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

Management of exercise-induced bronchospasm in children: the role of leukotriene antagonists

This review assesses the evidence on the efficacy of leukotriene antagonists in the management of exercise-induced bronchospasm (EIB) in children. Only two randomized, double-blind, placebo-controlled, crossover studies have examined the effect of leukotriene antagonists in EIB in a pediatric setting. All other studies, including those comparing leukotriene antagonists with other agents such as beta(2)-adrenoceptor agonists (beta(2)-agonists) and inhaled corticosteroids, primarily involve adult patients. In children, not receiving other asthma medication, leukotriene antagonists can offer statistically significant protection from EIB compared with placebo. However, protection is not complete, as a significant proportion of children will continue to experience a >15% reduction in FEV(1). None of the studies involved children treated concurrently with other asthma medications; therefore, comments on additive therapy cannot be made. Despite evidence from only a few studies, leukotriene antagonists are seen to be well tolerated, efficacious, and of benefit to some children. In addition, current management for EIB with short-acting beta(2)-agonists is less than ideal. It is therefore concluded that in children with EIB, leukotriene antagonists are indicated on a trial basis with individualized therapy and follow-up to evaluate treatment response.

Identifying exercise-induced bronchospasm. Treatment hinges on distinguishing it from chronic asthma

Exercise-induced bronchospasm (EIB) is an often-undiagnosed but common problem affecting both recreational and elite athletes. Although exercise can trigger exacerbation of chronic asthma, EIB should not be confused with the chronic inflammatory disease. In this article, Drs Hermansen and Kirchner review the incidence, diagnosis, and treatment of EIB and explain how to distinguish EIB from chronic asthma.

Eosinophilic esophagitis: asthma of the esophagus?

Eosinophilic esophagitis (EE) is rapidly emerging as a distinct disease entity in both pediatric and adult gastroenterology. The typical clinical presentation includes solid food dysphagia in young men who have an atopic predisposition. Food impaction necessitating endoscopic intervention is common. EE should be suspected, in particular, in patients with unexplained dysphagia or those with no response to antacid or anti-acid secretory therapy. Careful endoscopic and radiographic examinations reveal furrows, corrugations, rings, whitish plaques, fragile crêpe paper-like appearance, and a small-caliber esophagus. Mucosal erosion in the distal esophagus, characteristic to reflux esophagitis, is absent in EE. Marked eosinophil infiltration in the esophageal epithelia (>20 eosinophils per high-power field) is the diagnostic hallmark. Food antigens and aeroallergens may play a role in the pathogenesis of EE. The mechanisms may be dependent or independent of immunoglobulin E. Elimination diets, systemic and topical corticosteroids, leukotriene receptor antagonists, and, most recently, an anti-interleukin-5 monoclonal antibody have been used to treat EE. EE likely represents another example of eosinophil-associated inflammation of epithelia at the interface between external and internal milieu, similar to bronchial asthma and atopic dermatitis. This review summarizes recent progress in the diagnosis and management of EE and discusses future research directions.

A review of montelukast in the treatment of asthma and allergic rhinitis

Montelukast sodium (Singulair, Merck) is a selective and orally-active leukotriene-receptor antagonist (LTRA) that inhibits the cysteinyl leukotriene 1 (CysLT1) receptor. Montelukast is an effective and well-tolerated preventative treatment for asthma and allergic rhinitis in adults and children. The upper and lower airway show similar inflammatory responses to allergen challenge. Leukotrienes are inflammatory mediators that are known as the slow-reacting substance of anaphylaxis produced by a number of cell types including mast cells, eosinophils, basophils, macrophages and monocytes. Synthesis of these mediators results from the cleavage of arachidonic acid in cell membranes and they exert their biological effects by binding and activating specific receptors. This occurs in a series of events that lead to contraction of the human airway smooth muscle, chemotaxis and increased vascular permeability. These effects have led to their important role in the diseases of asthma and allergic rhinitis. As these agents lead to the production of symptoms in patients that are asthmatic or allergic, the use of LTRAs, particularly montelukast, may seem appropriate. Clinical trials have shown that montelukast is effective and safe in the treatment of patients with asthma, allergic rhinitis or both diseases.

Transgenic smooth muscle expression of the human CysLT1 receptor induces enhanced responsiveness of murine airways to leukotriene D4

Cysteinyl leukotrienes (CysLTs) exert potent proinflammatory actions and contribute to many of the symptoms of asthma. Using a model of allergic sensitization and airway challenge with Aspergillus fumigatus (Af), we have found that Th2-type inflammation and airway hyperresponsiveness (AHR) to methacholine (MCh) were associated with increased LTD(4) responsiveness in mice. To explore the importance of increased CysLT signaling in airway smooth muscle function, we generated transgenic mice that overexpress the human CysLT1 receptor (hCysLT(1)R) via the alpha-actin promoter. These receptors were expressed abundantly and induced intracellular calcium mobilization in airway smooth muscle cells from transgenic mice. Force generation in tracheal ring preparations ex vivo and airway reactivity in vivo in response to LTD(4) were greatly amplified in hCysLT(1)R-overexpressing mice, indicating that the enhanced signaling induces coordinated functional changes of the intact airway smooth muscle. The increase of AHR imposed by overexpression of the hCysLT(1)R was greater in transgenic BALB/c mice than in transgenic B6 x SJL mice. In addition, sensitization- and challenge-induced increases in airway responsiveness were significantly greater in transgenic mice than that of nontransgenic mice compared with their respective nonsensitized controls. The amplified AHR in sensitized transgenic mice was not due to an enhanced airway inflammation and was not associated with similar enhancement in MCh responsiveness. These results indicate that a selective hCysLT(1)R-induced contractile mechanism synergizes with allergic AHR. We speculate that hCysLT(1)R signaling contributes to a hypercontractile state of the airway smooth muscle.

Increase in urinary leukotriene LTE4 levels in acute asthma: correlation with airflow limitation

BACKGROUND

Leukotrienes play a key role in the pathophysiology of chronic asthma. Activation of leukotriene pathways is accompanied by rises in detectable urinary levels of leukotriene E4 (LTE4). The relationship between urinary LTE4 levels and factors associated with acute asthma has not been determined.

METHODS

Adults aged 15-54 years presenting with moderate to severe acute asthma were evaluated at emergency departments in 16 US sites. Forced expiratory volume in 1 second (FEV1) was measured during the first 60 minutes after arrival and at specified times until discharge or admission. Urine samples for measurement of LTE4 levels were obtained either on arrival at the study site and/or before discharge. Patients were seen 2 weeks later for follow up, at which time repeat FEV1 measurements and urine samples for LTE4 were obtained.

RESULTS

One hundred and eighty four patients were evaluated; LTE4 results from both the acute and follow up periods were available for analysis in 146. Urinary LTE4 levels were increased during asthma exacerbations compared with levels obtained 2 weeks later (geometric means 111.7 and 75.6 pg/mg creatinine, respectively, mean percentage change -32.3; 95% confidence interval (CI) for the mean percentage change -39.6 to -24.3, p<0.001). The correlation between improvement in FEV1 and decline in LTE4 over the 2 week interval was significant (p<0.001, r=0.43).

