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

Treatment of asthmatic patients with a cysteinyl leukotriene receptor-1 antagonist montelukast (Singulair), decreases the eosinophil survival-enhancing activity produced by peripheral blood mononuclear leukocytes in vitro

BACKGROUND

Montelukast (Singulair, MSD) has been shown to have a beneficial effect on the clinical symptoms of asthma. We aimed to investigate the effect of montelukast treatment on the production of eosinophil survival-enhancing cytokines by peripheral blood mononuclear cells (PBMNC).

METHODS

PBMNC obtained from 15 grass-allergic patients (7 treated with montelukast and 8 with a placebo) were cultured for 72 h. Eosinophils from allergic patients were cultured with MNC supernatants alone or with addition of neutralizing antibodies, and the proportion of living cells was assessed by flow cytometry. In another experiment PBMNC from 6 allergic patients were cultured in vitro in the presence of montelukast or vehicle. Following stimulation the production of GM-CSF in monocytes was assessed.

RESULTS

Eosinophil survival in the MNC supernatants from the placebo-treated patients was significantly (P < 0.05) higher than in supernatants from montelukast-treated patients. GM-CSF was the predominant cytokine responsible for the eosinophil survival-enhancing activity (ESEA). In vitro production of GM-CSF by allergen-stimulated monocytes was significantly suppressed by addition of montelukast.

CONCLUSION

Treatment of patients with montelukast decreased the production of MNC-derived cytokines, particularly GM-CSF. We suggest that cysteinyl leukotriene receptor-1 (CysLT-R1) antagonists may act, at least partially, by diminishing the production of GM-CSF from PBMNCs.

Long-term observations of the clinical course after step down of corticosteroid inhalation therapy in adult chronic asthmatics: correlation with serum levels of eosinophil cationic protein

BACKGROUND

Symptoms often deteriorate in well-controlled asthmatics after a step down in inhaled beclomethasone dipropionate (iBDP) therapy if the serum concentration of eosinophil cationic protein (sECP) is high. This deterioration is significantly abrogated by pranlukast, a leukotriene receptor antagonist, or by seratrodast, a thromboxane A2 receptor antagonist. However, these results were based on short-term (less than 6 months) observations.

METHODS

We studied 35 well-controlled adult asthmatics. We assigned the patients into different groups according to their sECP levels before the step down: (i) group A, sECP < 25 microg/L; (ii) group B, sECP > or = 25 microg/L; and (iii) group C, sECP > or = 25 microg/L but patients treated with pranlukast or seratrodast. We began the study with a step down in iBDP therapy (initial step down), then followed the clinical course of the asthma for 2 years. During the study period, we decreased, increased or maintained the iBDP dose on the basis of the stepwise approach described in the National Institutes of Health guidelines. We monitored the time and frequency of exacerbation and evaluated the iBDP dose required to control the asthma symptoms.

RESULTS

The rates of exacerbation after the step down were high in groups A and B. In group A, the conditions were again qualified for the step down in all patients, but this was not the case for most group B patients. From 15 to 21 months after the initial step down, the average dose of iBDP required to control symptoms was significantly higher in group B than in group A patients (P = 0.0127-0.0373). The exacerbation rate in group C after 12 months tended to be lower than in the other two patient groups (P = 0.0743). In group C, the average dose of iBDP from 9 to 24 months after the initial step down was significantly lower than before the step down (P < 0.0001) and was not significantly different from the mean dose of iBDP in groups A or B.

CONCLUSIONS

High sECP in well-controlled asthma may indicate the necessity for a higher iBDP dose over a long period than when the sECP concentration is not high. Even if sECP is high, pranlukast or seratrodast help to prevent exacerbation of asthma and enable successful step down in iBDP therapy for at least 2 years thereafter.

Refractory asthma

Treating patients with refractory asthma remains an ongoing challenge. Although most patients respond to large doses of systemic corticosteroid, the adverse effects associated with such a treatment limit its general use. Clinicians treating patients with refractory asthma must consider tapering systemic corticosteroid at every opportunity. Recent advances in the understanding of the pathogenesis of refractory asthma and corticosteroid resistance have fueled further study in the mechanisms of these processes and have prompted consideration of new treatment approaches. Unfortunately, most alternative approaches require more rigorous evidence to support their regular use.

Leukotriene modifiers

Leukotrienes (LTs) are 5-lipoxygenase products formed from arachidonic acid metabolism. There is compelling evidence that LTs play an important role in the pathogenesis of asthma. LTs affect vascular permeability, mucus production, and smooth muscle constriction, and may contribute to airway remodeling. In mild-to-moderate asthma, LT modifiers improve measures of airflow limitation and quality of life and reduce the frequency of asthma exacerbations and the need for short-acting bronchodilator therapy. In moderate-to-severe asthma, an LT modifier in combination with an inhaled corticosteroid results in improvements in lung function and asthma control over that achieved with an inhaled corticosteroid alone. LT modifiers are effective in the treatment of exercise-induced bronchoconstriction and aspirin-induced asthma. There are few adverse effects of LT modifiers.

The role of antileukotrienes in the treatment of asthma

Cysteinyl leukotrienes (Cys-LTs) are mediators released in asthma and are both direct bronchoconstrictors and proinflammatory substances that mediated several steps in the pathophysiology of chronic asthma, including inflammatory cells recruitment, vascular leakage, and possibly airway remodelling. Available evidence from clinical trials and real world experience derived from managing patients with asthma justifies a broader role for antiLTRAs in asthma management than that recommended in the National Asthma Education and Prevention Programm (NAEPP) and National Health Lung and Blood Institute (NHLBI) treatment guidelines. Leukotriene-receptor antagonist drugs (LTRAs) seem to be effective alternatives to inhaled corticosteroids (ICS) either as monotherapy or as adjunctive therapy that reduces the need for higher doses of ICS in patients with mild-to-moderate persistent asthma. LTRAs may be used as adjunctive therapy for al levels of disease severity because they are effective in combination with ICS during long-term maintenance therapy. The agents seem especially effective in preventing aspirin-induced asthma, exercise-induced asthma (EIA) and they may provide an additional advantage of reducing nasal congestion in patients with both asthma and rhinitis.

