Montelukast, a leukotriene-receptor antagonist, for the treatment of mild asthma and exercise-induced bronchoconstriction

The efficacy of montelukast in the treatment of cat allergen-induced asthma in children

BACKGROUND

Montelukast is a leukotriene antagonist approved for the treatment of childhood asthma in children age 2 years and older. There are limited studies on its effects on allergic asthma in children.

OBJECTIVE

We sought to evaluate montelukast's effects on upper and lower airway responses to intense cat allergen exposure.

METHODS

In a double-blind, placebo-controlled, cross-over trial 18 subjects aged 6 to 14 years with cat-induced asthma were randomly assigned to receive 1 week each of either montelukast or placebo, followed by a 1-hour cat challenge in an environmental exposure unit. Upper and lower respiratory tract symptoms were rated, and spirometry and acoustic rhinometry were performed. Challenges were stopped early if the subject became too uncomfortable or had a greater than 50% decrease in FEV1.

RESULTS

Overall changes in FEV1 were significantly different with montelukast treatment and remained significant after adjusting for allergen level (P =.02; adjusted P =.01). Lower respiratory tract symptom scores were significantly reduced with montelukast versus placebo (P =.007) but lost significance after adjusting for allergen level (P =.16). Challenge length was significantly longer with montelukast versus placebo (P <.001) and remained significant after adjusting for allergen level (P =.019). Montelukast did not significantly affect upper respiratory responses, as measured by means of symptom scores (P =.43) and changes in acoustic rhinometry (P =.078).

CONCLUSIONS

Montelukast was significantly more effective than placebo in attenuating lower respiratory responses and extending challenge length when cat-sensitive children with mild persistent asthma were exposed to high levels of cat allergen.

Effect of montelukast, a once-daily leukotriene receptor antagonist, on peak expiratory flow variability

BACKGROUND

Peak expiratory flow (PEF) is an important measure of airway functin in asthma. PEF variability (PEFvar) assessment is described in asthma treatment guidelines as another means of evaluating patient status and response to therapy.

OBJECTIVE

The goal of this study was to determine the clinical effect of oral montelukast, a leukotriene receptor antagonist, on PEFvar in asthmatic patients and to assess the relationship of PEFvar with other clinical measures.

METHODS

This was a retrospective analysis of data from a multicenter, randomized, double-blind, placebo-controlled, parallel-group study, details of which have been published previously. Eligible patients had chronic stable asthma, had a forced expiratory volume in 1 second (FEV1) that was 50% to 85% of the predicted value, used inhaled beta-agonists, had at least 15% improvement in absolute FEV1 after inhaled beta-agonist administration, and showed a minimal predefined level of daytime asthma symptoms. Treatment consisted of a 2-week, single-blind, placebo run-in period followed by a 12-week, double-blind treatment period (montelukast 10 mg or matching placebo once daily at bedtime).

RESULTS

Six hundred eighty-one patients (age range, 15-79 years) were randomized to treatment at 50 centers. Baseline PEFvar was 11.44% +/- 6.55% and 10.62% +/- 6.48% in the montelukast and placebo groups, respectively. PEFvar decreased 20.1% and 7.5% from baseline in the montelukast and placebo groups, respectively. The between-group difference was significant (P < 0.001). PEFvar had low correlation with other clinical measures.

CONCLUSIONS

Over 12 weeks of treatment, montelukast significantly reduced PEFvar compared with placebo, indicating improved asthma control. The relative reduction in PEFvar was similar in patients with different degrees of variability at baseline. PEFvar did not correlate highly with other outcome variables and may measure different aspects of the disease.

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.

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.

Pathophysiological role of leukotrienes in dermatological diseases: potential therapeutic implications

In vitro and in vivo data have demonstrated that leukotrienes play a key role not only in allergic airway diseases but also in inflammatory reactions of the skin. Antileukotriene drugs, i.e. leukotriene receptor antagonists and synthesis inhibitors, are a new class of anti-inflammatory drugs that have shown clinical efficacy in the management of asthma, allergic rhinitis and inflammatory bowel disease. To address the question of the validity and applicability of published evidence of the use of antileukotriene drugs in dermatological diseases, we reviewed data concerning the pathophysiological effect of leukotrienes in the skin and in skin diseases, and the experience with antileukotriene treatment that has been published. In vivo and in vitro data suggest that antileukotriene treatment may have efficacy in atopic dermatitis, different types of urticaria or psoriasis and other skin diseases such as bullous skin diseases, collagenoses, Sjogren-Larsson syndrome or Kawasaki disease. Nevertheless, published evidence is very limited and before any conclusions can be drawn, additional basic research needs to be performed with regard to the role of different leukotrienes and leukotriene receptors in skin diseases. On the basis of these data, randomised and placebo-controlled clinical trials with leukotriene antagonists and synthesis inhibitors should be performed. Moreover, future studies investigating the additive benefit of antileukotriene drugs are warranted, e.g. in combination with antihistamines, corticosteroids or other anti-inflammatory drugs.

