Leukotriene modifiers and Churg-Strauss syndrome: adverse effect or response to corticosteroid withdrawal?

Is Leukotriene Receptor Antagonist the Direct Cause of Churg-Strauss Syndrome in Asthmatic Patients?

One of the main reasons for continuous, persistent asthma is when there is a change in the structure of the airways and the Lung parenchyma. These persistent changes bring a much worse prognosis to asthmatic conditions and predispose the situation to severe asthmatic syndromes such as Churg-Strauss syndrome (CSS). CSS is an inflammation of systemic blood vessels and is a rare disorder that can be suspected in long-standing asthmatic patients. Leukotriene antagonists receptor antagonists (LTRA) have been used to treat asthma along with tapering steroids. But after the introduction of LTRA therapy in these patients suggests a causal relation between LTRA initiation and the development of CSS, or it is an unmasking of CSS as the dose of steroid tapers down with LTRA therapy. This review highlights the relationship between leukotriene antagonists and the pathogenesis of CSS. It summarizes the current literature regarding the development of CSS with the initiation of LTRA therapy on asthmatic patients. The literature on this topic was reviewed using different research/article searches, manual library searches, conference abstracts, and internet searches.

Environmental risk factors associated with ANCA associated vasculitis: A systematic mapping review

BACKGROUND

Anti-neutrophil cytoplasm antibody (ANCA)-associated vasculitis (AAV) is a rare multi-system autoimmune disease, characterised by a pauci-immune necrotising small-vessel vasculitis, with a relapsing and remitting course. Like many autoimmune diseases, the exact aetiology of AAV, and the factors that influence relapse are unknown. Evidence suggests a complex interaction of polygenic genetic susceptibility, epigenetic influences and environmental triggers. This systematic mapping review focuses on the environmental risk factors associated with AAV. The aim was to identify gaps in the literature, thus informing further research.

METHODS

Articles that examined any environmental risk factor in AAV disease activity (new onset disease or relapse) were included. Studies had to make explicit reference to AAV, which includes the 3 clinico-pathological phenotypes (GPA, MPA and EGPA), rather than isolated ANCA-positivity. All articles identified were English-language, full manuscripts involving adult humans (>16 years). There was no restriction on publication date and all study designs, except single case reports, were included. The systematic search was performed on 9th December 2019, using the following databases: EMBASE, Medline (Ovid), Cochrane Library, CINAHL and Web of Science.

RESULTS

The search yielded a total of 2375 articles. 307 duplicates were removed, resulting in the title and abstract of 2068 articles for screening. Of these, 1809 were excluded. Thus, 259 remained for full-text review, of which 181 were excluded. 78 articles were included in this review. The most notable findings support the role of various pollutants - primarily silica and other environmental antigens released during natural disasters and through farming. Assorted geoepidemiological triggers were also identified including seasonality and latitude-dependent factors such as UV radiation. Finally, infection was tightly associated, but the exact microorganism(s) is not clear - Staphylococcus aureus is the most presently convincing.

CONCLUSION

The precise aetiology of AAV has yet to be elucidated. It is likely that different triggers, and the degree to which they influence disease activity, vary by subgroup (e.g. ANCA subtype, geographic region). There is a need for more interoperable disease registries to facilitate international collaboration and hence large-scale epidemiological studies, with novel analytical techniques.

Side Effects of Leukotriene Receptor Antagonists in Asthmatic Children

Background:

Leukotriene receptor antagonists (LTRAs) are drugs which have been widely used more than ten years. As the use of LTRAs increases, our knowledge with respect to their side effects increases as well.

Objectives:

The objective of our study was to evaluat the observed side effects of LTRAs used in patients with astma.

Patients and Methods:

1024 patients treated only with LTRAs owing to asthma or early wheezing were included in the study for a five-year period. The observed side effects of LTRAs in these patients were retrospectively investigated. The side effects were divided into two parts as psychiatric and non-psychiatric.

Results:

Among the 1024 cases included in the study, 67.5% of the patients out of 41 with side effects were male, 32.5% were female and the average age was 6.5 years. The rate of patients with asthma was 63.41% and 36.58% of the patients had early wheezing. It was determined that sex, age and diagnosis (early wheezing or asthma) of the patients were ineffective in the emergence of side effects. The average period for the emergence of side effects was the first month. It was observed that hyperactivity was the most frequently observed psychiatric side effect and that abdominal pain was the non-psychiatric side effect.

Conclusions:

The side effects of LTRAs were common in children. Therefore, patients must be informed at the beginning of the treatment and they must be evaluated at certain intervals.

Qingfei Xiaoyan Wan alleviates asthma through multi-target network regulation

BACKGROUND

Qingfei Xiaoyan Wan (QFXY), a traditional Chinese formula, is widely used for relieving cough, asthma, upper respiratory tract infection, bronchitis, pneumonia, and etc. in clinic. Comparing with other anti-asthma drugs, it is characterised with moderate and persistent efficacy as well as few side effects, however, the underlying action mechanism still remains elusive. This study aimed to identify QFXY multi-target network regulation as an asthma controller.

METHODS

This study established asthma model induced by histamine phosphate and acetylcholine chloride (His&Ach) in guinea pigs, which then were administered orally with QFXY. Hematoxylin-Eosin staining sections were applied for evaluating QFXY effect. In both Model and QFXY groups, customized microarrays and 2D electrophoresis were adopted to detect differentially expressed genes (diff genes) and proteins (diff proteins) respectively, and some diff proteins were identified with MALDI-TOF/MS. The checked diff genes and proteins underwent Cluster, GO and KEGG analysis. Based on GAD and HPRD databases, QFXY-asthma target regulation network was constructed.

RESULTS

His&Ach-induced asthma model of guinea pigs was established. HE sections presented anti-inflammation and anti-remodelling effects of QFXY. Comparing with the Model group, 55 diff genes and 6 diff proteins were identified in QFXY group. Validation by qPCR and Western blot showed the microarray and 2D data reliable. Furthermore, QFXY-asthma target regulation network was achieved.

CONCLUSIONS

A primarily combined genomic and proteomic screening of QFXY targets displayed a series of candidate genes and proteins, which indicated that the effect of QFXY relied on the combined mechanism, anti-inflammation and anti-remodelling, as well as influencing signal transduction in vivo.