Leukotriene receptor antagonist, montelukast, can reduce the need for inhaled steroid while maintaining the clinical stability of asthmatic patients

BACKGROUND

Oral leukotriene receptor antagonists have been shown to have efficacy in chronic asthma.

OBJECTIVE

To determine whether the addition of montelukast could lead to a reduction in inhaled corticosteroid dose without a significant decrease in peak expiratory flow rate (PEFR).

METHODS

After a 4-week run-in period, 191 moderate-to-severe asthmatic patients whose asthma had been well controlled with daily inhaled corticosteroid therapy (beclometasone dipropionate 800 to 1600 micro g/day), were randomly assigned to one of two treatments - placebo (n = 98) or montelukast 10 mg once daily (n = 93) - for a 24-week, multicentre, double-blind, treatment period. At the beginning of the active treatment period, the daily dose of inhaled corticosteroid was halved in all of the patients. In addition, the inhaled corticosteroid dose was subsequently titrated every 8 weeks, based on PEFR, asthma symptoms and beta-agonist use.

RESULTS

After 8 weeks of a 50% reduction in inhaled corticosteroid use, morning PEFR increased by 5.3 +/- 32.3 L/min from baseline in patients receiving montelukast and significantly decreased by 6.9 +/- 29.0 L/min in those receiving placebo (P = 0.035). In addition, evening PEFR significantly decreased by 9.8 +/- 28.5 L/min (P = 0.003) in the placebo group, but was maintained in the montelukast group. In spite of a subsequent 50% reduction in the inhaled corticosteroid dose every 8 weeks, morning and evening PEFRs were maintained over the 24-week treatment period in the montelukast group; PEFR significantly decreased in the placebo group. There was a significant difference between the two groups with regard to morning PEFR, therapy score and asthmatic score at weeks 8, 16 and 24, as well as evening PEFR at week 8. However, the symptom scores were not significantly different between the two groups or within each group.

CONCLUSION

These data suggest that montelukast reduces the need for inhaled corticosteroids while maintaining asthma control over a 24-week period. Therefore, montelukast may be useful for long-term treatment in patients with asthma who require high doses of inhaled corticosteroids.

Effects of adding either a leukotriene receptor antagonist or low-dose theophylline to a low or medium dose of inhaled corticosteroid in patients with persistent asthma

STUDY OBJECTIVES

To evaluate the effect of adding zafirlukast or low-dose theophylline to a beclomethasone dipropionate (BDP) extra-fine hydrofluoroalkane aerosol on bronchial hyperresponsiveness as the primary outcome variable.

METHODS

Twenty-four patients with mild-to-moderate asthma were studied using a randomized crossover design with the following three treatment blocks: (1) beclomethasone, 100 microg/d, alone for the first 2 weeks followed by 400 microg/d alone for the next 2 weeks; (2) beclomethasone, 100 microg/d, followed by 400 microg/d, with the addition of zafirlukast, 20 mg bid; (3) beclomethasone, 100 microg/d, followed by 400 microg/d, with the addition of theophylline, 200 to 300 mg bid. Measurements were made after 2 and 4 weeks of each treatment and at pretreatment baseline.

RESULTS

The mean trough plasma theophylline concentration was 6.7 mg/L, coinciding with the anti-inflammatory target range (ie, 5 to 10 mg/L). The provocative dose of methacholine causing a 20% fall in FEV(1) (as doubling dose difference from baseline) was significantly (p < 0.05) greater with beclomethasone, 100 microg, plus zafirlukast (1.1 doubling dose) but not with beclomethasone, 100 microg, plus theophylline (0.7 doubling dose) compared to beclomethasone, 100 microg alone (0.4 doubling dose), but not compared to beclomethasone, 400 microg alone (1.1 doubling dose). There were also significant (p < 0.05) differences between beclomethasone, 100 microg, plus zafirlukast (but not BDP, 100 microg, plus theophylline) vs beclomethasone, 100 microg, alone in terms of nitric oxide level, midexpiratory phase of forced expiratory flow, and peak expiratory flow. There were no further significant improvements observed with the addition of zafirlukast or theophylline to beclomethasone, 400 microg.

CONCLUSIONS

A leukotriene receptor antagonist, but not low-dose theophylline, conferred significant additive anti-inflammatory effects to therapy with a low-dose inhaled corticosteroid but not to that with a medium dose of an inhaled corticosteroid. Thus, optimizing the dose of inhaled corticosteroid as monotherapy would seem to be the logical first step, which is in keeping with current guidelines.

Anti-leukotrienes as add-on therapy to inhaled glucocorticoids in patients with asthma: systematic review of current evidence

OBJECTIVES

To examine the evidence for the efficacy and glucocorticoid sparing effect of oral anti-leukotrienes taken daily as add-on therapy to inhaled glucocorticoids in patients with asthma.

DESIGN

Systematic review of randomised controlled trials of children and adults with asthma comparing the addition of anti-leukotrienes or placebo to inhaled glucocorticoids.

MAIN OUTCOME MEASURES

The rate of exacerbations of asthma requiring rescue systemic glucocorticoids when the intervention was compared to the same or double dose of inhaled glucocorticoids, and the glucocorticoid sparing effect when the intervention was aimed at tapering the glucocorticoid.

