Montelukast reduces airway eosinophilic inflammation in asthma: a randomized, controlled trial

Effect of a specific cysteinyl leukotriene-receptor 1-antagonist (montelukast) on the transmigration of eosinophils across human umbilical vein endothelial cells

BACKGROUND

Leukotrienes have been implicated in the selective infiltration of eosinophils into the bronchial mucosa in asthma.

OBJECTIVE

We studied whether eosinophil transmigration through cultured human umbilical vein endothelial cells (HUVECs) can be blocked by a specific cysteinyl LT1-receptor-antagonist.

METHODS

Unstimulated and stimulated eosinophils from patients with asthma and normal controls were subjected to confluent human umbilical vein endothelial cell (HUVEC) monolayers separating the upper and lower chamber of Transwell culture plates. Unstimulated eosinophils or cells pre-incubated in the presence of the eosinophil activating cytokines GM-CSF or IL-13 were placed in the upper chambers while PAF, a potent chemoattractant factor for eosinophils, was added to the lower chamber. Migration of eosinophils was quantified by a beta-glucuronidase assay.

RESULTS

The assumption that eosinophils express CysLT1 (cysteinyl-leukotriene 1)-receptors was based on our demonstration of mRNA-expression for the CysLT-1-receptor by polymerase chain reaction on purified eosinophils. The chemotactic response to PAF was significantly reduced when eosinophils were pre-incubated with montelukast for 15 min. When eosinophils were pre-incubated with GM-CSF and/or IL-13, the migratory response to PAF was also significantly reduced by montelukast.

CONCLUSION

From these data we conclude that the specific cysteinyl LT1-receptor antagonist montelukast can inhibit PAF-induced eosinophil transmigration through cultured HUVEC monolayers.

Analysis of montelukast in mild persistent asthmatic patients with near-normal lung function

Few studies have specifically evaluated controller therapy in patients with mild persistent asthma. We used a subgroup analysis to investigate the effects of montelukast, a potent cysteinyl leukotriene receptor antagonist, on adult patients on the milder end of the asthma severity spectrum. We have identified seven double-blind, randomized, placebo-controlled studies of adult patients with mild-to-moderate chronic asthma in which montelukast was investigated. Subsets of patients with baseline forced expiratory volume in 1 sec (FEV1) > 80% and > 75% predicted or further restricted by less than daily rescue beta-agonist use were included as four cohorts (A, B, C, D), and efficacy measures, including change in FEV1 rescue-free days, beta-agonist use, nocturnal awakenings and blood eosinophil counts were evaluated. Cohorts A to D comprised 21%, 8%, 11%, and 4%, respectively, of patients from these studies. Mean pretreatment FEV1 ranged from 81% to 84% predicted and daily beta-agonist use from 2.4 to 4.5 puffs day(-1) in the four cohorts. Pooled results demonstrated a treatment effect for montelukast over placebo in all cohorts, for all endpoints. There was a significant improvement in FEV1 in montelukast-treated patients (7-8% over baseline) compared with placebo (1-4% over baseline, between-group difference P < or = 0.02) for all cohorts. Similarly, the percentage of rescue-free days increased substantially more with montelukast (22-30%) than with placebo (8-13%). This subgroup analysis indicates that montelukast produced improvements in parameters of asthma control in patients with milder persistent asthma that should be confirmed in additional prospective trials.

Montelukast added to budesonide in children with persistent asthma: a randomized, double-blind, crossover study

OBJECTIVE

We tested the hypothesis that adding montelukast to budesonide would improve asthma control in children with inhaled glucocorticoid-dependent persistent asthma.

STUDY DESIGN

In a multicenter, randomized, double-blind, crossover study, we compared the benefit of adding montelukast, 5 mg, or placebo once daily to budesonide, 200 microg, twice daily.

RESULTS

After a 1-month run-in with budesonide, 200 microg, twice daily, 279 children were randomized to montelukast or placebo. The mean +/- SD age was 10.4 +/- 2.2 years, the mean forced expiratory volume in 1 second (FEV(1)) was 77.7% +/- 10.6% predicted, and reversibility was 18.1% +/- 12.9%. Compared with adding placebo to budesonide, adding montelukast produced significant improvements in mean percent change from baseline FEV(1) (P =.062 [P =.010 for per-protocol analysis]), mean absolute change from baseline FEV(1) (P =.040), mean increase from baseline in morning (P =.023) and evening (P =.012) peak expiratory flows, decrease in exacerbation days by approximately 23% (P <.001), decreased beta2-agonist use (P =.013), and reduced blood eosinophil counts (P <.001). The treatments did not differ significantly with regard to safety.

CONCLUSIONS

Montelukast, 5 mg, added to budesonide improved asthma control significantly, indicated by a small additive effect on lung function and a clinically relevant decrease in asthma exacerbation days.