Montelukast in 2- to 5-year-old children with asthma

Pediatric dose selection for montelukast in 2-5-year-old children was based on a pharmacokinetic approach that was also used in previously selecting a once-daily 5-mg chewable tablet for asthmatic children 6-14 years of age. A 4-mg chewable tablet administered once daily was determined to be the correct dose and was subsequently found to be safe and effective in asthmatic children 2-5 years of age.

Prevalence and mechanisms of development of asthma and airway hyperresponsiveness in athletes

A high prevalence of asthma and airway hyperresponsiveness (AHR) has been reported in the athlete population. Factors potentially predisposing athletes to these conditions have not been clearly identified. Although moderate exercise has been shown to be beneficial in patients with asthma, repeated high-intensity exercise could possibly contribute to the development of asthma and AHR. This report provides an overview of the prevalence and possible mechanisms of development of asthma and AHR in the athlete population. The prevalence of asthma and AHR are higher in athletes than in the general population, particularly in swimmers and athletes performing sports in cold air environments. Possible mechanisms involved in the development of asthma in athletes are still uncertain; however, the content and physical characteristics of the inhaled air seem to be important factors, while immune and neurohumoral influences could play a modulatory role. This report stresses the need for further studies to better define the aetiologic factors and mechanisms involved in the development of asthma and AHR in athletes, and proposes relevant preventive and therapeutic measures.

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.

Antileukotrienes in clinical development for asthma

Asthma is a serious world health problem characterised by a chronic inflammatory disorder of the airways. Asthma attacks, or exacerbations, are episodic but airway inflammation is chronically present. Thus, this disorder requires long-term management. The goals of asthma management include prevention steps for long-term control, action steps to stop attacks, recognising deteriorating asthma, how to treat deteriorating asthma, how and when to seek medical attention and education. In order to achieve the best therapeutic choice, a stepwise approach should be adopted. In recent years, much progress regarding the characterisation of leukotrienes (LTs) has been achieved. These substances are important products of action of the 5-lipoxygenase (5-LO) enzyme on arachidonic acid (AA) and it has been established that the leukotrienes are key mediators of both allergy and inflammation. Consequently, the important role of the cysteinyl-leukotrienes (Cys-LTs) in the pathophysiology of bronchial asthma has been suggested. Pharmacological support for the role of Cys-LTs in asthma has been observed using inhibitors of 5-LO and specific LT receptor antagonists. In the clinical setting, the LT receptor, which plays the most important role, is the Cys-LT1 receptor. The antagonists of this receptor have proven an effective therapy in chronic asthmatics, agonist antigens and exercise-induced bronchoconstriction and in aspirin-intolerant asthmatics. These drugs provide a new approach in asthmatic therapy and therefore may facilitate the compliance of daily therapy.

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.

Exercise-induced bronchospasm prevalence in collegiate cross-country runners

PURPOSE

The purpose of this study was to determine the prevalence of exercise-induced bronchospasm (EIB) in collegiate cross-country runners using a protocol involving an intense exercise challenge conducted in the same environment in which the athletes train and compete.

METHODS

One-hundred eighteen collegiate cross-country runners from the Los Angeles, California, metropolitan area participated in the study. All testing took place on a track at the time and location of a normal practice session. The baseline peak expiratory flow rate (PEFR) measurements (best of three) and preexercise heart rate were recorded, after which the athletes ran 2000 m on a track at 85% of maximum heart rate. The postexercise heart rate was recorded and then PEFR measurements at 2, 5, 10, and 30 min after exercise were recorded. The athletes completed a 16-item questionnaire regarding asthma symptoms and health history. Those athletes with a history of asthma and currently taking medications for the asthma were then excluded from statistical analysis of the questionnaire responses. A decrease in PEFR of 15% was considered positive for EIB.

RESULTS

Of the 114 athletes not currently taking medications for asthma, at least 14% (16 athletes) were EIB positive. There was a poor correlation between reported symptoms of asthma and testing positive for EIB.

CONCLUSION

This study demonstrates a high prevalence of EIB in collegiate cross-country runners (at least 14%) and that reported symptoms are a poor predictor of actual EIB.

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.

