Acetaminophen and the risk of asthma: the epidemiologic and pathophysiologic evidence

Associations between cord blood acetaminophen biomarkers and childhood asthma with and without allergic comorbidities

BACKGROUND

Previous studies have linked prenatal acetaminophen use to increased asthma risk in children. However, none have explored this association while differentiating between asthma cases with and without other allergic conditions or by employing objective biomarkers to assess acetaminophen exposure.

OBJECTIVE

To evaluate whether the detection of acetaminophen biomarkers in cord blood is associated with the subgroups of asthma both with and without allergic comorbidities in children.

METHODS

Acetaminophen biomarkers, including unchanged acetaminophen and acetaminophen glucuronide, were measured in neonatal cord blood samples from the Boston Birth Cohort. Asthma subgroups were defined on the basis of physician diagnoses of asthma and other allergic conditions (atopic dermatitis and allergic rhinitis). Multinomial regressions were used to evaluate the associations between acetaminophen biomarkers and asthma subgroups, adjusting for multiple confounders, including potential indications for maternal acetaminophen use such as maternal fever.

RESULTS

The study included 142 children with asthma and at least 1 other allergic condition, 55 children with asthma but no other allergic condition, and 613 children free of asthma. Detection of acetaminophen in cord blood, reflecting maternal exposure to acetaminophen shortly before delivery, was associated with 3.73 times the odds of developing asthma without allergic comorbidities (95% CI: 1.79-7.80, P = .0004). In contrast, the detection of acetaminophen in cord blood was not associated with an elevated risk of asthma with allergic comorbidities. Analysis of acetaminophen glucuronide yielded consistent results.

CONCLUSION

In a prospective birth cohort, cord blood acetaminophen biomarkers were associated with an increased risk of childhood asthma without allergic comorbidities, but were not associated with childhood asthma with allergic comorbidities.

Epidemiological characterization and risk factors of rhinitis and rhinoconjunctivitis among preschool children in Shanghai, China

BACKGROUND

Previous studies have reported an increasing prevalence of childhood allergic rhinitis in developing countries. There is still a lack of the recent epidemiology of allergic rhinitis among Chinese preschool children. Therefore, this study explored the prevalence of rhinitis symptoms and identified their associations with potential risk factors among children at the age of 3-6 in Shanghai, China.

METHODS

Validated International Study of Asthma and Allergies in Childhood (ISAAC) questionnaire was adopted to collect information about rhinitis symptoms and potential risk factors. Univariate and multivariate logistic regression analyses were used to assess associations between risk factors and allergic rhinitis and rhinoconjunctivitis.

RESULTS

A total of 6183 questionnaires were included in our study. The prevalence of rhinitis ever, current rhinitis, and physician-diagnosed rhinitis were 32.6%, 29.2%, and 14.3%, respectively, while the prevalence of current rhinoconjunctivitis was 11.3%. The higher prevalence was observed in boys than in girls in terms of rhinitis ever, current rhinitis, current rhinoconjunctivitis and doctor-diagnosed rhinitis. Autumn had the highest prevalence among four seasons. In our multivariate logistic regression analyses, history of allergic diseases and paracetamol use in the last year showed positive associations with the increased risk of both current rhinitis and rhinoconjunctivitis, and antibiotic use was an independent significant risk factor only for current rhinitis. Genetic factors, including maternal and paternal rhinitis, asthma, and eczema, were significantly associated with the prevalence of current rhinitis. Similar associations were seen between these factors and current rhinoconjunctivitis, except for paternal eczema. Among environmental factors, smoking exposure at home, heavy truck traffic in home's street, floor heating system were independent risk factors for both current rhinitis and rhinoconjunctivitis in the adjusted model, while cleaning the house less than once a week was only associated with current rhinitis.

CONCLUSION

The prevalence of current rhinitis was 29.2% among children aged 3-6 in Shanghai, China. Sex differences and seasonal variations were observed in the prevalence of rhinitis symptoms. The identified risk factors would provide a basis for policy makers and medical experts to take intervention measures to prevent allergic rhinitis and rhinoconjunctivitis.

Allergic diseases in India - Prevalence, risk factors and current challenges

Epidemiological studies have shown a rise in the prevalence of allergic diseases in India during the last two decades. However, recent evidence from the Global Asthma Network study has observed a decrease in allergic rhinitis, asthma and atopic dermatitis in children. Still, with a population over 1.3 billion, there is a huge burden of allergic rhinitis, asthma and atopic dermatitis, and this is compounded by an unmet demand for trained allergy specialists and poor health service framework. There is wide variation in the prevalence of allergic diseases between different geographical locations in India, and the reasons are unclear at present. This may at least in part be attributable to considerable heterogeneity in aero-biology, weather, air pollution levels, cultural and religious factors, diet, socioeconomic strata and literacy. At present, factors enhancing risks and those protecting from development of atopy and allergic diseases have not been well delineated, although there is some evidence for the influence of genetic factors alongside cultural and environmental variables such as diet, exposure to tobacco smoke and air pollution and residence in urban areas. This narrative review provides an overview of data from India regarding epidemiology, risk factors and genetics and highlights gaps in evidence as well as areas for future research.

Have the prevalence of eczema symptoms increased in the Mexican pediatric population? Prevalence and associated factors according to Global Asthma Network Phase I

Background

In children, atopic dermatitis or eczema is the most common inflammatory disease of the skin. According to the International Study of Asthma and Allergies in Childhood (ISAAC) Phase IIIB in Mexico, 5.8% of children and 4.9% of adolescents had eczema symptoms. In 2012, Global Asthma Network (GAN) was established to update the prevalence of eczema and estimate potential factors contributing to its development.

Objective

To estimate the prevalence and associated factors for atopic eczema symptoms and diagnosis in children and adolescents according to GAN Phase I and compare the results with ISAAC Phase IIIB in Mexico.

Methods

A cross-sectional, multicenter survey was conducted in 15 Mexican centers during the period of 2015-2017 using the GAN Phase I questionnaires in children (6-7-year-olds) and adolescents (13-14-year-olds). The prevalences obtained from the GAN Phase I study, were compared with ISAAC Phase IIIB results; a Spearman's correlation analysis was conducted between temperature, relative humidity, and altitude and eczema symptoms, and a logistic regression was performed to predict current eczema symptoms by age group.

Results

A total of 35 777 children and 41 399 adolescents were included. Since ISAAC Phase IIIB, the prevalence of itchy rash in the past 12 months significantly increased in the children's group [6.6% (95% CI 5.7-7.4) vs 7.8 (95% CI 7.5-8.1), p = 0.000] and adolescents' group [5.8% (95% CI 5.0-6.7) vs 6.7% (95% CI 6.5-7.0), p = 0.000].In the adolescents' group, the prevalence of nocturnal awakenings caused by rash symptoms on more than one night per week had a negative correlation between altitude (Spearman's Rho = -0.558, p value = 0.031), and a positive correlation with the average annual temperature (Spearman's Rho = 0.604, p value = 0.017) and annual relative humidity (Spearman's Rho = 0.742, p value = 0.002). The most significant associations in children were the presence of sneezing or runny or blocked nose in the past 12 months [(OR 3.13, 95% CI 2.60-3.77), p = 0.000], the use of paracetamol in the first year of life ([OR 1.52, 95% CI 1.15-2.01), p = 0.003] and the use of antibiotics in the first year of life [(OR 1.30, 95% CI 1.08-1.55) p = 0.004]. Moreover, altitude at 100-1000 m above sea level was associated with current eczema symptoms in adolescents (p = 0.001).

Conclusions

There has been a significant increase in eczema symptoms in both age groups since ISAAC Phase IIIB study. Additionally, eczema symptoms were associated with temperature, relative humidity, asthma, hay fever symptoms, the use of paracetamol and antibiotics.

