Churg-Strauss syndrome after zafirlukast in two patients not receiving systemic steroid treatment

Clinical Problem Solving: A 67-year-old Man With Painful Leg Weakness and Difficulty Walking

Rapidly progressive neurologic symptoms can be alarming to both the patient and the clinician, given the concern for serious pathologies. In this case, a 67-year-old patient presents with painful sensorimotor symptoms that progress rapidly within days of onset. Proper localization and consideration of medical co-morbidities is essential for accurate diagnosis. This case highlights the importance of a detailed neurologic examination to aid in the localization and differential diagnosis. The case will take readers through a stepwise approach to this complex neurologic presentation, work-up and management.

Mepolizumab as the first targeted treatment for eosinophilic granulomatosis with polyangiitis: a review of current evidence and potential place in therapy

Mepolizumab is an anti-interleukin-5 (IL-5) humanized monoclonal antibody that binds to free IL-5. It induces bone marrow eosinophil maturation arrest and decreases eosinophil progenitors and subsequent maturation in the blood and bronchial mucosa. Its use has been extensively studied in severe eosinophilic asthma at a dose of 100 mg subcutaneously (SC) every 4 weeks and, more recently, in other hypereosinophilic syndromes. Eosinophilic granulomatosis with polyangiitis (EGPA) is an eosinophilic vasculitis that may involve multiple organs. Characteristic clinical manifestations are asthma, sinusitis, transient pulmonary infiltrates and neuropathy. Among the numerous pathways involved in the pathogenesis of EGPA, the Th-2 phenotype has a main role, as suggested by the prominence of the asthmatic component, in triggering the release of key cytokines for the activation, maturation and survival of eosinophils. In particular, IL-5 is highly increased in active EGPA and its inhibition can represent a potential therapeutic target. In this scenario, mepolizumab may play a therapeutic role. After some positive preliminary observations on the use of mepolizumab in small case series of EGPA patients with refractory or relapsing disease despite standard of care treatment, a randomized controlled trial was published in 2017. Mepolizumab at a dose of 300 mg administered by SC injection every 4 weeks proved effective in prolonging the period of remission of the disease, allowing for reduced steroid use. The positive results of this study, which met both of the primary endpoints, led to the approval in the USA of mepolizumab in adult patients with EGPA by the Food and Drug Administration in 2017. Therefore, mepolizumab can be officially considered as an add-on therapy with steroid-sparing effect in cases of relapsing or refractory EGPA. However, the most appropriate dose and duration of therapy still need to be determined. Future studies on larger multinational populations with prolonged follow-up are warranted.

Diagnosis and classification of eosinophilic granulomatosis with polyangiitis (formerly named Churg-Strauss syndrome)

Recently, a group of experts in the field suggested to rename Churg-Strauss syndrome as eosinophilic granulomatosis with polyangiitis (EGPA). This condition, first described in 1951, is a rare small- and medium-sized-vessel vasculitis characterized by an almost constant association with asthma and eosinophilia, and, by the presence of anti-myeloperoxidase (MPO) antineutrophil cytoplasm antibodies (ANCA) in 30-38% of the patients. Vasculitis typically develops in a previously asthmatic and eosinophilic middle-aged patient. Asthma is severe, associated with eosinophilia and extrapulmonary symptoms. Most frequently EGPA involves the peripheral nerves and skin. Other organs, however, may be affected and must be screened for vasculitis, especially those associated with a poorer prognosis, such as the heart, kidney and gastrointestinal tract, as assessed by the recently revised Five-Factor Score (FFS). Recent insights, particularly concerning clinical differences associated with ANCA status, showed that EGPA patients might constitute a heterogeneous group. Thus, EGPA patients with anti-MPO ANCA suffered more, albeit not exclusively, from vasculitis symptoms, such as glomerulonephritis, mononeuritis multiplex and alveolar hemorrhage, whereas ANCA-negative patients more frequently develop heart involvement. This observation led to the hypothesis that EGPA might be divided into different clinical and pathophysiological subtypes, which could be managed better with more specifically adapted therapies. For now, EGPA treatment still relies mainly on corticosteroids and, when necessary for patients with poorer prognoses, combined immunosuppressant drugs, especially cyclophosphamide. Overall survival of EGPA patients is good, despite not uncommon relapses.

Dacryoadenitis and diffuse orbital inflammation: unusual first presentations of Churg-Strauss syndrome

Churg-Strauss syndrome (CSS) is a rare form of vasculitis involving small-to medium-sized blood vessels. CSS typically affects blood vessels of the lungs, gastrointestinal system, and peripheral nerves, but can also involve the heart, skin and kidneys. Here we present two CSS patients presenting with unusual ocular manifestations. Although ophthalmic complications remain relatively uncommon in vasculitides such as Churg-Strauss syndrome, these conditions should be considered in patients presenting with ocular manifestations and concurrent ear, nose and throat symptoms, arthralgia or with positive ANCA and eosinophilia.