Leukotriene receptor antagonists in the treatment of asthma

The role of leukotriene receptor antagonists in the treatment of persistent asthma is in evolution. Pivotal 8-12-week, randomized, controlled trials in both adults and children have shown efficacy, as defined by standard asthma outcomes. Tolerance to therapy did not develop, nor did rebound worsening of asthma symptoms once therapy was withdrawn. In a comparator trial of montelukast versus beclomethasone, the average percentage change from baseline in forced expiratory volume in 1 second was greater with the inhaled corticosteroid preparation; however, improvements in other asthma outcomes were similar. There was considerable heterogeneity of pulmonary response with both treatments, with good and poor responders in both groups. In an open-label, crossover comparison of montelukast versus cromolyn, both parents and children preferred montelukast, thus regimen adherence was greater with montelukast. Additional long-term, randomized, controlled trials will define the effectiveness of leukotriene receptor antagonists compared with established controllers, thus determining the leukotriene receptor antagonists' place in asthma management.

Antileukotrienes in asthma: present situation

Leukotrienes are key mediators in asthma. Over the last 5 years, several antileukotrienes, including three receptor antagonists (montelukast, pranlukast and zafirlukast) and one 5-lipoxygenase inhibitor (zileuton), have been marketed and, to date, this class of drugs is being used widely. Still, their definite place in the asthma treatment algorithm is not yet established. These novel drugs have not yet all been evaluated in the same depth, but they have all been shown to possess anti-inflammatory properties and to be effective in chronic asthma treatment. Zafirlukast and montelukast are particularly efficacious in exercise-induced asthma and zileuton appears valuable for treating aspirin-intolerant asthmatics. Clinical comparisons to other anti-asthma drugs are still sparse. The corticosteroid-sparing effect of antileukotrienes is fairly well established except for zileuton, even though this drug has been evaluated most thoroughly in terms of its anti-inflammatory effects. Montelukast is the antileukotriene most extensively evaluated in children and zafirlukast has recently been approved for use in children in the USA, although not yet in Europe. Therapeutic regimes are quite variable depending on the drug, but all of the antileukotrienes marketed to date are taken orally; hence, compliance is usually greater than that with inhaled medication. Response to antileukotrienes appears to depend on the individual patients' characteristics, in particular on genetic polymorphisms related to leukotriene metabolism. All drugs of this class are well tolerated and only in the case of zileuton is there potential for hepatic adverse effects. The diagnosis of Churg-Strauss syndrome made among patients taking antileukotrienes seems to be more related to the withdrawal of corticosteroids than to the antileukotrienes themselves.

Anti-inflammatory and lung function effects of montelukast in asthmatic volunteers exposed to sulfur dioxide

BACKGROUND

Sulfur dioxide (SO(2)) gas may induce acute asthmatic responses when inhaled by individuals in the setting of community or occupational air pollution during exercise. Some asthma medications mitigate the SO(2) response, which is not fully understood but appears to involve multiple mechanisms.

OBJECTIVE

We tested the hypothesis that pretreatment with the cysteinyl-leukotriene inhibitor montelukast sodium protects against the inflammatory and bronchoconstrictive effects of SO(2) in the airways of asthmatic subjects.

METHODS

Asthmatic volunteers (enrolled, 12 subjects; completed study, 11 subjects) were exposed to 0.75 ppm SO(2) for 10-min periods during exercise (mean ventilation, 35 L/min) and were exposed similarly to filtered air (control condition) after double-blinded pretreatments with montelukast (10 mg/d for 3 days) and placebo.

RESULTS

After montelukast pretreatment, specific airways resistance, FEV(1), symptoms, and eosinophil counts in induced sputum showed statistically and clinically significant improvements in preexposure measurements and/or decreased responses to SO(2) exposure or exercise. The mean FEV(1) immediately after exposure was 95% of baseline FEV(1) with montelukast pretreatment vs 82% with placebo.

CONCLUSION

Montelukast significantly protects against airways eosinophilic inflammation and bronchoconstriction from SO(2) exposure during exercise. This implies a role for leukotrienes in SO(2)-induced lung effects.