Treatment options for the management of exercise-induced asthma and bronchoconstriction

Treatment for exercise-induced bronchospasm and exercise-induced asthma includes both pharmacologic and nonpharmacologic options. Pharmacologic agents that have been proven to be effective for treating these conditions include short- and long-acting β2-adrenoceptor agonists, mast cell-stabilizing agents, anticholinergics, leukotriene receptor antagonists, and inhaled corticosteroids (ICS). When selecting the most appropriate medication, factors to consider include the effectiveness of each, the duration of action, frequency of administration, potential side effects, and tolerance level. Long-acting β2-adrenoceptor agonists should not be used without ICS. Nonpharmacologic treatments include physical conditioning, incorporating a warm-up before and a cool-down period after exercise, performing nasal breathing, avoiding cold weather or environmental allergens, using a face mask or other aid to warm and humidify inhaled air, and modifying dietary intake. The data to support nonpharmacologic treatments are limited; however, they are routinely recommended because of the low risk associated with their use. This article highlights the advantages and limitations of each treatment option.

Vasculitis of the upper and lower airway

The pulmonary vasculitides are a heterogeneous group of rare disorders that result from an inflammatory process damaging the vessel wall and consequent impaired blood flow, ischaemia and tissue necrosis. The clinical manifestation of these vasculitides depends on the site, size, type and severity of the inflammatory process. Vasculitis involving the airways is a common feature of the anti-neutrophil cytoplasmic antibody (ANCA)-associated systemic vasculitides (AASVs) and can predate the diagnosis by years. Secondary causes of vasculitis associated with connective tissue disorders are also capable of presenting with pulmonary features. Recognition of involvement, investigation and treatment are important to ameliorate symptoms for patients. This article concentrates on the assessment and specific management of upper and lower airway problems of AASV.

Churg-strauss syndrome in patients treated with omalizumab

BACKGROUND

Churg-Strauss syndrome (CSS) is a rare systemic vasculitis associated with asthma, eosinophilia, sinusitis, and pulmonary infiltrates. CSS has been reported in association with asthma therapies.

MATERIALS AND METHODS

The objective is to describe the characteristics of CSS in patients treated with the anti-IgE antibody omalizumab (Xolair; Genentech Inc; South San Francisco, CA). A retrospective review of available data to identify cases of CSS was performed using the Novartis Argus global drug safety database for omalizumab in asthma patients.

RESULTS

We identified 34 potential cases of CSS. Of these, 13 cases fulfilled at least four of the six criteria identified in the American College of Rheumatology classification criteria. Eight of the patients in these 13 definite or probable cases (62%) had CSS symptoms prior to receiving omalizumab or described symptom onset just after corticosteroid weaning. Six of the 13 patients (46%) were confirmed as having been treated with corticosteroids for what was perceived to be severe asthma; when corticosteroids were tapered in conjunction with omalizumab treatment, CSS symptoms appeared just after the tapering. There were 4 other cases of possible CSS, and the remaining 17 patients were judged to not have CSS.

CONCLUSIONS

CSS may develop in patients receiving asthma medications who have an underlying eosinophilic disorder that is unmasked by the withdrawal of therapy with corticosteroids, or in patients who delay therapy in favor of other medications. Omalizumab treatment may unmask CSS due to the weaning of corticosteroids in some asthma patients or may delay corticosteroid treatment allowing for CSS to manifest.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT00252135.

Fluticasone-associated cutaneous allergic granulomatous vasculitis: an underrecognized but important cause of drug-induced cutaneous Churg-Strauss syndrome

Allergic granulomatous vasculitis, or Churg-Strauss syndrome, is a small vessel, multisystem vasculitis that can affect multiple organs. It is usually idiopathic, but recent case reports have implicated leukotriene receptor antagonists (LTRA) and inhaled corticosteroids in the development of this rare syndrome. We report a case that acutely developed skin-limited Churg Strauss-like cutaneous allergic granulomatous vasculitis after initiating therapy with inhaled fluticasone and salmeterol for poorly controlled asthma symptoms. Our result thus highlights the importance of keeping the differential diagnosis of drug-induced Churg-Strauss syndrome in patients who have recently been prescribed inhaled steroids like fluticasone when they present with rashes of varying severity.

Pulmonary Eosinophilic Syndromes

Acute eosinophilic pneumonia, chronic eosinophilia, Churg-Strauss syndrome, and the hypereosinophilic syndrome are pulmonary eosinophilic syndromes characterized by an increased number of eosinophils in peripheral blood, in lung tissue, in sputum, in bronchoalveolar lavage fluid, or in all of these. These pulmonary eosinophilic syndromes generally are characterized by increased respiratory symptoms, abnormal radiographic appearance, and the potential for systemic manifestations. It is critical to exclude other causes of eosinophilia in patients who have lung disease, to make a quick diagnosis, and to treat aggressively with corticosteroids and other therapies to prevent long-term sequelae.

Pregnancy and vasculitis

Until recently, the prognosis associated with many forms of systemic vasculitis was quite grim. Advances in this field have allowed us to begin to focus on issues related to quality of life such as fertility, conception, and pregnancy among women with vasculitis. Because the systemic vasculitides are rare diagnoses, many important questions remain unanswered. Overall, it seems that women who have inactive vasculitis may not be subject to unusual complications during pregnancy, but our understanding of the interaction between pregnancy and specific forms of vasculitis continues to evolve.

Safety of Zafirlukast

OBJECTIVES

A prescription event monitoring (PEM) postmarketing surveillance study was carried out to examine the safety of zafirlukast as used in general practice in England.

METHODS

Exposure data were obtained from the first National Health Service (NHS) prescription dispensed for patients whose prescription details were processed by the Prescription Pricing Authority between August 1998 and December 2000. Outcome data were obtained from 'green form' questionnaires sent to general practitioners (GPs) at least 6 months following the first prescription issued. Incidence densities (IDs) were calculated for events reported per 1000 months of patient exposure and ID differences between the first month of treatment and months 2-6 combined were analysed. Events of medical interest were followed up by postal questionnaire sent to GPs.