Wells syndrome associated with Churg–Strauss syndrome

Churg–Strauss syndrome (CSS) is a systemic vasculitis occurring in patients with a history of asthma. Wells' syndrome (WS) is a rare inflammatory dermatosis that clinically resembles cellulitis, and is histologically characterized by eosinophilic infiltration and flame figures. We report a case of WS associated with CSS. There have been three previous reports of WS associated with CSS; ours is the fourth. All cases had bullous lesions, and three cases were positive for antineutrophil cytoplasmic antibodies.

Churg-Strauss syndrome with severe granulomatous angiitis and crescentic glomerulonephritis, which developed during therapy with a leukotriene receptor antagonist

A 77-year-old Japanese female developed Churg-Strauss syndrome (CSS), showing fever and numbness in bilateral hands. She was being treated for bronchial asthma with combination inhalant of corticosteroid with beta(2)-agonist, and an oral leukotriene receptor antagonist (LTRA), montelukast, for 15 months. She presented fever up to 38°C with microscopic hematuria and proteinuria, serum creatinine level of 0.7 mg/dl, and C-reactive protein of 11 mg/dl. After referral to our hospital, eosinophilia and high myeloperoxidase (MPO)-antineutrophil cytoplasmic antibody (ANCA) level were observed together with hematuria and proteinuria; renal biopsy examination was performed to clarify the disorder. Renal biopsy specimens showed necrotizing crescent formation, severe granulomatous angiitis in an interlobular artery, and interstitial eosinophilic infiltration. It was noted that nearly intact glomeruli were infiltrated with eosinophils. After treatment with oral prednisolone at initial dose of 40 mg (1 mg/kg body weight), urinary findings rapidly became normal with mild elevation of serum creatinine to 1.5 mg/dl and trace level of serum C-reactive protein in 1 month. Because she was previously treated with montelukast without oral corticosteroid, linkage between CSS and LTRA was highly suspected.

Therapeutic management of allergic diseases

Allergic diseases are characterized by the activation of inflammatory cells and by a massive release of mediators. The aim of this chapter was to describe succinctly the modes of action, indications, and side effects of the major antiallergic and antiasthmatic drugs. When considering the ideal pharmacokinetic characteristics of a drug, a poorly metabolized drug may confer a lower variability in plasma concentrations and metabolism-based drug interactions, although poorly metabolized drugs may be prone to transporter-based disposition and interactions. The ideal pharmacological properties of a drug include high binding affinity, high selectivity, and appropriate association and dissociation rates. Finally, from a patient perspective, the frequency and route of administration are important considerations for ease of use.

Churg-Strauss syndrome presenting with diffuse alveolar hemorrhage and rapidly progressive glomerulonephritis

A 46-year-old man with a 4-month history of bronchial asthma was admitted to our hospital complaining of progressive dyspnea, weakness of the lower extremities, multiple truncal erythematous purpura and hemoptysis. Neurological examination identified the presence of mononeuritis multiplex. Laboratory data indicated marked anemia, eosinophilia, severe renal failure with nephrotic condition and elevated serum myeloperoxidase anti-neutrophil cytoplasmic antibody (MPO-ANCA) levels (1,050 EU). Chest computed tomography showed diffuse ground glass opacity in both lungs. Bronchoalveolar lavage fluid revealed bloody fluid with eosinophilia (81%). Microscopic findings of a transbronchial lung biopsy were consistent with alveolar hemorrhage. A skin biopsy revealed eosinophilic vasculitis consistent with Churg-Strauss syndrome (CSS). A renal biopsy specimen revealed pauci-immune crescentic necrotizing glomerulonephritis. Consequently, he was diagnosed as having CSS presenting with diffuse alveolar hemorrhage (DAH) and rapidly progressive glomerulonephritis (RPGN) with MPO-ANCA-associated systemic vasculitis. His clinical condition markedly improved with the administration of intravenous corticosteroid (CS) and cyclophosphamide (CY). Thus, we report a case of CSS presenting with the rare complication of DAH and RPGN.

Churg-strauss syndrome in the pediatric age group

The rate of reporting of childhood Churg-Strauss syndrome (CSS) has increased lately because of either increased awareness to the disease or a real increase in incidence. It is defined as one of the antineutrophil cytoplasmic antibody-associated vasculitides, but the antineutrophil cytoplasmic antibody positivity is less reported in pediatric cases. The cause of CSS remains unknown. Several lines of evidence suggest genetic predisposition, which may entail inherited tendency to dysregulation of the cellular immune system. With the addition of leukotriene receptor antagonists to the treatment regimen of asthma, an association to CSS was presumed. However, the nature of this relationship remains to be elucidated. In addition, some environmental factors seem to provoke transient effects that resemble the disease. Patients' symptoms are defined by various degrees of eosinophilic inflammation and necrotizing vasculitis, which may affect any organ. Three clinical stages have been described in the clinical evolution of CSS: prodromal phase involving allergic rhinitis and asthma (usually without family history of atopy), a second phase that involves peripheral eosinophilia and eosinophilic tissue infiltration, and the hallmark of the final phase is systemic vasculitis. Pulmonary disease is a central feature of pediatric CSS, but other manifestations include skin lesions, testicular pain, hypertension, seizures, and nephropathy. More subtle presentations in children include cervical lymphadenopathy, acute abdominal pain, deep venous thrombosis, oral ulceration, multiple colonic ulcers, chorea, bilateral optic neuropathy, and retinal artery occlusions. Churg-Strauss syndrome patients usually respond well to corticosteroid therapy. Several trials reported additional benefit from cyclophosphamide, azathioprine, and methotrexate, whereas the therapeutic effects of etanercept, plasma exchange, and intravenous immunoglobulin therapy are controversial. The relapse rate is approximately 25% to 30%, but corticosteroids have significantly increased survival, which now approaches greater than 75% at 5 years. However, there is limited information about survival or long-term outcome in childhood.