Leukotriene modifiers in pediatric asthma management

Cysteinyl leukotrienes (Cys-LTs) are mediators released in asthma and virus-induced wheezing. Corticosteroids appear to have little or no effect on this release in vivo. Cys-LTs are both direct bronchoconstrictors and proinflammatory substances that mediate several steps in the pathophysiology of chronic asthma, including inflammatory cell recruitment, vascular leakage, and possibly airway remodeling. Blocking studies show that Cys-LTs are pivotal mediators in the pathophysiology of asthma. Cys-LTs are key components in the early and late allergic airway response and also contribute to bronchial obstruction after exercise and hyperventilation of cold, dry air in asthmatics. LT modifiers reduce airway eosinophil numbers and exhaled nitric oxide levels. Together these findings support an important role for the Cys-LTs in the asthma airway inflammation. Cys-LT receptor antagonists (Cys-LTRA) are generally well-tolerated. Phase III randomized, controlled clinical trials (RCT) show that LT modifiers are moderately effective, apparently with a particular between-patient variability in their clinical response. The clinical effects of LT modifiers are additive to those of beta-agonists and corticosteroids. The onset of action of LT modifiers is within 1 to several days, and not rapid enough to make them useful as rescue treatment. Although LT modifiers possess some antiinflammatory activity, they cannot substitute for corticosteroids for inflammation control. LT modifiers are alternatives to long-acting beta-agonists as complementary treatment to inhaled corticosteroids in pediatric asthma management because they provide bronchodilation and bronchoprotection without development of tolerance, and complement the antiinflammatory activity unchecked by steroids. In addition, the Cys-LTRA montelukast has been shown to ameliorate asthmatic symptoms and provide bronchoprotection in asthmatic preschool children from 2 years of age, which is of particular importance in this difficult-to-manage group of asthmatics. Given their efficacy, antiinflammatory activity, oral administration, and safety, LT modifiers will play an important role in the treatment of asthmatic children.

Leukotriene inhibitors and non-steroidal therapies in the treatment of asthma

Asthma is the most common chronic disease of childhood whose morbidity and mortality continues to rise [1]. Drugs used in the treatment of asthma must be targeted at reversing three principle pathophysiologic features: bronchoconstriction, mucus plugging/hypersecretion and inflammation. In the past two decades, the contribution of airway inflammation to the development and progression of asthma symptoms and airway pathology has become a critical focus. Chronic airway inflammation can lead to the progressive decline and irreversible loss of lung function and airway remodelling [2]. In recent years, therapies aimed at diminishing airway inflammation have been at the forefront of asthma management. Steroids have been extensively studied and used as primary anti-inflammatory agents in the management of the asthmatic patient with persistent symptoms of varying severity. Within the last decade, however, several additional non-steroidal classes of drugs have begun to emerge as anti-inflammatory agents for the treatment of asthma. This article will focus on these non-steroidal drugs which have been developed and investigated within the last 5 years. Particular emphasis will be placed on leukotriene receptor antagonists, but anti-IgE and anti-IL-4 therapies, as well as phosphodiesterase inhibitors will also be discussed. Of these new therapies, only two leukotriene receptor antagonists, montelukast (Singulairtrade mark, Merck) and zafirlukast (Accolatetrade mark, AstraZeneca) and the 5-lipoxygenase inhibitor, zileuton (Zyflotrade mark, Abbott Laboratories), have been recommended, approved and are currently available for use in the treatment of paediatric patients with asthma in the United States.

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.

Expression of the cysteinyl leukotriene 1 receptor in normal human lung and peripheral blood leukocytes

The cysteinyl leukotrienes (CysLTs) are important mediators of human asthma. Pharmacologic and clinical studies show that the CysLTs exert most of their bronchoconstrictive and proinflammatory effects through activation of a putative, 7-transmembrane domain, G-protein-coupled receptor, the CysLT1 receptor. The initial molecular characterization of the CysLT1 receptor showed by in situ hybridization, the presence of CysLT1 receptor messenger RNA (mRNA) in human lung smooth-muscle cells and lung macrophages. We confirmed the results of these in situ hybridization analyses for the CysLT1 receptor, and produced the first immunohistochemical characterization of the CysLT1 receptor protein in human lung. The identification of the CysLT1 receptor in the lung is consistent with the antibronchoconstrictive and antiinflammatory actions of CysLT1 receptor antagonists. We also report the expression of CysLT1 receptor mRNA and protein in most peripheral blood eosinophils and pregranulocytic CD34+ cells, and in subsets of monocytes and B lymphocytes.

Suppression of the early and late cutaneous allergic responses using fexofenadine and montelukast

BACKGROUND

The relative contribution of histamine and the cysteinyl leukotrienes to the early and late cutaneous allergic responses (ECAR and LCAR) can be studied using antagonists of these mediators.

OBJECTIVE

To determine the relative suppression of the ECARs and LCARs using standard doses of an H1-receptor antagonist, a cysteinyl leukotriene1-receptor antagonist, and the two antagonists administered concurrently.

METHODS

We carried out a prospective, randomized, double-blind, placebo-controlled, four-way crossover study in 12 highly allergic participants. Intradermal tests with standardized allergen, and with histamine phosphate, LTD4, and saline controls were performed on 5 different test days as follows: pretreatment baseline and at steady state immediately after the seventh and last dose of a 1-week course of treatment with once-daily fexofenadine, 120 mg; montelukast, 10 mg; fexofenadine and montelukast administered concurrently; or placebo. On each test day, the skin test results were read at intervals from 0.25 to 24 hours after the intradermal injections were performed.