Racing against time: leveraging preclinical models to understand pulmonary susceptibility to perinatal acetaminophen exposures

Over the past decade, clinicians have increasingly prescribed acetaminophen (APAP) for patients in the neonatal intensive care unit (NICU). Acetaminophen has been shown to reduce postoperative opiate burden, and may provide similar efficacy for closure of the patent ductus arteriosus (PDA) as nonsteroidal anti-inflammatory drugs (NSAIDs). Despite these potential benefits, APAP exposures have spread to increasingly less mature infants, a highly vulnerable population for whom robust pharmacokinetic and pharmacodynamic data for APAP are lacking. Concerningly, preclinical studies suggest that perinatal APAP exposures may result in unanticipated adverse effects that are unique to the developing lung. In this review, we discuss the clinical observations linking APAP exposures to adverse respiratory outcomes and the preclinical data demonstrating a developmental susceptibility to APAP-induced lung injury. We show how clinical observations linking perinatal APAP exposures to pulmonary injury have been taken to the bench to produce important insights into the potential mechanisms underlying these findings. We argue that the available data support a more cautious approach to APAP use in the NICU until large randomized controlled trials provide appropriate safety and efficacy data.

The association between exacerbation of chronic obstructive pulmonary disease and timing of paracetamol use: a cohort study in elderly Australians

Background

In elderly populations, paracetamol may be used regularly for conditions such as osteoarthritis. Paracetamol has been associated with respiratory disease through a proposed mechanism of glutathione depletion and oxidative stress. Given that chronic obstructive pulmonary disease (COPD) is frequently co-morbid with osteoarthritis, this study investigated whether the dose and timing of paracetamol exposure may induce COPD exacerbations.

Methods

The study population was 3523 Australian Government Department of Veterans’ Affairs full entitlement holders who had existing COPD on 1 January 2011, who were dispensed at least one prescription of paracetamol between 1 January 2011 and 30 September 2015, and had no paracetamol dispensed in the 6 months prior to 1 January 2011. The outcome was time to first hospitalisation for COPD exacerbation after initiation of paracetamol. A weighted cumulative exposure approach was used.

Results

The association between paracetamol exposure and COPD exacerbation was protective or harmful depending on the dose, duration, and recency of exposure. Compared to non-use, current use at the maximum dose of 4 g daily for 7 days was associated with a lower risk (HR = 0.78, 95% CI = 0.67–0.92) and a higher risk after 30 days (HR = 1.27, 95% CI = 1.06–1.52). Risk declined to baseline after 2 months. For past use, there was a short-term increase in risk on discontinuation depending of dose, duration and time since stopping.

Conclusions

Patients and doctors should be aware of the possible risk of COPD exacerbation with higher dose paracetamol 1 to 6 weeks after initiation or discontinuation, but no increased risk after 2 months.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12931-022-02010-z.

Pulmonary implications of acetaminophen exposures independent of hepatic toxicity

Both preclinical and clinical studies have demonstrated that exposures to acetaminophen (APAP) at levels that cause hepatic injury cause pulmonary injury as well. However, whether exposures that do not result in hepatic injury have acute pulmonary implications is unknown. Thus, we sought to determine how APAP exposures at levels that do not result in significant hepatic injury impact the mature lung. Adult male ICR mice (8-12 wk) were exposed to a dose of APAP known to cause hepatotoxicity in adult mice [280 mg/kg, intraperitoneal (ip)], as well as a lower dose previously reported to not cause hepatic injury (140 mg/kg, ip). We confirm that the lower dose exposures did not result in significant hepatic injury. However, like high dose, lower exposure resulted in increased cellular content of the bronchoalveolar lavage fluid and induced a proinflammatory pulmonary transcriptome. Both the lower and higher dose exposures resulted in measurable changes in lung morphometrics, with the lower dose exposure causing alveolar wall thinning. Using RNAScope, we were able to detect dose-dependent, APAP-induced pulmonary Cyp2e1 expression. Finally, using FLIM we determined that both APAP exposures resulted in acute pulmonary metabolic changes consistent with mitochondrial overload in lower doses and a shift to glycolysis at a high dose. Our findings demonstrate that APAP exposures that do not cause significant hepatic injury result in acute inflammatory, morphometric, and metabolic changes in the mature lung. These previously unreported findings may help explain the potential relationship between APAP exposures and pulmonary-related morbidity.

Allergic rhinitis is associated with atmospheric SO2: Follow-up study of children from elementary schools in Ulsan, Korea

OBJECTIVES

The purpose of this study was to examine the association of allergic rhinitis with air pollutant concentrations using the follow-up data of elementary school children in Ulsan, Korea.

METHODS

All students of four elementary schools in Ulsan, South Korea were surveyed at two-year intervals. The survey used data collected five times, over a nine-year period from June 2009 to April 2018. The questionnaire used in the survey was a modified version of the ISAAC (International society of asthma and allergy of children) questionnaire. A skin prick test (SPT) was performed with 24 standard antigens. To estimate the levels of exposure to outdoor air pollution, the concentrations of sulfur dioxide (SO2), nitrogen dioxide (NO2), ozone (O3), carbon monoxide (CO), and particulate matter 10 μm or less in diameter (PM10) were used. As a dependent variable, a history of allergic rhinitis diagnosed by a doctor during the last 1-year was considered. Logistic regression analysis was used to select variables suitable for the statistical model. The selected variables were then used to assess their association with the dependent variable using the generalized estimation equation.

RESULTS

Among environmental factors, SO2 was associated with a high risk and PM10 was associated with a low risk of allergic rhinitis. The risk of allergic rhinitis from living in a house built within the last year was high, and the risk from living in a multi-family house or apartment was higher than that from living in a segregated house. History of allergic diseases in the family was a high-risk factor for allergic rhinitis. There was a relationship between a history of bronchiolitis at less than 2 years of age and a high risk of allergic rhinitis. Boys were at a higher risk than girls.

CONCLUSION

From the follow-up data of elementary school students in Ulsan, Korea, the concentration of SO2, which is an indicator of the degree of industrialization, was related to the prevalence of allergic rhinitis. Among all the risk factors, history of allergic disease in the parents was the most important factor, and the study reconfirmed the results of the previous studies.

New perspectives in bronchial asthma: pathological, immunological alterations, biological targets, and pharmacotherapy

Asthma is the most common, long-lasting inflammatory airway disease that affects more than 10% of the world population. It is characterized by bronchial narrowing, airway hyperresponsiveness, vasodilatation, airway edema, and stimulation of sensory nerve endings that lead to recurring events of breathlessness, wheezing, chest tightness, and coughing. It is the main reason for global morbidity and occurs as a result of the weakening of the immune system in response to exposure to allergens or environmental exposure. In asthma condition, it results in the activation of numerous inflammatory cells like the mast and dendritic cells along with the accumulation of activated eosinophils and lymphocytes at the inflammation site. The structural cells such as airway epithelial cells and smooth muscle cells release inflammatory mediators that promote the bronchial inflammation. Long-lasting bronchial inflammation can cause pathological alterations, viz. the improved thickness of the bronchial epithelium and friability of airway epithelial cells, epithelium fibrosis, hyperplasia, and hypertrophy of airway smooth muscle, angiogenesis, and mucus gland hyperplasia. The stimulation of bronchial epithelial cell would result in the release of inflammatory cytokines and chemokines that attract inflammatory cells into bronchial airways and plays an important role in asthma. Asthma patients who do not respond to marketed antiasthmatic drugs needed novel biological medications to regulate the asthmatic situation. The present review enumerates various types of asthma, etiological factors, and in vivo animal models for the induction of asthma. The underlying pathological, immunological mechanism of action, the role of inflammatory mediators, the effect of inflammation on the bronchial airways, newer treatment approaches, and novel biological targets of asthma have been discussed in this review.

Risk of wheezing and asthma exacerbation in children treated with paracetamol versus ibuprofen: a systematic review and meta-analysis of randomised controlled trials

Background

Paracetamol and ibuprofen are the most commonly used medications for fever and pain management in children. While the efficacy appears similar with both drugs, there are contradictory findings related to adverse events. In particular, incidence of wheezing and asthma among children taking paracetamol compared to ibuprofen, remain unsettled.

Methods

We conducted a meta-analysis of randomized controlled trials (RCTs) that compared wheezing and asthma exacerbations in children taking paracetamol versus ibuprofen. A comprehensive search was conducted in five databases. RCTs reporting on cases of wheezing or asthma exacerbations in infants or children after the administration of paracetamol or ibuprofen were included. The pooled effect size was estimated using the Peto’s odds ratio.