Drug-induced arthritic and connective tissue disorders

OBJECTIVES

All pharmacologic agents have the potential for both benefit and toxicity. Among the more interesting and important adverse consequences of drug therapy are a range of joint and connective tissue complaints that may mimic or reproduce primary rheumatologic diseases. In this article, we review the literature on commonly used drugs reported to induce arthritis and/or connective tissue-based diseases. We assess the strength of the reported associations, discuss diagnostic features and treatment implications, and consider possible mechanisms for drug-induced genesis of rheumatic conditions.

METHODS

We reviewed the Medline database from 1987 to 2006 to identify drug-induced arthritic and connective-tissue disease syndromes, utilizing 48 search terms. A qualitative review was performed after the articles were abstracted and the relevant information was organized.

RESULTS

Three hundred fifty-seven articles of possible relevance were identified. Two hundred eleven publications were included in the final analysis (case series and reports, clinical trials, and reviews). Many drugs were identified as mimicking existing rheumatic conditions, including both well-established small molecules (eg, sulfasalazine) and recently introduced biologic agents (eg, antitumor necrosis factor agents). The most commonly reported drug-induced rheumatic conditions were lupus-like syndromes. Arthritis and vasculitis were also often reported.

CONCLUSIONS

Drug-induced rheumatic syndromes are manifold and offer the clinician an opportunity to define an illness that may remit with discontinuation of the offending agent. Early diagnosis and withdrawal of the drug may prevent unnecessary morbidity and disability.

An asthmatic adolescent with a rash and eosinophilia

Children frequently visit emergency departments with asthma exacerbations. Many of these asthmatic children may have fever and/or pneumonia, but when associated with eosinophilia or evidence of vasculitis, other diagnoses should be considered. Churg-Strauss syndrome is a rare form of systemic vasculitis, which usually occurs in patients with asthma in association with eosinophilia. The diagnosis of Churg-Strauss syndrome can be difficult because this syndrome may arise at first as a common association between asthma and allergic rhinitis. A delay in diagnosis and treatment may increase the morbidity from the complications of vasculitis. We report a young asthmatic adolescent who presented with vasculitis, eosinophilia, and peripheral neuropathy.

Cysteinyl-leukotrienes and their receptors in asthma and other inflammatory diseases: critical update and emerging trends

Cysteinyl-leukotrienes (cysteinyl-LTs), that is, LTC4, LTD4, and LTE4, trigger contractile and inflammatory responses through the specific interaction with G protein-coupled receptors (GPCRs) belonging to the purine receptor cluster of the rhodopsin family, and identified as CysLT receptors (CysLTRs). Cysteinyl-LTs have a clear role in pathophysiological conditions such as asthma and allergic rhinitis (AR), and have been implicated in other inflammatory conditions including cardiovascular diseases, cancer, atopic dermatitis, and urticaria. Molecular cloning of human CysLT1R and CysLT2R subtypes has confirmed most of the previous pharmacological characterization and identified distinct expression patterns only partially overlapping. Interestingly, recent data provide evidence for the immunomodulation of CysLTR expression, the existence of additional receptor subtypes, and of an intracellular pool of CysLTRs that may have roles different from those of plasma membrane receptors. Furthermore, genetic variants have been identified for the CysLTRs that may interact to confer risk for atopy. Finally, a crosstalk between the cysteinyl-LT and the purine systems is being delineated. This review will summarize and attempt to integrate recent data derived from studies on the molecular pharmacology and pharmacogenetics of CysLTRs, and will consider the therapeutic opportunities arising from the new roles suggested for cysteinyl-LTs and their receptors.

Asthma drug use and the development of Churg-Strauss syndrome (CSS)

PURPOSE

Case reports suggest that leukotriene modifier use may be associated with the onset of Churg-Strauss syndrome (CSS). Using pooled data from two nested case-control studies, we examined the association between asthma drug use and the development of CSS.

METHODS

The study was performed in three US managed care organizations and a US national health plan with chart access and complete electronic pharmacy data, with a covered population of 13.9 million. There were 47 cases of possible or definite CSS and 4700 asthma drug user controls identified between January 1, 1995 and December 31, 2002. We examined exposure to asthma drugs in cases and controls, including leukotriene modifiers (6 cases and 202 controls), in the two to 6 months prior to the onset of adjudicated CSS.