CONCLUSIONS

Activation of leukotriene pathways in acute asthma is correlated with the degree of airflow obstruction, and resolution of the asthma exacerbation is associated with a reduction in leukotriene levels.

Methacholine challenge testing: comparison of the two American Thoracic Society-recommended methods

STUDY OBJECTIVES

Recent American Thoracic Society guidelines recommend two different methods of methacholine challenge testing: the 2-min tidal breathing method with twofold increases in concentration, and the five-breath dosimeter method with fourfold increases. Since the tidal breathing method delivers more methacholine to the mouthpiece, we hypothesized that the provocative concentration of methacholine required to decrease FEV(1) by 20% (PC(20)) would be lower than with the dosimeter method.

DESIGN

Twelve subjects 18 to 45 years old with stable asthma were selected on the basis of a screening PC(20) (by tidal breathing) of < 1 mg/mL, 1 to 4 mg/mL, or 4 to 16 mg/mL (4 subjects in each concentration range). On subsequent visits within a 7-day period, methacholine challenge testing with tidal breathing or dosimeter were performed on separate days, in a randomized crossover manner.

RESULTS

The geometric mean PC(20) was 1.8 mg/mL (95% confidence interval [CI], 0.7 to 4.3) after tidal breathing and 1.6 mg/mL (95% CI, 0.7 to 3.7) after dosimeter (p = 0.2). There was no significant difference between the screening PC(20) and the PC(20) obtained by either method on randomized study days. The maximum decrease in FEV(1) from diluent baseline after the last concentration was 27.8% (range, 20 to 50%) during tidal breathing and 27.9% (range, 16 to 47%) during the dosimeter method (p = 0.35).

CONCLUSIONS

Both methods give similar results. Fourfold increases in methacholine concentration with the dosimeter method are as safe as twofold increases with the tidal breathing method.

Recent advances in the management of asthma using leukotriene modifiers

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

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

We searched MEDLINE (1966 to Aug 2003), EMBASE (1980 to Aug 2003), CINAHL (1982 to Aug 2003), the Cochrane Airways Group trials register, and the Cochrane Central Register of Controlled Trials (August 2003), abstract books, 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 anti-leukotrienes with inhaled corticosteroids during a minimal 30-day intervention period in asthmatic patients aged 2 years and older.

DATA COLLECTION AND ANALYSIS

Two reviewers independently assessed the methodological quality or trials and extracted trial data. 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

27 trials (including 1 trial testing two protocols) met the inclusion criteria; 13 were of high methodological quality; 20 are published in full-text. All trials pertained to patients with mild to moderate persistent asthma. Only 3 trials focused on children and adolescents. Trial duration varied from 4 to 37 weeks. In most trials, daily dose of ICS was 400 mcg of beclomethasone or equivalent. Patients treated with anti-leukotrienes were 65% more likely to suffer an exacerbation requiring systemic steroids [Relative Risk 1.65; 95% Confidence Interval (CI) 1.36 to 2.00]. Twenty six (95% CI: 17 to 47) patients must be treated with anti-leukotrienes instead of inhaled corticosteroids to cause one extra exacerbation. Significant differences favouring ICS were noted in secondary outcomes where()the improvement in FEV(1) reached 130 mL [13 trials; 95% CI: 50, 140 mL ]. Other significant benefits of ICS were seen for symptoms, nocturnal awakenings, rescue medication use, symptom-free days, and quality of life. Anti-leukotriene therapy was associated with 160% increased risk of withdrawals due to poor asthma control. Twenty nine (95% CI 20 to 48) patients must be treated with anti-leukotrienes instead of inhaled corticosteroids to cause one extra withdrawal due to poor control. Risk of side effects was not different between groups.

REVIEWERS' CONCLUSIONS

Inhaled steroids at a dose of 400 mcg/day of beclomethasone or 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. Inhaled glucocorticoids should remain the first line monotherapy for persistent asthma.

No effect of montelukast on asthma-like symptoms in elite ice hockey players

BACKGROUND

Controlled clinical trials on the effects of leukotriene antagonists on asthma-like symptoms, bronchial hyperresponsiveness and airway inflammation have not been performed in elite athletes.

METHODS

In 2001, we examined 88 of 102 (86%) players from three junior, national league ice hockey teams in Helsinki. Athletes were included in the intervention if they reported at least two exercise-induced bronchial symptoms (wheeze, cough, shortness of breath) weekly during the previous month on a previously validated respiratory-symptom questionnaire. Sixteen male ice hockey players fulfilled the study criteria. A double-blind, randomized, cross-over, placebo-controlled study included 4-week active treatment (10 mg oral montelukast, bedtime), 1-week washout period, and 4-week placebo treatment. Before entering the study, all patients were clinically examined, skin prick tested, filled in a respiratory symptom questionnaire, performed a spirometry and a histamine challenge test, and gave induced sputum samples. Exhaled NO was measured. These measures were repeated after both treatment periods. During the treatment the athletes kept daily diary on lower respiratory tract symptoms on a scale from 0 (no symptoms) to 10 (most severe symptoms), morning peak expiratory flow (PEF), training amount, and use of study medication. Primary end-point was daily lower respiratory tract symptom score.

RESULTS

Montelukast had no effect on daily lower respiratory symptom scores, spirometry parameters [forced expiratory volume in 1 s (FEV1), forced vital capacity (FVC), FEV1/FVC ratio, PEF], bronchial hyperresponsiveness, sputum eosinophil or neutrophil cell counts, exhaled NO measurements, or morning PEF. Nine subjects were atopic in skin prick test, but their results did not differ from the nonatopic subjects.

CONCLUSION

A leukotriene antagonist, montelukast, was of no benefit in the treatment of asthma-like symptoms, increased bronchial hyperresponsiveness or a mixed type of eosinophilic and neutrophilic airway inflammation in highly-trained ice hockey players.

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 August 2003), reference lists of review articles and trials, contacted international headquarters of AL manufacturers and looked at American Thoracic Society and European Respiratory Society meeting abstracts (1998 to 2003).

SELECTION CRITERIA

Randomised placebo-controlled trials of asthmatics aged two 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 587 citations, 27 (25 adult and 2 paediatric) trials met inclusion criteria. Sixteen trials were published in full-text and 16 trials reported data in a way that allowed meta-analysis. 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) 0.64; 95% Confidence Interval (CI) 0.38 to 1.07). A modest improvement group difference in PEF was seen (Weighted Mean Difference (WMD) 7.7 L/min; 95% CI 3.6 to 11.8 L/min) together with decrease in use of rescue short-acting beta2-agonist use (WMD 1 puff/week; 95%CI 0.5 to 2). With only 3 trials comparing the use of licensed doses of anti-leukotrienes with increasing the dose of inhaled glucocorticoids, no firm conclusion can be drawn about the equivalence of both treatment options. In ICS-sparing studies of patients who were well controlled at baseline, addition of anti-leukotrienes produced no overall difference in dose of inhaled glucocorticoids (WMD -21 mcg/d, 95%CI -65, 23 mcg/d), but it was associated with fewer withdrawals due to poor asthma control (RR 0.63, 95% CI 0.42 to 0.95).