Results

Five RCTs with 85,095 children were included in the analysis. The pooled estimate (OR 1.05; 95%CI 0.76–1.46) revealed no difference in the odds of developing asthma or presenting an exacerbation of asthma in children who received paracetamol compared to ibuprofen. When the analysis was restricted to RCTs that examined the incidence of asthma exacerbation or wheezing, the pooled estimate remained similar (OR 1.01; 95%CI 0.63–1.64). Additional bias adjusted quality effect sensitivity model yielded similar results (RR 1.03; 95%CI 0.84–1.28).

Conclusion

Although, Ibuprofen and paracetamol appear to have similar tolerance and safety profiles in terms of incidence of asthma exacerbations in children, we suggest high quality trials with clear definition of asthma outcomes after receiving ibuprofen or paracetamol at varying doses with longer follow-up are warranted for any conclusive finding.

Allergic rhinitis and asthma assessment of risk factors in pediatric patients: A systematic review

Allergic rhinitis (AR) is the most prevalent allergic disease in children and can be associated with asthma (A); this association can have significant effect on child's quality of life. The objective of this work was to systematically review existing literature on the risk factors of AR and A in children to better understand the link between these two diseases. We performed a literature search over the last 25 years in PubMed and Medline. Inclusion criteria comprised English language papers containing original human data with greater than 30 subjects and papers that statistically analyze the relationship between AR and A and the risk factor(s), in children population. A statistically significant correlation was found between children with AR and A and ambient Polycyclic Aromatic Hydrocarbons exposure, live in an industrialized city with elevated traffic, dampness and moulds exposure, electric cooking, male gender, single nucleotide polymorphisms in PTNP22 gene and CTLA-4 gene, fast food and margarine products consumption, use of paracetamol in last year, history of tuberculosis, parental atopy, high total serum IgE, antibiotics in uterus and infections in uterus exposure, history of formula feeding and caesarian section. A strong and complex link between AR and A was accounted: A represents a major risk factor for the onset of AR, that correlates with more severe asthmatic symptoms. Even the onset of A in a child with AR worsen it. The interaction of genetic and environmental risk factors and the consequent epigenetic, microbiota and immunological changes, were found to led to the development of AR and A in children, with both atopic and non-atopic pathways. Close monitoring of evidenced risk factors may help with an early recognize and treat A in patients with AR.

Toxic Acetaminophen Exposure Induces Distal Lung ER Stress, Proinflammatory Signaling, and Emphysematous Changes in the Adult Murine Lung

Clinical studies have demonstrated a strong association between both acute toxic exposure and the repetitive, chronic exposure to acetaminophen (APAP) with pulmonary dysfunction. However, the mechanisms underlying this association are unknown. Preclinical reports have demonstrated that significant bronchiolar injury occurs with toxic APAP exposure, but very little information exists on how the distal lung is affected. However, cells in the alveolar space, including the pulmonary epithelium and resident macrophages, express the APAP-metabolizing enzyme CYP2E1 and are a potential source of toxic metabolites and subsequent distal lung injury. Thus, we hypothesized that distal lung injury would occur in a murine model of toxic APAP exposure. Following exposure of APAP (280 mg/kg, IP), adult male mice were found to have significant proximal lung histopathology as well as distal lung inflammation and emphysematous changes. Toxic APAP exposure was associated with increased CYP2E1 expression in the distal lung and accumulation of APAP-protein adducts. This injury was associated with distal lung activation of oxidant stress, endoplasmic reticulum stress, and inflammatory stress response pathways. Our findings confirm that following toxic APAP exposure, distal lung CYP2E1 expression is associated with APAP metabolism, tissue injury, and oxidant, inflammatory, and endoplasmic reticulum signaling. This previously unrecognized injury may help improve our understanding of the relationship between APAP and pulmonary-related morbidity.

Long-term adverse effects of paracetamol - a review

Paracetamol (acetaminophen) is the most commonly used drug in the world, with a long record of use in acute and chronic pain. In recent years, the benefits of paracetamol use in chronic conditions has been questioned, notably in the areas of osteoarthritis and lower back pain. Over the same period, concerns over the long-term adverse effects of paracetamol use have increased, initially in the field of hypertension, but more recently in other areas as well. The evidence base for the adverse effects of chronic paracetamol use consists of many cohort and observational studies, with few randomized controlled trials, many of which contradict each other, so these studies must be interpreted with caution. Nevertheless, there are some areas where the evidence for harm is more robust, and if a clinician is starting paracetamol with the expectation of chronic use it might be advisable to discuss these side effects with patients beforehand. In particular, an increased risk of gastrointestinal bleeding and a small (~4 mmHg) increase in systolic blood pressure are adverse effects for which the evidence is particularly strong, and which show a degree of dose dependence. As our estimation of the benefits decreases, an accurate assessment of the harms is ever more important. The present review summarizes the current evidence on the harms associated with chronic paracetamol use, focusing on cardiovascular disease, asthma and renal injury, and the effects of in utero exposure.

Leptin receptor gene polymorphisms and sex modify the association between acetaminophen use and asthma among young adults: results from two observational studies

Background

Epidemiologic studies have demonstrated associations between acetaminophen use and asthma. This investigation sought to determine whether sex modifies the acetaminophen-asthma association and whether leptin (LEP) and leptin receptor (LEPR) gene polymorphisms modulate the sex-specific associations.

Methods

Data from the Isle of Wight birth cohort (IOW; n = 1456, aged 18 years) and Kuwait University Allergy (KUA; n = 1154, aged 18–26 years) studies were analyzed. Acetaminophen use and current asthma were self-reported. Genotype information for eighteen polymorphisms in LEP and LEPR genes were available in the IOW study. Associations between acetaminophen use and asthma were stratified by sex and genotype. Poisson regression models with robust variance estimation were evaluated to estimate adjusted prevalence ratios (aPR) and 95% confidence intervals (CI).

Results

Acetaminophen use was dose-dependently associated with an increased prevalence of current asthma in the IOW and KUA studies. In both studies, sex-stratified analysis showed that acetaminophen use was associated with asthma among males, but not in females (P_interaction <  0.05). Moreover, a sex- and genotype-stratified analysis of the IOW data indicated that acetaminophen was associated with asthma to a similar extent among males and females carrying two common alleles of LEPR polymorphisms. In contrast, among those carrying at least one copy of the minor allele of LEPR polymorphisms, the magnitude of association between acetaminophen use and asthma was pronounced among males (aPR = 6.83, 95% CI: 2.87–16.24), but not among females (aPR = 1.22, 95% CI: 0.61–2.45).

Conclusions

The identified sex-related effect modification of the acetaminophen-asthma association varied across LEPR genotypes, indicating that the sex-specific association was confined to individuals with certain genetic susceptibility. If the acetaminophen-asthma association is causal, then our findings will aid susceptibility-based stratification of at-risk individuals and augment preventive public health efforts.

Electronic supplementary material

The online version of this article (10.1186/s12931-018-0892-y) contains supplementary material, which is available to authorized users.

An international comparison of risk factors between two regions with distinct differences in asthma prevalence

BACKGROUND AND PURPOSE

Investigation of the geographic variation in asthma prevalence can improve our understanding of asthma etiology and management. The purpose of our investigation was to compare the prevalence of asthma and wheeze among adolescents living in two distinct international regions and to investigate reasons for observed differences.

METHODS

A cross-sectional survey of 13-14 year olds was completed in Saskatoon, Canada (n=1200) and Skopje, Republic of Macedonia (n=3026), as part of the International Study of Asthma and Allergies in Childhood (ISAAC) Phase 3 study. Surveys were self-completed by students following the ISAAC protocol. Multiple logistic regression models were used to investigate associations with reports of asthma and current wheeze. A mediation analysis was then completed.

RESULTS

Asthma prevalence was much higher in Saskatoon than Skopje (21.3% vs. 1.7%) as was the prevalence of current wheeze (28.2% vs. 8.8%). Higher paracetamol (acetaminophen) use was a consistent risk factor for asthma and wheeze in both locations and showed dose-response relationships. In both countries, paracetamol use and physical activity mediated some of the association for both asthma and wheeze. In Saskatoon, among those with current wheeze, 42.6% reported ever having a diagnosis of asthma compared to 10.2% among Skopje adolescents.