RESULTS

While the crude association between use of leukotriene modifiers and CSS was strong (odds ratio (OR) 4.00, 95% confidence interval (CI): 1.49-10.60), in a multivariable analysis controlling for use of oral corticosteroids, inhaled corticosteroids, and number of categories of asthma drugs dispensed, there was no significant association (OR 1.32, 95% CI: 0.44-3.96). Use of inhaled and oral corticosteroids, evaluated as markers of asthma severity, were associated with CSS (OR 3.07, 95% CI: 1.34-7.03 and OR 5.36, 95% CI: 2.51-11.45, respectively).

CONCLUSIONS

No association was found between CSS and leukotriene modifiers after controlling for asthma drug use However, it is not possible to rule out modest associations with asthma treatments given CSS is so rare and so highly correlated with asthma severity, suggesting further investigation is warranted.

[Antileukotrienes and Churg-Strauss syndrome]

Churg-Strauss syndrome is a systemic necrotizing vasculitis involving small and medium-sized vessels. Classic features include asthma and hypereosinophilia. Antineutrophil cytoplasm antibodies (ANCA) are detected in about 40% of patients. Churg-Strauss syndrome has been reported in patients receiving leukotriene modifiers for asthma, in particular, leukotriene receptor antagonists (LTRA) (montelukast, zafirlukast or pranlukast). Clinical manifestations cases do not differ in these cases from those in Churg-Strauss syndrome without antileukotriene exposure. It is increasingly less likely that LTRA is the direct cause of this syndrome in those patients, although this hypothesis has not been completely ruled out. In many patients, LTRA treatment is prescribed because of worsening asthma, which is an early sign of Churg-Strauss syndrome. LTRA for asthma patients should be prescribed with great care, especially in cases of atypical or rapidly aggravated asthma. The onset of Churg-Strauss syndrome in patients treated with LTRA usually requires that they stop this treatment. Prescription of LTRA In patients with Churg-Strauss syndrome should be discussed with specialists.

Pathogenesis and management of aspirin-intolerant asthma

In 2-23% of adults with asthma, and rarely in children with asthma, aspirin (acetylsalicylic acid) and non-steroidal anti-inflammatory drugs (NSAIDs) cause asthma exacerbations. Within 3 hours of ingestion of aspirin/NSAIDs, individuals with aspirin-intolerant asthma (AIA) develop bronchoconstriction, often accompanied by rhinorrhea, conjunctival irritation, and scarlet flush. In severe cases, a single therapeutic dose of aspirin/NSAIDs can provoke violent bronchospasm, loss of consciousness, and respiratory arrest. In order to diagnose AIA, oral, inhaled, nasal or intravenous aspirin challenge tests are performed in facilities where experienced physicians are present and emergency treatment is available. The exact differences in the pathogenesis of AIA and other types of asthma are not fully understood. The interference of aspirin/NSAIDs with arachidonic acid metabolism in the lungs plays an important role in the mechanism of AIA; inhibition of cyclo-oxygenase is accompanied by overproduction of cysteinyl leukotrienes (cys-LTs). It has been proposed that overproduction of cys-LTs, together with removal by aspirin/NSAIDs of the 'brake' imposed by the bronchodilator prostaglandin E2, may cause an asthma attack in patients with AIA. Development of a suitable animal model to investigate the pathogenesis of AIA would help to clarify this question. Although it is still controversial whether leukotriene modifiers are more effective in patients with AIA compared with other types of asthma, because LT plays an important role in the pathogenesis of AIA, leukotriene modifiers are the preferred medication for the long-term control of AIA. Add-on efficacy of leukotriene modifiers has been confirmed in patients with AIA already treated with inhaled corticosteroids. However, this does not mean that aspirin/NSAIDs can be safely taken by aspirin-sensitive patients treated with leukotriene modifiers. To prevent attacks of AIA, sensitive patients should avoid the use of aspirin/NSAIDs or use selective cyclo-oxygenase 2 inhibitors when required. When patients with AIA need aspirin for specific situations they should receive aspirin desensitization therapy or treatment with selective cyclo-oxygenase 2 inhibitors.

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.

Churg-Strauss syndrome and the leukotriene receptor antagonist pranlukast

The authors studied eight cases of Churg-Strauss syndrome (CSS) associated with the use of pranlukast, a common cysteinyl leukotriene receptor antagonist (LTRA) in Japan. The patients who received pranlukast showed significantly increased peripheral blood eosinophil count, neurological disability scores, and poor responses to corticosteroid in comparison with those patients not receiving pranlukast. We suggest that preceding administration of pranlukast aggravates clinical presentations of CSS.

The Churg Strauss syndrome (allergic granulomatous angiitis): review and update

OBJECTIVES

Review the clinical and physiopathologic aspects of the Churg-Strauss syndrome (CSS), including recent data regarding treatment and possible etiologic and triggering factors.