REVIEWERS' CONCLUSIONS

The addition of licensed doses of anti-leukotrienes to add-on therapy to inhaled glucocorticoids brings modest improvement in lung function. Although addition of anti-leukotrienes to inhaled glucocorticoids appears comparable to increasing the dose of inhaled steroids, the power of the review is insufficient to confirm the equivalence of both treatment options. Addition of anti-leukotrienes is associated with superior asthma control after glucocorticoid tapering; although the glucocorticoid-sparing effect cannot be quantified at present, it appears modest.

Fish oil supplementation reduces severity of exercise-induced bronchoconstriction in elite athletes

In elite athletes, exercise-induced bronchoconstriction (EIB) may respond to dietary modification, thereby reducing the need for pharmacologic treatment. Ten elite athletes with EIB and 10 elite athletes without EIB (control subjects) participated in a randomized, double-blind crossover study. Subjects entered the study on their normal diet, and then received either fish oil capsules containing 3.2 g eicosapentaenoic acid and 2.2 g docohexaenoic acid (n-3 polyunsaturated fatty acid [PUFA] diet; n = 5) or placebo capsules containing olive oil (placebo diet; n = 5) taken daily for 3 weeks. Diet had no effect on preexercise pulmonary function in either group or on postexercise pulmonary function in control subjects. However, in subjects with EIB, the n-3 PUFA diet improved postexercise pulmonary function compared with the normal and placebo diets. FEV1 decreased by 3 +/- 2% on n-3 PUFA diet, 14.5 +/- 5% on placebo diet, and 17.3 +/- 6% on normal diet at 15 minutes postexercise. Leukotriene (LT)E4, 9alpha, 11beta-prostaglandin F2, LTB4, tumor necrosis factor-alpha, and interleukin-1beta, all significantly decreased on the n-3 PUFA diet compared with normal and placebo diets and after the exercise challenge. These data suggest that dietary fish oil supplementation has a markedly protective effect in suppressing EIB in elite athletes, and this may be attributed to their antiinflammatory properties.

Benefit-risk assessment of antileukotrienes in the management of asthma

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

Relationship between airway hyperresponsiveness to mannitol and adenosine monophosphate

BACKGROUND

Assessment of airway hyperresponsiveness (AHR) to indirect bronchoconstrictor stimuli is a useful noninvasive tool in the evaluation of asthma and its treatment. We investigated the putative relationship in AHR between inhaled adenosine monophosphate and mannitol.

METHODS

Fifteen mild-to-moderate atopic asthmatics were evaluated. On two separate screening days, the threshold AMP concentration and threshold mannitol dose to provoke a given fall in FEV1 were measured.

RESULTS

For AMP PC20vs. mannitol PD15, the Pearsons correlation coefficient was 0.80, P < 0.001. For AMP PC15vs. mannitol PD15 and AMP PC10vs. mannitol PD10 corresponding values were 0.83, P < 0.001 and 0.68, P = 0.005.

CONCLUSIONS

There was a highly significant association between the threshold concentration of AMP and dose of mannitol causing a given fall in FEV1. Further studies are required to evaluate the relationship between inhaled mannitol and other surrogate inflammatory markers.

The role of leukotrienes in asthma

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

Comparison of montelukast and budesonide on bronchial reactivity in subjects with mild-moderate persistent asthma

We studied 51 atopic non-smoking subjects who were divided to four treatments groups: (A) montelukast 10mg daily, (B) budesonide 400 microg twice a day (bid), (C) montelukast 10 mg daily plus budesonide 400 microg bid and (D) budesonide 800 microg bid. Bronchial responsiveness was assessed before and after 12 weeks of treatment. The bronchial responsiveness, evaluated by means of PC(20) values, showed a strong significant increase in groups B, C and D, and a weak but significant rise in group A, when compared to basal data. Regarding other pulmonary parameters (FEV(1), PEF) there were no significant differences among the groups after 12 weeks of therapy. A statistical significance was founded after therapy between group A and C (p < 0.05), but not between the group B and D treated with only budesonide at different doses. No significant differences was observed in the side effect pattern among the various treatments. The study data demonstrated that administration of montelukast provided an important and additional effect on bronchial hyperresponsiveness. Oral administration represents a significant advantage over the majority of other anti-asthmatic drugs. Our results confirm the anti-inflammatory properties of both the inhaled corticosteroid (ICS) and montelukast and the possible role of these drugs can have on airway remodelling. While currently low dose ICS remains the reference drug as a controller in mild-moderate persistent asthma, montelukast may be viewed as a possible option, either in monotherapy or in association.

Activity-induced asthma

Exercise is the most common trigger of persistent childhood asthma. The history for EIA can be complicated by the lack of perception of significant airway obstruction during exercise. One must carefully identify those children with EIA from the group of children who report low level of activity because of lack of interest or because they are out of shape. Baseline spirometry of children with persistent asthma is frequently normal. Spirometry is important to identify those children with EIA who underrecognize their disease, but normal results should not be used as evidence of absence of disease. Formal exercise testing should be considered when the diagnosis is unclear or if there seems to be a lack of bronchoprotection with inhaled albuterol. The goal of treatment of EIA should be the attainment of a normal activity level for children and adolescents. Identification of the limits imposed by EIA and establishment of goals of therapy with the child and family should be the initial action. Inactivity or reduced exertion, in the presence of this diagnosis. should not be accepted. Therapy for EIA starts with control of the underlying persistent asthma. Inhaled corticosteroids are the most effective initial treatment of both EIA and persistent asthma in children and adolescents. Exercise-induced asthma is a common aspect of a prevalent disease that warrants proper diagnosis and treatment. With appropriate therapy, children with EIA should be able to participate in sports and maintain normal activity. They should strive to compete in the same playing field as their peers and have the same goals as those children and athletes who do not have exercise-induced asthma.

Effects of mediator antagonism on mannitol and adenosine monophosphate challenges

BACKGROUND

Airway hyper-responsiveness (AHR) to indirect stimuli is a useful non-invasive surrogate inflammatory marker in the evaluation of asthma, while histamine and cysteinyl leukotrienes are important inflammatory mediators.

OBJECTIVE

To evaluate AHR to indirect bronchoconstrictor stimuli and time taken to recover following single doses of montelukast 10 mg and desloratadine 5 mg in combination, montelukast 10 mg alone and placebo.

METHODS

Fifteen mild-to-moderate persistent asthmatics completed a randomized, double-blind, cross-over study. Patients received encapsulated montelukast 10 mg/desloratadine 5 mg combination, montelukast 10 mg alone and placebo, 10-14 h prior to challenge on two separate occasions. The mannitol threshold dose, AMP threshold concentration and recovery times after challenge were measured along with lung function.

RESULTS

Compared to placebo, montelukast/desloratadine conferred improvements (P < 0.05) in adenosine monophosphate (AMP) threshold concentration and mannitol threshold dose: a 3.2-fold (95% CI 2.2-4.6) and 2.4-fold (95% CI 1.7-3.3) difference, respectively, while compared to montelukast this amounted to a 2.0-fold (95% CI 1.2-3.4) and 1.5-fold (95% CI 1.1-2.4) improvement, respectively. Montelukast was not significantly different from placebo. Both montelukast/desloratadine and montelukast compared to placebo, shortened recovery following both challenges (P < 0.05): a 27-min (95% CI 17-37) and 29-min (95% CI 20-36) reduction, respectively, for AMP, and a 27-min (95% CI 17-37) and 26-min (95% CI 17-35) reduction, respectively for mannitol.