CONCLUSIONS

The results suggest that the variation in risk factors between the two locations may explain some of the differences in the prevalence of asthma and wheeze between these two study sites. However, diagnostic labeling patterns should not be ruled out as another potential explanatory factor.

Conjugation of nitrated acetaminophen to Der p1 amplifies peripheral blood monocyte response to Der p1

BACKGROUND

An association of acetaminophen use and asthma was observed in the International Study of Asthma and Allergies in Childhood study. However there are no clear mechanisms to explain an association between acetaminophen use and immunologic pathology. In acidic conditions like those in the stomach and inflamed airway, tyrosine residues are nitrated by nitrous and peroxynitrous acids. The resulting nitrotyrosine is structurally similar to 2,4-dinitrophenol and 2,4-dinitrochlorobenzene, known haptens that enhance immune responses by covalently binding proteins. Nitrated acetaminophen shares similar molecular structure.

OBJECTIVE

We hypothesized the acetaminophen phenol ring undergoes nitration under acidic conditions, producing 3-nitro-acetaminophen which augments allergic responses by acting as a hapten for environmental allergens.

METHODS

3-nitro-acetaminophen was formed from acetaminophen in the presence of acidified nitrite, purified by high performance liquid chromatography, and assayed by gas-chromatography mass spectrometry. Purified 3-nitro-acetaminophen was reacted with Dermatophagoides pteronyssinus (Der p1) and analyzed by mass spectrometry to identify the modification site. Human peripheral blood mononuclear cells proliferation response was measured in response to 3-nitro-acetaminophen and to 3-nitro-acetaminophen-modified Der p1.

RESULTS

Acetaminophen was modified by nitrous acid forming 3-nitro-acetaminophen over a range of different acidic conditions consistent with airway inflammation and stomach acidity. The Der p1 protein-hapten adduct creation was confirmed by liquid chromatography-mass spectrometry proteomics modifying cysteine 132. Peripheral blood mononuclear cells exposed to 3-nitro-acetaminophen-modified Der p1 had increased proliferation and cytokine production compared to acetaminophen and Der p1 alone (n = 7; p < 0.05).

CONCLUSION

These data suggests 3-nitro-acetaminophen formation and reaction with Der p1 provides a mechanism by which stomach acid or infection-induced low airway pH in patients could enhance the allergic response to proteins such as Der p1.

A clinical and safety review of paracetamol and ibuprofen in children

The antipyretic analgesics, paracetamol, and non-steroidal anti-inflammatory agents NSAIDs are one of the most widely used classes of medications in children. The aim of this review is to determine if there are any clinically relevant differences in safety between ibuprofen and paracetamol that may recommend one agent over the other in the management of fever and discomfort in children older than 3 months of age.

Allergic rhinitis, rhinoconjunctivitis, and eczema: prevalence and associated factors in children

OBJECTIVE

We aim to describe the data collected from India during phase 3 of the International study of asthma and allergy in childhood (ISAAC) study. Prevalence, severity, and population characteristics associated with rhinitis, rhinoconjunctivitis, and eczema were assessed.

METHODS

Children from two age groups (6-7 and 13-14 years) were included in the study as per the ISAAC protocol. The symptoms of allergy and associated features were assessed using a questionnaire.

RESULTS

The prevalence of allergic rhinitis among the 6-7 years age group was 11.3%, while it was 24.4% in the 13-14 years age group. The prevalence of allergic rhinoconjunctivitis was 3.9% in the 6-7 years age group and 10.9% in the 13-14 years age group. The prevalence of eczema was 2.8% in the 6-7 years age group and 3.7% in the 13-14 years age group. The passage of trucks near home, parental smoking, use of paracetamol, use of antibiotics, cooking with firewood, and television watching were associated with allergic rhinitis, rhinoconjunctivitis, and eczema. Maternal smoking was the strongest of all the associated features for allergic rhinitis, rhinoconjunctivitis, and eczema, especially in the 6-7 years age group (odds ratio: 1.9, 95% CI: 1.5-2.4; odds ratio: 2.9, 95% CI, 2.2-3.9; and odds ratio: 3.5, 95% CI: 2.6-4.8, respectively).

CONCLUSION

Allergic conditions like allergic rhinitis, rhinoconjunctivitis, and eczema are prevalent among Indian children and are associated with environmental tobacco smoke, paracetamol use, antibiotic use, television watching, and outdoor and indoor air pollution.

Propacetamol-Induced Injection Pain Is Associated with Activation of Transient Receptor Potential Vanilloid 1 Channels

Propacetamol (PPCM) is a prodrug of paracetamol (PCM), which was generated to increase water solubility of PCM for intravenous delivery. PPCM is rapidly hydrolyzed by plasma esterases to PCM and diethylglycine and shares some structural and metabolic properties with lidocaine. Although PPCM is considered to be comparable to PCM regarding its analgesic properties, injection pain is a common side effect described for PPCM but not PCM. Injection pain is a frequent and unpleasant side effect of numerous drugs in clinical use, and previous reports have indicated that the ligand gated ion channels transient receptor potential ankyrin 1 (TRPA1) and transient receptor potential vanilloid 1 (TRPV1) can mediate this effect on sensory neurons. This study aimed to investigate molecular mechanisms by which PPCM, in contrast to PCM, causes injection pain. Therefore, human TRPV1 and TRPA1 receptors were expressed in human embryonic kidney 293 cells and investigated by means of whole-cell patch clamp and ratiometric calcium imaging. PPCM (but not PCM) activated TRPV1, sensitized heat-induced currents, and caused an increase in intracellular calcium. In TRPA1-expressing cells however, both PPCM and PCM evoked calcium responses but failed to induce inward currents. Intracutaneous injection of PPCM, but not of PCM, in human volunteers induced an intense and short-lasting pain and an increase in superficial blood flow, indicating activation of nociceptive C fibers and subsequent neuropeptide release. In conclusion, activation of human TRPV1 by PPCM seems to be a relevant mechanism for induction of pain upon intracutaneous injection and thus also for pain reported as an adverse side effect upon intravenous administration.

The association between paracetamol and asthma is still under debate

OBJECTIVE

To analyse the relationship between paracetamol and asthma.

DATA SOURCES

An English literature search using electronic search engines (PubMed and EMBASE) was conducted.

STUDY SELECTIONS

Articles published in peer-review journals, from 1990 to December 2015 were included. To perform the search for the most suitable and representative articles, keywords were selected ("asthma," "paracetamol" and "acetaminophen"). The evidence level was rated according to the criteria of the Oxford Centre For Evidence-Based Medicine.

RESULTS

The exposure to paracetamol during pregnancy was analysed in several cohort studies, showing an association between the prenatal exposure to paracetamol with suffering from asthma or presence of wheezing in childhood, especially for persistent wheezing. Nevertheless, a recent study concluded that the relationship between asthma and paracetamol is explained, at least in part, by confounding factors. Several works have also associated the exposure to paracetamol in the first years of life or in adults with the development of childhood asthma. Several pathophysiological mechanisms are known that could explain this relationship, such as the glutathione pathway, the decrease in the release of Th1 cytokines that are normally produced during febrile episodes, which would then lead to a predominance of Th2 cytokines, the cytotoxic effect of paracetamol for pneumocytes, a modulator effect on the activity of myeloperoxidase, as well as the possible antigenic effect of paracetamol, mediated by IgE.

CONCLUSIONS

There are many arguments that suggest a relationship between the use of paracetamol with the appearance of asthmatic symptoms, however the evidence is inconclusive.

The association between paracetamol use and asthma: causation or coincidence?

A better understanding of the causation of asthma and allergic disorders could potentially lead to intervention strategies that reduce their prevalence and severity. One potential causative factor is the use of paracetamol. Most of the evidence for the link with asthma is from non-experimental studies of paracetamol exposure in utero, infancy, childhood and adult life; however, it has been difficult to rule out confounding and bias in the associations observed. The two randomized clinical trials of the effect of paracetamol in patients with asthma have been difficult to interpret, due to methodological issues. There have been no randomized controlled trials of paracetamol use and the development of asthma. Both asthma and paracetamol use are common, and so even if there is a relatively small effect of paracetamol exposure on the development of asthma or its severity, then such an effect would be of major public health significance. It is proposed that randomized controlled trials of the effect of paracetamol on the development of asthma and its severity are a high research priority.