RESULTS

Of 376 citations, 13 were included: 12 in adult patients and one in children. The addition of licensed doses of anti-leukotrienes to inhaled glucocorticoids resulted in a non-significant reduction in the risk of exacerbations requiring systemic steroids (two trials; relative risk 0.61, 95% confidence interval 0.36 to 1.05). No trials comparing the use of anti-leukotrienes with double the dose of inhaled glucocorticoids could be pooled. The use of anti-leukotrienes resulted in no overall group difference in the lowest achieved dose of inhaled glucocorticoids (three trials; weighted mean difference -44.43 microg/day, -147.87 to 59.02: random effect model) but was associated with a reduction in withdrawals owing to poor asthma control (four trials; relative risk 0.56, 0.35 to 0.89).

CONCLUSIONS

The addition of anti-leukotrienes to inhaled glucocorticoids may modestly improve asthma control compared with inhaled glucocorticoids alone but this strategy cannot be recommended as a substitute for increasing the dose of inhaled glucocorticoids. The addition of anti-leukotrienes is possibly associated with superior asthma control after tapering of glucocorticoids, but the glucocorticoids sparing effect cannot be quantified at present.

Balancing safety and efficacy in the treatment of pediatric asthma

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

Health-care resource use by asthmatics in Croatia

We report a survey of the impact of asthma on daily life and on health-care resource use by adult asthma patients in four counties in Croatia. Over a 1-year period beginning November 1998, 185 general practitioners recruited 504 asthma patients, who completed a questionnaire about their drug therapy, health-care resource use, symptoms, limitations in daily activities, and work loss due to asthma. Over a 2-week period, inhaled corticosteroids were used by 51.5% of patients, short-acting and long-acting beta-agonists by 70.8% and 53.5%, respectively, and oral extended-release theophyllines by 29.8%. Nocturnal awakenings were experienced by 58.7% of patients, 75.5% experienced daytime symptoms, and 42.5% were limited in their daily activities. In the previous year, 12.5% of the patients were hospitalized, 33% missed work, and 70% reported reduced effectiveness in the workplace. In the previous 6 months, 35.2% of the patients visited an emergency room due to worsening of asthma symptoms. The human and socioeconomic burden of asthma in Croatia is considerable. These results can help guide the development of asthma policy in Croatia and raise awareness of asthma as a public health issue.

Use of oral montelukast in the treatment of asthma

Montelukast, a new leukotriene modifier, has several benefits in the treatment of asthma in adults and children including improved relief of asthma symptoms, rapid onset, a safety profile comparable with placebo, and oral, once-daily dosing means excellent adherence.

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.

Quality assurance of asthma clinical trials

Accuracy and repeatability of spirometry measurements are essential to obtain reliable efficacy data in randomized asthma clinical trials. We report our experience with a centralized spirometry quality assurance program that we implemented in our phase III asthma trials. Six asthma trials of 4 to 21 weeks in duration were conducted at 232 clinical centers in 31 countries. Approximately 23,100 prebronchodilator and 13,700 postbronchodilator spirometry tests were collected from 2523 adult and 336 pediatric asthmatic patients. The program used a standard spirometer (the Renaissance spirometry system) with maneuver quality messages and automated quality grading of the spirometry tests. Each clinical center transmitted spirometry data weekly to a central database, where uniform monitoring of data quality was performed and feedback was provided in weekly quality reports. Seventy-nine percent of all patients performed spirometry sessions with quality that either met or exceeded American Thoracic Society standards and improved over time. Good-quality spirometry was associated with (1) less severe asthma; (2) active treatment; (3) infrequent nocturnal awakenings; (4) age above 15 years; and (5) low body weight. Maneuver-induced bronchospasm was rare. Good-quality spirometry was observed in multicenter asthma clinical trials that employed a standard spirometer and continuous monitoring. Both within- and between-patient variability decreased. Spirometry quality improved with time as study participants and technicians gained experience.

Reduction of eosinophilic inflammation in the airways of patients with asthma using montelukast

OBJECTIVE

Leukotrienes (LTs) are involved in airway eosinophilic inflammation in patients with asthma. We examined the effects of a cysteinyl LT 1-receptor antagonist, montelukast, on sputum eosinophil levels, and the correlation between sputum eosinophils and bronchodilatation in patients with asthma.

DESIGN

Double-blind, randomized, crossover study.

SETTING

University hospital and private hospital.

PATIENTS

Twenty-nine patients with mild-to-moderate asthma.

INTERVENTIONS

Montelukast, 10 mg, and placebo tablet, once daily, each for 4 weeks.

MEASUREMENTS

Sputum eosinophils analyzed using hypertonic saline solution-induced sputum and airway hyperresponsiveness to histamine were evaluated before and after treatment. In addition, morning and evening peak expiratory flow (PEF), asthma symptoms, and peripheral blood eosinophil levels were assessed.

RESULTS

The percentage of eosinophils in sputum decreased from 24.6 +/- 12.3% at baseline to 15.1 +/- 11.8% after montelukast treatment, for a change of - 9.5 +/- 12.7% (n = 20). During placebo administration, the percentage of eosinophils fell from 21.3 +/- 12.1% to 21.0 +/- 11.5%, resulting in a decrease of - 0.3 +/- 10.8% (n = 20). There was a statistically significant difference in the change in sputum eosinophil levels between these two periods (p < 0.005). The number of peripheral blood eosinophils also significantly decreased after montelukast treatment (314.1 +/- 237.6/mL) compared with placebo (413.1 +/- 232.1/mL; p < 0.005, n = 21). Although morning and evening PEF values were significantly improved from baseline after montelukast treatment (p < 0.01, n = 20), asthma symptoms and airway responsiveness to histamine were not significantly altered. Furthermore, there was no significant correlation between the decrease in sputum eosinophils and the increase in PEF.

