The acetaminophen enigma in asthma

Effects of disinfection by-products in swimming pool environments on the immunological mechanisms of respiratory diseases

Swimming in pools is a popular and healthy recreational activity. However, potential adverse health effects from disinfection byproduct (DBP) exposure in pool water are concerning. This study evaluated how such DBP exposure affects the respiratory system. DBP exposure was simulated with an animal-specific pool environment model. Experimental animals were exposed to DBPs for a specified duration and frequency over 4 weeks. The wet and dry weights of murine lungs were measured, with no significant differences observed. There were no significant differences in interkeukin (IL)-2/4/10, and interferon-γ levels. However, IL-6 expression decreased in the experimental group. To investigate the effects of DBP exposure on immune cell response, various samples, such as bronchoalveolar lavage fluid, lymph nodes, spleen, and thymus, were collected for T-cell isolation and fluorescence-activated cell sorting. Asthma-related blood cell distribution was analyzed using a complete blood count test; no significant differences were found. Thus, DBP exposure through this model did not induce substantial lung tissue damage, major alterations in cytokine expression (besides IL-6), significant immune cell responses, or changes in asthma-associated blood cell distribution. However, considering earlier results, future studies should focus on specific types, intensity, and duration of exercise that could affect DBP exposure-related immune-inflammatory responses.

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.

Prescribed analgesics in pregnancy and risk of childhood asthma

Many epidemiological studies have reported a positive association between prenatal exposure to paracetamol and childhood wheezing and asthma. We investigated whether the link between prenatal analgesic exposure and asthma/wheeze is specific to paracetamol, and whether it is causal or confounded.Using linked Swedish health register data we investigated the relation between various prescribed analgesics in pregnancy and the risk of childhood asthma/wheeze in a population of 492 999, and used negative paternal control and sibling comparison approaches to explore unmeasured confounding.After controlling for potential confounders, prescribed opioids, antimigraine drugs and paracetamol were all positively associated with childhood asthma/wheeze risk at all ages (e.g. for asthma/wheeze at age 4 years: adjusted OR 1.39 (95% CI 1.30-1.49), 1.19 (95% CI 1.01-1.40) and 1.47 (95% CI 1.36-1.59) for opioids, antimigraine drugs and paracetamol, respectively). The results of the paternal control analysis did not suggest the presence of unmeasured confounding by genetics or shared environment. However, the sibling control analysis broadly suggested that associations between prenatal exposure to the analgesics and asthma/wheeze were confounded by specific maternal factors (e.g. for asthma/wheeze at age 4 years: adjusted OR 0.91 (95% CI 0.62-1.31), 0.50 (95% CI 0.17-1.45) and 0.80 (95% CI 0.50-1.29) for opioids, antimigraine drugs and paracetamol, respectively).We propose that analgesic use in pregnancy does not cause childhood asthma/wheeze and that the association is confounded by unmeasured factors that are intrinsic to the mother, such as chronic pain or anxiety.

Prevalence and factors associated with adult bronchial asthma in Aseer region, Southwestern Saudi Arabia

BACKGROUND:

Bronchial asthma (BA) is one of the most common chronic respiratory diseases in Saudi Arabia (SA). Most of the studies investigating the prevalence of BA in SA have focused on children and its exact prevalence in adults is unknown.

OBJECTIVES:

The objective of this study is tto investigate the prevalence and factors associated with adult BA in Aseer region, southwestern SA.

METHODS:

A cross-sectional study was conducted on a representative sample of adults who attended primary health care centers. A validated Arabic version of the International Study of Asthma and Allergies in Childhood questionnaire was used. The presence of wheeze in the past 12 months was used as a proxy for BA.

RESULTS:

The study included 960 adults. The prevalence rate of BA was 19.2% (95% confidence interval [CI]: 16.72–21.80). In a multivariable analysis, the following factors were significantly associated with BA in adults; living in low-altitude areas (adjusted odds ratio [aOR] = 1.51, 95% CI: 1.04–2.21), being in rural areas (aOR = 1.58, 95% CI: 1.12–2.23), using analgesics (aOR = 1.52, 95% CI: 1.06–2.20), residing near heavy trucks traffics (aOR = 1.67, 95% CI: 1.13–2.46), having cats in the house (aOR = 2.27, 95% CI: 1.30–5.94), and being aged 55–64-year-old (aOR = 1.94, 95% CI: 1.02–3.69).