Montelukast, a leukotriene receptor antagonist, for the treatment of persistent asthma in children aged 2 to 5 years

BACKGROUND

The greatest prevalence of asthma is in preschool children; however, the clinical utility of asthma therapy for this age group is limited by a narrow therapeutic index, long-term tolerability, and frequency and/or difficulty of administration. Inhaled corticosteroids and inhaled cromolyn are the most commonly prescribed controller therapies for young children with persistent asthma, although very young patients may have difficulty using inhalers, and dose delivery can be variable. Moreover, reduced compliance with inhaled therapy relative to orally administered therapy has been reported. One potential advantage of montelukast is the ease of administering a once-daily chewable tablet; additionally, no tachyphylaxis or change in the safety profile has been evidenced after up to 140 and 80 weeks of montelukast therapy in adults and pediatric patients aged 6 to 14 years, respectively. To our knowledge, this represents the first large, multicenter study to address the effects of a leukotriene receptor antagonist in children younger than 5 years of age with persistent asthma, as well as one of the few asthma studies that incorporated end points validated for use in preschool children.

OBJECTIVE

Our primary objective was to determine the safety profile of montelukast, an oral leukotriene receptor antagonist, in preschool children with persistent asthma. Secondarily, the effect of montelukast on exploratory measures of asthma control was also studied. DESIGN AND STATISTICAL ANALYSIS: We conducted a double-blind, multicenter, multinational study at 93 centers worldwide: including 56 in the United States, and 21 in countries in Africa, Australia, Europe, North America, and South America. In this study, we randomly assigned 689 patients (aged 2-5 years) to 12 weeks of treatment with placebo (228 patients) or 4 mg of montelukast as a chewable tablet (461 patients) after a 2-week placebo baseline period. Patients had a history of physician-diagnosed asthma requiring use of beta-agonist and a predefined level of daytime asthma symptoms. Caregivers answered questions twice daily on a validated, asthma-specific diary card and, at specified times during the study, completed a validated asthma-specific quality-of-life questionnaire. Physicians and caregivers completed a global evaluation of asthma control at the end of the study. Efficacy end points included: daytime and overnight asthma symptoms, daily use of beta-agonist, days without asthma, frequency of asthma attacks, number of patients discontinued because of asthma, need for rescue medication, physician and caregiver global evaluations of change, asthma-specific caregiver quality of life, and peripheral blood eosinophil counts. Although exploratory, the efficacy end points were predefined and their analyses were written in a data analysis plan before study unblinding. At screening and at study completion, a complete physical examination was performed. Routine laboratory tests were drawn at screening and weeks 6 and 12, and submitted to a central laboratory for analysis. Adverse effects were collected from caregivers at each clinic visit. An intention-to-treat approach, including all patients with a baseline measurement and at least 1 postrandomization measurement, was performed for all efficacy end points. An analysis-of-variance model with terms for treatment, study center and stratum (inhaled/nebulized corticosteroid use, cromolyn use, or none) was used to estimate treatment group means and between-group differences and to construct 95% confidence intervals. Treatment-by-age, -sex, -race, -radioallergosorbent test, -stratum, and -study center interactions were evaluated by including each term separately. Fisher's exact test was used for between-group comparisons of the frequency of asthma attacks, discontinuations from the study because of worsening asthma, need for rescue medication, and the frequencies of adverse effects. Because of an imbalance in baseline values for eosinophil counts for the 2 treatment groups, an analysis of covariance was performed on the eosinophil change from baseline with the patient's baseline as covariate.

STUDY PARTICIPANTS

Of the 689 patients enrolled, approximately 60% were boys and 60% were white. Patients were relatively evenly divided by age: 21%, 24%, 30%, and 23% were aged 2, 3, 4, and 5 years, respectively. For 77% of the patients, asthma symptoms first developed during the first 3 years of life. During the placebo baseline period, patients had asthma symptoms on 6.1 days/week and used beta-agonist on 6.0 days/week.

RESULTS

In over 12 weeks of treatment of patients aged 2 to 5 years, montelukast administered as a 4-mg chewable tablet produced significant improvements compared with placebo in multiple parameters of asthma control including: daytime asthma symptoms (cough, wheeze, trouble breathing, and activity limitation); overnight asthma symptoms (cough); the percentage of days with asthma symptoms; the percentage of days without asthma; the need for beta-agonist or oral corticosteroids; physician global evaluations; and peripheral blood eosinophils. The clinical benefit of montelukast was evident within 1 day of starting therapy. Improvements in asthma control were consistent across age, sex, race, and study center, and whether or not patients had a positive radioallergosorbent test. Montelukast demonstrated a consistent effect regardless of concomitant use of inhaled/nebulized corticosteroid or cromolyn therapy. Caregiver global evaluations, the percentage of patients experiencing asthma attacks, and improvements in quality-of-life scores favored montelukast, but were not significantly different from placebo. There were no clinically meaningful differences between treatment groups in overall frequency of adverse effects or of individual adverse effects, with the exception of asthma, which occurred significantly more frequently in the placebo group. There were no significant differences between treatment groups in the frequency of laboratory adverse effects or in the frequency of elevated serum transaminase levels. Approximately 90% of the patients completed the study.