CONCLUSION

These results suggest that montelukast has anti-inflammatory effects on the airway in patients with asthma, and that its bronchodilatory effect is not solely dependent on a decrease in airway eosinophilia.

Combination therapy with inhaled long-acting beta2-agonists and inhaled corticosteroids: a paradigm shift in asthma management

Long-acting inhaled beta2-agonists and inhaled corticosteroids are classes of drugs with different mechanisms of action that are commonly used to provide effective long-term control of persistent asthma. Scientific and clinical data support the complementary mechanisms of action of the inhaled corticosteroids and the long-acting beta2-agonists in achieving a superior level of asthma control. In addition, evidence supports significant reductions in exacerbations and effective control of airway inflammation with an inhaled corticosteroid and a long-acting beta2-agonist versus higher dosages of inhaled corticosteroids or combinations of other therapeutic agents with an inhaled corticosteroid. Finally, there are distinct economic advantages to combining an inhaled corticosteroid and a long-acting beta2-agonist in the treatment of asthma relative to other treatment regimens.

A randomized, double-blind trial of the effect of treatment with montelukast on bronchial hyperresponsiveness and serum eosinophilic cationic protein (ECP), soluble interleukin 2 receptor (sIL-2R), IL-4, and soluble intercellular adhesion molecule 1 (sICAM-1) in children with asthma

BACKGROUND

Anti-inflammatory properties of leukotriene modifiers and their effect on bronchial hyperresponsiveness have not been studied in children with asthma.

OBJECTIVE

The primary objective of this study was to determine the changes in serum levels of inflammatory mediators, clinical efficacy, and bronchial hyperresponsiveness after treatment with montelukast.

METHODS

In this double-blind, randomized, placebo-controlled trial, 39 children with mild-to-moderate atopic asthma were randomly allocated to receive montelukast or placebo for 6 weeks. Main outcome measures were changes in serum concentrations of soluble interleukin 2 receptor (sIL-2R), IL-4, and soluble intercellular adhesion molecule 1 (sICAM-1); peripheral blood eosinophil count; and eosinophilic cationic protein (ECP). Asthma severity score, FEV(1), and bronchial hyperreactivity (BHR) for histamine were secondary end points.

RESULTS

Compared to placebo, serum concentrations of IL-4, sICAM-1, and ECP and eosinophil blood counts significantly decreased after 6 weeks of treatment with montelukast. Montelukast significantly improved asthma control and FEV(1). Montelukast resulted in within-group significant decrease in levels of serum sIL-2R (611 vs. 483 pg/mL), IL-4 (0.123 vs 0.102 pg/mL), sICAM-1 (280 vs. 244 ng/mL), and ECP (74 vs. 59 microg/mL) and in eosinophil blood counts (349 vs. 310 cells/mm(3)). Mean FEV(1) value changed from 85% of predicted to 95% (P <.001) and for histamine (PC(20)H) from 2.8 mg/mL to 3.8 mg/mL (P <.001) after treatment with montelukast. There was no significant difference between montelukast and placebo recipients in the serum concentrations of sIL-2R and PC(20)H after treatment.

CONCLUSION

Montelukast provides clinical benefit to patients with chronic asthma and decreases bronchial hyperresponsiveness. Montelukast caused a statistically significant decrease of serum concentrations in cytokine, ICAM-1, and ECP and peripheral blood eosinophil counts over the 6-week treatment period. This observation raises the possibility that leukotriene receptor antagonists, such as montelukast, may have effects on parameters of asthmatic inflammation.

Marginal utility of montelukast for persistent asthma

BACKGROUND

The efficacy of a new pharmacologic agent for asthma, in this instance the leukotriene receptor antagonist montelukast, is determined in controlled trials in research subjects. The utility of a new drug is determined by multiple uncontrollable factors in individual patients.

OBJECTIVE

To assess the utility of montelukast in the management of persistent asthma.

DESIGN

Observational, retrospective.

SETTING

Suburban multispecialty medical clinic.

METHODS

From April 1998, montelukast was prescribed for 110 patients with persistent but controlled asthma, primarily for the corticosteroid-sparing effect. Outcomes after 1 year were determined from audits of medical records and responses to questionnaires.

RESULTS

At least 56% of patients continued receiving montelukast for the entire year. However, compared to those patients who had discontinued montelukast therapy, those who continued receiving it had no difference in the use of inhaled or systemic corticosteroid or inhaled beta(2)-agonist therapy.

CONCLUSION

Montelukast had marginal utility in the management of these adult patients with controlled persistent asthma.

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.

Addition of anti-leukotriene agents to inhaled corticosteroids for chronic asthma

BACKGROUND

Anti-leukotriene (AL) agents are being considered as "add-on" therapy to inhaled corticosteroids (ICS), in chronic asthma.

OBJECTIVES

To examine the safety and efficacy of daily AL plus ICS compared to ICS alone, and determine the corticosteroid-sparing effect of AL when added to ICS in chronic asthma.

SEARCH STRATEGY

We searched Medline, Embase, Cinahl (until September 2001), reference lists of review articles and trials, contacted international headquarters of AL manufacturers and ATS meeting abstracts (1998-2000).

SELECTION CRITERIA

Randomised placebo-controlled trials of asthmatics aged 2 years and older with at least one month intervention.

DATA COLLECTION AND ANALYSIS

Two reviewers assessed quality and extracted data independently. Trials were grouped by asthma control at baseline (symptomatic or well-controlled) and dose of ICS in the control group (same or double).