RESULTS

21 557 green forms were sent to 8051 doctors, of which 9124 (42.3%) were returned. Useful clinical data was obtained for 7976 patients of which 4664 (58.5%) were female and 3265 (40.9%) were male. The patient's sex was not specified in 47 (0.6%) forms. The median age of the cohort was 53 years (interquartile range 38-66 years). The most frequently reported primary indication was the licensed indication of asthma, but for a small proportion of the cohort it was prescribed 'off label'.A total of 152 events in 120 (1.5%) patients were reported as adverse drug reactions (ADRs) by GPs on the green forms. ADRs with the highest reported frequency were headache and nausea. There were 3514 reasons for stopping zafirlukast in 3148 (39.5%) patients, the most frequently reported of which was that the drug was 'ineffective' (2008 patients; 25.2%). The most frequently reported specified clinical reason for stopping was headache (82 patients; 1.0%). There were 28 pregnancies reported in this cohort, 20 of which were reported to have exposure to zafirlukast during the first trimester. Nine live births with no recorded congenital abnormalities were reported for pregnancies with exposure in the first trimester. There were 151 deaths reported during the study period (1.9%). The most frequently reported causes of death were related to the respiratory system (57; 37.7%), including chronic obstructive pulmonary disease, asthma and bronchopneumonia.

CONCLUSION

This study showed that zafirlukast, as used in general practice in England, is a generally well tolerated drug with few associated adverse events.

Cost effectiveness of leukotriene modifiers in adults with asthma

Asthma is the most common chronic disorder in industrialised nations, with over 100 million people worldwide affected. Leukotrienes are chemical mediators released from mast cells, eosinophils and basophils. They cause bronchoconstriction, an increase in mucous secretions and activation of inflammatory cells. Leukotriene modifiers are a long-term controller medication used to treat asthma. They function by selectively competing for the leukotriene receptor sites, thereby blocking their action, or by inhibiting 5-lipoxygenase and thus preventing leukotriene formation. Both current US and Global Initiative for Asthma treatment guidelines have clarified the role of leukotriene modifiers in the management of asthma in adults and children. Leukotriene modifiers have two distinct roles: to replace inhaled corticosteroids in milder asthma and as an add-on therapy to inhaled corticosteroids in more severe asthma. While efficacy is certainly an important issue, economic considerations are also important in a disease such as asthma where there are a variety of treatment options and the severity of the disease varies widely. This review examined published studies to better understand the cost effectiveness of leukotriene modifiers in adults with asthma. Fifteen articles were found that analysed the cost effectiveness of leukotriene modifiers, with almost all performed in the US. The vast majority of the studies were retrospective claims analyses, but three randomised controlled trials incorporating economic outcomes have been reported. The majority of the articles found that for both monotherapy in mild persistent asthma and add-on therapy in moderate persistent asthma, leukotriene modifiers were less cost effective than inhaled corticosteroids with or without a long-acting beta2-adrenoceptor agonist. However, these results must be viewed cautiously as in several studies there were methodological issues such as comparisons of unequal treatment groups or inappropriate use of leukotriene modifiers in stepwise treatment.

An update of the leukotriene modulators for the treatment of asthma

Bronchial asthma is a chronic inflammatory airway disease involving many cells and mediators. Chronic inflammation constitutes an important predisposing condition for airway remodelling with secondary irreversible airflow obstruction. Current approaches for asthma treatment involve many classes of drugs, adequate patient education for their correct use, environmental exposure control and daily monitoring of pulmonary function. Unfortunately, the use of multiple therapies complicates treatment regimens, thus leading to a reduced compliance to therapy. Available evidence from randomised clinical trials and real-word experience derived from managing patients with asthma justifies a broader role for leukotriene receptor antagonist drugs in asthma management than that recommended in the National Asthma Education and Prevention Programme and National Health Lung and Blood Institute Treatment Guidelines. While a low dose of inhaled corticosteroids remains the reference drug as a controller in mild-to-moderate persistent asthma, oral therapy with an leukotriene-receptor antagonist drug represents a good option providing the clinical efficacy requested in common clinical practice. For this reason the recent Global Initiative for Asthma Guidelines allocate this drug to the second and third steps of asthma treatment.

The challenge of mild persistent asthma

OBJECTIVE

To review the current data and treatment options for mild persistent asthma.

DATA SOURCES

A MEDLINE search was performed for relevant articles.

STUDY SELECTION

The expert opinion of the author was used to select studies for inclusion in this review.

RESULTS

Current data suggest that asthma severity is determined early in life and that disease progression may not occur outside early childhood. Furthermore, no therapy has been demonstrated to clearly prevent or reverse structural airway changes in patients with persistent asthma. Thus, the primary goal of asthma therapy is to prevent disease exacerbations rather than to halt disease progress, at least in patients past early childhood. Published reports of severe exacerbations in patients with reported mild asthma may actually reflect inclusion of patients with more severe forms of the disease who were inappropriately classified in terms of asthma severity.

CONCLUSION

Unlike the case for moderate and severe asthma, where regular therapy with inhaled corticosteroids is clearly the treatment of choice, clear guidelines for treating patients with mild persistent asthma have not been established. Patients with mild disease without severe exacerbations may require only the minimum therapy necessary for disease control.

The linkage between Churg-Strauss syndrome and leukotriene receptor antagonists: fact or fiction?

Epidemiologic evidence has shown that the worldwide prevalence of asthma is increasing. The leukotriene receptor antagonists (LTRAs) represent a new class of therapy for asthma. They have been developed in the last decade and play a pivotal steroid-sparing role in treating the inflammatory component of asthma. Consequently, reports of Churg-Strauss syndrome (CSS), a rare form of systemic vasculitis, have been recognized as a potential side effect in individuals with moderate to severe asthma on LTRA therapy. The serious nature of this disorder is worthy of prompt recognition by clinicians and aggressive therapy to avoid the subsequent longstanding effects of vasculitis. To validate the postulated linkage between the LTRAs and CSS, this review comprehensively evaluates reported cases in the literature and supports a pathophysiological relationship between the LTRAs and the development of CSS.

Association of asthma therapy and Churg-Strauss syndrome: an analysis of postmarketing surveillance data

BACKGROUND

Churg-Strauss syndrome (CSS), also known as allergic granulomatous angiitis (AGA), is a rare vasculitis that occurs in patients with bronchial asthma. The nature of the association of CSS with various asthma therapies is unclear.

OBJECTIVE

This study investigated the associations of different multidrug asthma therapy regimens and the reporting of AGA (the preferred code for CSS in the coding dictionary for the Adverse Event Reporting System [AERS]) by applying an iterative method of disproportionally analysis to th AERS database maintained by the US Food and Drug Administration.