CONCLUSIONS

Oral montelukast (4-mg chewable tablet) administered once daily is effective therapy for asthma in children aged 2 to 5 years and is generally well tolerated without clinically important adverse effects. Similarly, in adults and children aged 6 to 14 years, montelukast improves multiple parameters of asthma control. Thus, this study confirms and extends the benefit of montelukast to younger children with persistent asthma.

Choices of therapy for exercise-induced asthma in children

Cough and wheezing interferes with sport and other forms of physical activity in half of asthmatic children. Airway obstruction can be induced by a standard exercise test in over 70% of children with asthma. A beta-adrenergic agonist or cromone taken by inhalation beforehand will usually inhibit bronchoconstriction provoked by a free running exercise test. The duration of protective effect with salbutamol, terbutaline and cromones is less than 4 h. The long acting beta-adrenergic agonists formoterol and salmeterol give protection against exercise-induced airway obstruction for up to 12 h, which implies that treatment given in the morning will offer protection from the effects of physical activity throughout the day. However, the duration of protective effect after a morning dose declines if these compounds are given regularly. Leukotriene receptor antagonists (LRAs) also provide good protection against exercise-induced asthma. Regular administration of LRAs is not associated with tolerance and loss of protective effect. The oral route makes for unobtrusive administration and this may help adherence to prescribed regimens.

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.

Differential inhibition of inflammatory effector functions by petasin, isopetasin and neopetasin in human eosinophils

BACKGROUND

Priming of eosinophils with granulocyte-macrophage colony-stimulating factor (GM-CSF) and subsequent stimulation with platelet-activating factor (PAF) or the anaphylatoxin C5a is associated with a rapid production of leukotrienes (LTs) and release of eosinophil cationic protein (ECP).

OBJECTIVE

This study was designed to determine the effects of the sesquiterpene esters petasin, isopetasin and neopetasin on LT generation and ECP release in eosinophils in vitro.

METHODS

The model of eosinophil activation described above was used to induce LT production and ECP release. Cells were incubated with petasins and control inhibitors prior to priming and stimulation. To analyse intracellular steps of eosinophil activation and determine potential drug targets, some key signalling events were studied. Activity of cytosolic phospholipase A2 (cPLA(2)) was measured by analysing the generation of arachidonic acid (AA). Translocation of 5-lipoxygenase (5-LO) was observed using immunofluorescence microscopy. Intracellular calcium concentrations [Ca2+]i were measured by a bulk spectrofluorometric assay.

RESULTS

Whereas all three compounds inhibited LT synthesis, ECP release from eosinophils was blocked by petasin only, but not isopetasin or neopetasin. Similarly, PAF- or C5a-induced increases in [Ca2+]i were completely abrogated by petasin only, whereas isopetasin and neopetasin had significant lower blocking efficacy. Moreover, only petasin, but not isopetasin or neopetasin, prevented increases in cPLA(2) activity and 5-LO translocation from the cytosolic compartment to the nucleus envelope in calcium ionophore-stimulated eosinophils.

CONCLUSION

These data suggest that different petasins may at least partially block different intracellular signalling molecules. To reduce LT synthesis, isopetasin and neopetasin may act at the level of or distal to 5-LO. In contrast, petasin may inhibit inflammatory effector functions in human eosinophils by disrupting signalling events at the level of or proximal to phospholipase Cbeta (PLCbeta), besides its potential inhibitory activity within mitogen-activated protein kinase (MAPK) and LT pathways.

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.