MAIN RESULTS

Of 438 citations, 13 (12 adult and 1 paediatric) trials met inclusion criteria. Seven were published in full-text. In symptomatic patients, addition of licensed doses of anti-leukotrienes to ICS resulted in a non-significant reduction in the risk of exacerbations requiring systemic steroids: Relative Risk (RR) 0.61; 95% Confidence Interval (CI) 0.36,1.05). A modest improvement group difference in PEF was seen (Weighted Mean Difference (WMD) 7.71 L/min; 95%CI 2.98, 12.44 L/min) together with beta2-agonist use (WMD= -0.32 puffs/day; 95%CI -0.0.08, -0.56). No trials that compared the use of licensed doses of anti-leukotrienes with doubling-dose of inhaled glucocorticoids could be pooled. In ICS-sparing studies in patients who were well controlled at baseline, addition of anti-leukotrienes produced no overall difference in dose of inhaled glucocorticoids (WMD -44.4 mcg/d, 95%CI -147.9, 59.0 mcg/d), but it was associated with fewer withdrawals due to poor asthma control (RR= 0.56, 95%CI 0.35, 0.89).

REVIEWER'S CONCLUSIONS

There is insufficient evidence to firmly support the use of licensed doses of anti-leukotrienes as add-on therapy to inhaled glucocorticoids. Addition of anti-leukotrienes to inhaled glucocorticoids may slightly improve asthma control, but the available data do not permit this strategy to be recommended as a substitute for increasing the dose of inhaled glucocorticoids. Addition of anti-leukotrienes may be associated with superior asthma control after glucocorticoid tapering, but a glucocorticoid-sparing effect cannot be quantified at present.

Improvement of aspirin-intolerant asthma by montelukast, a leukotriene antagonist: a randomized, double-blind, placebo-controlled trial

Leukotriene antagonists block the proinflammatory actions of leukotrienes (LT) and have been introduced as new treatments for asthma. Conventional therapy with glucocorticosteroids does not inhibit the biosynthesis of leukotrienes. We therefore tested whether addition of the leukotriene receptor antagonist montelukast was of therapeutic benefit in a group of aspirin-intolerant patients with asthma of whom 90% already were treated with moderate to high doses of glucocorticosteroids. Under double-blind conditions, 80 aspirin-intolerant patients with asthma were randomized to receive 4 wk oral treatment of either 10 mg of montelukast or placebo once daily at bedtime. Pulmonary function was measured as forced expiratory volume in 1 s (FEV(1)) once a week in the clinic and daily as morning and evening peak expiratory flow rate (PEFR). Asthma symptoms and use of rescue bronchodilator were also recorded daily. Asthma specific quality of life (QoL) was assessed before and after the treatments. The group receiving montelukast showed a remarkable improvement of their asthma, whereas the group given placebo showed no change. Thus, from equal baseline values, the mean difference between the groups over the 4-wk treatment period was 10.2% for FEV(1) and 28.0 L for morning PEFR (p for both < 0.001). The improved pulmonary function in the group receiving montelukast occurred at the same time as 27% less bronchodilator was used (p < 0.05), and it was associated with fewer asthma symptoms than in the group given placebo, including 1.3 nights more of sleep per week and 54% fewer asthma exacerbations (p < 0.05). There was also an improvement in asthma-specific QoL (p < 0.05). The therapeutic response to montelukast was consistent across patients with different baseline characteristics and did not correlate with baseline urinary LTE(4). Addition of a leukotriene receptor antagonist such as montelukast improves asthma in aspirin-intolerant patients over and above what can be achieved by glucocorticosteroids.

Anti-leukotriene agents compared to inhaled corticosteroids in the management of recurrent and/or chronic asthma in adults and children

BACKGROUND

Anti-leukotrienes agents are currently being studied as alternative first line agents to inhaled corticosteroids in mild to moderate chronic asthma.

OBJECTIVES

To compare the safety and efficacy of anti-leukotriene agents with inhaled glucocorticoids (ICS) and to determine the dose-equivalence of anti-leukotrienes to daily dose of ICS.

SEARCH STRATEGY

Medline (1966 to Jan 2002), Embase (1980 to Jan 2002), and Cinahl (1982 to Jan 2002) were searched and reference lists of review articles and trials. We contacted colleagues and international headquarters of anti-leukotrienes producers.

SELECTION CRITERIA

Randomised controlled trials that compared leukotriene antagonists with inhaled corticosteroids during a minimal 30-day intervention period in asthmatic patients aged 2 years and older.

DATA COLLECTION AND ANALYSIS

Two reviewers performed assessments of methodological quality and data extraction independently and blindly. The primary outcome was the rate of exacerbations requiring systemic corticosteroids. Secondary outcomes included lung function, indices of chronic asthma control, adverse effects and withdrawal rates.

MAIN RESULTS

14 trials met the inclusion criteria; 10 were of high methodological quality; 8 are published in full-text. All were in mild-to-moderate chronic asthma, Two included children or adolescents. Trial duration was 4 - 37 weeks. In most trials, daily dose of ICS was 400 mcg of beclomethasone-equivalent. Patients treated with anti-leukotrienes were 60% more likely to suffer an exacerbation requiring systemic steroids [12 trials; Relative Risk 1.61; 95% Confidence Interval (CI) 1.15, 2.25]. Significant differences favouring ICS were noted in most secondary outcomes, eg improvement in FEV1 [7 trials; Weighted Mean Difference 120 ml; 95% CI: 80, 170 ml ]; symptom scores [5 trials: Standardized Mean Difference 0.3; 95% CI 0.2, 0.4]. Other significant benefits of ICS were seen for nocturnal awakenings, rescue medication use, and quality of life. Risk of side effects was not different between groups, but anti-leukotriene therapy was associated with 30% increased risk of "withdrawals for any cause" or "withdrawals due to poor asthma control".

