Antiasthmatic effects of mediator blockade versus topical corticosteroids in allergic rhinitis and asthma

The role of antihistamines in asthma management

Histamine is an important mediator in airway inflammation. It is elevated in the airways of asthmatic patients and is responsible for many of the pathophysiological features in asthma. Antihistamines block the actions of histamine and also have effects on inflammation which is independent of histamine-H(1)-receptor antagonism. Antihistamines have been shown to have bronchodilatory effects, effects on allergen-, exercise-, and adenosine-monophosphate-challenge testing, and also to prevent allergen-induced nonspecific airways hyperresponsiveness. Clinical studies have shown mixed results, and some studies have reported beneficial effects of azelastine, cetirizine, desloratadine, and fexofenadine on asthma symptoms or physiological measures in patients with asthma. The combination of an antihistamine and a leukotriene receptor antagonist has been shown to have additive effects in certain studies. Antihistamines have also been shown to delay or prevent the development of asthma in a subgroup of atopic children. These data suggest that antihistamines may have beneficial effects in the management of asthma.

Improvement and prevention of asthma with concomitant treatment of allergic rhinitis and allergen-specific therapy

BACKGROUND

Asthma and allergic rhinitis are 2 of the most prevalent chronic medical diseases. Asthma is estimated to affect 8% of adults and 9% of children, with nearly 300 million people affected worldwide. Poorly controlled allergic rhinitis may be associated with worsening asthma symptoms over time. Various treatments have been proposed in the improvement and prevention of asthma in children and adults with allergic symptoms, which have included pharmacotherapy with antihistamines and topical intranasal corticosteroids, as well as allergen-specific immunotherapy.

METHODS

Articles were selected through PubMed and personal knowledge of the authors based on a comprehensive literature review examining whether treatment of allergic rhinitis improves and/or prevents concomitant symptoms of asthma. The largest and highest-quality studies were included in the literature review. The search selection was not standardized. Articles written in a language other than English were excluded.

RESULTS

Clinical trials have showed improvement in asthma symptoms with concomitant treatment of allergic rhinitis with antihistamines and topical intranasal corticosteroids, though improvement in objective pulmonary function parameters has not been uniformly demonstrated with antihistamine use alone. There is very strong evidence to suggest that subcutaneous and sublingual immunotherapy may in addition prevent the progression of asthma in high-risk atopic patients by inducing immunological tolerance.

CONCLUSION

Traditional pharmacotherapy with antihistamines and topical intranasal steroids has been shown to improve allergic rhinitis symptoms with concomitant allergic asthma; however, only allergen-specific immunotherapy offers long-term control in improving asthma symptoms, exacerbations, and likely ultimate prevention in developing asthma.

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

BACKGROUND

Anti-leukotrienes (5-lipoxygenase inhibitors and leukotriene receptors antagonists) serve as alternative monotherapy to inhaled corticosteroids (ICS) in the management of recurrent and/or chronic asthma in adults and children.

OBJECTIVES

To determine the safety and efficacy of anti-leukotrienes compared to inhaled corticosteroids as monotherapy in adults and children with asthma and to provide better insight into the influence of patient and treatment characteristics on the magnitude of effects.

SEARCH METHODS

We searched MEDLINE (1966 to Dec 2010), EMBASE (1980 to Dec 2010), CINAHL (1982 to Dec 2010), the Cochrane Airways Group trials register, and the Cochrane Central Register of Controlled Trials (Dec 2010), abstract books, and reference lists of review articles and trials. We contacted colleagues and the international headquarters of anti-leukotrienes producers.

SELECTION CRITERIA

We included randomised trials that compared anti-leukotrienes with inhaled corticosteroids as monotherapy for a minimum period of four weeks in patients with asthma aged two years and older.

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed the methodological quality of trials and extracted data. The primary outcome was the number of patients with at least one exacerbation requiring systemic corticosteroids. Secondary outcomes included patients with at least one exacerbation requiring hospital admission, lung function tests, indices of chronic asthma control, adverse effects, withdrawal rates and biological inflammatory markers.