CONCLUSION:

The prevalence of BA was high, affecting one-fifth of adults in Aseer region. The study revealed some modifiable factors significantly associated with BA in adults. There is a need to improve asthma control programs at the primary health-care level, particularly at rural and at low-altitude areas, and more focus should address the elders. In addition, enhancing community-based health promotion programs tackling the identified modifiable factors of BA are required.

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.

Association of Acetaminophen and Ibuprofen Use With Wheezing in Children With Acute Febrile Illness

BACKGROUND

Many infants and children receive acetaminophen and/or ibuprofen during febrile illness. Previously, some studies have linked acetaminophen and ibuprofen use to wheezing and exacerbation of asthma symptoms in infants and children.

OBJECTIVE

To assess whether acetaminophen or ibuprofen use are associated with wheezing in children presenting to the emergency department (ED) with febrile illness.

METHODS

This was a cross-sectional study of children who presented with fever to the pediatric ED between 2009 and 2013. The data were collected from questionnaires and from the children's medical files. Patients with wheezing in the ED were compared with nonwheezing patients. Associations between medication use and wheezing were assessed using univariate and multivariate analyses. The multivariate analysis adjusted for potential confounding variables (ie, age, atopic dermatitis, allergies, smoking, antibiotics use, etc) via propensity scores.

RESULTS

During the study period, 534 children admitted to the ED met our inclusion criteria, of whom 347 (65%) were included in the study. The use of acetaminophen was similar in children diagnosed with wheezing compared with those without wheezing (n = 39, 81.3%, vs n = 229, 82.7%, respectively). Ibuprofen use was significantly lower in children diagnosed with wheezing (n = 22, 52.4%, vs n = 168, 69.4%, respectively). In multivariate analysis, acetaminophen was not associated with a higher rate of wheezing during acute febrile illness (adjusted odds ratio [OR] = 0.76, 95% CI = 0.24- 2.39), whereas ibuprofen was associated with a lower risk of wheezing (adjusted OR = 0.36, 95% CI = 0.13-0.96).

CONCLUSIONS

Our study suggests that acetaminophen and ibuprofen are not associated with increased risk for wheezing during acute febrile illness.

Effects of Acetaminophen on Oxidant and Irritant Respiratory Tract Responses to Environmental Tobacco Smoke in Female Mice

BACKGROUND

Although it is known that acetaminophen causes oxidative injury in the liver, it is not known whether it causes oxidative stress in the respiratory tract. If so, this widely used analgesic may potentiate the adverse effects of oxidant air pollutants.

OBJECTIVES

The goal of this study was to determine if acetaminophen induces respiratory tract oxidative stress and/or potentiates the oxidative stress and irritant responses to an inhaled oxidant: environmental tobacco smoke (ETS).

METHODS

Acetaminophen [100 mg/kg intraperitoneal (ip)] and/or sidestream tobacco smoke (as a surrogate for ETS, 5 mg/m3 for 10 min) were administered to female C57Bl/6J mice, and airway oxidative stress was assessed by loss of tissue antioxidants [estimated by nonprotein sulfhydryl (NPSH) levels] and/or induction of oxidant stress response genes. In addition, the effects of acetaminophen on airway irritation reflex responses to ETS were examined by plethysmography.

RESULTS

Acetaminophen diminished NPSH in nasal, thoracic extrapulmonary, and lung tissues; it also induced the oxidant stress response genes glutamate-cysteine ligase, catalytic subunit, and NAD(P)H dehydrogenase, quinone 1, in these sites. ETS produced a similar response. The response to acetaminophen plus ETS was equal to or greater than the sum of the responses to either agent alone. Although it had no effect by itself, acetaminophen greatly increased the reflex irritant response to ETS.

CONCLUSIONS

At supratherapeutic levels, acetaminophen induced oxidative stress throughout the respiratory tract and appeared to potentiate some responses to environmentally relevant ETS exposure in female C57Bl/6J mice. These results highlight the potential for this widely used drug to modulate responsiveness to oxidant air pollutants.