REVIEWER'S CONCLUSIONS

For most asthma outcomes, ICS at 400 mcg/day of beclomethasone-equivalent are more effective than anti-leukotriene agents given in the usual licensed doses. The exact dose-equivalence of anti-leukotriene agents in mcg of ICS remains to be determined.

Outcome of asthma in children and adolescents at a specialty-based care program

BACKGROUND

Asthma remains a major cause of morbidity for children despite national guidelines.

OBJECTIVE

To evaluate outcome from a structured specialty-based care program.

METHODS

Comparison of previous and subsequent years for children ranging from infancy to adolescence who entered a specialty clinic program at a university hospital serving a widely dispersed patient population. One hundred fifty-seven patients previously receiving primary care for their respiratory symptoms were seen during the study period; 23 were lost to followup, 15 were excluded because of other serious concurrent medical problems, and 119 were available for outcome analysis. Evaluation included historical data base from a structured interview, evaluation of pulmonary physiology, and allergy skin testing. Treatment decisions were evidence-based. Patient and/or family education was targeted at decision-making. Toll-free telephone access to the specialty service was provided around the clock. Frequency of unscheduled medical care, hospitalizations, sleep disturbance, activity interference, attainment of defined criteria for control, and medication use were quantified.

RESULTS

Seven hundred thirty-five acute care visits were reduced to 47, and 99 hospitalizations were decreased to 10 (P < 0.001 for both). Nocturnal symptoms and exercise limitation decreased significantly (P < 0.001 for both). All criteria for control of asthma were met in 89% of 75 without tobacco smoke exposure and 50% of 44 with exposure (P < 0.0001 for the difference in outcome). Frequent antibiotic use for respiratory symptoms were eliminated after entering the program. Maintenance medications were not used in 72 with an intermittent pattern of viral respiratory infection-induced asthma. Inhaled corticosteroid use increased from 38 to 68% among 47 subjects with a chronic pattern.

CONCLUSIONS

Morbidity from asthma is largely prevented with often less, but better selected, medication than had been occurring in previous primary care. These data have implications for revised guidelines directed at primary care physicians.

Leukotrienes in respiratory disease

Arachidonic acid metabolism via 5-lipoxygenase gives rise to a group of biologically active lipids known as leukotrienes: leukotriene B(4), which is a potent activator of leukocyte chemotaxis, and cysteinyl leukotrienes (leukotriene C(4), D(4)and E(4)) which account for the spasmogenic activity previously described as slow-reacting substance of anaphylaxis. The biological actions of leukotrienes and the observations that leukotrienes are synthesised in the lung following antigen provocation and are elevated in asthma, stimulated considerable activity in the pharmaceutical industry to find drugs that modulate the synthesis or actions of leukotrienes. Three cysteinyl leukotriene antagonists (zafirlukast [Accolate], montelukast [Singulair] and pranlukast) and one 5-lipoxygenase inhibitor (zileuton) have received regulatory approval for the treatment of asthma. The clinical data obtained from using these drugs are generally consistent and complimentary. As a class the leukotriene modulators produce a rapid improvement in lung function after the first oral dose. Lung function improvements are maintained on chronic administration and are associated with reductions in a variety of asthma symptom scores. All of the available data are consistent with the hypothesis that all the leukotriene modulators exert their clinical benefit primarily through interference with cysteinyl leukotrienes. There are no compelling clinical data for an additional contribution by leukotriene B(4)in human asthma. In other respiratory conditions such as COPD, which are characterised by pronounced neutrophil infiltration, it may be that the chemotactic properties of leukotriene B(4)are more important and therefore evaluation of 5-lipoxygenase inhibitors in this condition is warranted. The introduction of the leukotriene modulators into clinical practice is the culmination of over 60 years of research since the initial discovery of the slow-reacting substances. The leukotriene modulators, and in particular the cysteinyl leukotriene antagonists, provide respiratory physicians with an oral therapeutic option and have set an efficacy standard which new oral anti-inflammatory approaches will have to beat.

An open audit of montelukast, a leukotriene receptor antagonist, in nasal polyposis associated with asthma

BACKGROUND

Nasal polyposis occurs frequently in patients with intrinsic asthma, especially in those who are aspirin sensitive. It can be difficult to treat effectively, even with surgery and regular topical intranasal corticosteroids many patients are still symptomatic.

OBJECTIVE

To investigate the response to montelukast, a leukotriene D4 receptor antagonist, as an add-on therapy to topical and inhaled corticosteroids in patients, both aspirin sensitive (AS) and aspirin tolerant (AT), with nasal polyposis and asthma.

METHODS

Nasal polyposis symptoms were assessed by visual analogue scales; nasal polyps were assessed by nasendoscopy and via the measurement of nasal volumes by acoustic rhinometry. The nasal airway was assessed by nasal inspiratory peakflow (NIPF). Asthma was monitored using symptom scores and peak expiratory flow measurements. Aspirin sensitivity was assessed by history together with intranasal lysine aspirin challenge. Upper and lower airway nitric oxide measurements were made before and during treatment.

RESULTS

Clinical subjective improvement in nasal polyposis occurred in 64% AT (P < 0.01), patients and 50% AS patients (P > 0.05); asthma improvement in 87% AT and 61% AS patients (P < 0.05 for both). Objective changes in peak flow occurred only in AT patients (P < 0.05). Acoustic rhinometry, nasal inspiratory peak flow and nitric oxide levels did not change significantly in any group, however, correlations were seen between nitric oxide levels and polyp scores and between nitric oxide levels and acoustic rhinometry changes. Improvement on montelukast therapy was not associated with any of the following variables: age, sex, skin prick test positivity, disease duration or aspirin sensitivity. (P > 0.05 for all).

CONCLUSION

The findings are consistent with a subgroup of nasal polyps/asthma patients in whom leukotriene receptor antagonists are effective. This is not related to aspirin sensitivity. Further placebo-controlled studies need to be undertaken.