METHODS

The public-release version of the AERS database was used to identify reports of AGA in patients receiving asthma therapy. Reporting of AGA was examined using iterative disproportionality methods in patients receiving > or =1 of the following drug classes: inhaled corticosteroid (ICS), leukotriene receptor antagonist (LTRA), short-acting beta(2)-agonist (SABA), or long-acting beta(2)-agonist (LABA). The Bayesian data-mining algorithm known as the multi-item gamma poisson shrinker was used to determine the relative reporting rates by calculation of the empirical Bayes geometric mean (EBGM) and its 90% CI (EB05 = lower limit and EB95 = upper limit) for each drug. Subset analyses were performed for each drug with different medication combinations to differentiate the relative reporting of AGA for each.

RESULTS

A strong association was found between LTRA use and AGA (EBGM = 104.0, EB05 = 95.0, EB95 = 113.8) that persisted with all combinations of therapy studied. AGA was also associated with the ICS, SABA and LABA classes (EBGM values of 27.8, 14.6 and 40.4, respectively). However, the latter associations were mostly dependent on the presence of concurrent LTRA and, to a lesser extemt, oral corticosteroid therapy and became negligible (ie, EB05 < 2) for patients who were not receiving these concurrent treatments.

CONCLUSIONS

Differences based on relative reporting were observed in the patterns of association of AGA with LTRA, ICS, and beta(2)-agonist therapies. A strong association between LTRA use and AGA was present regardless of the use of other asthma drugs.

Churg-Strauss Syndrome Development during Asthma Therapy with Leukotriene Receptor Antagonists: Just a Coincidental Association?

A report on our clinical experience based on 3 male patients who developed Churg-Strauss syndrome (CSS) after standard oral montelukast use. All patients affected by moderate asthma and chronic hyperplastic rhinosinusitis were treated with inhaled corticosteroids and ß2 agonists. Systemic corticosteroid treatment consisted in oral daily prednisone in case 1, in short courses of oral betamethasone in case 2, and in remote and isolated administrations of oral betamethasone and intramuscular methylprednisolone in case 3. Because of the improvement of the asthma symptoms after montelukast use, patient 1 decided to take half the dose of prednisone for 10 days and patient 2 decided to discontinue systemic and inhaled corticosteroids for 45 days. Overt CSS was heralded by vasculitic skin lesions and developed in each patient with severe organ damage, consisting in renal, myocardial and gastrointestinal involvement. Remission was obtained by standard CSS therapy after montelukast withdrawal.

According to the unmasking hypothesis, antileukotriene treatment, by enabling the reduction in systemic corticosteroid therapy in case 1 and its discontinuation in case 2, might have only permitted the precipitation of the vasculitis. However antileukotriene-associated CSS reportedly occurred in systemic corticosteroid-naïve patients and relapsed in one patient after antileukotriene treatment. These observations lend support to the concept that the precipitation of the vasculitic phase may be associated with leukotriene modifier deleterious effects. In conclusion there is not enough evidence to prove that antileukotriene treatment plays a direct causative role in the pathogenesis of CSS. Further clinical and experimental research is required to clarify the antileukotriene associated CSS controversy.

Montelukast-induced generalized urticaria

OBJECTIVE

To report a case of generalized urticaria induced by montelukast treatment.

CASE SUMMARY

A 28-year-old man with allergic rhinitis and moderate persistent asthma developed generalized urticaria 5 days after the initiation of montelukast and inhaled fluticasone. Symptoms disappeared within one day after suspension of both drugs. Two months later, after the resumption of montelukast and fluticasone, the patient developed generalized urticaria and eyelid angioedema, which were successfully treated with intravenous betamethasone, achieving complete remission within hours. After 2 days, the patient resumed inhaled fluticasone only and continued this therapy for several months without any adverse reaction.

DISCUSSION

We attributed the adverse reaction to montelukast because of the temporal relationship between use of montelukast and urticaria, the absence of other identified causative factors and other explanations for allergic reactions, and the positive dechallenge and rechallenge. The Naranjo probability scale showed a probable relationship between skin manifestations and montelukast treatment.

CONCLUSIONS

The use of antileukotrienes is increasing in asthma therapy. In cases of generalized urticaria in asthmatic patients undergoing montelukast therapy, physicians should be aware of a potential adverse reaction to this drug.

Recent advances in the management of asthma using leukotriene modifiers

Asthma is a chronic inflammatory disease of the airways that affects approximately 100 million people worldwide. In order to reduce symptoms, improve pulmonary function, and decrease morbidity, current treatment guidelines emphasize the importance of controlling the underlying inflammation in patients with asthma. Leukotrienes are leukocyte-generated lipid mediators that promote airway inflammation. Recognition of the importance of leukotrienes in the pathogenesis of asthma has led to the development of leukotriene modifiers, the first new class of drugs for the treatment of asthma to become available in 25 years. Controlled clinical trials with the four currently used leukotriene modifiers (montelukast, zafirlukast, and zileuton in the US and pranlukast in Japan) have established their efficacy in improving pulmonary function, reducing symptoms, decreasing night-time awakenings, and decreasing the need for rescue medications. They exert anti-inflammatory effects that attenuate cellular infiltration and bronchial hyperresponsiveness and complement the anti-inflammatory properties of inhaled corticosteroids. In patients with moderate and severe asthma, they permit tapering of the corticosteroid dose. In patients with exercise-induced asthma, leukotriene modifiers limit the decline in and quicken the recovery of pulmonary functions without the tolerance issues seen with chronic long-acting beta(2)-adrenoceptor agonist use. In patients with aspirin (acetylsalicylic acid)-induced asthma, they improve pulmonary function and shift the dose response curve to the right, reducing the patient's response to aspirin. In patients with seasonal allergic rhinitis, with or without concomitant asthma, they improve nasal, eye, and throat symptoms as well as quality of life. Leukotriene modifiers are generally safe and well tolerated with adverse effect profiles similar to that of placebo. The one safety issue raised with leukotriene modifiers, Churg-Strauss Syndrome, appears to be the unmasking of an already present syndrome that is manifested when the leukotriene modifiers permit corticosteroid doses to be reduced. Although current treatment guidelines recommend their use in patients with mild persistent asthma, these guidelines were developed just as leukotriene modifiers were coming to the market, before much of the clinical efficacy data were published. Because asthma is a heterogeneous disease, the different asthma phenotypes respond differently to therapies; consequently asthma therapy needs to be individualized. Leukotriene modifiers increase the therapeutic options for patients with asthma and, based on recent data, it is expected that future guidelines will describe expanded uses for these agents in clinical circumstances where these drugs are effective.