RESULTS

After allergen injection, compared with baseline, all treatment regimens significantly decreased the ECAR and LCAR. After allergen injection, compared with placebo, fexofenadine significantly decreased the ECAR and the LCAR from 0.25 to 2 hours and at 8 hours. Montelukast did not significantly decrease the ECAR or LCAR. Fexofenadine and montelukast administered concurrently were not more effective than fexofenadine alone at any time. In the control skin tests, compared with placebo, fexofenadine, but not montelukast, significantly decreased the histamine-induced response, and montelukast, but not fexofenadine, significantly decreased the LTD4-induced response.

CONCLUSIONS

Fexofenadine and montelukast administered concurrently were not significantly more effective than fexofenadine alone in decreasing the ECAR and LCAR. Montelukast does not need to be discontinued before allergen skin testing. Further studies of the effect of concurrent treatment with higher doses of a histamine antagonist and a leukotriene modifier on the allergic response in the skin are needed.

Priming of alveolar macrophages by leukotriene D(4): potentiation of inflammation

Cysteinyl leukotrienes (LTs), including LTC(4), LTD(4), and LTE(4), are well known to induce bronchoconstriction and increase bronchial hyperreactivity, mucus secretion, and vascular permeability. Interestingly, alveolar macrophages (AMs) express LTD(4) high-affinity receptor. These cells represent a major source of inflammatory mediators implicated in the pathophysiology of asthma. Thus, we investigated the immunomodulatory effects of LTD(4) on the production of inflammatory mediators such as macrophage inflammatory protein (MIP)- 1alpha, tumor necrosis factor (TNF), and nitric oxide (NO) by AMs. NR8383 cells, an AM cell line, were pretreated with LTD(4) (10(-11) M) for different periods of time and stimulated or not with lipopolysaccharide (LPS) for 2 h. Although LTD(4) treatment did not modulate the release of MIP-1alpha and TNF, this treatment (6 h) significantly increased the release of these mediators when AMs were further stimulated with LPS (increases of 47 and 21%, respectively). Further, LTD(4) pretreatment increased messenger RNA (mRNA) levels of MIP-1alpha and TNF. These effects of LTD(4) were abrogated by the presence of a LTD(4) receptor antagonist, Verlukast (MK-679), showing the specificity of LTD(4). Interestingly, LTD(4) treatment significantly increased the release of NO by LPS-stimulated AMs without modulating mRNA levels of the inducible NO synthase. Our data suggest that LTD(4) primes AMs to release more MIP-1alpha, TNF, and NO after stimulation. Thus, in addition to its potent bronchoconstrictor effect, LTD(4) may participate in the inflammatory process seen in asthma by potentiating the production of proinflammatory mediators by AMs during immunologic stimuli.

Allergy and asthma in elite summer sport athletes

Exercise may increase ventilation up to 200 L/min for short periods of time in speed and power athletes, and for longer periods in endurance athletes, such as long-distance runners and swimmers. Therefore highly trained athletes are repeatedly and strongly exposed to cold air during winter training and to many pollen allergens in spring and summer. Competitive swimmers inhale and microaspirate large amounts of air that floats above the water surface, which means exposure to chlorine derivatives from swimming pool disinfectants. In the summer Olympic Games, 4% to 15% of the athletes showed evidence of asthma or used antiasthmatic medication. Asthma is most commonly found in endurance events, such as cycling, swimming, or long-distance running. The risk of asthma is especially increased among competitive swimmers, of which 36% to 79% show bronchial hyperresponsiveness to methacholine or histamine. The risk of asthma is closely associated with atopy and its severity among athletes. A few studies have investigated occurrence of exercise-induced bronchospasm among highly trained athletes. The occurrences of exercise-induced bronchospasm vary from 3% to 35% and depend on testing environment, type of exercise used, and athlete population tested. Mild eosinophilic airway inflammation has been shown to affect elite swimmers and cross-country skiers. This eosinophilic inflammation correlates with clinical parameters (ie, exercise-induced bronchial symptoms and bronchial hyperresponsiveness). Athletes commonly use antiasthmatic medication to treat their exercise-induced bronchial symptoms. However, controlled studies on their long-term effects on bronchial hyperresponsiveness and airway inflammation in the athletes are lacking. Follow-up studies on asthma in athletes are also lacking. What will happen to bronchial hyperresponsiveness and airway inflammation after discontinuation of competitional career is unclear. In the future, follow-up studies on bronchial responsiveness and airway inflammation, as well as controlled studies on both short- and long-term effects of antiasthmatic drugs in the athletes are needed.