Fexofenadine decreases sensitivity to and montelukast improves recovery from inhaled mannitol

We studied, separately, the effects of the histamine antagonist, fexofenadine hydrochloride, and the leukotriene antagonist, montelukast sodium, and their placebos on airway sensitivity to and recovery from inhaled mannitol in subjects with asthma. Two 180-mg doses of fexofenadine were taken over 14 h, and three 10-mg doses of montelukast over 36 h, with the last dose 5 h before challenge. Fexofenadine reduced sensitivity to mannitol and the PD(15) was (mean [95% confidence interval] 138 [95, 201]) mg versus placebo (51 [25, 106] mg) (p < 0.001). The final percent reduction in FEV(1) with fexofenadine was 20.8 +/- 5.4% and not different from placebo (20.1 +/- 5.3%) (p = 0.7); however, recovery was slower with fexofenadine compared with placebo (p < 0.001). By contrast, montelukast had no effect on sensitivity to mannitol and the PD(15) was 71 [36, 144] mg versus placebo (87 [51, 148] mg (p = 0.35). The total dose of mannitol delivered and the final percent reduction in FEV(1) with montelukast were 171 +/- 142 mg and 21 +/- 4% and for placebo were 182 +/- 144 mg and 20 +/- 5% (p = 0.35, p = 0.59, respectively). However, recovery of FEV(1) to baseline was faster with montelukast, with the area under the percent reduction FEV(1)-versus-time curve reduced (220 +/- 121% change.min) compared with placebo (513 +/- 182% change.min) (p < 0.001). We conclude that whereas histamine is important for the initial airway response, leukotrienes are important in sustaining the airway response to inhaled mannitol.

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.

Long-term asthma control with oral montelukast and inhaled beclomethasone for adults and children 6 years and older

BACKGROUND

Leukotriene receptor antagonists have demonstrated clinical benefits in chronic asthma studies of up to 3 months in duration. The effects of these agents over extended periods of time have not been reported.

OBJECTIVE

To describe the long-term effect of oral montelukast, a potent and specific cysteinyl leukotriene receptor antagonist, compared with inhaled corticosteroids in both adult and paediatric patients with chronic asthma.

METHODS

Male and female patients with chronic, stable asthma (adults aged 15-85 years, children aged 6-14 years), who had completed double-blind, placebo-controlled clinical studies, participated in three extension studies with oral montelukast taken once daily (10 mg tablet for adults, 5 mg chewable tablet for paediatric patients) or inhaled corticosteroids (beclomethasone 200 microg twice daily for adults, beclomethasone 100 microg or equivalent three times daily for children). A double-blind adult extension study was 37 weeks in duration; open-label adult extension studies were 156 (adults) and 112 (paediatric) weeks in duration. A total of 436, 374, and 245 patients entered these extension studies, respectively.

RESULTS

Treatment with both montelukast and inhaled corticosteroids resulted in improvement in multiple parameters of asthma control. Improvements in daytime symptom scores were generally comparable among treatment groups. No tachyphylaxis to the effects of montelukast was evident. In the adult open-label study, however, the effect of beclomethasone on mean forced expiratory volume in 1 second (FEV1) gradually decreased from start of the study to the end of the follow-up treatment period.

CONCLUSION

Both montelukast and inhaled corticosteroids were effective in controlling mild to moderate chronic asthma; the relative effectiveness of montelukast and beclomethasone were similar in open-label conditions. The hypothesis, that clinical practice conditions (e.g., adherence) may have a significant impact on the effectiveness of these therapies, should be tested in future clinical trials.

Asthma

Asthma is an important and increasingly prevalent respiratory disease. Its proper diagnosis and treatment lie at the heart of improving asthma outcome. Unfortunately, asthma has many faces and is affected by many variables, many of them difficult to control. Like many chronic illnesses, asthma tends to affect the poor and less advantaged individuals in society. Heightened awareness among patients and physicians of the serious nature of the disease is needed to reduce the morbidity and mortality of asthma. Treatment clearly requires a multifaceted approach, including behavioral, environmental, social, and medical interventions, in which the National Asthma Education and Prevention Program guidelines provide a logical, step-wise, and effective approach.

The role of antileukotrienes in the treatment of asthma

OBJECTIVE

This article reviews the literature on the role of antileukotrienes (anti-LTs), specifically montelukast, zafirlukast, and zileuton, in the treatment of asthma.

DATA SOURCES

Relevant and appropriate controlled clinical studies were used. Only literature in the English language was reviewed.

STUDY SELECTION

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

RESULTS

In guidelines established by the National Asthma Education and Prevention Program and the National Heart, Lung, and Blood Institute, a stepwise approach to asthma management is recommended, with recommendations varying depending on degree of disease severity. The anti-LTs, the newest class of drugs for the treatment of asthma, play a circumscribed role in the guidelines as they were only recently available when the latest guidelines were published. Subsequently, however, extensive clinical experience with the anti-LTs has been amassed. Multiple clinical studies have demonstrated that the anti-LTs improve pulmonary function and quality of life, and reduce asthma symptoms, asthma exacerbations, and use of beta2-agonists and oral steroids. The anti-LTs may be particularly useful in asthma patients with aspirin sensitivity or concomitant allergic rhinitis, as well as in pediatric patients. These agents have additive effects with inhaled corticosteroids and may permit a reduction in inhaled corticosteroid dosages.