MAIN RESULTS

Sixty-five trials met the inclusion criteria for this review. Fifty-six trials (19 paediatric trials) contributed data (representing total of 10,005 adults and 3,333 children); 21 trials were of high methodological quality; 44 were published in full-text. All trials pertained to patients with mild or moderate persistent asthma. Trial durations varied from four to 52 weeks. The median dose of inhaled corticosteroids was quite homogeneous at 200 µg/day of microfine hydrofluoroalkane-propelled beclomethasone or equivalent (HFA-BDP eq). Patients treated with anti-leukotrienes were more likely to suffer an exacerbation requiring systemic corticosteroids (N = 6077 participants; risk ratio (RR) 1.51, 95% confidence interval (CI) 1.17, 1.96). For every 28 (95% CI 15 to 82) patients treated with anti-leukotrienes instead of inhaled corticosteroids, there was one additional patient with an exacerbation requiring rescue systemic corticosteroids. The magnitude of effect was significantly greater in patients with moderate compared with those with mild airway obstruction (RR 2.03, 95% CI 1.41, 2.91 versus RR 1.25, 95% CI 0.97, 1.61), but was not significantly influenced by age group (children representing 23% of the weight versus adults), anti-leukotriene used, duration of intervention, methodological quality, and funding source. Significant group differences favouring inhaled corticosteroids were noted in most secondary outcomes including patients with at least one exacerbation requiring hospital admission (N = 2715 participants; RR 3.33; 95% CI 1.02 to 10.94), the change from baseline FEV(1) (N = 7128 participants; mean group difference (MD) 110 mL, 95% CI 140 to 80) as well as other lung function parameters, asthma symptoms, nocturnal awakenings, rescue medication use, symptom-free days, the quality of life, parents' and physicians' satisfaction. Anti-leukotriene therapy was associated with increased risk of withdrawals due to poor asthma control (N = 7669 participants; RR 2.56; 95% CI 2.01 to 3.27). For every thirty one (95% CI 22 to 47) patients treated with anti-leukotrienes instead of inhaled corticosteroids, there was one additional withdrawal due to poor control. Risk of side effects was not significantly different between both groups.

AUTHORS' CONCLUSIONS

As monotherapy, inhaled corticosteroids display superior efficacy to anti-leukotrienes in adults and children with persistent asthma; the superiority is particularly marked in patients with moderate airway obstruction. On the basis of efficacy, the results support the current guidelines' recommendation that inhaled corticosteroids remain the preferred monotherapy. 

Monitoring asthma therapy using indirect bronchial provocation tests

OBJECTIVES

Bronchial provocation tests that assess airway hyperresponsiveness (AHR) are known to be useful in assisting the diagnosis of asthma and in monitoring inhaled corticosteroid therapy. We reviewed the use of bronchial provocation tests that use stimuli that act indirectly for monitoring the benefits of inhaled corticosteroids.

DATA SOURCE

Published clinical trials investigating the effect of inhaled corticosteroids on bronchial hyperresponsiveness in persons with asthma were used for this review.

STUDY SELECTION

Studies using indirect stimuli to provoke airway narrowing such as exercise, eucapnic voluntary hyperventilation, cold air hyperventilation, hypertonic saline, mannitol, or adenosine monophosphate (AMP) to assess the effect of inhaled corticosteroids were selected.

RESULTS

Stimuli acting indirectly result in the release of a variety of bronchoconstricting mediators such as leukotrienes, prostaglandins, and histamine, from cells such as mast cells and eosinophils. A positive response to indirect stimuli is suggestive of active inflammation and AHR that is consistent with a diagnosis of asthma. Persons with a positive response to indirect stimuli benefit from daily treatment with inhaled corticosteroids. Symptoms and lung function are not useful to predict the long-term success of inhaled corticosteroid dose as they usually resolve rapidly, and well before inflammation and AHR has resolved. Following treatment, AHR to indirect stimuli is attenuated. Further, during long-term treatment, asthmatics can become as non-responsive as non-asthmatic healthy persons, suggesting that asthma is not active.

CONCLUSIONS

Non-responsiveness to indirect bronchial provocation tests following inhaled corticosteroids occurs weeks to months following the resolution of symptoms and lung function. Non-responsiveness to indirect stimuli may provide a goal for adequate therapy with inhaled corticosteroids.

Effects of asthma treatment: the present and future

The increasing burden of asthma in both primary and secondary care has led to extensive research into its genetics, pathophysiology and treatment over the past few decades. Inhaled corticosteroids remain an integral component in all but the mildest disease, although despite a low-to-moderate dose, many individuals remain symptomatic. In patients with persistent symptoms despite inhaled corticosteroids, a variety of different nonsteroidal second-line therapies are available as add-on therapy. In this review, existing and potential future pharmacological strategies involved in the management of asthma will be highlighted.