Zafirlukast improves asthma control in patients receiving high-dose inhaled corticosteroids

Not all asthma can be adequately controlled, despite the use of high-dose inhaled corticosteroids. Because cysteinyl-leukotrienes (Cys-LT) have been implicated in the pathogenesis of asthma, we hypothesized that the leukotriene receptor antagonist zafirlukast, in combination with high-doses of inhaled corticosteroids, might be efficacious in severe asthma. In a double-blind, parallel group study, 368 chronic adult asthmatic patients treated with inhaled corticosteroids (1,000 to 4,000 microgram/d), who had a predefined level of asthma symptoms during the run in period of the study, were randomly assigned to receive additional treatment with a high dose of zafirlukast (80 mg twice daily) (n = 180) or placebo (n = 188) for 6 wk. Compared with placebo, zafirlukast produced a significant improvement over baseline in the primary study endpoint of mean morning peak expiratory flow rate (PEFR) (18.7 L/min versus 1.5 L/min, p < 0.001), as well as in evening PEFR (p < 0.01), FEV(1) (p < 0.05), daytime symptom score (p < 0.001), and beta(2)-agonist use (p < 0.001). Furthermore, zafirlukast significantly reduced the risk of an exacerbation of asthma (odds ratio [OR]: 0.61; 95% confidence interval [CI]: 0.38 to 0.99) and the risk of patients requiring a further increase in asthma controller therapy (OR: 0.4; 95% CI: 0.2 to 0.8). In conclusion, in patients taking high-dose inhaled corticosteroids, zafirlukast improves pulmonary function and asthma symptoms, and reduces the risk of an asthma exacerbation, suggesting that the contribution of leukotrienes to asthma symptoms and exacerbations is not adequately controlled by high-dose inhaled corticosteroids.

Effects of adding a leukotriene antagonist or a long-acting beta(2)-agonist in asthmatic patients with the glycine-16 beta(2)-adrenoceptor genotype

PURPOSE

In the United Kingdom, about 40% of patients with asthma are homozygous for the glycine-16 beta(2)-adrenoceptor polymorphism, which predisposes them to agonist-induced down-regulation and desensitization of the beta(2)-adrenoceptor. We assessed the effects of adding treatment with either a long-acting beta(2)-agonist (inhaled formoterol, 12 microg twice daily) or a leukotriene receptor antagonist (oral zafirlukast, 20 mg twice daily) to inhaled corticosteroid therapy in patients with this genotype.

SUBJECTS AND METHODS

We enrolled 24 patients with mild to moderate asthma who were being treated with inhaled corticosteroids. Patients were randomly assigned to receive one of three treatments (placebo, zafirlukast, or formoterol in addition to inhaled corticosteroids) for 1 week each in a crossover fashion, separated by a 1-week placebo run-in and washout period. Measurements of bronchoprotection (measured as the provocative dose of methacholine that produced a 20% decline in forced expiratory volume in 1 second [FEV(1)]), exhaled nitric oxide (a surrogate marker of airway inflammation), and symptoms were made before each treatment and 12 hours after the last dose of each treatment.

RESULTS

Both formoterol and zafirlukast were equally effective in maintaining asthma control compared with placebo: the geometric mean-fold difference in the methacholine provocative dose was 1.5-fold (95% confidence interval [CI]: 1.1- to 2.2-fold) for zafirlukast and 1.9-fold (95% CI: 1.2- to 2.9-fold) for formoterol. As compared with placebo, zafirlukast caused a significant suppression in exhaled nitric oxide (1.7-fold difference in geometric mean values, 95% CI: 1.1- to 2.6-fold) but formoterol did not (1.2-fold difference, 95% CI: 0.8- to 1.9-fold). Diary cards showed significant (P <0.05) improvements in the peak flow with formoterol (morning and evening) and zafirlukast (evening) as compared with placebo.

CONCLUSIONS

Formoterol and zafirlukast maintained asthma control in patients who might be genetically predisposed to fare worse with long-acting beta(2)-agonists. The reduction in exhaled nitric oxide with zafirlukast suggests that it may have anti-inflammatory effects in addition to those seen with inhaled corticosteroids.

Role of leukotrienes in asthma pathophysiology

Inflammation is an essential component of asthma pathophysiology. While beta(2)-agonists are often used for short-term relief of acute bronchospasm, anti-inflammatory agents are required for the long-term management of chronic inflammation in this disease. Corticosteroids have emerged as the first-line anti-inflammatory therapy for asthma management. However, in some patients, especially children, the high doses of corticosteroids that may be required to control features of hyperresponsiveness, including exercise-induced asthma, raise safety concerns. Thus, there is a need for complementary anti-inflammatory, steroid-sparing agents in asthma therapy. Several inflammatory mediators have been targeted in an attempt to thwart this inflammatory process, but so far with little success. The cysteinyl leukotrienes (CysLT), LTC(4), LTD(4), and LTE(4), have been shown to be essential mediators in asthma, making them obvious targets for therapy. These cysteinyl leukotrienes, previously known as the slow-reacting substance of anaphylaxis (SRS-A), mediate many of the features of asthma, including bronchial constriction, bronchial hyperreactivity, edema, and eosinophilia. Data show that selective cysteinyl leukotriene receptor antagonists (CysLTRAs) effectively reverse these pathologic changes. Corticosteroids do not inhibit the production of CysLTs in vivo, suggesting that CysLTRAs and corticosteroids affect different targets. The bronchodilator properties of CysLTRAs seem to be additive to those of beta(2)-agonists and corticosteroids. These data suggest that CysLTs are important therapeutic targets in the management of inflammation in asthma.