CONCLUSIONS

The anti-LTs have several features that are likey to promote adherence to treatment and are generally well tolerated. The available clinical data suggest that anti-LTs should be considered as a therapeutic option or as additive therapy in patients with mild to severe asthma.

Comparison of montelukast versus budesonide in the treatment of exercise-induced bronchoconstriction

BACKGROUND

Previous studies in which leukotriene-receptor antagonist and corticosteroids were used have suggested a possible role for these anti-inflammatory drugs in the prevention of exercise-induced bronchoconstriction, but no direct comparisons have been made.

OBJECTIVE

A crossover study was undertaken to compare the ability of both montelukast and budesonide to protect patients from exercise-induced bronchoconstriction.

METHODS

A total of 20 patients (median age, 17 years; range, 8 to 36 years), who had clinical exercise-induced bronchoconstriction for 1 year and decreased FEV1 of at least 20% after exercise on two occasions, were enrolled in this study. To compare the therapies in each patient, we administered, consecutively, 10 mg of montelukast once daily at bedtime for 3 days and, later, 400 microg of budesonide twice daily for 15 days, or vice versa, with a 15-day intervening washout period during which no patient received treatment. Exercise challenges were performed at baseline (no therapy) and after each treatment. The percentage of FEV1 declines at 2, 7, and 12 minutes after exercise and the area under the curve (summarizing the extent and modification of FEV1 decreases relative to time) were measured and compared.

RESULTS

Both budesonide and montelukast significantly reduced the decrease in FEV1 (area under the curve) after exercise with respect to the baseline condition of no therapy (P = 0.0001). Overall, budesonide offered better protection (area under the curve) than did montelukast (P = 0.01), particularly in the short-term evaluation (2 minutes after exercise; P = 0.003); however, considerable individual variations in the responses to both budesonide and montelukast were observed. The degree of protection against decreases in FEV1 ranged from 0% to almost 100% for both treatments. In 16 of 20 patients, budesonide therapy offered better protection than did montelukast, and in the other 4 patients, montelukast showed better protection than did budesonide. No side effects of either montelukast or budesonide were detected during the study.

CONCLUSIONS

Treatment with budesonide or montelukast prevents exercise-induced bronchoconstriction. Because substantial variation in the response may be present among patients, both drugs should be tested in each patient before long-term therapy is chosen.

Expedient liquid chromatographic method with fluorescence detection for montelukast sodium in micro-samples of plasma

This study describes an expedient assay for the analysis of the asthma medication, montelukast sodium (Singulair, MK-0476), in human plasma samples. After a simple extraction of the plasma, the drug and internal standard, quinine bisulfate, were measured by HPLC. The chromatographic system consisted of a single pump, a refrigerated autosampler, a C8 4-microm particle size radial compression cartridge at 40 degrees C and a fluorescence detector with the excitation and emission wavelengths set at 350 and 400 nm, respectively. The mobile phase which was delivered at 1.0 ml/min, was prepared by adding 200 ml of 0.025 M sodium acetate, pH adjusted to 4.0 with acetic acid, to 800 ml of acetonitrile, with 50 microl triethylamine. With a run time of only 10 min per sample, this assay had an overall recovery of >97% with a detection limit of 1 ng/ml. The inter- and intra-run relative standard deviations at 0.05, 0.2 and 1.0 microg/ml were all <9.2%, while the analytical recovery at the same concentrations were within 7.7% of the amount added.

Role of petasin in the potential anti-inflammatory activity of a plant extract of petasites hybridus

A large production of leukotrienes (LTs) can be induced in human eosinophils or neutrophils by priming with granulocyte-macrophage colony-stimulating factor and subsequent stimulation with platelet-activating factor (PAF) or the anaphylatoxin C5a. Here, we investigated the effects of a plant extract of petasites hybridus (Ze339) and its isolated active sesquiterpene ester petasin in these two in vitro cell models. Zileuton, a 5-lipoxygenase inhibitor, was used as a positive control. All compounds inhibited both cysteinyl-LT synthesis in eosinophils and LTB(4) synthesis in neutrophils. In contrast, only Ze339 and petasin, but not zileuton, abrogated PAF- and C5a-induced increases in intracellular calcium concentrations. These data suggest that Ze339 and petasin may block, compared to zileuton, earlier signalling events initiated by G protein-coupled receptors in granulocytes, perhaps at the level of or proximal to phospholipase C(beta). Taken together, petasin appears to be one major active compound of petasites hybridus extract, since it demonstrates the same inhibitory activities on calcium fluxes and subsequent LT generation in both eosinophils and neutrophils as Ze339 does.