Causal assessment of pharmaceutical treatments: why standards of evidence should not be the same for benefits and harms?

It is increasingly acknowledged both among epidemiologists and regulators that the assessment of pharmaceutical harm requires specific methodological approaches that cannot simply duplicate those developed for testing efficacy. However, this intuition lacks sound epistemic bases and delivers ad hoc advice. This paper explains why the same methods of scientific inference do not fare equally well for efficacy and safety assessment by tracing them back to their epistemic foundations. To illustrate this, Cartwright's distinction into clinching and vouching methods is adopted and a series of reasons is provided for preferring the latter to the former: (1) the need to take into account all available knowledge and integrate it with incoming data; (2) the awareness that a latent unknown risk may always change the safety profile of a given drug (precautionary principle); (3) cumulative learning over time; (4) requirement of probabilistic causal assessment to allow decision under uncertainty; (5) impartiality; and (6) limited and local information provided by randomised controlled trials. Subsequently, the clinchers/vouchers distinction is applied to a case study concerning the debated causal association between paracetamol and asthma. This study illustrates the tension between implicit epistemologies adopted in evaluating evidence and causality; furthermore, it also shows that discounting causal evidence may be a result of unacknowledged low priors or lack of valid alternative options. We conclude with a presentation of the changing landscape in pharmacology and the trend towards an increased use of Bayesian tools for assessment of harms.

A practical approach to the treatment of low-risk childhood fever

Fever is a common symptom of childhood infections that in itself does not require treatment. The UK’s National Institute for Health and Care Excellence (NICE) advises home-based antipyretic treatment for low-risk feverish children only if the child appears distressed. The recommended antipyretics are ibuprofen or paracetamol (acetaminophen). They are equally recommended for the distressed, feverish child; therefore, healthcare professionals, parents and caregivers need to decide which of these agents to administer if the child is distressed. This narrative literature review examines recent data on ibuprofen and paracetamol in feverish children to determine any clinically relevant differences between these agents. The data suggest that these agents have similar safety profiles in this setting and in the absence of underlying health issues, ibuprofen seems to be more effective than paracetamol at reducing NICE’s treatment criterion, ‘distress’ (as assessed by discomfort levels, symptom relief, and general behavior).

[Pediatric perioperative systemic pain therapy: Austrian interdisciplinary recommendations on pediatric perioperative pain management]

BACKGROUND

Many analgesics used in adult medicine are not licensed for pediatric use. Licensing limitations do not, however, justify that children are deprived of a sufficient pain therapy particularly in perioperative pain therapy. The treatment is principally oriented to the strength of the pain. Due to the degree of pain caused, intramuscular and subcutaneous injections should be avoided generally.

NON-OPIOIDS

The basis of systemic pain therapy for children are non-opioids and primarily non-steroidal anti-inflammatory drugs (NSAIDs). They should be used prophylactically. The NSAIDs are clearly more effective than paracetamol for acute posttraumatic and postoperative pain and additionally allow economization of opioids. Severe side effects are rare in children but administration should be carefully considered especially in cases of hepatic and renal dysfunction or coagulation disorders. Paracetamol should only be taken in pregnancy and by children when there are appropriate indications because a possible causal connection with bronchial asthma exists. To ensure a safe dosing the age, body weight, duration of therapy, maximum daily dose and dosing intervals must be taken into account. Dipyrone is used in children for treatment of visceral pain and cholic. According to the current state of knowledge the rare but severe side effect of agranulocytosis does not justify a general rejection for short-term perioperative administration.

OPIOIDS

In cases of insufficient analgesia with non-opioid analgesics, the complementary use of opioids is also appropriate for children of all age groups. They are the medication of choice for episodes of medium to strong pain and are administered in a titrated form oriented to effectiveness. If severe pain is expected to last for more than 24 h, patient-controlled anesthesia should be implemented but requires a comprehensive surveillance by nursing personnel.

KETAMINE

Ketamine is used as an adjuvant in postoperative pain therapy and is recommended for use in pediatric sedation and analgosedation.

Safety vs. efficacy assessment of pharmaceuticals: Epistemological rationales and methods

In their comparative analysis of Randomised Clinical Trials and observational studies, Papanikoloau et al. (2006) assert that "it may be unfair to invoke bias and confounding to discredit observational studies as a source of evidence on harms". There are two kinds of answers to the question why this is so. One is based on metaphysical assumptions, such as the problem of causal sufficiency, modularity and other statistical assumptions. The other is epistemological and relates to foundational issues and how they determine the constraints we put on evidence. I will address here the latter dimension and present recent proposals to amend evidence hierarchies for the purpose of safety assessment of pharmaceuticals; I then relate these suggestions to a case study: the recent debate on the causal association between paracetamol and asthma. The upshot of this analysis is that different epistemologies impose different constraints on the methods we adopt to collect and evaluate evidence; thus they grant "lower level" evidence on distinct grounds and at different conditions. Appreciating this state of affairs illuminates the debate on the epistemic asymmetry concerning benefits and harms and sets the basis for a foundational, as opposed to heuristic, justification of safety assessment based on heterogeneous evidence.

Acetaminophen and/or antibiotic use in early life and the development of childhood allergic diseases

BACKGROUND

Our understanding of whether the use of acetaminophen and/or antibiotics in early life can cause allergic diseases in later childhood remains inconclusive. The objective of this study was to investigate the temporal relationship between exposure to acetaminophen and/or antibiotics in early life and the development of allergic diseases in later childhood, using two independent birth cohorts derived from the National Health Insurance Research Database (NHIRD) in Taiwan.

METHODS

The authors conducted a prospective birth cohort study of 263 620 children born in 1998 and 9910 children born in 2003, separately, from the NHIRD. Exposure status of acetaminophen and/or antibiotics and potential confounding factors were included in the analyses. Cox proportional hazards models were applied to determine the temporal relationship between acetaminophen and/or antibiotic exposure and the development of allergic diseases.

RESULTS

We observed a positive relationship between acetaminophen and/or antibiotic exposure during the 1st year of life and the subsequent development of the three examined allergic diseases (atopic dermatitis, asthma and allergic rhinitis) in the 1998 birth cohort, but the observed relationship of drug exposure in the 2003 cohort, especially for atopic dermatitis and asthma, was lower than for those in the 1998 cohort and was not statistically significant.

CONCLUSIONS

Our findings provide suggestive evidence that the temporal effect of exposure to acetaminophen and/or antibiotics influences the development of common allergic diseases in later childhood. Further functional studies and/or animal studies are needed to better understand the underlying regulatory mechanisms driving this important clinical and public health issue.

Diagnosis, management, and prognosis of preschool wheeze

Preschool children (ie, those aged 5 years or younger) with wheeze consume a disproportionately high amount of health-care resources compared with older children and adults with wheeze or asthma, representing a diagnostic challenge. Although several phenotype classifications have been described, none have been validated to identify individuals responding to specific therapeutic approaches. Several risk factors related to genetic, prenatal, and postnatal environment are associated with preschool wheezing. Findings from several cohort studies have shown that preschool children with wheeze have deficits in lung function at 6 years of age that persisted until early and middle adulthood, suggesting increased susceptibility in the first years of life that might lead to persistent sequelae. Daily inhaled corticosteroids seem to be the most effective therapy for recurrent wheezing in trials of children with interim symptoms or atopy; intermittent high-dose inhaled corticosteroids are effective in moderate-to-severe viral-induced wheezing without interim symptoms. The role of leukotriene receptor antagonist is less clear. Interventions to modify the short-term and long-term outcomes of preschool wheeze should be a research priority.