Bronchoprotection with a leukotriene receptor antagonist in asthmatic preschool children

We hypothesized that a leukotriene receptor antagonist (LTRA) could provide bronchoprotection against the cold, dry air-induced response in asthmatic preschool children. In a randomized, double-blind, placebo-controlled crossover study, we examined the effect of the specific LTRA montelukast at 5 mg/d for 2 d on the bronchoconstriction induced by hyperventilation of cold, dry air in 13 asthmatic children 3 to 5 yr old. The bronchoconstriction was measured as the specific airway resistance (sRaw) in a whole-body plethysmograph before and 4 min after challenge with cold, dry air. The repeatability of the bronchoprotection was examined by repeating the placebo-controlled study in six of the 13 children. sRaw increased by an average of 46% (95% confidence interval [CI]: 30 to 63%) after placebo treatment and 17% (95% CI: 3 to 31%) after montelukast (p < 0.01). Eight of the children were receiving regular treatment with budesonide delivered by an inhaler with a spacer in a mean daily dose of 350 microg, but the bronchoprotection provided by montelukast was independent of concurrent steroid treatment. There was no convincing evidence of failure to respond, and the protective effect of montelukast was consistent upon repeated testing (p = 0. 02). We conclude that the LTRA montelukast provided clinically significant bronchoprotection against the effect of hyperventilation of cold dry air in asthmatic children 3 to 5 yr old. The bronchoprotection appeared to be homogeneous among the children, and seemed independent of steroid treatment. This suggests that LTRAs may be of therapeutic use in limiting clinical symptoms of asthma in young children.

Leukotriene receptor antagonists and synthesis inhibitors reverse survival in eosinophils of asthmatic individuals

Eosinophilia is a feature of airway inflammation associated with asthma. Leukotriene antagonists provide therapeutic benefit in asthma, but their potential antiinflammatory actions have not been fully explored. We have examined the role of eosinophil-derived cysteinyl leukotrienes in the maintenance of eosinophil survival, and the involvement of leukotrienes in the paracrine stimulation of eosinophil survival by mast cells and lymphocytes. We obtained eosinophils and autologous lymphocytes from peripheral blood of asthmatic subjects. Leukotriene (LT)-B(4), LTC(4) and LTD(4), granulocyte-macrophage colony-stimulating factor (GM-CSF), and fibronectin promoted eosinophil survival. LTD(4) (10(-)(6) M) was as effective as GM-CSF (5 ng/ml) and fibronectin (400 ng/ml) in promoting survival. Lymphocytes and conditioned medium from a human mast cell line (HMC-1) induced eosinophil survival. Blockade of cysteinyl leukotriene receptors with SKF 104353 (pobilukast, 3 nM), and inhibition of 5-lipoxygenase (5-LO) with BW A4C (1 microM) and of 5-LO activating protein with MK 886 (1 microM), all increased basal rates of eosinophil apoptosis and reversed GM-CSF-induced eosinophil survival. Fifty percent reversal of GM-CSF- induced survival was achieved with SKF 104353 at 0.3 nM. The potency of SKF 104353 was two orders of magnitude greater than that of the LTB(4) receptor antagonist SB 201146. Mast cell- and lymphocyte-induced eosinophil survival were completely reversed by SB 201146, SKF 104353, BW A4C, and MK 886. These findings provide evidence for the involvement of an autocrine cysteinyl leukotriene pathway that supports eosinophil survival in response to a range of survival stimuli. They also suggest that LTB(4) could act as a paracrine stimulus of eosinophil survival.

Montelukast or salmeterol combined with an inhaled steroid in adult asthma: design and rationale of a randomized, double-blind comparative study (the IMPACT Investigation of Montelukast as a Partner Agent for Complementary Therapy-trial)