CONCLUSION

The dissociated effects of single doses of montelukast alone but not montelukast/desloratadine combination on AHR and recovery time, highlights the relative roles of histamine in initiating the bronchoconstrictor response and cysteinyl leukotrienes in sustaining it. Similar improvements in AHR and recovery time were observed following both indirect bronchoconstrictor stimuli.

Effect of zafirlukast on methacholine and ultrasonically nebulized distilled water challenge in patients with mild asthma

BACKGROUND

Bronchial asthma is a chronic inflammatory disease characterized by airway inflammation and hyperresponsiveness due to the release of multiple mediators, such as cysteinyl-leukotrienes (cys-LTs).

OBJECTIVE

Our study was designed to investigate whether oral pretreatment with zafirlukast (a cys-LTs receptor antagonist) reduces bronchoconstriction against methacholine (MC) and ultrasonically nebulized distilled water (UNDW) challenge in patients with mild asthma.

METHODS

Fourteen non-atopic patients (8 males, 20-42 years, forced expiratory volume in 1 s (FEV(1)) 97% SD +/- 0.4) with mild, intermittent bronchial asthma performed a sequential weekly pulmonary function test following challenge with MC or UNDW 2 h after zafirlukast or placebo administration, according to a single-blind method.

RESULTS

We found that pretreatment with zafirlukast significantly decreased bronchoconstriction MC (maximum FEV(1) drop -10.75% SD +/- 1.89, p < 0.001) and UNDW induced (maximum FEV(1) drop -12% SD +/- 0.15, p < 0.001), while pretreatment with placebo did not protect patients against FEV(1) drop following MC (maximum FEV(1) drop -33.22% SD +/- 1.42, p < 0.001) and UNDW challenge (maximum FEV(1) drop -30.02% SD +/- 0.4, p < 0.001).

CONCLUSIONS

Pretreatment with zafirlukast significantly reduced bronchoconstriction against MC and UNDW challenge in individuals with mild intermittent asthma, indicating that cys-LTs receptor antagonists might be useful as preventive therapy in these patients population.

Management of asthma in adults: current therapy and future directions

Asthma is increasing in prevalence worldwide and results in significant use of healthcare resources. Although most patients with asthma can be adequately treated with inhaled corticosteroids, an important number of patients require additional therapy and an increasing number of options are available. A further minority of patients develop severe persistent asthma which remains difficult to manage despite current pharmacological therapies. This review discusses the various treatment options currently available for each stage of asthma severity, highlights some of the limitations of current management, and outlines directions which may improve the management of asthma in the future.

Pharmacological profile of MEN91507, a new CysLT(1) receptor antagonist

MEN91507 (8-[2-(E)-[4-[4-(4-fluorophenyl)butyloxy]phenyl]vinyl]-4-oxo-2-(5-1H-tetrazolyl)-4H-1-benzopyran sodium salt)) potently displaced [3H]leukotriene D(4) binding from guinea-pig lung and dimethylsulphoxide-differentiated U937 (dU937) cell membranes (K(i) 0.50 +/- 0.16 and 0.65 +/- 0.29 nM, respectively). On the other hand, MEN91507 did not display significant binding affinity for a series of receptors or channels. In functional studies on dU937 cells, MEN91507 behaved as insurmountable antagonist of leukotriene D(4)-induced calcium transients, with an apparent pK(B) of 10.25 +/- 0.15. In anaesthetized guinea-pigs, MEN91507 antagonized in a dose-dependent manner leukotriene D(4)-induced bronchoconstriction following i.v. or oral administration: the ED(50s) were 3.0 +/- 0.3 and 140 +/- 90 nmol/kg, respectively. The inhibition of leukotriene D(4)-induced bronchoconstriction by MEN91507 was long-lasting, since a dose of 0.6 micromol/kg produced 74% reduction of the response after 8 h from administration. Likewise, leukotriene D(4)-induced microvascular leakage was antagonized by MEN91507 either following i.v. or oral administration: a significant inhibitory effect was still evident at 16 h from oral administration of a dose of 6 micromol/kg. It is concluded that MEN91507 is a potent and selective antagonist of both guinea-pig and human CysLT(1) receptors; in addition, in vivo studies on guinea-pigs indicate that MEN91507 is an orally available and long-lasting antagonist of the bronchomotor and pro-inflammatory effects induced by leukotriene D(4) through the stimulation of CysLT(1) receptors.

Inhibition of leukotriene biosynthesis by a novel dietary fatty acid formulation in patients with atopic asthma: a randomized, placebo-controlled, parallel-group, prospective trial

BACKGROUND

Leukotriene inhibitors and leukotriene-receptor antagonists are effective in the treatment of inflammatory diseases such as asthma. A search of the entirety of MEDLINE using the terms diet plus leukotrienes identified numerous studies that have explored dietary-management strategies to reduce leukotriene levels through supplementation with polyunsaturated fatty acids such as gamma-linolenic acid (GLA) and eicosapentaenoic acid (EPA). However, the search found no studies on the use of combinations of these fatty acids in patients with asthma.

OBJECTIVE

The goal of this study was to determine the effect of daily intake of an emulsion (PLT 3514) containing dietary GLA and EPA on ex vivo stimulated whole blood leukotriene biosynthesis in patients with atopic asthma.

METHODS

This was a randomized, double-blind, placebo-controlled, parallel-group, prospective trial in patients with mild to moderate atopic asthma. Patients consumed 10 g PLT 3514 emulsion (containing 0.75 g GLA + 0.5 g EPA), 15 g PLT 3514 emulsion (containing 1.13 g GLA + 0.75 g EPA), or placebo (olive oil) emulsion daily for 4 weeks. Plasma fatty acids were measured by gas chromatography, and stimulated whole blood leukotrienes were measured by reverse-phase high-performance liquid chromatography with ultraviolet detection using a diode array detector.

RESULTS

Forty-three patients (33 women, 10 men) participated in the study. Leukotriene biosynthesis was significantly decreased in patients consuming 10 or 15 g PLT 3514 compared with placebo (P < 0.05, analysis of covariance). No clinically significant changes in vital signs were observed throughout the study, and there were no significant between-group differences in treatment-emergent adverse events or mean clinical laboratory values.

CONCLUSION

Daily consumption of dietary GLA and EPA in a novel emulsion formulation inhibited leukotriene biosynthesis in this population of patients with atopic asthma and was well tolerated.

Pharmacoeconomics of asthma treatment

The burden of asthma is increasing in terms of prevalence, severity of symptoms and other markers of asthma control. Poor control of symptoms is a major issue that can result in adverse clinical and economic outcomes. Prescribing costs are the most obvious and visible expense in asthma care but these are but the tip of the iceberg. We need to take all factors into account when considering the overall costs of asthma treatments and recognise that treatment that results in better asthma control may result in lessening of both direct and indirect costs. To assess this accurately, health economic evaluations need to be undertaken in relevant settings, on representative populations. They need to use appropriate measures of asthma outcome. Drug-related costs need to take into account savings made by decreased costs of other prescribed medication and patient factors must be taken into account. We need information that is applicable to the types of patients we see in the real world to make proper cost analyses. Such information can come from 'pragmatic' randomised trials, from retrospective claims analysis from observational studies or using primary care clinical and prescribing databases.