Comparative efficacy of inhaled corticosteroids and antileukotriene drugs in asthma

Asthma is an inflammatory disease of the airways that is best treated by minimising exposure to factors that provoke the inflammation (e.g. allergens) and by administering drugs that reduce the inflammatory response. The cornerstone of asthma treatment is inhaled corticosteroids. Their effectiveness is a result of their potent and broad anti-inflammatory properties. Antileukotriene drugs (leukotriene modifiers) provide an alternative and novel approach to the treatment of asthma. The novelty of these new compounds is that their effectiveness is firmly based on the pathophysiology of asthma, specifically the role played by the cysteinyl leukotrienes. At the same time, the availability of the antileukotriene drugs has stirred debate over when they should be used and how they compare to inhaled corticosteroids. Although the answers are not fully known at this time, the currently available published and presented data are adequate for us to draw some conclusions about their relative effectiveness and role in asthma treatment. The antileukotriene drugs are more effective than placebo, but they are not as effective as inhaled corticosteroids in improving lung function [measured as the forced expiratory volume in 1 second (FEV(1)) or peak expiratory flow rate (PEFR)], reducing beta(2)-agonist use, and decreasing symptom-free days. In contrast, they may have similar beneficial effects on reducing asthma exacerbations and decreasing peripheral blood eosinophil counts. In the absence of knowing a priori the response of an individual patient to treatment with either therapy, the data favour initiating treatment with an inhaled corticosteroid. However, for patients with mild to moderate disease there are a number of circumstances that support using an antileukotriene drug first. A few examples are aspirin intolerance, predominantly exercise-induced symptoms and problems with using an inhaler or the adverse effects of inhaled corticosteroids such as dysphonia and thrush. For patients with more severe disease, inhaled corticosteroids remain the treatment of choice. Antileukotriene drugs should be considered as add-on therapy, especially in view of their possible complementary effects on reducing airway inflammation.

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

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

The anti-inflammatory effects of leukotriene-modifying drugs and their use in asthma

Asthma is a chronic inflammatory disease of the airways. Anti-inflammatory drug therapy, primarily using corticosteroids, is now considered the first-line treatment in the management of all grades of asthma severity. Although corticosteroids are believed to be the most potent anti-inflammatory agents available, they do not suppress all inflammatory mediators involved in the asthmatic response. Leukotrienes, which are lipid mediators generated from the metabolism of arachidonic acid, play an important role in the pathogenesis of asthma. They produce bronchospasm, increase bronchial hyperresponsiveness, mucus production, and mucosal edema, and enhance airway smooth muscle cell proliferation and eosinophil recruitment into the airways, and their synthesis or release is unaffected by corticosteroid administration. The use of leukotriene synthesis inhibitors or leukotriene receptor antagonists as anti-inflammatory therapies in asthma has therefore been investigated. Beneficial effects of leukotriene-modifying drugs have been demonstrated in the management of all grades of asthma severity, and there is evidence that certain patient groups (such as those with exercise-induced asthma or aspirin-induced asthma) may be particularly suitable for such therapy.

Addition of leukotriene antagonists to therapy in chronic persistent asthma: a randomised double-blind placebo-controlled trial

BACKGROUND

Controlled trials suggest that leukotriene receptor antagonists can improve lung function and reduce requirement for oral or inhaled corticosteroids in patients with asthma. We aimed to assess whether montelukast, a leukotriene receptor antagonist, can improve symptoms or lung function in patients with chronic asthma with symptoms already taking corticosteroids.

METHODS

We did a double-blind, placebo-controlled, crossover, randomised add-on study in which 100 patients with asthma and symptoms despite treatment with inhaled corticosteroids and additional therapy were given 10 mg montelukast sodium for 14 days in an outpatient clinic setting. Outcome measures were symptoms and peak flow diaries.

FINDINGS

72 patients had diary data for analysis. Compared with placebo, addition of montelukast did not result in any significant change in symptom scores (mean difference between the last 7 days of each treatment period 0.05; 95% CI --0.86 to 1.14), rescue inhaled beta(2) agonist use (mean difference in puffs per day 0.41; -0.29 to 0.57), or twice daily peak expiratory flow (PEF) measurements (mean difference in morning PEF 1.18 L/min; -14.29 to 17.14), and mean difference in evening peak flow (-0.50; -17.42 to 12.86). When treatment response was defined as a 15% or greater increase in mean peak flow readings, there were four responders to montelukast and seven responders to placebo.

INTERPRETATION

Based on PEF data from our previous studies of a similar patient group we would have expected to detect changes of more than 5%. Used as additional therapy in a hospital outpatient clinic setting, montelukast did not provide such additional benefit in patients with moderate or severe asthma.

Efficacy of antileukotriene agents in asthma management

OBJECTIVE

This article reviews information on the role of three antileukotrienes (anti-LTs), montelukast, zafirlukast, and zileuton, in the management of asthma. After reading this article, readers should have an understanding of the efficacy of anti-LTs in specific patient populations.

DATA SOURCES

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

STUDY SELECTION

Material was taken from peer-reviewed journals and published abstracts.

RESULTS

The efficacy of anti-LTs has been established in numerous randomized, controlled, multicenter trials involving patients with mild-to-moderate disease. These agents reduce asthma symptoms, beta2-agonist use, and asthma exacerbations, in addition to improving pulmonary function. The anti-LTs are also effective when added to low-dose or high-dose corticosteroid regimens in symptomatic asthma patients. They have proven efficacy in patients with aspirin-sensitive asthma, and they appear able to reduce nasal congestion in asthma patients with concomitant upper airway symptoms. Some anti-LTs have been shown to be effective in pediatric asthma patients.