CITATION

Smith GJ, Cichocki JA, Doughty BJ, Manautou JE, Jordt SE, Morris JB. 2016. Effects of acetaminophen on oxidant and irritant respiratory tract responses to environmental tobacco smoke in female mice. Environ Health Perspect 124:642-650; http://dx.doi.org/10.1289/ehp.1509851.

A Randomized Placebo Controlled Trial of Ibuprofen for Respiratory Syncytial Virus Infection in a Bovine Model

Background

Respiratory syncytial virus (RSV) is the most common cause of bronchiolitis and hospital admission in infants. An analogous disease occurs in cattle and costs US agriculture a billion dollars a year. RSV causes much of its morbidity indirectly via adverse effects of the host response to the virus. RSV is accompanied by elevated prostaglandin E₂ (PGE₂) which is followed by neutrophil led inflammation in the lung. Ibuprofen is a prototypical non-steroidal anti-inflammatory drug that decreases PGE₂ levels by inhibiting cyclooxygenase.

Hypotheses

We hypothesized that treatment of RSV with ibuprofen would decrease PGE₂ levels, modulate the immune response, decrease clinical illness, and decrease the histopathological lung changes in a bovine model of RSV. We further hypothesized that viral replication would be unaffected.

Methods

We performed a randomized placebo controlled trial of ibuprofen in 16 outbred Holstein calves that we infected with RSV. We measured clinical scores, cyclooxygenase, lipoxygenase and endocannabinoid products in plasma and mediastinal lymph nodes and interleukin (Il)-4, Il-13, Il-17 and interferon-γ in mediastinal lymph nodes. RSV shedding was measured daily and nasal Il-6, Il-8 and Il-17 every other day. The calves were necropsied on Day 10 post inoculation and histology performed.

Results

One calf in the ibuprofen group required euthanasia on Day 8 of infection for respiratory distress. Clinical scores (p<0.01) and weight gain (p = 0.08) seemed better in the ibuprofen group. Ibuprofen decreased cyclooxygenase, lipoxygenase, and cytochrome P450 products, and increased monoacylglycerols in lung lymph nodes. Ibuprofen modulated the immune response as measured by narrowed range of observed Il-13, Il-17 and IFN-γ gene expression in mediastinal lymph nodes. Lung histology was not different between groups, and viral shedding was increased in calves randomized to ibuprofen.

Conclusions

Ibuprofen decreased PGE₂, modulated the immune response, and improved clinical outcomes. However lung histopathology was not affected and viral shedding was increased.

Clinical pharmacology of paracetamol in neonates: a review

Paracetamol is commonly used to control mild-to-moderate pain or to reduce opioid exposure as part of multimodal analgesia, and is the only compound recommended to treat fever in neonates. Paracetamol clearance is lower in neonates than in children and adults. After metabolic conversion, paracetamol is subsequently eliminated by the renal route. The main metabolic conversions are conjugation with glucuronic acid and with sulphate. In the urine of neonates sulphated paracetamol concentration is higher than the glucuronidated paracetamol level, suggesting that sulfation prevails over glucuronidation in neonates. A loading dose of 20 mg/kg followed by 10 mg/kg every 6 hours of intravenous paracetamol is suggested to achieve a compartment concentration of 11 mg/L in late preterm and term neonates. Aiming for the same target concentration, oral doses are similar with rectal administration of 25 to 30 mg/kg/d in preterm neonates of 30 weeks' gestation, 45 mg/kg/d in preterm infants of 34 weeks' gestation, and 60 mg/kg/d in term neonates are suggested. The above-mentioned paracetamol doses for these indications (pain, fever) are well tolerated in neonates, but do not result in a significant increase in liver enzymes, and do not affect blood pressure and have limited effects on heart rate. In contrast, the higher doses suggested in extreme preterm neonates to induce closure of the patent ductus arteriosus have not yet been sufficiently evaluated regarding efficacy or safety. Moreover, focussed pharmacovigilance to explore the potential causal association between paracetamol exposure during perinatal life and infancy and subsequent atopy is warranted.

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).