Asthma patients who continue to experience symptoms despite taking regular inhaled corticosteroids represent a management challenge. Leukotrienes play a key role in asthma pathophysiology, and since pro-inflammatory leukotrienes are poorly suppressed by corticosteroids it seems rational to add a leukotriene receptor antagonist (LTRA) when a low to moderate dose of inhaled corticosteroids does not provide sufficient disease control. Long acting beta2-agonist (LABA) treatment represents an alternative to LTRAs and both treatment modalities have been shown to provide additional disease control when added to corticosteroid treatment. To compare the relative clinical benefits of adding either a LTRA or a LABA to asthma patients inadequately controlled by inhaled corticosteroids, a randomized, double-blind, multi-centre, 48-week study will be initiated at approximately 120 centres throughout Europe, Latin America, Middle East, Africa and the Asia-Pacific region in early 2000. The study will compare the oral LTRA montelukast with the inhaled LABA salmeterol, each administered on a background of inhaled fluticasone, on asthma attacks, quality of life, lung function, eosinophil levels, healthcare utilization, and safety, in approximately 1200 adult asthmatic patients. The requirements for study enrollment include a history of asthma, FEV1 or PEFR values between 50% and 90% of the predicted value together with > or = 12% improvement in FEV1 after beta-agonist administration, a minimum pre-determined level of asthma symptoms and daily beta-agonist medication. The study will include a 4-week run-in period, during which patients previously taking inhaled corticosteroids are switched to open-label fluticasone (200 microg daily), followed by a 48-week double-blind, treatment period in which patients continuing to experience abnormal pulmonary function and daytime symptoms are randomized to receive montelukast (10 mg once daily) and salmeterol placebo, or inhaled salmeterol (100 microg daily) and montelukast placebo. All patients will continue with inhaled fluticasone (200 microg daily). During the study, asthma attacks, overnight asthma symptoms, and morning peak expiratory flow rate will be assessed using patient diary cards; quality of life will also be assessed using an asthma-specific quality-of life questionnaire. The results of this study are expected to provide physicians with important clinical evidence to help them make a rational and logical treatment choice for asthmatic patients experiencing breakthrough symptoms on inhaled corticosteroids.

Clinical evidence with montelukast in the management of chronic childhood asthma

OBJECTIVE

The aim of this article is to review data on the efficacy and safety of montelukast in the treatment of children with asthma.

METHODOLOGY

Available published literature, including published abstracts, is reviewed.

RESULTS

In patients aged 6 to 14 years with asthma (n = 27), montelukast 5mg demonstrated a significant decrease in exercise-induced bronchoconstriction 20 to 24 hours postdose after 2 days of treatment. For children with chronic asthma, only one study of the regular use of a leukotriene receptor antagonist has been published. The efficacy and safety of montelukast in children aged 6 to 14 years with asthma (n = 336) were studied during an 8-week, double-blind, placebocontrolled trial. There was a significantly greater improvement in forced expiratory volume in 1 second (FEV1) from baseline for the montelukast group (8.23%) compared with the placebo group (3.58%). There was a significant decrease in the use of a 3-agonist for symptom relief, as well as in the percentage of days and percentage of patients with asthma exacerbations. An asthma specific quality-of-life (QOL) questionnaire revealed a significant overall improvement in QOL and a significant improvement in the QOL domains for symptoms, activity and emotions in montelukast recipients. There was no significant difference between montelukast and placebo recipients in the frequency of adverse events, with the exception of allergic rhinitis, which was more prevalent in the placebo group. An open label follow-up of patients from the above study was undertaken. The effect of montelukast on FEV1 was consistent for up to 1.4 years, with the increase in FEV1 being not significantly different from that in a small control group treated with inhaled beclomethasone dipropionate. QOL remained significantly improved during the open treatment period.

CONCLUSIONS

Montelukast appears effective and safe for the treatment of children with asthma.

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.

Role for cysteinyl leukotriene receptor antagonist therapy in asthma and their potential role in allergic rhinitis based on the concept of "one linked airway disease"

OBJECTIVE

This review focuses on the shared pathophysiology of asthma and allergic rhinitis. The similarities illustrate the "one linked airway disease" concept, a unifying theory of these upper and lower airway inflammatory disorders. Since leukotrienes are mediators in both conditions, studies have been performed to assess the potential therapeutic role of cysteinyl leukotriene antagonists. The purpose of this paper is to provide an overview of the accumulating data concerning these agents in treating asthma and allergic rhinitis.

DATA SOURCES

Relevant publications obtained from a literature review.

STUDY SELECTION

Relevant publications on the topics of leukotrienes, leukotriene receptor antagonists, asthma, and allergic rhinitis were critically evaluated.

RESULTS AND CONCLUSIONS

Studies to date have documented the efficacy of cysteinyl leukotriene receptor antagonists for asthma. The pathophysiology of allergic rhinitis and its similarities to asthma suggest that these agents could play a significant therapeutic role in managing this upper airway disorder. Because the leukotriene antagonists are oral agents, they may be valuable in treating not only either condition but also both at the same time when they coexist. They appear to be beneficial when prescribed as the initial medicine and when used in conjunction with other therapies.