METHODS

A search of the Medline database was conducted between 1966 and 2002, regarding CSS and related vasculitic conditions. Original articles were reviewed as well as major vasculitis textbooks, which were also examined for original references.

RESULTS

CSS has been increasingly recognized during the past few decades, but remains an uncommon disease of unknown cause. The disorder had been traditionally classified as a variant of polyarteritis nodosa until its updated description by Churg and Strauss in 1951. Although it shares various clinical laboratory and pathologic characteristics with polyarteritis nodosa and Wegener granulomatosis, a distinct combination of features makes it a separate entity. The presence of asthma, usually of adult onset, along with other allergic symptoms, peripheral and tissue eosinophilia, and systemic vasculitis should prompt the clinician to consider the diagnosis, seek potential confirmation with a tissue biopsy, and begin therapy to minimize complications and prevent permanent organ damage. The treatment of CSS has been mainly extrapolated from other vasculitides, and the literature addressing drug therapy for this specific syndrome is limited.

CONCLUSIONS

CSS is a distinct entity that should be recognized and distinguished from other forms of vasculitis to provide the appropriate early treatment, which could prevent permanent organ damage.

Drug-induced diffuse alveolar hemorrhage syndromes and vasculitis

Current and past drug intake is essential in the evaluation of a patient who has DAH. Simple treatments, such as reversal of a coagulation defect or withdrawal of the drug, can reverse a life-threatening situation. DAO may result in DAH, and depending on the severity of the drug withdrawl, will not be adequate and corticosteroid therapy is recommended.

Benefit-risk assessment of antileukotrienes in the management of asthma

Antileukotrienes are a relatively new class of anti-asthma drugs that either block leukotriene synthesis (5-lipoxygenase inhibitors) like zileuton, or antagonise the most relevant of their receptors (the cysteinyl leukotriene 1 receptor [CysLT1]) like montelukast, zafirlukast or pranlukast. Hence, their major effect is an anti-inflammatory one. With the exception of pranlukast, the other antileukotrienes have been studied and marketed in the US and Europe for long enough to establish that they are useful drugs in the management of asthma. Their effects, significantly better than placebo, seem more pronounced in subjective measurements (i.e. symptoms scores or quality-of-life tests) than in objective parameters (i.e. forced expiratory volume in 1 second or peak expiratory flow rate). Also, there is some evidence that these drugs work better in some subsets of patients with certain genetic polymorphisms - probably related to their leukotriene metabolism - or patients with certain asthma characteristics. There are a small number of comparative studies only, and with regard to long-term asthma control differences between the agents have not been evaluated. Nevertheless, their overall effect appears comparable with sodium cromoglycate (cromolyn sodium) or theophylline, but significantly less than low-dose inhaled corticosteroids. Antileukotrienes have been shown to have a degree of corticosteroid-sparing effect, but salmeterol appears to perform better as an add-on drug. Montelukast is probably the most useful antileukotriene for continuous treatment of exercise-induced asthma, performing as well as salmeterol without inducing any tolerance. All antileukotrienes are taken orally; their frequency of administration is quite different ranging from four times daily (zileuton) to once daily (montelukast). Antileukotrienes are well tolerated drugs, even though zileuton intake has been related to transitional liver enzyme elevations in some cases. Also Churg-Strauss syndrome (a systemic vasculitis), has been described in small numbers of patients taking CysLT1 antagonists. It is quite probable that this disease appears as a consequence of an 'unmasking' effect when corticosteroid dosages are reduced in patients with severe asthma once CysLT1 antagonists are introduced, but more data are needed to definitely establish the mechanism behind this effect. Overall, however, the benefits of antileukotrienes in the treatment of asthma greatly outweigh their risks.

Churg-Strauss syndrome: clinical presentation, antineutrophil cytoplasmic antibodies, and leukotriene receptor antagonists

PURPOSE

To determine the association of antineutrophil cytoplasmic antibodies (ANCA) and leukotriene receptor antagonists with disease activity in a large series of patients with Churg-Strauss syndrome.

METHODS

Potential subjects were identified by a computerized search of the Mayo Clinic Rochester database for the years 1990 to 2000. Patients meeting one of three classification schemes for Churg-Strauss syndrome were included.

RESULTS

Ninety-one patients met the inclusion criteria. Clinical manifestations were similar to those in previous reports. Mortality was similar to that in the general population. ANCA testing was performed in 74 patients. Seventy-three percent (n = 22) of the 30 patients tested before therapy were ANCA positive, as were 75% (n = 12) of the 16 patients tested during a disease flare. In comparison, 16% (n = 8) of the 49 tested during remission were ANCA positive. Serial measurements indicated a correlation of ANCA levels with disease activity. Central nervous system involvement was the only clinical manifestation that correlated with ANCA status (P = 0.05). Twenty-three patients received leukotriene receptor antagonists, of whom 16 (70%) began treatment before diagnosis and 6 (27%) began during remission. Two of those treated after diagnosis relapsed. In 1 patient the relation between disease and leukotriene receptor antagonist use could not be determined. Use of leukotriene receptor antagonists did not affect the time between onset of asthma and manifestations of vasculitis, and was not correlated with organ manifestations, except sinus disease.