Pranlukast: a review of its use in the management of asthma

Pranlukast (Onon, Azlaire), is an orally administered, selective, competitive antagonist of the cysteinyl leukotrienes (LT) C(4), LTD(4) and LTE(4). It is indicated for the prophylactic treatment of chronic bronchial asthma in paediatric and adult patients. The efficacy of pranlukast 225mg twice daily in adults with mild to moderate asthma was demonstrated in double-blind, placebo- or azelastine-controlled studies of 4 or 8 weeks' duration. The drug at this dosage was superior to both comparators in improving mean attack scores and morning and/or evening peak expiratory flow rates, and decreasing the use of rescue bronchodilators (p < 0.05). In limited clinical studies, pranlukast 225mg twice daily appeared to be as effective as montelukast 10mg once daily and zafirlukast 40mg twice daily in adults with mild to moderate asthma. Tachyphylaxis was absent when the drug was administered for up to 4 years. In patients requiring high-dose inhaled corticosteroid therapy, pranlukast 225 mg twice daily plus a halved dosage of inhaled corticosteroid was as effective as the original dosage of inhaled corticosteroid. Pranlukast was also effective in patients with mild to severe asthma in a clinical practice setting. In a double-blind trial, greater improvements in most outcome measures were observed with pranlukast than with oxatomide in children and adolescents with asthma. In clinical trials, pranlukast was well tolerated in adult and paediatric patients with asthma, with an adverse event profile similar to that of placebo. Gastrointestinal events and hepatic function abnormalities were the most commonly reported adverse events. No clinically significant differences in adverse event profiles between pranlukast, zafirlukast or montelukast were shown in limited comparisons. Although Churg-Strauss syndrome has been noted in pranlukast recipients, a direct causal relationship is unlikely.

CONCLUSIONS

Pranlukast is a well tolerated and effective preventative treatment in adult and paediatric patients with persistent asthma of all severities. In some patients, pranlukast may be beneficial when added to low-dose inhaled corticosteroids; it may also be a viable alternative to increasing inhaled corticosteroid dosages. The efficacy of pranlukast relative to placebo has been confirmed; its efficacy relative to other therapy awaits further investigation. Nonetheless, pranlukast is a useful therapeutic option (with as-required short-acting beta(2)-agonists), either as preventative monotherapy for the treatment of mild persistent asthma or in conjunction with inhaled corticosteroids in the management of moderate or severe persistent asthma.

The role of leukotrienes in asthma

Leukotrienes (LT), both the cysteinyl LTs, LTC(4), LTD(4) and LTE(4), as well as LTB(4) have been implicated in the clinical course, physiologic changes, and pathogenesis of asthma. The cysteinyl LTs are potent bronchoconstrictors, which have additional effects on blood vessels, mucociliary clearance and eosinophilic inflammation. In addition, the cysteinyl LTs are formed from cells commonly associated with asthma, including eosinophils and mast cells. LTB(4), whose role is less well defined in asthma, is a potent chemoattractant (and cell activator) for both neutrophils and eosinophils. In the last 5 years, drugs have been developed which block the actions or formation of these mediators. Clinical and physiologic studies have demonstrated that they are modest short-acting bronchodilators, with sustained improvement in FEV(1) occurring in double-blind, placebo-controlled clinical trials for up to 6 months. These drugs have demonstrated efficacy in preventing bronchoconstriction caused by LTs, allergen, exercise and other agents. Additionally, there are multiple published studies which have demonstrated improvement in asthma symptoms, beta agonist use and, importantly, exacerbations of asthma in both adults and children. Comparison studies with inhaled corticosteroids (ICS) suggest that ICS are superior to leukotriene modifying drugs in moderate persistent asthma. However, several published studies now suggest that leukotriene modifying drugs are effective when added to ongoing therapy with ICS, either to improve current symptoms or to decrease the dose of ICS required to maintain control. While an anti-inflammatory effect is suggested, longer-term, earlier intervention, studies are needed to determine whether these compounds will have any effect on the natural history of the disease.

Leukotriene antagonists

Hepatotoxicity is the most common cause of fulminant hepatic failure in the United States and the main indication for market withdrawal of drugs. This condition has been increasingly recognized as a problem of enormous medical, financial legal, and regulatory importance. It is in context of this heightened awareness of hepatotoxicity, particularly associated with new high profile drugs, that the authors reviews the published data regarding liver injury related to a novel group of asthma drugs.

Montelukast: a review of its therapeutic potential in asthma in children 2 to 14 years of age

Montelukast is a cysteinyl leukotriene receptor antagonist which is used as a preventive treatment for persistent asthma in patients > or =2 years of age. In children aged 6 to 14 years montelukast (5 mg/day) treatment resulted in a significant increase in FEV(1) (forced expiratory volume in 1 second, primary clinical outcome) during an 8-week randomized, double-blind trial. Moreover, significant improvements were observed for a range of secondary endpoints assessing symptoms, exacerbation rates, beta-agonist usage and quality of life. Concomitant administration of montelukast (5 mg/day) and inhaled budesonide (200 microg twice daily) resulted in a trend towards an increase in FEV(1) (p = 0.06, primary endpoint) and a statistically significant reduction in both as-needed beta(2)-agonist usage and the percentage of days with asthma exacerbations compared with budesonide plus placebo. No significant differences were observed in asthma-related quality of life between the two groups. During clinical trials both improvements in lung function and reductions in as-needed beta(2)-agonist usage were generally observed within 1 day after initiation of therapy in children 2 to 14 years of age with persistent asthma. Data from a randomized, nonblind trial in 6- to 11-year-old children and a 6-month extension to this trial suggest that both compliance to therapy and patient satisfaction are greater for montelukast than for either inhaled sodium cromoglycate or inhaled beclomethasone. In addition, patients and parents preferred oral montelukast over sodium cromoglycate. In 2- to 5-year-old children with persistent asthma, montelukast (4 mg/day) treatment resulted in significant improvements in a range of outcomes, such as as-needed beta(2)-agonist usage, symptom scores and percentage of days with asthma symptoms, as assessed during a randomized, double-blind trial primarily designed to assess tolerability. Data from small randomized, double-blind trials suggest that montelukast reduces exercise-induced bronchoconstriction in 6- to 14-year-old children. Montelukast is generally well tolerated. The frequency of adverse events in montelukast-treated children of all ages was comparable to that in patients receiving placebo.