Association between recent acetaminophen use and asthma: modification by polymorphism at TLR4

The risk of asthma has been increasing in parallel with use of acetaminophen, which is a potential source of oxidative stress. Toll-like receptor 4 (TLR4) plays a critical role not only in innate immunity, but also in mediating reactive oxygen species induced inflammation. Therefore, we investigated associations between acetaminophen usage and TLR4 polymorphism on asthma and bronchial hyperresponsiveness (BHR). The number of 2,428 elementary school children in Seoul and Jeongeup cities was recruited. Subjects who used acetaminophen with a family history of asthma had an increased risk of both asthma diagnosis ever and current asthma. Individuals with CT+TT genotypes at the TLR4 polymorphism, in combination with acetaminophen usage, also demonstrated an increased risk of asthma diagnosis ever (aOR, 2.08; 95% confidence interval [CI], 1.10-3.92). Family history of asthma and acetaminophen usage were risk factors for BHR. Although TLR4 was not an independent risk factor for BHR, individuals with CT+TT genotypes at the TLR4 polymorphism had an increased risk of BHR when combined with acetaminophen usage (aOR, 1.74; 95% CI, 1.03-2.94). In conclusion, acetaminophen usage may be associated with asthma and BHR in genetically susceptible subjects. This effect may be modified by polymorphism at TLR4.

Randomised placebo-controlled study of the effect of paracetamol on asthma severity in adults

OBJECTIVE

To investigate the effect of regular paracetamol on bronchial hyper-responsiveness (BHR) and asthma control in adult asthma.

SETTING

Single research-based outpatient clinic.

PARTICIPANTS

94 adults with mild-to-moderate asthma received randomised treatment; 85 completed the study. Key inclusion criteria were age 18-65 years, forced expiratory volume in 1 s (FEV1) >70% predicted, provocation concentration of methacholine causing a 20% reduction in FEV1 (PC20) between 0.125 and 16 mg/mL. Key exclusion criteria included an asthma exacerbation within the previous 2 months, current regular use of paracetamol, use of high-dose aspirin or non-steroidal anti-inflammatory drugs, current or past cigarette smoking >10 pack-years.

INTERVENTIONS

In a 12-week randomised, double-blind, placebo-controlled, parallel-group study, participants received 12 weeks of 1 g paracetamol twice daily or placebo twice daily.

PRIMARY AND SECONDARY OUTCOME MEASURES

The primary outcome variable was BHR, measured as the PC20 at week 12. Secondary outcome variables included FEV1, fractional exhaled nitric oxide (FeNO) and asthma control questionnaire (ACQ) score.

RESULTS

At 12 weeks, the mean (SD) logarithm base two PC20 was 1.07 (2.36) in the control group (N=54) and 0.62 (2.09) in the paracetamol group (N=31). After controlling for baseline PC20, the mean difference (paracetamol minus placebo) was -0.48 doubling dose worsening in BHR in the paracetamol group (95% CI -1.28 to 0.32), p=0.24. There were no statistically significant differences (paracetamol minus placebo) in log FeNO (0.09 (95% CI -0.097 to 0.27)), FEV1 (-0.07 L (95% CI -0.15 to 0.01)) or ACQ score (-0.04 (95% CI -0.27 to 0.18)).

CONCLUSIONS

There was no significant effect of paracetamol on BHR and asthma control in adults with mild-to-moderate asthma. However, the study findings are limited by low power and the upper confidence limits did not rule out clinically relevant adverse effects.

TRIAL REGISTRATION

Australia New Zealand Clinical Trials Registry Number: NZCTR12609000551291.

Effect of paracetamol use on the modification of the development of asthma by reactive oxygen species genes

BACKGROUND

Recent studies have identified an increase in the prevalence of asthma associated with paracetamol use.

OBJECTIVE

To identify the relationship among asthma, biomarkers, genes, and paracetamol use in preschool children.

METHODS

We undertook a population-based, cross-sectional survey of 933 preschool children. Asthma status was classified according to medical history and asthmatic symptoms. History of paracetamol use in infancy was recorded. Impulse oscillometry, blood tests for eosinophils and total IgE, and genotyping of NAT2, Nrf2, and GSTP1 polymorphisms by TaqMan assay were conducted.

RESULT

Paracetamol use in infancy was associated with an increased risk of treatment for asthma within the previous 12 months. Paracetamol use together with a family history of asthma increased the risk of asthma diagnosis ever, current asthma, and treatment for asthma within the previous 12 months. Gene polymorphisms in NAT2 (rs4271002), Nrf2 (rd6726395), and GSTP1 (rd1695) increased the risk of treatment for asthma within the last 12 months. Eosinophils were significantly elevated in the group with paracetamol use and a family history of asthma; however, the serum total IgE level and IOS did not show any significant difference.

CONCLUSION

Paracetamol use in infancy was significantly associated with increased risk of asthma. The association is more significant in genetically susceptible children, related to antioxidant genes, and the effect may be mediated by eosinophilic inflammation.

Until RCT proven? On the asymmetry of evidence requirements for risk assessment

The problem of collecting, analysing and evaluating evidence on adverse drug reactions is an example of the more general class of epistemological problems related to scientific inference and prediction, as well as a central problem of health care practice. Philosophical discussions have analysed critically the methodological pitfalls and epistemological implications of evidence assessment in medicine; however, they have focused predominantly on evidence of treatment efficacy. Most of this work is devoted to statistical methods of causal inference with a special focus on the privileged role assigned to randomized controlled trials (RCTs) in evidence-based medicine. Regardless of whether the RCT's privilege holds for efficacy assessment, it is nevertheless important to make a distinction between causal inference in relation to intended and unintended effects, in that the unknowns at stake are heterogeneous in the two contexts. This point has been emphasized by epidemiologists in the last decade. Their primary focus is methodological and regards the fact that bias and confounding factors do not affect studies on intended and unintended effects in the same way. However, deeper concerns ground the intuition for such a distinction; these are related to the constraints we impose on evidence and their epistemological justification. My thesis is that such constraints ought to be understood as being different in evidence for risk versus for efficacy. I present the recent debate on the causal association between acetaminophen and asthma in order to illustrate the point at issue. The upshot of my analysis is that different epistemologies confer different methodological choices, which in turn bring about relevant practical implications such as the decision to restrict or suspend drug use rather than leaving it on the market. Thus, it is worth considering the criteria underlying our evidence constraints because they may be ill suited to the purpose for which they are used.

Inhibition of cytochrome P450 enzymes and biochemical aspects of mechanism-based inactivation (MBI)

Mechanism-based inactivation (MBI) often involves metabolic bioactivation of the xenobiotic by cytochrome P450s (CYPs) to an electrophilic reactive intermediate and results in quasi-irreversible or irreversible inactivation. Such reactive intermediate can cause quasi-irreversible inhibition through coordination to the ferrous state, Fe(II), of the P450 enzyme forming a tight noncovalent bond leading to the formation of metabolic-intermediate complex (MIC). By contrast, irreversible inactivation is one of the most common causes for the observed drug–drug interaction (DDI) and usually implies the formation of a covalent bond between the metabolite and the enzyme via alkylation of either the heme or the P450 apoprotein. Here we illustrate the important points of the current literature understanding of the mechanisms of inhibition of CYP enzymes with emphasis on general mechanistic aspects of MBI for some drugs/moieties associated with the phenomenon. Additionally, the utility of computational and in silico approaches to address bioactivation issues will be briefly discussed.

Prescription-acquired acetaminophen use and the risk of asthma in adults: a case-control study

BACKGROUND

Studies have examined the association between acetaminophen use and asthma; however, their interpretation is limited by several methodologic issues.

OBJECTIVE

To investigate the association between recent and chronic prescription-acquired acetaminophen use and asthma.

METHODS

This retrospective case-control study used a 10% random sample of the IMS LifeLink commercial claims data from 1997 to 2009. Cases had to have at least 1 incident claim of asthma; 3:1 controls matched on age, sex, and region were randomly chosen. Acetaminophen exposure, dose, and duration were measured in the 7- and 30-day (recent) and the 1-year (chronic) look-back periods. Multivariable conditional logistic regression was used to estimate the risk of asthma associated with acetaminophen use adjusted for comorbidities, other drugs increasing asthma risk, and health system factors.