CONCLUSION

No one classification scheme identified all patients. Churg-Strauss syndrome has a better prognosis than other ANCA-associated vasculitides. ANCA status correlates with disease activity, whereas a pathogenic role for leukotriene receptor antagonists in the development of Churg-Strauss syndrome was not noted.

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.

Where do leukotriene modifiers fit in asthma management?

Effective asthma treatment requires long-term inflammation control. Patient adherence to corticosteroid treatment regimens remains problematic. Leukotriene modifiers, a newer drug class, add to the pharmacologic approaches to asthma management. Here, we review the role of leukotrienes in asthma pathogenesis and appropriate uses for leukotriene modifiers in asthma management.

Leukotriene antagonists and the Churg-Strauss syndrome

BACKGROUND AND OBJECTIVES

Leukotriene antagonists (LTAs), or antileukotrienes, are a new group of anti-inflammatory drugs used for the treatment of asthma. They might substitute for or allow tapering of corticosteroids in asthmatic patients. These drugs have been associated with the development of Churg-Strauss syndrome (CSS), a rare form of vasculitic angiitis. It is unclear whether the development of CSS is a direct drug effect or an unmasking of a preexisting condition on withdrawal of steroids for asthma. We present a case of CSS in a patient treated with montelukast and review the literature to analyze the association between LTAs and the development of CSS.

METHOD

We reviewed the literature using MEDLINE from February 1966 to October 2000. To the cases identified, we present an additional case of a patient who underwent a diagnostic lung biopsy.

RESULTS

Twenty-two case reports of patients receiving LTAs who developed CSS were identified. The onset of CSS occurred 2 days to 10 months after starting treatment with LTAs. All patients had received inhaled or oral steroids for asthma. The interval between the last oral corticosteroid treatment and CSS onset ranged from 3 days to 8 months.

CONCLUSIONS

To date, there is no compelling evidence that the development of CSS in asthmatic patients receiving LTAs results from a direct drug effect. Rather, it appears that tapering of corticosteroids in these patients unmasks the multiorgan manifestations of the disease. We believe that the use of LTAs should not be influenced by the apparent increase in the incidence of CSS and that these are still safe drugs for asthma.

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.

Cutaneous and systemic manifestations of drug-induced vasculitis

OBJECTIVE

To evaluate the literature for published cases of drug-induced vasculitis with cutaneous and/or systemic manifestations.

DATA SOURCES

The MEDLINE database was searched from 1965 to December 1999 for articles focusing on drugs and vasculitis, using various search terminologies (e.g., Churg-Strauss syndrome, Goodpasture's syndrome, Henoch-Schönlein purpura, various drugs suspected to induce vasculitis). Cases were included when they met the established criteria as described in the methodology.

DATA SYNTHESIS

Drugs found to be most frequently associated with vasculitis were propylthiouracil, hydralazine, colony-stimulating factors, allopurinol, cefaclor, minocycline, D-penicillamine, phenytoin, isotretinoin, and methotrexate. The interval between the first exposure and appearance of symptoms was reported to be extremely variable (hours to years). Vasculitis has occurred after drug dosage increases and after rechallenge with the suspected drug. In the majority of cases, vasculitis has resolved after discontinuing the drug. Patients with more severe, often life-threatening, manifestations have required treatment with corticosteroids, plasmapheresis, hemodialysis, or cyclophosphamide. Death was the result in 10% of all published cases, with a predominance in patients in whom multiple organ systems were involved.

CONCLUSIONS

Clinicians need to be suspect of drug-induced vasculitis to enable prompt diagnosis and treatment. This should improve patient outcomes based on the data referenced for this article.

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.

Fulminant eosinophilic endomyocarditis in an asthmatic patient treated with pranlukast after corticosteroid withdrawal

Several cases of eosinophilic conditions including Churg-Strauss syndrome have been reported in association with the use of cysteinyl leukotriene receptor antagonists, including zafirlukast, montelukast, and pranlukast, in asthmatic patients. The case of a 26 year old woman with a three year history of asthma, rhinitis, and nasal polyps is reported in whom eosinophilia, pulmonary infiltrates, and fulminant eosinophilic endomyocarditis accompanied by cardiogenic shock developed during pranlukast treatment after corticosteroid withdrawal. Acute necrotising eosinophilic endomyocarditis was confirmed by endomyocardial biopsy. The patient recovered after intensive treatment, including mechanical assistance involving intra-aortic balloon pumping and steroid pulse therapy, along with the discontinuation of pranlukast. It is recommended that careful attention must be paid to signs of a systemic eosinophilic condition or even fulminant eosinophilic myocarditis in asthmatic patients who have begun treatment with antileukotriene drugs following withdrawal of steroids.

Experience of 10 years with Churg-Strauss syndrome: An accompaniment to or a transition from aspirin-induced asthma?