CONCLUSION

Oral montelukast has shown efficacy as a preventive treatment for asthma during clinical trials in children aged 2 to 14 years. The drug offers benefits over more standard therapies such as inhaled sodium cromoglycate and nedocromil in terms of compliance and convenience. In addition, the drug offers significant benefits when added to inhaled corticosteroids (according to secondary endpoints). Montelukast offers an effective, well tolerated and convenient treatment option for children with asthma.

Pharmacokinetic profile of zafirlukast

Zafirlukast is a cysteinyl leukotriene type 1 receptor antagonist that causes bronchodilation and has anti-inflammatory properties. Clinical efficacy has been demonstrated when using oral doses of 20 to 40 mg twice daily. The pharmacokinetics of zafirlukast are best described by a two-compartment model. Maximum plasma concentrations (Cmax) were achieved 3 hours after a single oral dose of 20 or 40 mg to healthy volunteers. The absolute bioavailability of zafirlukast is unknown. However, coadministration of zafirlukast with food reduces bioavailability by approximately 40%. The drug binds to plasma proteins (>99%), predominantly to albumin, and has a mean terminal elimination half-life of approximately 10 hours in both healthy volunteers and patients with asthma. Zafirlukast undergoes extensive hepatic metabolism. Hydroxylation by cytochrome P450 (CYP) 2C9 is the major biotransformation pathway. The metabolites of zafirlukast contribute little to its overall activity. Zafirlukast is mainly eliminated in the faeces, while urinary excretion accounts for <10% of an orally administered dose. Because of its primarily hepatic metabolism, the clearance of zafirlukast is reduced in patients with hepatic impairment. In patients with stable alcoholic cirrhosis, Cmax and area under the plasma concentration-time curve for zafirlukast were increased by 50 to 60% compared with healthy volunteers. Asymptomatic elevations of serum liver enzymes have been reported with high dosages of zafirlukast (80 mg twice daily), returning to normal after cessation of the drug. Inhibition of the CYP2C9 and CYP3A isoenzymes by zafirlukast has been reported in vitro. Zafirlukast interacts with warfarin and produces a clinically significant increase in the prothrombin time, but it does not alter the pharmacokinetics of terfenadine carboxylate, the active metabolite of terfenadine. Plasma concentrations of zafirlukast decreased when the drug was administered concomitantly with erythromycin, terfenadine or theophylline, and increased when it was coadministered with aspirin (acetylsalicylic acid). Theophylline metabolism is unchanged in most cases by zafirlukast, but there is a report of one patient with increased theophylline plasma concentrations when zafirlukast was coadministered. Recently, cases of Churg-Strauss syndrome have been described in patients with asthma receiving zafirlukast treatment. This occurrence in patients being withdrawn from corticosteroid therapy while receiving zafirlukast has been attributed to a previously undiagnosed presence of this syndrome in these patients.

Balancing safety and efficacy in the treatment of pediatric asthma

The treatment of pediatric asthma requires balancing the efficacy and safety of various asthma medications, facilitating patient and family education, and developing a supportive treatment network. The efficacy and safety of the major asthma controllers--cromolyn, long-acting beta(2)-agonists, inhaled corticosteroids, and leukotriene receptor antagonists-are well tolerated overall when used appropriately. Cromolyn is used often as first-line therapy in treating pediatric asthma, but the inhaled corticosteroids remain the cornerstone of pediatric asthma control. Long-acting beta(2)-agonists are most beneficial when used intermittently or in combination with other asthma medications. The most recent class of drugs, the leukotriene receptor antagonists are effective in controlling asthma and are well tolerated in children as young as 2 years of age. In moderate-to-severe pediatric asthma, combination therapy is often required to achieve optimal asthma control. Leukotriene receptor antagonists combined with inhaled corticosteroids reduce the need for steroid rescue, the rate of serious exacerbations, and the level of inflammation. The treatment of asthma requires the ability to diagnose and treat asthma effectively. In subpopulations with special needs such as very young or inner-city minority children, treating asthma requires a comprehensive approach that includes a supportive patient-physician relationship and the involvement of schools, churches, and neighborhood outreach programs that will identify children with asthma and promote quality care.

Asthma therapies and Churg-Strauss syndrome

The pulmonary vasculitides are a group of rare but serious disorders that require early recognition, accurate diagnosis, and effective therapy. Churg-Strauss syndrome (CSS) is classified as small vessel vasculitis. Four different definitions for the diagnosis of CSS have been developed: (1) the pathologic criteria put forth by Churg and Strauss, (2) the criteria based on clinical grounds from Lanham and colleagues, (3) the criteria based on clinical grounds from the American College of Rheumatology, and (4) the criteria from the Chapel Hill Consensus Conference, which closely concur with the Churg and Strauss definition. It is apparent that cessation, diminution, or even a switch from low-dose systemic to inhaled corticosteroid therapy can precipitate the appearance of CSS. The term forme fruste has been used to indicate that the signs and symptoms of CSS were (inadvertently) suppressed by cortico-steroids. The clinical risk factors for CSS are moderately severe or severe asthma, chronic sinusitis, or reductions in systemic corticosteroid therapy. Differential diagnosis, treatment, and ongoing monitoring of CSS therapeutic responses are reviewed. The introduction of leukotriene modifiers and high-potency inhaled corticosteroids have allowed control of asthma symptoms, which results in avoidance or reduction in oral corticosteroid use. The advent of these agents has been associated with reports of CSS appearing in patients with asthma. The available data regarding the association of CSS and antiasthma agents are most consistent with the unmasking of a previously contained pathologic condition (forme-fruste CSS) or disease that progresses because systemic corticosteroids were avoided. Early recognition and immunosuppressive therapy are the keystones of successful treatment of this rare disorder.