Effect of montelukast added to inhaled budesonide on control of mild to moderate asthma

BACKGROUND

Proinflammatory leukotrienes, which are not completely inhibited by inhaled corticosteroids, may contribute to asthmatic problems [corrected]. A 16 week multicentre, randomised, double blind, controlled study was undertaken to study the efficacy of adding oral montelukast, a leukotriene receptor antagonist, to a constant dose of inhaled budesonide.

METHODS

A total of 639 patients aged 18-70 years with forced expiratory volume in 1 second (FEV(1)) > or =55% predicted and a minimum predefined level of asthma symptoms during a 2 week placebo run in period were randomised to receive montelukast 10 mg (n=326) or placebo (n=313) once daily for 16 weeks. All patients received a constant dose of budesonide (400-1600 microg/day) by Turbuhaler throughout the study.

RESULTS

Mean FEV(1) at baseline was 81% predicted. The median percentage of asthma exacerbation days was 35% lower (3.1% v 4.8%; p=0.03) and the median percentage of asthma free days was 56% higher (66.1% v 42.3%; p=0.001) in the montelukast group than in the placebo group. Patients receiving concomitant treatment with montelukast had significantly (p<0.05) fewer nocturnal awakenings and significantly (p<0.05) greater improvements in beta agonist use and morning peak expiratory flow rate (PEFR).

CONCLUSIONS

For patients with mild airway obstruction and persistent asthma symptoms despite budesonide treatment, concomitant treatment with montelukast significantly improves asthma control.

Inhibition of leukotriene synthesis, pharmacokinetics, and tolerability of a novel dietary fatty acid formulation in healthy adult subjects

BACKGROUND

Numerous studies have explored dietary-management strategies for decreasing leukotriene synthesis by inflammatory cells through supplementation with polyunsaturated fatty acids such as gamma-linolenic acid (GLA) and eicosapentaenoic acid (EPA).

OBJECTIVES

This study sought to determine the optimal daily intake, ratios, and formulation of dietary GLA and EPA required to safely reduce leukotriene biosynthesis in healthy individuals, and to evaluate the pharmacokinetics and safety profile of such a formulation.

METHODS

Two preliminary trials were conducted to determine the minimum effective levels of GLA and EPA intake needed to reduce leukotriene biosynthesis and prevent increases in plasma arachidonic acid (AA) concentrations. These preliminary trials were followed by a single-center, randomized, double-blind, placebo-controlled, parallel-group, escalating-intake inpatient trial of a dietary GLA/EPA emulsion (PLT 3514) in healthy adult subjects. Subjects consumed either 10, 20, or 100 g of the PLT 3514 emulsion (respectively containing 0.75 g GLA + 0.5 g EPA, 1.5 g GLA + 1 g EPA, and 7.5 g GLA + 5 g EPA), or a placebo emulsion containing olive oil daily for 14 days. Plasma fatty acids were measured by gas chromatography Stimulated whole blood leukotrienes were measured by high-performance liquid chromatography with ultraviolet detection.

RESULTS

Thirty subjects were included in the preliminary trials; 47 subjects were enrolled in the escalating-intake trial, of whom 42 completed the study. In the preliminary trials, intake of GLA 1.5 g/d in gelatin capsules decreased the capacity to synthesize leukotrienes but increased plasma levels of AA (both, P < 0.05). Inclusion of 0.25 or 1 g of dietary EPA prevented the increase in plasma AA concentrations. Dietary GLA and EPA showed significantly enhanced bioavailability when consumed in 20 g PLT 3514 emulsion compared with consumption in gelatin capsules (P < 0.05), resulting in a reduction in the amount of intake required to block leukotriene biosynthesis. Pharmacokinetic analyses indicated that fasting plasma GLA and EPA levels plateaued within 7 days' daily consumption at all levels of intake, whereas the time to maximum plasma concentration (Tmax) was shorter for GLA than for EPA. The Tmax was similar on days 1 and 14 for both GLA and EPA. There were no clinically significant between-group differences in changes in vital signs, mean clinical laboratory values, or abbreviated hematology laboratory tests, or significant differences in the occurrence of treatment-emergent adverse events between the group consuming up to 20 g/d of the GLA/EPA emulsion and the group consuming placebo.

CONCLUSION

Consumption of specific proportions and intake levels of dietary GLA and EPA in a novel emulsion formulation inhibited leukotriene biosynthesis and appeared to be well tolerated in this population of healthy adult subjects.

Exercise-induced bronchoconstriction in children: montelukast attenuates the immediate-phase and late-phase responses

BACKGROUND

Montelukast, a leukotriene receptor antagonist, attenuates exercise-induced bronchoconstriction. We and others have shown that there is a late-phase response 3 to 8 hours after exercise in a subset of asthmatic patients.

OBJECTIVE

We sought to evaluate the protective effect of montelukast on immediate-phase and late-phase responses after exercise challenges.

METHODS

Twenty-two atopic asthmatic children aged 7 to 16 years with reproducible exercise-induced bronchoconstriction (minimum of 15% decrease of FEV(1) from baseline) were enrolled in this placebo-controlled crossover study. Exercise challenges were performed while breathing cold dry air, and FEV(1) measurements were taken up to 480 minutes after exercise. Patients underwent exercise challenges on a screening day and 1 week after placebo treatment. Subsequently, after a week with no treatment, pulmonary function was assessed after breathing dry cold air (control day). Finally, an exercise challenge was carried out after a week of treatment with montelukast.

RESULTS

Reproducible late-phase reactions occurred in 5 of 22 patients, which correlated with the extent of the immediate response (P <.05). After 1 week of treatment with montelukast, a significant decrease of immediate responses was observed. Montelukast treatment compared with placebo was associated with a lower mean maximum decrease of FEV(1) (mean +/- SEM: 17.3% +/- 2.4% and 35.1% +/- 2.6%, respectively), decrease of the area above the curve (267.8% +/- 42.7%/min and 868.0% +/- 103.8%/min, respectively), and shorter time for recovery (6.9 +/- 1.1 minutes and 30.9 +/- 4.0 minutes, respectively; P <.05). Treatment with montelukast also abolished late-phase responses.

CONCLUSION

Once daily treatment with oral montelukast attenuated the immediate-phase response and abolished the late-phase response induced by means of exercise challenge in asthmatic children.