Churg-Strauss syndrome is a rare, idiopathic, eosinophilic vasculitis appearing in concurrence with asthma which is often severe. Aspirin-induced asthma is a special clinical syndrome existing in nearly 10 % of adult asthmatics. After leukotriene antagonists had been marketed there has been marked increase in Churg-Strauss syndrome reports among the patients who had been followed up with asthma. This syndrome seems to be more frequent among the patients with aspirin-induced asthma. The role of leukotriene antagonists on the conversion from aspirin-induced asthma to Churg-Strauss syndrome has aroused attention and been questioned. Here we report 7 cases of Churg-Strauss syndrome where three had aspirin induced asthma which we have diagnosed in the last 10 years and where only one of them seems to be related to antileukotriene drug use.

The relationship of asthma therapy and Churg-Strauss syndrome: NIH workshop summary report

The Churg-Strauss syndrome (CSS) is a distinct form of vasculitis that is notable for its eosinophilia and frequent associations with asthma and sinusitis. Because there has been an increasing recognition that CSS can develop in patients with asthma and that CSS might be associated with specific asthma treatments, the National Heart, Lung, and Blood Institute, the National Institute of Allergy and Infectious Diseases, the Office of Rare Diseases, National Institutes of Health, and the US Food and Drug Administration jointly sponsored a workshop to consider interrelationships among CSS, asthma, and asthma therapeutics and to assess what is known about underlying mechanisms of CSS. Issues related to the criteria for defining and diagnosing CSS were reviewed, including the contemporary understanding that diagnostic biopsies need only reveal eosinophilic perivascular infiltrates and that asthma need not be present when CSS develops. From published reports and reports to the US Food and Drug Administration, treatment of patients with asthma with any of 3 cysteinyl leukotriene receptor antagonists, a 5-lipoxygenase inhibitor, and inhaled corticosteroids has been associated with CSS development. It is unknown whether these agents were eliciting CSS. A variety of physiologic and study design issues might lead to the reported associations of these drugs with CSS. Because many asthma patients receiving these therapies were able to diminish their systemic corticosteroid therapy, it is possible that incipient CSS was unmasked by lessened steroid use. The underlying pathophysiologic mechanisms of CSS, however, are unknown, and there is no means of identifying which patients with asthma might be at risk for CSS. Accordingly, investigations with the goals of defining the underlying pathophysiologic processes of CSS and establishing the relationships of asthma and its therapies to CSS are needed.

Safety of antileukotriene agents in asthma management

OBJECTIVE

This article presents information on the safety of zafirlukast, montelukast, and zileuton, three antileukotrienes (anti-LTs) approved in the United States for the prophylaxis and treatment of asthma. After reading this article, readers should have an understanding both of the general safety of anti-LTs and their specific adverse effects.

DATA SOURCES

Relevant and appropriate controlled clinical studies on the safety of anti-LTs in asthma were used. Only literature in the English language was reviewed.

STUDY SELECTION

Material was taken from academic/scholarly journals and appropriate reviews.

RESULTS

Antiasthma agents, including corticosteroids, beta2-agonists, and methylxanthines, may be categorized into two classes: those used for the long-term control and prevention of persistent asthma and those used for the prompt relief of acute symptoms and exacerbations of the disease. Although most agents are safe and well tolerated when used properly, adverse effects may occur with use at higher dose levels. The anti-LTs, including zafirlukast, montelukast, and zileuton, are the first new pharmacologic class in the therapeutic armamentarium for asthma management to be approved in the United States in the past 20 years. Both zafirlukast and montelukast carry pregnancy category B classification whereas zileuton carries pregnancy category C classification. The most common adverse effects observed in clinical trials were headache, pharyngitis, abdominal pain, dyspepsia, and cough.

CONCLUSIONS

The results of clinical trials and real-world experience indicate that these agents are generally safe and well tolerated, with an incidence of adverse effects comparable with placebo.

Churg-Strauss syndrome

OBJECTIVES

This article discusses the clinical manifestations and treatment protocols of Churg-Strauss syndrome (CSS). A review of the definition, pathophysiology, and prognosis of CSS is included, as well as more recent evidence of the presumed association between antileukotriene antagonists and CSS.

DATA SOURCES

Relevant articles in the medical literature derived from searching the MEDLINE database (1966 to present) with key terms Churg-Strauss syndrome, allergic granulomatosis, and allergic granulomatous angiitis. Sources included review articles, meta-analyses, randomized control trials, case reports, case series, and seminal articles, the majority of which had been published within the past decade.

STUDY SELECTION

Studies that described the clinical manifestations, pathophysiology, etiology, treatment, or prognosis of CSS.

RESULTS

CSS is a systemic vasculitic disorder with multiorgan involvement and diverse presentations.

CONCLUSIONS

Recognition of the multiorgan manifestations of CSS is crucial to clinical management. Whether a causal relationship exists between antileukotriene antagonists and onset of CSS remains unclear.

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.