Novel therapy for asthma

The health burden of asthma is increasing globally at an alarming rate, providing a strong impetus for the development of new therapeutics. Currently available inhaled bronchodilators and anti-inflammatory drugs are effective in most asthmatics, but this palliative therapy requires long-term daily administration. Despite considerable efforts by the pharmaceutical industry, it has been difficult to develop novel therapeutic agents; the leukotriene antagonists and synthesis inhibitors being the only new class of asthma treatments to have been licensed in the last 30 years. It is clearly important to understand more about the underlying mechanisms of asthma and about how current drugs work before rational improvements in therapy can be expected. There are numerous therapies in clinical development that combat the inflammation found in asthma, specifically targeting eosinophils, IgE, adhesion molecules, cytokines and chemokines, inflammatory mediators and cell signalling. In particular, there is the obvious need for new therapy for severe asthma that is poorly controlled by high doses of corticosteroids, as well as agents to counter acute emergency asthma. A long-term goal is to develop disease-modifying immunotherapy, that could be introduced in childhood to alter the natural history of asthma. Thanks to the extensive efforts of the pharmaceutical industry, in the near future we can expect the introduction of a range of novel therapies for asthma.

Montelukast: data from clinical trials in the management of asthma

OBJECTIVE

To review the pharmacology, pharmacokinetics, clinical efficacy, and adverse effects of montelukast, a leukotriene receptor antagonist used to treat asthma, and to discuss the therapeutic role of montelukast as long-term medication and difficulties associated with the management of asthma.

DATA SOURCES

A MEDLINE search (up to May 1999) was conducted to identify relevant English-language publications, including preclinical studies, clinical trials, and recent reviews.

STUDY SELECTION

All available published reports of controlled, clinical trials of montelukast in adults and children with asthma were summarized, including pharmacokinetic and pharmacologic effects of montelukast.

DATA EXTRACTION

Information on the safety and efficacy of montelukast was evaluated on the basis of patient selection, study design, methodology, and statistical significance as compared with placebo or inhaled corticosteroid treatment.

DATA SYNTHESIS

Montelukast is approved for the prophylaxis and chronic treatment of asthma at a dose of 10 mg once daily for adolescents (> or =15 y) and adults and 5 mg once daily for children (6-14 y). In placebo-controlled clinical trials, montelukast significantly improved pulmonary lung function (as measured by forced expiratory volume in 1 sec), significantly reduced beta2-agonist use, and significantly improved patient-reported end points in adults and children (> or =6 y) with chronic asthma. In adults, a similar magnitude of improvement in lung function is seen with or without inhaled corticosteroid use; the effects of montelukast may be additive to those of inhaled corticosteroids and permit the reduction of the required dose of inhaled corticosteroids. In cases of exercise-induced asthma (adults and children), montelukast treatment attenuates the fall in pulmonary function following exercise. It attenuates both the early- and late-phase responses of asthma after allergen inhalation. Improvements in asthma control are similar in asthmatic patients who are aspirin-sensitive or not aspirin-sensitive and can be seen within one day of treatment. Tolerance does not develop, and the adverse events do not differ from those of placebo.

CONCLUSIONS

Montelukast is indicated for the prophylaxis of chronic asthma in adults and children (> or =6 y). It may be considered for use as first-line therapy in patients with mild persistent asthma or for additional control in patients who are still symptomatic while receiving treatment with inhaled corticosteroids. It may also be used for additional control in aspirin-sensitive asthmatic patients. Consideration may be given for using montelukast to allow tapering of the dose of inhaled corticosteroids while maintaining clinical stability. Chronic treatment with montelukast can provide additional control of symptoms during exercise, but inhaled beta2-agonists remain first-line therapy for prophylaxis and treatment.

Randomised, placebo controlled trial of effect of a leukotriene receptor antagonist, montelukast, on tapering inhaled corticosteroids in asthmatic patients

OBJECTIVE

To determine the ability of montelukast, a leukotriene receptor antagonist, to allow tapering of inhaled corticosteroids in clinically stable asthmatic patients.

DESIGN

Double blind, randomised, placebo controlled, parallel group study. After a single blind placebo run in period, during which (at most) two inhaled corticosteroids dose decreases occurred, qualifying, clinically stable patients were allocated randomly to receive montelukast (10 mg tablet) or matching placebo once daily at bedtime for up to 12 weeks.

SETTING

23 academic asthma centres in United States, Canada, and Europe.

PARTICIPANTS

226 clinically stable patients with chronic asthma receiving high doses of inhaled corticosteroids (113 randomised to montelukast and 113 to placebo).

INTERVENTIONS

Every 2 weeks, the inhaled corticosteroids dose was tapered, maintained, or increased (rescue) based on a standardised clinical score.

MAIN OUTCOME MEASURES

Last tolerated dose of inhaled corticosteroids.

RESULTS

Compared with placebo, montelukast allowed significant (P=0. 046) reduction in the inhaled corticosteroid dose (montelukast 47% v placebo 30%; least square mean difference 17.6%, 95% confidence interval 0.3 to 34.8). Fewer patients on montelukast (18 (16%) v 34 (30%) placebo, P=0.01) required discontinuation because of failed rescue.

CONCLUSIONS

Montelukast reduces the need for inhaled corticosteroids among patients requiring moderate to high doses of corticosteroid to maintain asthma control.