Churg-Strauss syndrome: update on recent developments

Churg-Strauss syndrome (CSS) is a form of primary vasculitis characterized by allergy and angiitis. In the organ systems involved (lung, heart, peripheral nervous system, and so forth), eosinophilic infiltration can be found. Eosinophilia and normochromic normocytic anemia are leading laboratory findings together with elevated IgE. New seromarkers for the activation of endothelial cells, lymphocytes, and eosinophils (soluble thrombomodulin, soluble interleukin-2 receptor, eosinophil cationic protein) may be able to predict a relapse. Antineutrophil cytoplasmic antibodies are found in only approximately 50% of all patients with CSS, and their diagnostic value is questionable. Etiologically, hyperresponsiveness to an antigenic stimulus seems to underlie the syndrome. In asthmatics, cysteinyl leukotriene receptor type 1 antagonists are reported to trigger the disease. Cytokine profile findings on the cells involved in CSS remain contradictory. Some think CSS may be a Th2-mediated disease; its pathophysiology is not known fully. Interleukin-5 and tumor necrosis factor-alpha are elevated in serum and fluid of bronchoalveolar lavage, suggesting target cytokines for future treatment protocols. Treatment consists of glucocorticoid monotherapy. Data on outcome and effectiveness is lacking for other immunosuppressive regimens, such as cyclophosphamide or glucocorticoid plus cyclophosphamide. Treatment with interferon-alpha has been effective in patients refractory to glucocorticoid plus cyclophosphamide.

Recent advances in the diagnosis of Churg-Strauss syndrome

Most pathologists assume that a diagnosis of Churg-Strauss syndrome (CSS) requires the finding of necrotizing vasculitis accompanied by granulomas with eosinophilic necrosis in the setting of asthma and eosinophilia. However, recent data indicate that this definition is too narrow and that adherence to it leads to cases of CSS being missed. CSS has an early, prevasculitic phase that is characterized by tissue infiltration by eosinophils without overt vasculitis. Tissue infiltration may take the form of a simple eosinophilia in any organ, and a fine-needle aspirate showing only eosinophils may suffice for the diagnosis in this situation. The prevasculitic phase appears to respond particularly well to steroids. Even in the vasculitic phase of CSS, many cases do not show a necrotizing vasculitis but often only an apparently nondestructive infiltration of vessel walls by eosinophils. In modern biopsy materials, granulomas frequently cannot be found. In the postvasculitic phase of CSS, healed vascular lesions resemble organized thrombi but typically show very extensive destruction of elastica and, often, an absence of eosinophils. The widespread use of steroids as therapy for asthma has led to the peculiar and confusing situation in which the steroid therapy accidentally suppresses CSS and changes in steroid treatment uncover the disease; this type of "formes frustes" CSS is now well recognized with leukotriene receptor antagonist treatment and will be seen with increasing frequency as other steroid-sparing therapies for asthma are introduced.

Drug-induced vasculitis

DIV is a relatively common cause of inflammatory vasculitis. Drugs from almost every pharmacologic class have been implicated in causing vasculitis in sporadic cases. The level of certainty and quality of evidence for these associations between specific agents and vasculitis vary greatly. The clinical manifestations of DIV range from single organ involvement (most commonly, skin) to life-threatening multiorgan disease. The recently described subset of cases of DIV associated with positive tests for ANCA are an interesting subset of DIV. The diagnosis of DIV is usually one of exclusion. The treatment of DIV is dependent on the severity of disease activity but should always include withdrawal of the suspected drug. If no agent can be implicated, as many drugs as feasible should be discontinued. The necessity of prescribing glucocorticoids or immunosuppressive agents depends on the disease severity and other case-specific information. Increasing understanding of the pathophysiologic characteristics of all inflammatory vasculitides should lead to better diagnostic and therapeutic approaches to DIV.

The role of leukotriene receptor antagonists in the treatment of chronic asthma in childhood

A considerable increase in the prevalence of childhood asthma over the last few decades has been mirrored by a dramatic increase in usage of anti-asthma drugs; however, there has been no reduction in the numbers of patients dying of asthma. Concern has been expressed about the development of tolerance with continuous use of inhaled beta-agonist bronchodilators and about the potential adverse systemic effects of high-dose inhaled corticosteroids in children. Moreover, patient compliance with inhaled therapy tends to be poor. The leukotriene receptor antagonists, including montelukast, pranlukast and zafirlukast, are orally administered agents with proven benefits in asthma. In a large, placebo-controlled pediatric trial, montelukast significantly (P < 0.02) reduced requirements for rescue beta-agonist bronchodilators, improved quality of life, reduced the circulating level of blood eosinophils and produced improvements in lung function. In adult studies, montelukast reduced sputum eosinophils and attenuated early and late phase allergen-induced reactions. Montelukast has also demonstrated protective effects against exercise-induced bronchospasm in both adults and children, and this protection was maintained during the trough period at the end of the once-daily administration interval (namely, 20-24 h post-dose). Several studies have demonstrated that the formation of cysteinyl leukotrienes in the airways of asthmatic patients is not suppressed by corticosteroids; thus, it is not surprising that montelukast demonstrates complementary effects when given with inhaled corticosteroids. Currently, the most compelling evidence from published trials suggests that leukotriene receptor antagonists can be used as add-on therapy to inhaled corticosteroids to allow tapering of corticosteroid dose and reduction in beta-agonist use. Recent clinical trial results suggest there may also be a role for these agents as first-line therapy in children with mild asthma.

Pharmacologic treatment of the adult hospitalized asthma patient

Acute severe asthma calls for aggressive and early therapy of a multifaceted and all-inclusive approach (Fig. 2). Therapy merely begins in the ED and manifold distinct issues need to find consideration during ongoing hospital care. Currently, beta-agonists, anti-cholinergic agents, and corticosteroids remain the mainstay of therapy. Methylxanthines and magnesium may find consideration in carefully selected patients. Multiple new therapeutic avenues, such as the anti-leukotriene drugs, seem promising and future studies will hopefully extend our armamentarium against life threatening complication of a common disease. Asthma education begun in the hospital may provide the platform for preventing severe acute exacerbations and hospitalization.