Clinical safety and tolerability of montelukast, a leukotriene receptor antagonist, in controlled clinical trials in patients aged > or = 6 years

OBJECTIVE

Montelukast is a leukotriene receptor antagonist administered orally once daily for treatment of chronic asthma in adults and children. A comprehensive analysis of safety data from double-blind, randomized, placebo-controlled trials with montelukast has not been previously reported.

PATIENTS AND METHODS

A pooled analysis of safety data from 11 multicentre, randomized, controlled montelukast Phase IIb and III trials and five long-term extension studies was performed. A total of 3386 adult patients (aged 15-85 years) and 336 paediatric patients (aged 6-14 years) were enrolled in the trials; 2031 adults received montelukast for up to 4.1 years, and 257 children received montelukast for up to 1.8 years. Summary statistics comparing incidences of adverse events among treatment groups were calculated.

RESULTS

The overall incidence of clinical and laboratory adverse events among montelukast-treated patients, both adult and paediatric, was similar to that among patients receiving placebo. There were no clinically relevant differences in individual adverse events, including infectious upper respiratory conditions and transaminase elevations, between montelukast and placebo groups. Discontinuations due to adverse events occurred with similar frequencies during placebo, montelukast and inhaled beclomethasone therapy. No dose-related adverse effects of montelukast were observed in adults treated with dosages as high as 200 mg per day (20 times the recommended dose) for 5 months. This tolerability profile montelukast observed in clinical trials has been generally reflected in the post-marketing safety experience seen to date.

CONCLUSIONS

These data indicate a tolerability profile for montelukast similar to placebo during both short-term and long-term administration, even at doses substantially higher than the recommended clinical dose of 10 mg once daily for adults and 5 mg once daily for children aged 6-14 years.

Antileukotriene drugs in childhood asthma: what is their place in therapy?

Leukotriene antagonists are a new class of anti-inflammatory drugs which have shown clinical efficacy in the management of asthma. However, their role in paediatric asthma is still unclear. In essence, while there are theoretical reasons as to why leukotriene antagonists would be of use in the management of childhood asthma, there is little clinical data on their use in this patient group. Studies with leukotriene antagonists to date have been performed in children with chronic 'undertreated' asthma which, under current recommendations, should be treated with inhaled corticosteroids. Furthermore, the magnitude of effect of leukotriene antagonists on lung function (forced expiratory volume in one second of less than 5% better than placebo) and daily symptoms (0.23 puffs per day of B2 agonist less than placebo), while reaching statistical significance, is unlikely to be of clinical significance in children with chronic undertreated asthma. There is, however, good evidence for leukotriene antagonist use in exercise induced asthma in children. We conclude that although leukotriene antagonists may play an important role in the management of childhood asthma in the future, particularly as corticosteroid sparing agents and in exercise induced asthma, clinical data in paediatric asthma is poor.

[Role of leukotriene inhibitors in the treatment of childhood asthma]

Leukotriene inhibitors are new pharmacological agents for the treatment of mild to moderate persistent asthma and exercise-induced asthma (EIA). Studies concerning their use in children remain scarce. Available data in the treatment of persistent asthma in children suggest that they could be an alternative to long-acting beta 2-agonists when asthma control cannot be obtained with inhaled steroids alone. Their main advantages are first that they are given orally once daily; second, that they do not induce tachyphylaxis to bronchoprotection against EIA, unlike long-acting beta 2-agonists. Studies specifically conducted in children are necessary to best describe their place in pediatric asthma treatment.

Current treatment of asthma--focus on leukotrienes

Since their identification in 1979, the cysteinyl leukotrienes (cysLTs) have been shown to be prominent in many inflammatory conditions, including asthma, allergic rhinitis, rheumatoid arthritis, psoriasis, cystic fibrosis and inflammatory bowel disease. They are potent pro-inflammatory agents, as well as causing bronchoconstriction, and undoubtedly have a role in asthma. The cysLTs are products of arachidonic acid metabolism and have been shown to have effects via a cysteinyl leukotriene receptor (CysLTR1) on vascular permeability, mucus production, chemotaxis and bronchial smooth muscle. Their detection in certain body fluids in allergic, aspirin-sensitive and exercise-induced asthma is well documented and potential roles in pathogenesis, proposed. The development of agents affecting production or action offers an exciting new approach to the treatment of asthma. Two approaches to antileukotriene therapy have been developed: blocking their production by inhibiting the action of 5-lipoxygenase enzyme or blocking the CysLTR1. Both approaches have been tried in studies in asthma and overall the results are encouraging, with a decrease in both daytime and nocturnal symptoms, a decrease in additional beta 2 agonist usage and improvement in lung function. The changes, however, are small in some studies. This may be a reflection of disease severity in the study subjects, but of note is a heterogeneity of response to these treatments that may be genetically determined. Antileukotriene therapy has been shown to have an effect in specific types of asthma where the role of cysLTs seems well established--aspirin-sensitive/intolerant asthma and exercise-induced asthma. Longer term studies are needed in other areas such as severe asthma and chronic persistent asthma in both children and adults to provide evidence for the appropriate placement of antileukotriene treatment in current asthma guidelines, in comparison with other established treatments.

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.