Exercise-Induced Asthma

Exercise-induced asthma is a common complex pulmonary disorder associated with a diagnosis of chronic asthma including cough, dyspnea, wheezing, and chest tightness that affects millions of patients worldwide. Exercise-induced asthma patients are frequently inhibited from participating in physical activities because of the degree of pulmonary dysfunction. Pharmacological agents, the cornerstone of treatment for exercise-induced asthma, improve pulmonary function and quality of life. Short-term and long-term adrenergic β2 sympathomimetics, mast cell stabilizers, leukotriene receptor antagonists, 5-lipoxygenase inhibitors, and corticosteroids are commonly used. β2 sympathomimetics are the most potent bronchodilators and are considered the first drug of choice. Inhaled corticosteroids and mast cell stabilizers assist with the reduction of airway inflammation and response to exercise and are generally added in combination with β2 sympathomimetics for maximum efficacy. Leukotriene receptor antagonists and inhibitors may be alternatives for patients who do not receive adequate prophylaxis with inhaled β2 sympathomimetics, corticosteroids, or mast cell stabilizers. Pharmacotherapeutic regimens must be tailored to meet the specific needs of patients. However, other factors must be considered, including side-effect profiles of the agents, cost, medication compliance, drug-drug and drug-disease interactions, insurance limitations, improvements in pulmonary function parameters, and understanding of the disease.

Inflammatory cells in asthma: mechanisms and implications for therapy

Recent clinical studies have brought asthma's complex inflammatory processes into clearer focus, and understanding them can help to delineate therapeutic implications. Asthma is a chronic airway inflammatory disease characterized by the infiltration of airway T cells, CD(+) (T helper) cells, mast cells, basophils, macrophages, and eosinophils. The cysteinyl leukotrienes also are important mediators in asthma and modulators of cytokine function, and they have been implicated in the pathophysiology of asthma through multiple mechanisms. Although the role of eosinophils in asthma and their contribution to bronchial hyperresponsiveness are still debated, it is widely accepted that their numbers and activation status are increased. Eosinophils may be targets for various pharmacologic activities of leukotriene receptor antagonists through their ability to downregulate a number of events that may be key to the effector function of these cells.

Time efficacy of a single dose of montelukast on exercise-induced asthma in children

The aim of this study was to evaluate the timing of onset and the duration of action of a single oral-dose treatment with montelukast in comparison to placebo on exercise-induced asthma (EIA) in asthmatic children. Nineteen children (7-13 years) with stable asthma were evaluated. Patients undertook three consecutive treadmill exercise tests, respectively, 2, 12 and 24 h after a single-dose administration. A double-blind randomized, single-dose, placebo-controlled, crossover design was used. To assess bronchoconstriction after the exercise challenge, the maximal percentage fall in FEV1 (DeltaFEV1) from the baseline value was considered. Two hours after dosing, DeltaFEV1 was -15.33 +/- 2.93 for placebo and -13.33 +/- 2.03 for montelukast. At 12 h, DeltaFEV1 was -18.69 +/- 2.83 for placebo, -9.78 +/- 1.85 for montelukast (p < 0.005). No difference was observed between placebo (DeltaFEV1-10.21 +/- 2.07) and montelukast (DeltaFEV1-9.10 +/- 2.02) at 24 h. Analysis of the degree of protection showed a significant efficacy of montelukast (p = 0.02) in comparison with placebo only at 12 h. Montelukast showed a significant protective effect 12 h after dosing, but no effect after 2 and 24 h. In mild asthmatics, the timing of administration of single dosage before exercise should be strictly considered in order to obtain the drug protective effects.

Asthma control and patient satisfaction among early pediatric users of montelukast

OBJECTIVE

To assess asthma control and patient satisfaction among pediatric users of montelukast in a clinical practice setting.

STUDY DESIGN

A prospective study of 175 children with persistent asthma, 6 to 14 years of age, who initiated treatment with montelukast between Feb-1998 and Aug-1998, in primary care and pediatric offices across the United States. Data on asthma control and satisfaction with treatment was collected in physicians' offices after enrollment and by survey to the patients' homes at 1 month of treatment.

RESULTS

Across the study population, improvements in mean scores for asthma control and parent satisfaction were observed at the 1-month follow-up compared with baseline. At 1 month, 57.7% of patients had none offour issues indicative of poor asthma control, compared with 19.4% at baseline. Similarly, after 1 month of treatment with montelukast, 2.7 times as many parents reported being very satisfied with asthma therapy (using montelukast) compared with the previous controller therapy regimen at baseline. During the 1-month follow-up period, montelukast was used as the only controller medication by 18.3% of patients, and in combination with another controller medication by 81.7%.

CONCLUSIONS

Observations from this study over one month suggest that a significant percentage of pediatric patients successfully managed their asthma with montelukast and their parents were satisfied with their medication, compared to baseline.

Use of aerosols for bronchial provocation testing in the laboratory: where we have been and where we are going

Bronchial provocation testing with pharmacological agents that act directly on airway smooth muscle has important limitations. These include the inability to identify exercise-induced asthma (EIA), to differentiate the airway hyperresponsiveness (AHR) of airway remodelling from the AHR of active inflammation and to differentiate between doses of steroids. Recent studies show that tests that act indirectly to narrow airways are more sensitive than pharmacological agents for identifying airway inflammation and response to treatment. Adenosine monophosphate (AMP) is an indirect challenge that acts on mast cells to cause release of mediators. Hypertonic saline is another and, since its development in the 1980s, has become widely used in Australia. Hypertonic (4.5%) saline is used to identify those with active asthma, those with EIA and those who wish to enter certain occupations or sports (e.g., diving). The recent development, again in Australia, of a test that uses dry powder mannitol has promise for use in the laboratory, the office, or for testing in the field. AHR to mannitol identifies people with EIA and is an estimate of its severity. The mannitol response is modified by drugs used to prevent EIA, implying that similar mediators are involved. A mannitol test can be used to monitor response to steroids and is more sensitive than histamine for identifying persistent airway hyperresponsiveness in asthmatics well controlled on steroids. These findings suggest that indirect challenges give more useful clinical information about currently active asthma and the response to treatment than direct challenge and they will become more widely used.

Effects of montelukast and budesonide on airway responses and airway inflammation in asthma

Inhaled corticosteroids are effective antiinflammatory therapy for asthma; however, they do not completely abolish allergen-induced airway inflammation. Leukotriene modifiers attenuate both early and late allergen responses and have antiinflammatory properties. We reasoned that treatment with budesonide and montelukast in combination might provide greater antiinflammatory effects than either drug alone, and the purpose of this study was to compare the effects of treatment with budesonide and montelukast, alone or in combination, on outcome variables after allergen inhalation. Ten subjects with asthma with dual responses after allergen inhalation were included in this randomized, double-blind, crossover study. Outcomes included early and late asthmatic responses, and changes in airway responsiveness and sputum eosinophilia, measured before and after challenge. Treatment with montelukast attenuated the maximal early asthmatic response compared with placebo (p < 0.001) and budesonide (p = 0.002). Both budesonide and montelukast, alone and in combination, attenuated the maximal late asthmatic response compared with placebo (p < 0.01). Budesonide and montelukast, alone and in combination, afforded protection against allergen-induced airway hyperresponsiveness (p < 0.05), although the treatment effect of budesonide was greater than that of montelukast (p < 0.05). Treatment with budesonide and montelukast, alone and in combination, also attenuated allergen-induced sputum eosinophilia. Thus, montelukast and budesonide attenuated allergen-induced asthmatic responses, airway hyperresponsiveness, and sputum eosinophilia, although combination treatment did not provide greater antiinflammatory effects than either drug alone.

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.