RESULTS

There were 28,892 cases and 86,676 controls, with mean age of 42.8 years; 37.7% were males, and 22.6% of cases and 18.2% of controls had acetaminophen exposure in the pre-index year, with mean cumulative doses of 78.7 g and 59.8 g, respectively. There was no significant association between recent prescription acetaminophen exposure and asthma (7 days: OR 1.02, p = 0.74; 30 days: OR 0.97, p = 0.38). Cumulative prescription acetaminophen dose in the year prior increased asthma risk compared to acetaminophen nonusers (≤1 kg: OR 1.09, p < 0.001 and >1 kg: OR = 1.60, p = 0.02). Duration of prescription acetaminophen use greater than 30 days was associated with elevated asthma risk (OR 1.39, p < 0.001).

CONCLUSIONS

Chronic prescription-acquired acetaminophen use was associated with an increased risk of asthma, while recent use was not. However, over-the-counter acetaminophen use was not captured in this study and further epidemiologic research with complete acetaminophen exposure ascertainment and research on pathophysiologic mechanisms is needed to confirm these relationships.

Plasma microRNA profiles distinguish lethal injury in acetaminophen toxicity: A research study

AIM: To investigate plasma microRNA (miRNA) profiles indicative of hepatotoxicity in the setting of lethal acetaminophen (APAP) toxicity in mice.

METHODS: Using plasma from APAP poisoned mice, either lethally (500 mg/kg) or sublethally (150 mg/kg) dosed, we screened commercially available murine microRNA libraries (SABiosciences, Qiagen Sciences, MD) to evaluate for unique miRNA profiles between these two dosing parameters.

RESULTS: We distinguished numerous, unique plasma miRNAs both up- and downregulated in lethally compared to sublethally dosed mice. Of note, many of the greatest up- and downregulated miRNAs, namely 574-5p, 466g, 466f-3p, 375, 29c, and 148a, have been shown to be associated with asthma in prior studies. Interestingly, a relationship between APAP and asthma has been previously well described in the literature, with an as yet unknown mechanism of pathology. There was a statistically significant increase in alanine aminotransferase levels in the lethal compared to sublethal APAP dosing groups at the 12 h time point (P < 0.001). There was 90% mortality in the lethally compared to sublethally dosed mice at the 48 h time point (P = 0.011).

CONCLUSION: We identified unique plasma miRNAs both up- and downregulated in APAP poisoning which are correlated to asthma development.

Update on perioperative management of the child with asthma

Asthma represents the leading cause of morbidity from a chronic disease among children. Dealing with this disease during the perioperative period of pediatric surgical procedures is, therefore, quite common for the anesthesiologist and other professionalities involved. Preoperative assessment has a key role in detecting children at increased risk of perioperative respiratory complications. For children without an optimal control of symptoms or with a recent respiratory tract infection elective surgery should be postponed, if possible, after the optimization of therapy. According to clinical setting, loco-regional anesthesia represents the desirable option since it allows to avoid airway instrumentation. Airway management goals are preventing the increase of airflow resistance during general anesthesia along with avoiding triggers of bronchospasm. When their use is possible, face mask ventilation and laringeal mask are considered more reliable than tracheal intubation for children with asthma. Sevoflurane is the most commonly used anesthetic for induction and manteinance. Salbutamol seems to be useful in preventing airflow resistance rise after endotracheal intubation. Mechanical ventilation should be tailored according to pathophysiology of asthma: an adequate expiratory time should be setted in order to avoid a positive end-expiratory pressure due to expiratory airflow obstruction. Pain should be prevented and promptly controlled with a loco-regional anesthesia technique when it is possible. Potential allergic reactions to drugs or latex should always be considered during the whole perioperative period. Creating a serene atmosphere should be adopted as an important component of interventions in order to guarantee the best care to the asthmatic child.

Acetaminophen enhances pruritus in a mouse model of contact dermatitis induced by suboptimal concentration of hapten

Acetaminophen (APAP) is one of the most commonly used drugs worldwide to reduce fever, particularly in children. It is generally considered to be a safe drug. However, a number of studies have shown that regular use of APAP increases the risk of developing allergic diseases. Nonetheless, no animal models have been used to investigate these findings. Therefore, we aimed to create an animal model of APAP-induced pruritus in mice. APAP (0.25% and 0.5%) was administered via drinking water daily from infancy, and a suboptimal concentration of 2,4,6-trinitrochlorobenzene (TNCB) was applied repeatedly to each ear three times a week for 7 weeks to evoke chronic allergic contact dermatitis. Neither 0.25% nor 0.5% APAP was overtly hepatotoxic after 73 days of daily administration. Repeated challenge with TNCB evoked increase in the number of scratching bouts compared to day 1. This increase in the number of scratching bouts was significant in 0.25% and 0.5% APAP groups but not in the group treated with TNCB alone. Daily administration of 0.5% APAP significantly increased in the number of scratching bouts compared to TNCB alone on day 29. This animal model will be useful for investigating the mechanism underlying the increased risk of development of eczema caused by regular APAP use and for examining safer and more effective therapy with APAP.

The association of acetaminophen and asthma prevalence and severity

The epidemiologic association between acetaminophen use and asthma prevalence and severity in children and adults is well established. A variety of observations suggest that acetaminophen use has contributed to the recent increase in asthma prevalence in children: (1) the strength of the association; (2) the consistency of the association across age, geography, and culture; (3) the dose-response relationship; (4) the timing of increased acetaminophen use and the asthma epidemic; (5) the relationship between per-capita sales of acetaminophen and asthma prevalence across countries; (6) the results of a double-blind trial of ibuprofen and acetaminophen for treatment of fever in asthmatic children; and (7) the biologically plausible mechanism of glutathione depletion in airway mucosa. Until future studies document the safety of this drug, children with asthma or at risk for asthma should avoid the use of acetaminophen.

Early exposure to acetaminophen and allergic disorders

PURPOSE OF REVIEW

To summarize the data related to the association between acetaminophen and allergic diseases, and to try to establish a conclusion regarding the extent to which the association is unbiased and what its strength might be.

RECENT FINDINGS

Several studies have shown an association between acetaminophen use during pregnancy and allergic diseases in the offspring. Furthermore, this association has also been found between early exposure and recent exposure to the drug and several allergic conditions. However, other studies did not confirm those associations. Taken together, the available data suggest an unbiased but weak association between acetaminophen consumption and asthma/wheezing. Additional studies are needed to definitely confirm the association with rhinitis, eczema and sensitization.

SUMMARY

Although the use of acetaminophen is weakly associated with asthma/wheezing, the widespread use of the drug might have important public health implications. Thus, controlled studies to definitely establish not only causality but also the magnitude in which acetaminophen might increase allergic disorders are needed.

Frequent use of paracetamol and risk of allergic disease among women in an Ethiopian population

Introduction

The hypothesis that paracetamol might increase the risk of asthma and other allergic diseases have gained support from a range of independent studies. However, in studies based in developed countries, the possibility that paracetamol and asthma are associated through aspirin avoidance is difficult to exclude.

Objectives

To explore this hypothesis among women in a developing country, where we have previously reported aspirin avoidance to be rare.

Methods

In 2005/6 a population based cohort of 1065 pregnant women was established in Butajira, Ethiopia and baseline demographic data collected. At 3 years post birth, an interview-based questionnaire administered to 945 (94%) of these women collected data on asthma, eczema, and hay fever in the past 12 month, frequency of paracetamol use and potential confounders. Allergen skin tests to Dermatophagoides pteronyssinus and cockroach were also performed. The independent effects of paracetamol use on allergic outcomes were determined using multiple logistic regression analysis.

Findings

The prevalence of asthma, eczema and hay fever was 1.7%, 0.9% and 3.8% respectively; of any one of these conditions 5.5%, and of allergen sensitization 7.8%. Paracetamol use in the past month was reported by 29%, and associations of borderline significance were seen for eczema (adjusted OR (95% CI) = 8.51 (1.68 to 43.19) for 1–3 tablets and 2.19 (0.36 to 13.38) for ≥4 tablets, compared to no tablets in the past month; overall p = 0.055) and for ‘any allergic condition’ (adjusted OR (95% CI) = 2.73 (1.22 to 6.11) for 1–3 tablets and 1.35 (0.67 to 2.70) for ≥4 tablets compared to 0 in the past month; overall p = 0.071).

Conclusions

This study provides further cross-sectional evidence that paracetamol use increases the risk of allergic disease.

Paracetamol and antibiotics in childhood and subsequent development of wheezing/asthma: association or causation?