Randomized controlled trial of asthma risk with paracetamol use in infancy--a feasibility study

BACKGROUND

There is non-experimental evidence that paracetamol (acetaminophen) use may increase the risk of developing asthma. However, numerous methodological issues need to be resolved before undertaking a randomized controlled trial to investigate this hypothesis.

OBJECTIVE

To establish the feasibility of a randomized controlled trial of liberal paracetamol as usually given by parents/guardians vs. a comparator (restricted paracetamol in accordance with WHO guidelines, ibuprofen or placebo), and childhood asthma risk.

METHODS

Questionnaires were completed by parents/guardians of infants admitted to Wellington Hospital with bronchiolitis to assess views about comparator treatments. Subsequently, infants of parents/guardians who provided informed consent were randomized to restricted or liberal paracetamol use for 3 months with paracetamol use recorded.

RESULTS

Of 120 eligible participants, 72 (60%) parents/guardians completed the questionnaire. Ibuprofen, restricted paracetamol and placebo were acceptable to 42 (58%), 29 (40%) and 9 (12%) parents/guardians, respectively. 36 (30%) infants were randomized to restricted or liberal paracetamol. Paracetamol use was greater for the liberal vs. restricted group for reported [Hodges-Lehmann estimator of difference 0.94 mg/kg/day (95% CI 0.2-3.52), P = 0.02] and measured use [Hodges-Lehmann estimator of difference 2.11 mg/kg/day (95% CI 0.9-4.18), P = 0.004]. The median reported and measured use of paracetamol was 2.0-fold and 3.5-fold greater in the liberal vs. restricted group.

CONCLUSIONS AND CLINICAL RELEVANCE

Although separation in paracetamol dosing is likely to be achieved with a liberal vs. restricted paracetamol regime, ibuprofen is the preferred comparator treatment in the proposed RCT of paracetamol use and risk of asthma in childhood.

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.

Risk factors for eczema in infants born in Cuba: a population-based cross-sectional study

Background

There is a concern that allergic disease in childhood is higher than expected in Cuba. The aim of this study was to determine the risk factors for eczema of infants aged 12–15 months living in Havana.

Methods

We used a cross-sectional epidemiological study design. Data on eczema symptoms and a wide range of lifestyle factors were collected by researcher administered questionnaires.

Results

Data were collected on 1956 children (96% response rate), of whom 672 (34%) were reported as having had eczema. Independent risk factors for eczema included young maternal age (adjusted odds ratio (OR) 0.98 per additional year of age; 95% confidence interval (CI) 0.97-0.99), child’s weight (OR 1.13 per additional kg; 95% CI: 1.03-1.25), insect sting allergy (OR 2.11; 95% CI: 1.33-3.35), rodents in the home (OR 1.39; 95% CI: 1.10-1.76), attendance at childcare facilities (OR 1.34: 95% CI: 1.05-1.70) and self-reported mould in the home (OR 1.23; 95% CI: 1.07-1.41). Infant exposure to paracetamol was associated with an increased risk of eczema even after adjustment for wheeze (OR 1.22; 95% CI: 1.03-1.46).

Conclusion

Despite a very different culture and environment, the consistency of these findings with those from more economically developed countries suggests potential causal associations. The association with paracetamol, even after adjustment for wheeze, suggests that intervention studies are required in young infants, to ascertain if this commonly used anti-pyretic medication increases allergic disease.

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.

Asthma management in sickle cell disease

Asthma is a common comorbid factor in sickle cell disease (SCD). However, the incidence of asthma in SCD is much higher than expected compared to rates in the general population. Whether "asthma" in SCD is purely related to genetic and environmental factors or rather is the consequence of the underlying hemolytic and inflammatory state is a topic of recent debate. Regardless of the etiology, hypoxemia induced by bronchoconstriction and inflammation associated with asthma exacerbations will contribute to a cycle of sickling and subsequent complications of SCD. Recent studies confirm that asthma predisposes to complications of SCD such as pain crises, acute chest syndrome, and stroke and is associated with increased mortality. Early recognition and aggressive standard of care management of asthma may prevent serious pulmonary complications and reduce mortality. However, data regarding the management of asthma in SCD is very limited. Clinical trials are needed to evaluate the effectiveness of current asthma therapy in patients with SCD and coincident asthma, while mechanistic studies are needed to delineate the underlying pathophysiology.