Zafirlukast: an update of its pharmacology and therapeutic efficacy in asthma

Zafirlukast is a selective and competitive orally administered inhibitor of the cysteinyl leukotrienes LTC4, LTD4 and LTE4. The drug is indicated for the prophylaxis and treatment of chronic asthma, and has been developed in response to mounting evidence indicating the importance of the cysteinyl leukotrienes in the pathogenesis of this disorder. The efficacy of zafirlukast 20 mg twice daily has been shown in double-blind placebo-controlled studies of up to 13 weeks' duration in patients aged > or = 12 years. Zafirlukast was consistently superior to placebo in improving objective measures of lung function and subjective measures such as symptom scores and use of as-required bronchodilator therapy. This dosage is also as effective when added to low-dosage inhaled corticosteroid therapy as doubling of corticosteroid dosages. Recent studies indicate superior efficacy over zafirlukast of twice-daily inhaled fluticasone propionate 88 microg or salmeterol 42 microg, although zafirlukast was nevertheless associated with clinical improvement. Data also show zafirlukast 40 mg to be of similar efficacy to pranlukast 225 mg (both twice daily). Overall, preliminary pharmacoeconomic data suggest that healthcare costs are reduced by zafirlukast therapy, although superior cost effectiveness has been reported with inhaled fluticasone propionate. and further studies are needed. Data are available to show improvements in patient-rated quality of life, and preference for and high rates of compliance with zafirlukast. In clinical trials, zafirlukast has shown an adverse event profile similar to that of placebo. Isolated reports of hepatic dysfunction in a small number of individuals receiving the drug have been received, and recommendations for monitoring of patients are in place. Although no causal relationship has been established between zafirlukast and Churg-Strauss Syndrome, patients undergoing corticosteroid dosage reductions require careful surveillance.

CONCLUSIONS

zafirlukast is an effective and well tolerated agent for preventive monotherapy in mild to moderate persistent asthma. Emerging data indicate benefit of the drug when added to low-dosage inhaled corticosteroids and show that it may be a viable alternative to inhaled adjunctive treatments and increased corticosteroid dosages in some patients. Although inhaled fluticasone propionate and salmeterol have been associated with greater clinical improvement than zafirlukast in clinical studies, compliance considerations and the confirmed clinical efficacy relative to placebo of the drug denote zafirlukast as an effective alternative in treatment programmes based on individualised therapy. As experience with zafirlukast accumulates, it is expected that the drug will be positioned more definitively in national and international treatment guidelines.

Aspirin and asthma

Aspirin is not only one of the best-documented medicines in the world, but also one of the most frequently used drugs of all times. In addition to its role as an analgesic, aspirin is being increasingly used in the prophylaxis of ischemic heart disease and strokes. The prevalence of aspirin intolerance is around 5 to 6%. Up to 20% of the asthmatic population is sensitive to aspirin and other nonsteroidal anti-inflammatory drugs (NSAIDs) and present with a triad of rhinitis, sinusitis, and asthma when exposed to the offending drugs. This syndrome is referred to as aspirin-induced asthma (AIA). The pathogenesis of AIA has implicated both the lipoxygenase (LO) and the cyclooxygenase (COX) pathways. By inhibiting the COX pathway, aspirin diverts arachidonic acid metabolites to the LO pathway. This also leads to a decrease in the levels of prostaglandin (PG) E(2), the anti-inflammatory PG, along with an increase in the synthesis of cysteinyl leukotrienes (LTs). Evidence suggests that patients with AIA have increased activity of LTC(4) synthase, the rate-limiting enzyme in the cysteinyl LT synthesis, in their bronchial biopsy specimens, thereby tilting the balance in favor of inflammation. LT-modifying drugs are effective in blocking the bronchoconstriction provoked by aspirin and are used in the treatment of this condition. Aspirin desensitization has a role in the management of AIA, especially in patients who need prophylaxis from thromboembolic diseases, myocardial infarction, and stroke. This review covers the latest understanding of pathogenesis, clinical features, and management of AIA.

Montelukast: a review of its therapeutic potential in persistent asthma

Montelukast is a cysteinyl leukotriene receptor antagonist used to treat persistent asthma in patients aged > or = 6 years. The drug has a rapid onset of action. Improvements in lung function and reductions in as-needed beta2-agonist usage are apparent within 1 day of initiating montelukast treatment in adults and adolescents (aged > or = 15 years treated with 10 mg/day) or children (aged 6 to 14 years treated with 5 mg/day) with persistent asthma as shown in clinical trials. In two 12-week, multicentre, randomised, double-blind studies in adults and adolescents aged > or = 15 years with persistent asthma [forced expiratory volume in 1 second (FEV1) = 50 to 85% predicted] there was significantly (p < 0.05) greater improvement in FEV1, symptom scores, peak expiratory flow (PEF), as-needed beta2-agonist use, peripheral eosinophil counts and health-related quality of life (QOL) in patients treated with montelukast 10 mg/day than in recipients of placebo. Improvements were significantly greater in patients treated with inhaled beclomethasone 400 microg/day than in recipients of montelukast 10 mg/day in 1 of these studies. Nonetheless, 42% of montelukast recipients experienced > or = 11% improvement in FEV1, the median improvement in this parameter in beclomethasone-treated patients. In an 8-week multicentre, randomised, double-blind, study in children aged 6 to 14 years with persistent asthma (FEV1 50 to 85% predicted), montelukast 5 mg/day produced significantly greater improvements in FEV1, clinic PEF, as-needed beta2-agonist use, peripheral eosinophil counts, asthma exacerbations and QOL scores than placebo. The combination of montelukast 10 mg/day plus inhaled beclomethasone 200 microg twice daily provided significantly better asthma control than inhaled beclomethasone 200 microg twice daily in adults with poorly controlled asthma (mean FEV1 = 72% predicted) despite 4 weeks treatment with inhaled beclomethasone. Patients receiving the combination experienced significant improvements in FEV1 and morning PEF, significant reductions in daytime symptom scores, as-needed beta2 agonist usage and night-time awakenings with asthma, and had significantly lower peripheral blood eosinophil counts after 16 weeks in this multicentre, randomised, double-blind, placebo-controlled study. Among adults (FEV1 > or = 70%) treated with montelukast 10 mg/day for 12 weeks, inhaled corticosteroid dosages were titrated downward by 47% (vs 30% in placebo recipients), 40% of patients were tapered off of inhaled corticosteroids (vs 29%), and significantly fewer patients (16 vs 30%) experienced failed corticosteroid rescues in a multicentre, randomised, double-blind study. During clinical studies, the frequency of adverse events in montelukast-treated adults, adolescents and children was similar to that in placebo recipients. In conclusion, montelukast is well tolerated and effective in adults and children aged > or = 6 years with persistent asthma including those with exercise-induced bronchoconstriction and/or aspirin sensitivity. Furthermore, montelukast has glucocorticoid sparing properties. Hence, montelukast, as monotherapy in patients with mild persistent asthma, or as an adjunct to inhaled corticosteroids is useful across a broad spectrum of patients with persistent asthma.