Leukotrienes as mediators of asthma

This review describes the aspects of leukotriene (LT) pharmacology and biology that are relevant to their important role in asthma. The biosynthesis and metabolism, including transcellular metabolism, of LTB4 and the cysteinyl-LTs (i.e. LTC4, LTD4 and LTE4) are described, and their transport is briefly outlined. The existence, distribution and pharmacological characterization of the receptors (BLT, CysLT1, CysLT2), as well as the transduction mechanisms triggered, are discussed in detail. We also describe their effects on airway smooth muscle tone, hyperresponsiveness and proliferation, on vascular tone and permeability, on mucus secretion, on neural fibers and inflammatory cell functions. Finally, the evidence supporting their role as asthma mediators is reviewed, including the effects of anti LT drugs (both biosynthesis inhibitors and receptor antagonists) in experimental and clinical asthma.

Role of nitric oxide during hyperventilation-induced bronchoconstriction in the guinea pig

Airway function is largely preserved during exercise or isocapnic hyperventilation in humans and guinea pigs despite likely changes in airway milieu during hyperpnea. It is only on cessation of a hyperpneic challenge that airway function deteriorates significantly. We tested the hypothesis that nitric oxide, a known bronchodilator that is produced in the lungs and bronchi, might be responsible for the relative bronchodilation observed during hyperventilation (HV) in guinea pigs. Three groups of anesthetized guinea pigs were given saline and three groups given 50 mg/kg N(G)-monomethyl-L-arginine (L-NMMA), a potent nitric oxide synthase inhibitor. Three isocapnic ventilation groups included normal ventilation [40 breaths/min, 6 ml/kg tidal volume (VT)], increased respiratory rate only (150 breaths/min, 6 ml/kg VT), and increased respiratory rate and increased volume (100 breaths/min, 8 ml/kg VT). L-NMMA reduced expired nitric oxide in all groups. Expired nitric oxide was slightly but significantly increased by HV in the saline groups. However, inhibition of nitric oxide production had no significant effect on rate of rise of respiratory system resistance (Rrs) during HV or on the larger rise in Rrs seen 6 min after HV. We conclude that nitric oxide synthase inhibition has no effect on changes in Rrs, either during or after HV in guinea pigs.

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.

Preventing and managing exercise-induced asthma

Managing exercise-induced asthma is a challenge for the patient and the clinician. As the incidence of exercise-induced asthma increases, health care providers need effective protocols to diagnose and treat these patients in outpatient settings. This article discusses the incidence, risk factors, pathophysiology, diagnosis, and treatment of exercise-induced asthma. Both traditional and new methods of disease diagnosis and treatment in the outpatient setting are explored.

Cloning, expression, and up-regulation of inducible rat prostaglandin e synthase during lipopolysaccharide-induced pyresis and adjuvant-induced arthritis

We have cloned and expressed the inducible form of prostaglandin (PG) E synthase from rat and characterized its regulation of expression in several tissues after in vivo lipopoylsaccharide (LPS) challenge. The rat PGE synthase is 80% identical to the human enzyme at the amino acid level and catalyzes the conversion of PGH(2) to PGE(2) when overexpressed in Chinese hamster ovary K1 (CHO-K1) cells. PGE synthase activity was measured using [(3)H]PGH(2) as substrate and stannous chloride to terminate the reaction and convert all unreacted unstable PGH(2) to PGF(2alpha) before high pressure liquid chromatography analysis. We assessed the induction of PGE synthase in tissues from Harlan Sprague-Dawley rats after LPS-induced pyresis in vivo. Rat PGE synthase was up-regulated at the mRNA level in lung, colon, brain, heart, testis, spleen, and seminal vesicles. Cyclooxygenase (COX)-2 and interleukin 1beta were also up-regulated in these tissues, although to different extents than PGE synthase. PGE synthase and COX-2 were also up-regulated to the greatest extent in a rat model of adjuvant-induced arthritis. The RNA induction of PGE synthase in lung and the adjuvant-treated paw correlated with a 3.8- and 16-fold induction of protein seen in these tissues by immunoblot analysis. Because PGE synthase is a member of the membrane-associated proteins in eicosanoid and glutathione metabolism (MAPEG) family, of which leukotriene (LT) C(4) synthase and 5-lipoxygenase-activating protein are also members, we tested the effect of LTC(4) and the 5-lipoxygenase-activating protein inhibitor MK-886 on PGE synthase activity. LTC(4) and MK-886 were found to inhibit the activity with IC(50) values of 1.2 and 3.2 microm, respectively. The results demonstrate that PGE synthase is up-regulated in vivo after LPS or adjuvant administration and suggest that this is a key enzyme involved in the formation of PGE(2) in COX-2-mediated inflammatory and pyretic responses.