Time trends of co-existing atopic conditions in Singapore school children: prevalence and related factors

Atopic diseases are known to co-exist and are interrelated. Their co-existence in a patient increases disease burden and morbidity. We sought to study the prevalence of co-existing atopic conditions over time and its associated risk factors among Singapore children. Data was collected from two respective The International Study of Asthma and Allergies in Childhood surveys conducted in 1994 and 2001. Data on asthma, rhinitis and eczema were obtained from the responses to questions about wheezing, exercise-induced wheezing, nocturnal cough, rhinitis symptoms, rash, and diagnoses of asthma, rhinitis and eczema in the last 12 months. Data on demographic and known risk factors were also obtained. The prevalence of children who have had more than one atopic disorder increased significantly from 6.0% in 1994 to 10.2% in 2001 (p < 0.001). Parental history of atopic disease, maternal educational level, male gender and smoke exposure were significantly associated with co-existent atopic symptoms in the child. Among Singapore schoolchildren, there was a significant prevalence of co-existent atopic disease and this prevalence was rising. The influences of both genetic and environmental factors were likely to have contributed to these observations.

Effects of pranlukast hydrate on airway hyperresponsiveness in non-asthmatic patients with Japanese cedar pollinosis

BACKGROUND

Recent studies have suggested that allergic rhinitis is closely related to bronchial asthma, reflecting the "one airway-one disease" hypothesis. It is unclear if the effects of pranlukast, a leukotriene-receptor antagonist, are consistent with this hypothesis.

OBJECTIVE

The goal of the study was to determine if pranlukast has effects on the upper and lower airways through a comparison of the effects of fexofenadine and pranlukast on airway hyperresponsiveness in non-asthmatic patients with cedar pollinosis before the Japanese cedar pollen season and during the peak pollen season.

METHODS

Patients received fexofenadine hydrochloride plus oral mequitazine (fexofenadine group) or pranlukast hydrate plus oral mequitazine (pranlukast group) as an initial treatment. Subsequent changes in airway responsiveness to acetylcholine were measured.

RESULTS

Among patients in whom coughing developed during the peak pollen season, airway responsiveness significantly increased in the fexofenadine group. In the pranlukast group, airway responsiveness did not increase significantly, regardless of the presence or absence of coughing.

CONCLUSIONS

The results indicate that pranlukast hydrate inhibits airway hyperresponsiveness in non-asthmatic patients with Japanese cedar pollinosis. In turn, this suggests that cysteinyl leukotrienes have a role in increased airway responsiveness.

Effect of levocetirizine on nasal provocation testing with adenosine monophosphate compared with allergen challenge in allergic rhinitis

BACKGROUND

End-organ hyperreactivity is an important feature of the allergic airway. There are no data directly comparing the responsiveness to treatment of different nasal provocation tests (NPT).

OBJECTIVE

We compared the effect of levocetirizine on nasal adenosine 5'-monophosphate (AMP) with specific allergen challenge in patients with intermittent and persistent allergic rhinitis (AR).

METHODS

Patients with AR were randomized in double-blind cross-over fashion to receive single doses of levocetirizine 5 mg or identical placebo, with nasal challenge performed 12 h after dosing. Sixteen participants completed per protocol. Nasal AMP or allergen challenge was conducted on separate days with 1- and 2-week washout periods in between, respectively. Measurements of peak nasal inspiratory flow (PNIF) were made over 60 min after each challenge. The primary end-point was the provocative concentration of AMP or allergen causing a 20% drop in the PNIF (PC(20)).

RESULTS

The time-profile for PNIF recovery [area under the 60 min time-response curve as % PNIF change (min)] were significantly attenuated for AMP challenge, as mean difference [95% confidence interval (CI)]: 11.57 (3.87, 19.25), P=0.005 and for allergen challenge: 17.82 (0.11, 35.53), P=0.04. A highly significant correlation was shown between methods for the area under the curve: (R=0.86, P<0.001). A statistically significant correlation was also seen for the PC(20): (R=0.94, P<0.001). PC(20) improvement amounted to a 1.26 (95% CI 0.16, 2.35) and 0.16 (95% CI -0.41, 0.73) doubling-dilution shifts for allergen and AMP challenges, respectively. Bland-Altman plots confirmed good agreement between methods.

CONCLUSION

A high correlation and statistical agreement has been demonstrated between AMP and allergen challenge for all outcome measures. In particular, the recovery profile after NPT is a sensitive and discriminatory measure of anti-allergic treatment.