Leukotriene antagonism reduces the generation of endothelin-1 and interferon-gamma and inhibits eosinophilic airway inflammation

The cysteinyl leukotrienes (cysLTs) and the peptide hormone endothelin (ET)-1 are potent bronchoconstrictor substances, and these mediators are also claimed to be implicated in the development of eosinophilic airway inflammation. In the present study, we have investigated the effect of the cysLT1 receptor antagonist montelukaston the development of an eosinophilic airway inflammation 24 h after intratracheal Sephadex (SDX) provocation in rats. Furthermore, the effect of montelukast treatment on the generation of ET-1 and other pro-inflammatory mediators has been studied. The inflammatory response was significantly reduced in the animals receiving SDX + montelukast compared to animals receiving solely SDX, as evaluated by a decrease in bronchoalveolar lavage fluid total cell count (10.3 +/- 1.2 vs. 18.5 +/- 1.8 x 10(4) ml(-1), P<0.001), number of eosinophils (299.7 +/- 43.8 vs. 577.6 +/- 46.6 x 10(2) ml(-1), P<0.001), and lymphocytes (116.8 +/- 20 vs. 222.0 +/- 34.8 x 10(2) ml(-1), P<0.05), as well as the degree of tissue inflammation (P<0.05). Montelukast also inhibited the increase in the concentration of the pro-inflammatory mediators ET-1 (28.5 +/- 75 vs. 40.9 +/- 7.3 x pg ml(-1), P<0.05) and interferon (IFN)-gamma (4.3 +/- 2.2 vs. 15.6+/-8.7 x pg ml(-1), P<0.05), but not tumor necrosis factor-gamma or interleukin-8. In summary, treatment with the cysLT1 receptor antagonist montelukast reduced the inflammatory response during development of an eosinophilic airway inflammation, possibly by inhibiting the release of pro-inflammatory mediators like ET-1 and IFN-gamma.

Exercise-induced asthma: diagnosis and management

OBJECTIVE

To review the diagnosis and management of exercise-induced asthma (EIA).

DATA SOURCES

Computer-assisted literature searches on MEDLINE for articles, abstracts, and other relevant data on exercise-induced asthma

STUDY SELECTION

Published articles, abstracts, and conference proceedings were selected.

RESULTS

EIA is seen in 40 to 90% of asthmatic patients. Exercise can be the sole trigger or be one of multiple triggers of asthma exacerbations. A good history and physical examination can diagnose most cases of EIA. Spirometry can confirm the diagnosis. Exercise testing may be necessary in certain cases. Prevention through both pharmacologic and nonpharmacologic measures is the key to EIA management. Inhaled beta-agonists remain the medications of choice for EIA prophylaxis. Inhaled cromolyn and antileukotrienes are alternatives. Good long-term control of asthma with anti-inflammatory medications such as inhaled steroids will also decrease the incidence of EIA.

CONCLUSIONS

Early diagnosis and proper preventive and maintenance therapy can reduce episodes of EIA and enable patients to continue to engage in sports and lead an active life.

Asthma: a case study, review of pathophysiology, and management strategies

PURPOSE

To review the pathophysiology of asthma, present a case study, and provide management strategies for treating this common, yet complex disorder in children and adults.

DATA SOURCES

Selected clinical guidelines, clinical articles, and research studies.

CONCLUSIONS

Asthma is a chronic inflammatory airway disorder with acute exacerbations that currently affects approximately 14 million-15 million children and adults in the United States. Costs for asthma are staggering and nurse practitioners (NPs) are frequently presented with management decisions for the acute treatment and chronic management of this disorder. Disparities exist with the occurrence of asthma between race and gender. Additionally, there is an increased incidence in acute exacerbations resulting from poor long-term control and follow-up care among the socioeconomically disadvantaged.

IMPLICATIONS FOR PRACTICE

Standards of care, along with new and emerging treatment strategies, guide NPs in providing the most comprehensive care to those affected with this chronic disorder. Knowledge about the pathophysiology of asthma and correlated to the case presentation enhances understanding treatment strategies for NPs who are often faced with providing care for patients with this chronic disorder that may sometimes present in an acute exacerbation.

Exercise-induced asthma in children

Exercise-induced asthma (EIA) is a relatively common problem in children, but may not be recognized because children either do not report their symptoms, or avoid activities that cause it. Clarifying the diagnosis of EIA, in particular separating EIA from other causes of exertional dyspnea, is essential. Treating EIA in children is challenging because of the nature of their physical activities, which are often not planned, and may be prolonged. Keeping children active is an important goal to ensure healthy physical and social development. Many children with EIA are well managed with an inhaled short-acting beta(2)-adrenoceptor agonist before exercise or if symptoms develop. The approach to more troublesome EIA depends on whether the child has persistent asthma and requires better prevention, or the EIA is an isolated clinical problem. The options for treatment also depend on the timing, frequency, and duration of activity that induces EIA. Options include the addition of a cromone, a leukotriene modifier, an inhaled corticosteroid, or switching to use a long-acting beta(2)-adrenoceptor agonist. The use of warm-up exercises has been shown to be helpful by using the refractory period but is not practical for most children with EIA. A final consideration for successful management of EIA in children is that the delivery of medication needs to be age-appropriate.

Effectiveness of screening examinations to detect unrecognized exercise-induced bronchoconstriction

OBJECTIVE

To determine if a physician-administered physical examination and screening questionnaire accurately detects exercise-induced bronchoconstriction (EIB) in adolescent athletes.

STUDY DESIGN

Cross-sectional study of 256 adolescents participating in organized sports from 3 suburban high schools. The number of persons screened positive for EIB by physical examination and questionnaire was compared with the number of persons with EIB diagnosed by a "gold standard" test that consisted of a 7-minute exercise challenge followed by serial spirometry.

RESULTS

We diagnosed EIB in 9.4% of adolescent athletes. The screening history identified persons with symptoms or a previous diagnosis suggestive of EIB in 39.5% of the participants, but only 12.9% of these persons actually had EIB. Among adolescents with a negative review of symptoms of asthma or EIB, 7.8% had EIB. Among adolescents with no previous diagnosis of asthma, allergic rhinitis, or EIB, 7.2% had EIB diagnosed by exercise challenge. Persons who screened negative on all questions about symptoms or history of asthma, EIB, and allergic rhinitis accounted for 45.8% of the adolescents with EIB.

CONCLUSIONS

EIB occurs frequently in adolescent athletes, and screening by physical examination and medical history does not accurately detect it.

Protection against exercise-induced bronchoconstriction by montelukast in aspirin-sensitive and aspirin-tolerant patients with asthma

BACKGROUND

Montelukast, a cysteinyl-leukotriene receptor antagonist, was reported to have a protective effect against exercise-induced bronchoconstriction (EIB). Aspirin-induced asthma (AIA) is characterized by overproduction of cysteinyl-leukotrienes.

OBJECTIVE

The aim of the study was to compare the response to exercise and the effect of montelukast on EIB in AIA as compared to aspirin-tolerant asthma (ATA).

METHODS

A placebo-controlled, double blind, cross-over randomized study was performed in 19 AIA and 21 ATA patients with stable asthma. A single dose of montelukast (10 mg) or placebo (PL), was given orally one hour prior to exercise challenge. FEV1 was measured before and 5, 10, 15 min after exercise and then at 15-minute intervals for 4 h. Urinary LTE4 excretion and blood eosinophil count were measured at baseline, 2 h and 4 h following exercise challenge.