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.

Changes in asthma drug therapy costs for patients receiving chronic montelukast therapy in the U.K

The aim of this study was to assess changes in the costs of asthma drug therapy before and during the use of chronic montelukast treatment in the U.K. A retrospective cohort analysis of a primary care database in the U.K. was carried out. Patients with chronic montelukast use (> or = 140 once-daily doses) were selected for analysis. Benchmarking data were obtained for matched patients with chronic inhaled corticosteroid (ICS) use and patients with chronic salmeterol therapy with concomitant ICS use. The main outcome measures were changes in utilization and monthly cost of asthma therapies costs. Asthma patients experienced significant (P<0.05) reductions in the monthly costs of ICS, short-acting beta-agonists and antibiotics following chronic montelukast therapy. Monthly concomitant drug costs were reduced by Pound Sterling 7.49 per month, which offset 27.5% of the additional cost of montelukast, yielding an increase in total drug costs of Pound Sterling 19.78 per month. Meanwhile, increased total drug costs for matched patients with chronic ICS use, and matched patients with chronic salmeterol therapy and concomitant ICS use, increased by Pound Sterling 5.37 per month and Pound Sterling 44.55 per month respectively. Additionally, patients using chronic montelukast therapy experienced a statistically significant (P<0.05) reduction in the use of short acting beta-agonists, and antibiotics, suggesting improvement in asthma control. Chronic use of montelukast therapy is associated with a reduction of concomitant drug therapy costs.

Leukotriene receptor antagonist therapy

Leukotriene receptor antagonists (LTRA) are a new class of drugs for asthma treatment, available in tablet form. Their unique mechanism of action results in a combination of both bronchodilator and anti-inflammatory effects. While their optimal place in asthma management is still under review, LTRA represent an important advance in asthma pharmacotherapy.

Eicosanoid and muscarinic receptor blockade abolishes hyperventilation-induced bronchoconstriction

This study was designed to test the hypothesis that hyperventilation-induced bronchoconstriction (HIB) results from the combined effects of prostanoid and leukotriene metabolism. A bronchoscope was used in anesthetized dogs to record peripheral airway resistance and HIB before and after combined treatment with inhibitors of cyclooxygenase (indomethacin) and 5-lipoxygenase (MK-0591). Bronchoalveolar lavage fluid (BALF) cells and mediators from hyperventilated and control airways were also measured. Pretreatment with MK-0591 and indomethacin significantly attenuated, but did not abolish, HIB. However, addition of atropine nearly eliminated the residual response. Blockade of eicosanoid metabolism markedly reduced the concentrations of eicosanoids recovered in BALF after hyperventilation. Positive correlations between posthyperventilation BALF prostanoid and epithelial cell concentrations are suggestive of mucosal injury-induced mediator production and release. We conclude that HIB is prevented in the presence of eicosanoid and muscarinic-receptor blockade and that both classes of eicosanoids contribute similarly to the development of HIB.

Airway function after cyclooxygenase inhibition during hyperpnea-induced bronchoconstriction in guinea pigs

Airway function deteriorates significantly on cessation of exercise or isocapnic hyperventilation challenges but is largely preserved during the challenge in humans and guinea pigs. PGE(2), an endogenous bronchodilator, might be responsible for the preservation of lung function during hyperventilation (HV). We hypothesized that PGE(2) might have a protective effect during HV, partially explaining the minimal changes in respiratory system resistance (Rrs) usually seen during HV in humans and guinea pigs. Therefore, changes in Rrs were measured during and after HV in anesthetized, mechanically ventilated guinea pigs treated with flurbiprofen (FBN) or placebo. With HV, there was an initial bronchodilation that was unaffected by FBN. Rrs then increased with time during HV, an effect that was blocked by FBN. After HV, Rrs increased further in all groups, but the increase in Rrs was less in the FBN-treated groups. FBN treatment reduced the PGE(2) concentration slightly in lung lavage fluid compared with placebo. We found no enhancement or refractoriness of the Rrs response to repeat bouts of HV and no effect of FBN treatment on the response of Rrs to repeat HV. These results suggest that a constrictor PG is released during and possibly after HV and that the post-HV increase in Rrs is the sum of effects of the PG released during HV and a second constrictor mechanism operating after HV. We found no evidence for bronchodilator PG during or after HV in the guinea pig.