BACKGROUND

Several studies found an association between early administration of paracetamol and antibiotics and development of wheezing. This could be due to confounding: wheeze and asthmatic symptoms in early childhood are difficult to distinguish from respiratory tract infections that are widely treated with these drugs; in case of persistence of symptoms up to school age, this could explain the observed relationship.

METHODS

We investigated the association between paracetamol and antibiotics use in the first year of life and wheezing phenotypes, i.e. wheezing starting in different time periods (early, persistent and late-onset) in the SIDRIA-2 study, a cross-sectional survey of 16,933 children aged 6-7 years. Directed acyclic graph (DAG) was used to depict the causal structure.

RESULTS

Paracetamol and antibiotics administration in the first year were associated with early wheezing (first 2 years of life only) [odds ratio (OR): 2.27; 95% confidence interval (95% CI): 1.98-2.62 and OR = 3.76, 95% CI: 3.31-4.27] and with persistent wheezing (first 2 years + last 12 months) (OR = 1.77, 95% CI: 1.49-2.10 and OR = 3.06, 95% CI: 2.60-3.60), whereas the association with late-onset wheezing (in the last 12 months only) was weak (OR = 1.12, 95% CI: 0.97-1.31 and OR = 1.18, 95% CI: 1.02-1.38 for paracetamol and antibiotics, respectively). DAG shows that even in the absence of a direct (causal) arrow from early drugs use to wheezing at school age, the two are associated due to confounding (through the 'infection' node).

CONCLUSIONS

It is important to take into account different phenotypes in order to disentangle the association of paracetamol and antibiotics with wheezing.

The role of acetaminophen and geohelminth infection on the incidence of wheeze and eczema: a longitudinal birth-cohort study

RATIONALE

Acetaminophen has been hypothesized to increase the risk of asthma and allergic disease, and geohelminth infection to reduce the risk, but evidence from longitudinal cohort studies is lacking.

OBJECTIVES

To investigate the independent effects of these exposures on the incidence of wheeze and eczema in a birth cohort.

METHODS

In 2005-2006 a population-based cohort of 1,065 pregnant women from Butajira, Ethiopia, was established, to whom 1,006 live singleton babies were born. At ages 1 and 3, questionnaire data were collected on wheeze, eczema, child's use of acetaminophen, and various potential confounders, along with a stool sample for geohelminth analysis. Those without wheeze (n = 756) or eczema (n = 780) at age 1 were analyzed to determine the independent effects of geohelminth infection and acetaminophen use in the first year of life on the incidence of wheeze and eczema by age 3.

MEASUREMENTS AND MAIN RESULTS

Wheeze and eczema incidence between the ages of 1 and 3 were reported in 7.7% (58 of 756) and 7.3% (57 of 780) of children, respectively. Acetaminophen use was significantly associated with a dose-dependent increased risk of incident wheeze (adjusted odds ratio = 1.88 and 95% confidence interval 1.03-3.44 for one to three tablets and 7.25 and 2.02-25.95 for ≥ 4 tablets in the past month at age 1 vs. never), but not eczema. Geohelminth infection was insufficiently prevalent (<4%) to compute estimates of effect.

CONCLUSIONS

These findings suggest frequent acetaminophen use early in life increases the risk of new-onset wheeze, whereas the role of geohelminth infection on allergic disease incidence remains to be seen as the cohort matures.

Early exposure to paracetamol or to antibiotics and eczema at school age: modification by asthma and rhinoconjunctivitis

The association between early exposure to paracetamol or to antibiotics and eczema is conflicting. This study aims to know whether the early exposure to those drugs is associated with eczema at school age, and whether the strength of the association is modified by the presence of asthma or rhinoconjunctivitis. Children aged 6-7 (n = 13908) from the International Study of Asthma and Allergies in Childhood in Spain provided data about current asthma, rhinoconjunctivitis and eczema. Parent-reported information was also obtained on paracetamol and antibiotic consumption during the first year of life. Logistic regression analysis with eczema as outcome and including exposure to paracetamol or to antibiotics, together with possible confounders, was carried out in the whole sample of children and in five different strata: no respiratory symptom and any respiratory symptom further subdivided into: asthma with rhinoconjunctivitis, asthma without rhinoconjunctivitis and rhinoconjunctivitis without asthma. In the whole sample, exposure to paracetamol was associated with eczema (aOR 1.56 [1.36-1.80]) as was antibiotic consumption (aOR 1.66 [1.43-1.92]). These associations did not substantially change after additionally adjusting for the other drug. A similar pattern was found among children without respiratory symptoms. In children with symptoms, adjusting for the other drug modified the association with paracetamol (aOR from 1.32 [1.03-1.71] to 1.09 [0.83-1.43]) but did not change that with antibiotics (aOR from 1.80 [1.38-2.35] to 1.81 [1.37-2.39]). Early exposure to paracetamol or to antibiotics is associated with an increased prevalence of eczema at school age. Asthma and/or rhinoconjunctivitis substantially modifies this association.

Paracetamol use in early life and asthma: prospective birth cohort study

OBJECTIVE

To determine if use of paracetamol in early life is an independent risk factor for childhood asthma.

DESIGN

Prospective birth cohort study.

SETTING

Melbourne Atopy Cohort Study.

PARTICIPANTS

620 children with a family history of allergic disease, with paracetamol use prospectively documented on 18 occasions from birth to 2 years of age, followed until age 7 years.

MAIN OUTCOME MEASURES

The primary outcome was childhood asthma, ascertained by questionnaire at 6 and 7 years. Secondary outcomes were infantile wheeze, allergic rhinitis, eczema, and skin prick test positivity.

RESULTS

Paracetamol had been used in 51% (295/575) of children by 12 weeks of age and in 97% (556/575) by 2 years. Between 6 and 7 years, 80% (495/620) were followed up; 30% (148) had current asthma. Increasing frequency of paracetamol use was weakly associated with increased risk of childhood asthma (crude odds ratio 1.18, 95% confidence interval 1.00 to 1.39, per doubling of days of use). However, after adjustment for frequency of respiratory infections, this association essentially disappeared (odds ratio 1.08, 0.91 to 1.29). Paracetamol use for non-respiratory causes was not associated with asthma (crude odds ratio 0.95, 0.81 to 1.12).

CONCLUSIONS

In children with a family history of allergic diseases, no association was found between early paracetamol use and risk of subsequent allergic disease after adjustment for respiratory infections or when paracetamol use was restricted to non-respiratory tract infections. These findings suggest that early paracetamol use does not increase the risk of asthma.

Acetaminophen, via its reactive metabolite N-acetyl-p-benzo-quinoneimine and transient receptor potential ankyrin-1 stimulation, causes neurogenic inflammation in the airways and other tissues in rodents

Acetaminophen [N-acetyl-p-aminophenol (APAP)] is the most common antipyretic/analgesic medicine worldwide. If APAP is overdosed, its metabolite, N-acetyl-p-benzo-quinoneimine (NAPQI), causes liver damage. However, epidemiological evidence has associated previous use of therapeutic APAP doses with the risk of chronic obstructive pulmonary disease (COPD) and asthma. The transient receptor potential ankyrin-1 (TRPA1) channel is expressed by peptidergic primary sensory neurons. Because NAPQI, like other TRPA1 activators, is an electrophilic molecule, we hypothesized that APAP, via NAPQI, stimulates TRPA1, thus causing airway neurogenic inflammation. NAPQI selectively excites human recombinant and native (neuroblastoma cells) TRPA1. TRPA1 activation by NAPQI releases proinflammatory neuropeptides (substance P and calcitonin gene-related peptide) from sensory nerve terminals in rodent airways, thereby causing neurogenic edema and neutrophilia. Single or repeated administration of therapeutic (15-60 mg/kg) APAP doses to mice produces detectable levels of NAPQI in the lung, and increases neutrophil numbers, myeloperoxidase activity, and cytokine and chemokine levels in the airways or skin. Inflammatory responses evoked by NAPQI and APAP are abated by TRPA1 antagonism or are absent in TRPA1-deficient mice. This novel pathway, distinguished from the tissue-damaging effect of NAPQI, may contribute to the risk of COPD and asthma associated with therapeutic APAP use.