Acetaminophen (paracetamol)

Therapeutic Reviews aim to provide essential independent information for health professionals about drugs used in palliative and hospice care. Additional content is available on www.palliativedrugs.com. Country-specific books (Hospice and Palliative Care Formulary USA, and Palliative Care Formulary, British and Canadian editions) are also available and can be ordered from www.palliativedrugs.com. The series editors welcome feedback on the articles (hq@palliativedrugs.com).

The association between acetaminophen and asthma: should its pediatric use be banned?

During the last few decades, a huge epidemiological effort has been made all over the world in order to cast some light on the origin of asthma (or 'wheezing disorders' as a general term) and its recent increase in prevalence. The focus on genetic factors has failed to show any genetic signal strong enough to be seriously considered, and the tiny genetic signals found have never been appropriately replicated. The focus on environmental factors has provided some variable signals on the role of infections, allergens and bacterial substances, the direction of which have curiously varied from protecting to inducing asthma. The only environmental factor that has launched a large and consistent epidemiological signal, found in almost every epidemiological study addressing the issue, is previous acetaminophen exposure, which consistently increases the prevalence and clinical manifestations of every wheezing disorder under study. Is acetaminophen a real asthma promoter or an innocent bystander?

Acetaminophen and asthma

Acetaminophen is a widely used medication for the treatment of pain and fever in children and pregnant women. There is substantial epidemiological evidence in adults and children that acetaminophen use is associated with asthma symptoms. There is also a considerable body of evidence that supports a modest but consistent association of acetaminophen use in pregnancy and early infancy with asthma in later childhood. This relationship is robust to adjustment for a large range of potential confounding factors and, in some studies, shows clear evidence of a dose-dependent association but the possibility of confounding by indication has remained a concern. However, the epidemiological evidence is now compelling and there is a clear need to establish causation so that appropriate advice and interventions can be developed for children at risk of asthma. This requires randomised trials of analgesics and antipyretics, including acetaminophen, in a variety of clinical settings.

The effect of a single dose of acetaminophen on airways response in children with asthma

Accumulating evidence suggests that the use of acetaminophen increases the risk of developing asthma and that its widespread use has contributed to the increasing prevalence of asthma.

STUDY DESIGN

To investigate the immediate effect of a single dose of acetaminophen on airways reactivity and inflammation in asthmatic and controls. A double blind placebo-controlled study was conducted on 42 asthmatic children and 21 healthy age-matched controls. Each participant received one oral dose of acetaminophen (15 mg/kg [160 mg/mL]) and one dose of a volume-matched placebo. Physical examination, spirometry results, and fractional exhaled nitric oxide levels were assessed before and 60 minutes following acetaminophen or placebo ingestion.

RESULTS

None of the studied variables showed any significant change after acetaminophen or placebo ingestion in either the asthmatic or the control groups.

CONCLUSIONS

One single dose of acetaminophen neither evokes a bronchoconstriction response nor an increase in airway inflammation in children with asthma.

Pharmacokinetics and pharmacodynamics of intravenous acetaminophen in neonates

Effective analgesia in neonates is still hampered owing to a lack of data on pharmacokinetics and pharmacodynamics of analgesics. In this article, the consecutive steps taken to document aspects of disposition (pharmacokinetics and metabolism) and safety (hepatic tolerance, hemodynamic stability and effects on body temperature) during exposure to intravenous acetaminophen in neonates are summarized. Based on these data, dosing suggestions were formulated. However, we have to be aware that such dosing suggestions are - at present - without any validated pharmacodynamic correlates since the applicability of a fixed acetaminophen target concentration (10 mg·l(-1)) in neonates of different subpopulations remains to be documented. In addition, the number of observations in extreme preterm neonates is limited. Finally, epidemiological data suggest a link between perinatal acetaminophen exposure and an increased risk to developing asthma. Consequently, well designed and appropriately powered pharmacodynamic studies in neonates are urgently required, with specific emphasis on extreme preterm neonates.

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.