteract the adverse effects of toxic agents, as supported by previous studies, but also to attenuate birth-related DNA alterations.

Genomic and transcriptional alterations in mouse fetus liver after transplacental exposure to cigarette smoke

The transplacental exposure of fetuses to maternal cigarette smoke may increase the risk of developmental impairments, congenital diseases, and childhood cancer. The whole-body exposure of Swiss mice to environmental cigarette smoke (ECS) during pregnancy decreased the number of fetuses per dam, placenta weight, and fetus weight. ECS increased DNA adducts, oxidative nucleotide alterations, and cytogenetic damage in fetus liver. Evaluation by cDNA array of 746 genes showed that 61 of them were expressed in fetus liver under basal conditions. The oral administration of N-acetylcysteine (NAC) during pregnancy enhanced the expression of three genes only, including two glutathione S-transferases and alpha1-antitrypsin precursor, whose deficiency plays a pathogenetic role in congenital emphysema. Transplacental ECS upregulated the expression of 116 genes involved in metabolism, response to oxidative stress, DNA and protein repair, and signal transduction. NAC inhibited the ECS-related genetic damage and upregulation of most genes. ECS stimulated pro-apoptotic genes and genes downregulating the cell cycle, which may justify growth impairments in the developing fetus. Thus, both genetic and epigenetic mechanisms were modulated by ECS. Moreover, hypoxia-related genes and several oncogenes and receptors involved in proliferation and differentiation of leukocytes were induced in the fetal liver, which also bears hematopoietic functions.

Are there teratogenic risks associated with antidotes used in the acute management of poisoned pregnant women?

OBJECTIVE

We reviewed evidence suggesting teratogenic risk associated with the use of antidotes in the acute management of poisoned pregnant women.

METHODS

Medline, Toxline, and DART/ETIC searches; references of retrieved articles, pertinent databases and textbooks were also searched.

RESULTS

There are case reports or case series of women who received antidotes for poisoning during (*) or after (+) the period of organogenesis who showed no fetal adverse effects. Some antidotes, however, have no teratogenic risk: atropine (cohort/surveillance studies)+, calcium (oral supplement: cohort study)+ and pyridoxine (Bendectin studies). Also, ethanol+, methylene blue (intra-amniotic injection but not oral) and penicillamine* can be considered teratogens but their risks in the treatment of poisonings are unknown. There is no epidemiologic study evaluating the risk of the following antidotes during pregnancy: N-acetylcysteine(*+), BAL (dimercaprol)+, black widow spider antivenin+, calcium EDTA+, crotalidae antivenin, crotalidae polyvalent immune FAB, cyanide antidote kit (amyl and sodium nitrate, sodium thiosulfate), deferoxamine(*+), digoxin immune FAB+, DMSA+, flumazenil+, fomepizole, methylene blue (IV), naloxone, physostigmine, pralidoxime+, protamine+; and parenteral pharmacologic doses of calcium+, folinic acid*, glucagon+, hydroxycobalamin, phytonadione (vitamin K), and pyridoxine.

CONCLUSIONS

Despite the limited evidence supporting the risk of antidote use during pregnancy, antidotes should be used when there is a clear maternal indication to decrease the morbidity or mortality associated with poisoning. The only exception may be penicillamine, which is a teratogen. Better antidotes exist for most poisonings that penicillamine could potentially treat. At this time, there is no known fetal indication for all antidotes. Reporting the use of an antidote during pregnancy should be encouraged, especially if used during the critical period of organogenesis.

Management of paracetamol overdose: current controversies

Paracetamol (acetaminophen) is one of the most frequently used analgesics, and is the most commonly used substance in self-poisoning in the US and UK. Paracetamol toxicity is manifested primarily in the liver. Treatment with N-acetyl-cysteine (NAC), if started within 10 hours from ingestion, can prevent hepatic damage in most cases. Pharmacokinetic data relating plasma paracetamol concentration to time after ingestion have been used to generate a 'probable hepatoxicity line' to predict which cases of paracetamol overdose will result in hepatotoxicity and should be treated with NAC. However, later studies use a 25% lower line as their 'possible hepatotoxicity line'. Although adopting the original line may save considerable resources, further studies are needed to determine whether such an approach is safe. On the basis of the metabolism of paracetamol, several risk factors for paracetamol toxicity have been proposed. These risk factors include long term alcohol (ethanol) ingestion, fasting and treatment with drugs that induce the cytochrome P450 2E1 enzyme system. Although some studies have suggested that these risk factors may be associated with worse prognosis, the data are inconclusive. However, until further evidence is available, we suggest that the lower line should be used when risk factors are present. In Canada and the UK, the intravenous regimen for NAC is used almost exclusively; in the US, an oral regimen is used. Both regimens have been shown to be effective. There is no large scale study with direct comparison between these 2 therapeutic protocols and controversy still exists as to which regimen is superior. During the last few years there has been an increase in the number of reports of liver failure associated with prolonged paracetamol administration for therapeutic reasons. The true incidence of this phenomenon is not known. We suggest testing liver enzyme levels if a child has received more than 75 mg/kg/day of paracetamol for more than 24 hours during febrile illness, and to treat with NAC when transaminase levels are elevated. Paracetamol overdose during pregnancy should be treated with either oral or intravenous NAC according to the regular protocols in order to prevent maternal, and potentially fetal, toxicity. Unless severe maternal toxicity develops, paracetamol overdose does not appear to increase the risk for adverse pregnancy outcome.

Deficient detoxifying capacity in the pathophysiology of preeclampsia

An imbalance between oxidative stress and maternal detoxification or antioxidant capacity may explain the symptoms of preeclampsia and the haemolysis-elevated liver enzymes-low platelets (HELLP) syndrome. Oxidative stress is known to induce damage of the endothelium, which is one of the pathophysiological features of preeclampsia and the HELLP syndrome. Administration of N-acetylcysteine, an antioxidant itself and a precursor of the endogenous antioxidant glutathione, might stabilize or even partly recover the process of endothelial damage and may lead to prolongation of pregnancy.