CONCLUSIONS

In reviewing available clinical results as well as real-world experience in managing asthma patients, the Antileukotriene Working Group concludes that anti-LTs may be used in patients with mild persistent asthma as well as in combination with other asthma medications at all levels of disease severity for long-term maintenance of asthma control.

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.

Children with difficult asthma: a practical approach

Many open studies investigating the effects of innovative treatments for steroid-dependent asthma demonstrate some benefit. This is also true of the majority of placebo arms in placebo-controlled trials. This suggests that children with difficult asthma benefit from the high level of input that is typically provided in clinical trials, with or without additional medication. Such intensive management of patients, with the emphasis on establishing the diagnosis, improving adherence, and identifying provoking factors, is the key to optimizing asthma control for these children. For patients with genuinely severe asthma, despite high doses of conventional treatment, a greater understanding of the pathological basis of persistent symptoms is needed. Identification of different pathological subtypes of severe asthma should allow for more rational prescribing of asthma therapy, as well as the design of further trials of potential steroid-sparing treatments.

Evaluation of salmeterol or montelukast as second-line therapy for asthma not controlled with inhaled corticosteroids

OBJECTIVE

To assess the addition of a leukotriene receptor antagonist and a long-acting beta(2)-agonist as second-line therapy in asthma.

DESIGN

Placebo-controlled, double-dummy, crossover study.

SETTING

Outpatient clinic.

PATIENTS

Twenty patients with persistent asthma not controlled with inhaled corticosteroid therapy.

INTERVENTIONS

Montelukast 10 mg once daily, or salmeterol, 50 microg bid, each for 2 weeks with 1-week run-in and washout placebo periods.

MEASUREMENTS AND RESULTS

Adenosine monophosphate (AMP) bronchial challenge, blood eosinophil count (EOS), exhaled nitric oxide, and lung function after both placebo periods and after the first and last doses of each active treatment. Patients recorded their domiciliary peak expiratory flow (PEF), asthma symptoms, and rescue bronchodilator requirement (RES) twice daily throughout the study. For the primary end point of the provocative concentration of AMP causing a 20% fall in FEV(1), compared to placebo (47.5 +/- 13.0 mg/mL), there were significant differences with the first (114.1 +/- 36.9 mg/mL) and last (94.2 +/- 30.4 mg/mL) doses of montelukast as well as the first (160.1 +/- 64.5 mg/mL) but not the last (70.1 +/- 23.7 mg/mL) dose of salmeterol. Only montelukast produced significant suppression of the EOS. Neither drug affected exhaled nitric oxide levels. There were significant improvements with the first doses of salmeterol for all parameters of lung function. After 2 weeks of treatment, there were significant improvements with both drugs for RES and morning PEF. There were no significant differences between drugs for any end points except EOS.

CONCLUSIONS

Montelukast and salmeterol exhibited significant improvements in asthma control when given as second-line therapy. Montelukast also produced significant effects on AMP challenge and EOS suggesting anti-inflammatory activity.

Management Considerations for Chronic Asthma

Asthma is a common chronic disease affecting millions of individuals in the United States. Appropriate management and prevention of asthma symptoms is essential in order to maintain quality of life and reduce healthcare costs. Published consensus guidelines provide recommendations for asthma management and emphasize pharmacologic and nonpharmacologic components for long-term management. Major components of asthma management include environmental control measures, patient education and self-management, pharmacotherapy and periodic assessment. Since publication of the guidelines in 1997, there has been additional research and advances in our knowledge and understanding of asthma. Ongoing research focuses on issues such as regular versus as needed use of short-acting bronchodilators, early initiation of inhaled corticosteroids, safety of inhaled corticosteroids in children with asthma, combination therapy with inhaled corticosteroids and other long-term control agents, and reduction of inhaled corticosteroid doses. Advances in therapy and new knowledge about appropriate management strategies should be incorporated into clinical management strategies.

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.

New combination therapies for asthma

Combination products often have useful clinical benefits in asthma. The scientific rationale for combination therapy includes the fact that different agents have complimentary modes of action. Long-acting beta(2)-agonists have effects on airway smooth muscle, and inhaled corticosteroids have potent topical antiinflammatory effect. This combination has been shown to effectively reduce exacerbations and improve symptoms. Substantial clinical trial data provide a rationale for dual-control therapy supported by basic scientific data. Another combined therapy is inhaled steroids plus leukotriene-receptor antagonists, which provides the patient with two effective therapies. Leukotriene-receptor antagonist can also be combined with antihistamines for improved asthma control. Older therapies including theophylline and controlled release albuterol have been effectively added to inhaled corticosteroids, enabling a reduction in the dose of the inhaled steroids. Many other combination therapies are presently being tested.

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.

Clinical considerations in the use of inhaled corticosteroids for asthma

Inhaled corticosteroids are the most potent and effective therapy for treating asthma. They exert their pharmacologic action through activation of the glucocorticoid receptor, which helps regulate gene transcription. Corticosteroids also directly inhibit several inflammatory mediators involved in the pathophysiology of asthma. In randomized, controlled clinical trials, inhaled corticosteroids, as monotherapy, are superior to other therapies in improving lung function and clinical outcomes in patients with asthma. However, the use of inhaled corticosteroids is limited by concerns of dose-related adverse effects, including growth suppression and decreased bone density. Combination regimens with these agents and other long-term therapies are beneficial in maintaining asthma control while minimizing dose-related toxicities. Several inhaled corticosteroid products are available in the United States. They differ in potency; however, clinical efficacy is similar when equipotent doses are administered. A variety of factors influence product selection and patient response, including the therapeutic ratio, pharmacokinetic properties, and the inhalation delivery device. In addition, adherence to therapy and the patient's skill in administering the inhaled drug contribute to the therapeutic outcome.

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.