RESULTS

Positive bronchial response to exercise was observed in 47.5% of all patients studied. Exercise led to almost identical maximal fall in FEV1 in AIA and ATA patients (23.5% +/- 6.8% vs. 21.8% +/- 12.0%, respectively; P = 0.7). Montelukast, as compared to PL, significantly attenuated EIB in 63.2% of 19 patients with positive exercise test preceded by PL. The mean of maximum fall in FEV1 from the pre-exercise value was 10.2% +/- 13.8 after montelukast as compared to 22.5% +/- 10.2 after placebo (P < 0.001). No significant differences between protective effect of montelukast was observed in AIA as compared to ATA patients (P = 0.63, anova). Urinary LTE4 excretion showed no change following exercise, irrespective of the result of the test in all subjects.

CONCLUSION

Patients with AIA and ATA react similarly to exercise challenge and obtain similar protection against EIB by montelukast.

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 montelukast on physical performance and exercise economy in adult asthmatics with exercise-induced bronchoconstriction

Leukotriene antagonists are effective in the treatment of exercise-induced bronchoconstriction. Montelukast is a specific cysteinyl-leukotriene receptor1 antagonist without known effects on the pulmonary vessels, which in theory should be advantageous with respect to gas exchange. In addition to lung function, we investigated the effects of montelukast on parameters of gas exchange and physical performance in 16 asthmatics with exercise-induced bronchoconstriction in a double-blind cross-over placebo-controlled study. Subjects were tested at an ambient temperature of -15 degrees C with a tread mill exercise protocol consisting of consecutive workloads of 80% V'O(2max) (6 min), rest (4 min), 60% V'O(2max) (6 min) and step increments of exercise until exhaustion. Montelukast reduced the maximum post-exercise fall in FEV1 (P < 0.01), improved the running time to exhaustion in 11 of 16 test subjects (one unchanged) (P = 0.03), and reduced the Borg score at exhaustion (P = 0.03) and the breathing frequency after 3 min at 60% V'O(2max) (P = 0.03). V'(O2), V'CO(2), minute ventilation, ventilatory equivalents, respiratory exchange ratio, heart rate and oxygen pulse were not significantly different after montelukast and placebo. We conclude that montelukast has a beneficial effect on physical performance in most adults with exercise-induced asthma without any observed effect on gas-exchange parameters.

Bronchoprotective effects of leukotriene receptor antagonists in asthma: a meta-analysis

STUDY OBJECTIVE

Cysteinyl leukotrienes are important proinflammatory mediators in the pathogenesis of asthma. Since bronchial hyperresponsiveness is a noninvasive surrogate marker of asthmatic airway inflammation, we evaluated the bronchoprotection afforded by leukotriene receptor antagonists (LTRAs).

DESIGN

Systematic review of randomized, placebo-controlled trials in which LTRAs were administered for >or= 5 days. Studies in which active drug was administered as a first-line or second-line therapy were used.

SETTING

MEDLINE, BIDS, and Cochrane Library data registers.

MEASUREMENTS

The doubling dose/dilution difference that caused a 20% fall in the FEV(1) between LTRA and placebo.

RESULTS

Thirteen trials (353 subjects) fulfilled eligibility criteria. Combining the results the overall weighted estimated protection amounted to a 0.85 doubling dose shift (95% confidence interval, 0.69 to 1.02).

CONCLUSION

Since the estimated protection amounted to almost one doubling dose, this reinforces the role of LTRAs as anti-inflammatory therapy in asthma.

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.

The Role of Leukotriene Modifiers in the Management of Exercise-Induced Bronchoconstriction

Objective

To review the use of leukotriene modifiers in exercise-induced bronchoconstriction (EIB).

Data Source

A MEDLINE search (1966–March 2001) identified pertinent English-language publications on EIB in humans.

Study Selection

Selection of prospective clinical studies was limited to those that focused on prevention of EIB with leukotriene modifiers, including both leukotriene receptor antagonists and 5-lipoxygenase inhibitors.

Data Synthesis

Leukotriene modifiers have been shown to attenuate EIB in patients with mild to intermittent, stable asthma from exacerbations after exercise, especially those with a predicted forced expiratory volume in 1 second (FEV1) >80% and who did not require corticosteroids. Extrapolation to patients with more severe forms of asthma cannot be made because of the lack of currently available data in these types of patients. Children may benefit from the oral dosage forms of leukotriene modifiers if they have difficulty using a metered-dose inhaler. The current literature supports a lack of a tolerance effect with leukotriene modifiers, as opposed to tachyphylaxis seen with beta2-adrenergic drugs after repeated dosing. As many as 25% of EIB patients will not respond to therapy with leukotriene modifiers. Montelukast has the greatest volume of data and the most positive benefits of the available leukotriene modifiers.

Conclusions

Evidence supports the use of leukotriene modifiers for protection of EIB in patients with stable, mild to intermittent asthma with a predicted FEV1 ≥80% if beta-agonists are intolerable or ineffective. Potential benefits include the lack of a tolerance effect, the long duration of action exhibited by some leukotriene modifiers, and the availability of a tablet form. Beta2-adrenergic drugs should remain the first-line therapy for EIB; however, leukotriene modifiers may provide a valuable alternative in those few who cannot use short-acting beta-agonists. Long-term safety studies of leukotriene modifiers in children and the elderly with EIB are necessary before widespread use can be advocated in the pediatric and geriatric populations.

Influence of zafirlukast and loratadine on exercise-induced bronchoconstriction

BACKGROUND

Airway obstruction induced by physical exercise is a common feature in asthma, and conventional treatments do not offer optimal protection. There is thus a need for additional therapies for optimal control of exercise-induced bronchoconstriction (EIB).

OBJECTIVE

The influence of treatment with the antihistamine loratadine and the antileukotriene zafirlukast alone and in combination on EIB was investigated. This combination has previously shown beneficial additive effects in allergen-induced bronchoconstriction.

METHODS

In a double-blind cross-over study loratadine (10 mg twice daily) and zafirlukast (80 mg twice daily) were evaluated alone and in combination in 16 nonsmoking patients with mild asthma, previously documented EIB, and airways hyperresponsiveness to histamine.

RESULTS

The mean +/- SE maximum decrease in FEV1 after a standardized exercise provocation was 21.6% +/- 3% after placebo, 22.8% +/- 3% after loratadine, 13.9% +/- 2% after zafirlukast (P <.05 vs placebo), and 10.3% +/- 2% after the combination of loratadine and zafirlukast (P <.05 vs placebo). Expressed as the area under the FEV1 percentage change versus time curve, the mean protection produced by zafirlukast and the combination of zafirlukast and loratadine was 57% and 65%, respectively, whereas loratadine alone had no significant protective effect. There was also no significant difference between the effect of zafirlukast alone or in combination with loratadine.

CONCLUSION

The study confirmed the beneficial effect of a leukotriene receptor antagonist in EIB but failed to obtain evidence that H1-receptor antagonism alone or together with the cysteinyl-leukotriene 1 receptor antagonist zafirlukast offers a protective effect.