Allergic rhinitis and rhinosinusitis

A relationship between allergic rhinitis and acute and chronic rhinosinusitis has been postulated for many years. Epidemiologic evidence suggests that such a relationship is likely. In addition, evidence of a common pathophysiologic mechanism linking these diseases is compelling and continues to evolve. Although a clear and definitive causal relationship remains to be elucidated, an increasing number of studies support the plausibility of this link. The current paradigm of the "unified airway" and evidence to support this model further strengthen this link. This article reviews the literature relating allergic rhinitis and acute and chronic rhinosinusitis.

The unified airway--conceptual framework

Substantial evidence exists to support the concept that the respiratory system functions as an integrated unit. Pathophysiological processes that involve the upper airway generally occur in conjunction with lower airway diseases, and diffuse inflammation often affects mucosal surfaces of the middle ear, nose, sinuses, and tracheobronchial tree simultaneously. Support for this relationship can be found in epidemiological studies, in shared pathophysiological mechanisms, and in observed interactive treatment effects. This model and its implications are discussed.

A proof-of-concept study to assess the putative dose response to topical corticosteroid in persistent allergic rhinitis using adenosine monophosphate challenge

INTRODUCTION

The aim of this proof-of-concept study was to assess whether nasal adenosine monophosphate (AMP) challenge may be used to quantify dose response to topical fluticasone propionate (FP) in persistent allergic rhinitis (PER).

METHODS

Eligible subjects with PER entered a randomized double-blind crossover study of 2 weeks of intranasal FP at 100 microg or 400 microg daily, with a 2-week placebo washout period before each randomized treatment. Measurements after each washout or treatment comprised: peak nasal inspiratory flow (PNIF) response to nasal AMP (the primary outcome), domiciliary PNIF, the mini rhinoconjunctivitis quality of life questionnaire (miniRQLQ), symptom scores, nasal nitric oxide levels and overnight urinary cortisol:creatinine ratios.

RESULTS

Thirteen patients completed per protocol. Maximal PNIF response to AMP was attenuated 0.9% (95% confidence interval -7.1 to 9.0, P=NS) by FP 100 microg, and 12.9% (4.8-20.9, P=0.009) by FP 400 microg. The 400-100 microg difference was 12.0% U (2.6-21.3, P=0.049). None of the other outcomes were responsive enough to detect any significant treatment effects. The standardized response means to FP 400 microg were 81% for AMP challenge, 54% for domiciliary PNIF, 53% for miniRQLQ, 24% for symptom scores and 18% for nasal nitric oxide. No adrenal suppression was detected at either dose.

CONCLUSION

FP exhibited dose-related suppression of nasal airway hyperresponsiveness to AMP challenge, but without associated detectable adrenal suppression at the higher dose. Moreover, the AMP response demonstrated the highest signal to noise ratio compared with other outcome measures in PER.

The impact of comorbid atopic disease on asthma: clinical expression and treatment

Clinically, asthma and allergic rhinitis involve separate regions of the respiratory tract while representing a common underlying inflammatory syndrome. Much evidence supports an epidemiologic association between the diseases, paranasal sinus involvement in both conditions, and parallel relationship in severity and treatment outcomes. Pathophysiologic mechanisms, including immunoglobulin E (IgE)- mediated inflammation, are also shared. Blocking IgE with the recombinant humanized monoclonal antibody omalizumab demonstrated clinical efficacy in patients with upper and lower airway diseases. IgE blockade, leukotriene modulation, and B-cell depletion therapy have all exhibited success in chronic inflammation, reinforcing and expanding the beneficial role of immunomodulation of global mediators.

The expanding role of leukotriene receptor antagonists in chronic asthma

OBJECTIVE

To provide a comprehensive review of studies that evaluate the effects of leukotriene receptor antagonists in adult chronic asthma.

DATA SOURCES

A literature search using MEDLINE, Clinical Evidence, and the Cochrane Library was performed using the following keywords: randomized controlled trial, asthma, cysteinyl leukotriene, leukotriene receptor antagonist, antileukotriene, montelukast, zafirlukast, pranlukast, inflammation, lung function, exacerbations, and symptoms.

STUDY SELECTION

Relevant peer-reviewed articles (mostly randomized controlled trials, meta-analyses, and reviews) published up to July 2006 were selected and extracted.

RESULTS

Leukotriene receptor antagonists are beneficial across a range of asthma severities and may have a particular role in exercise-induced asthma, aspirin-sensitive asthma, and individuals with concomitant allergic rhinitis.

CONCLUSION

In the management of chronic asthma, leukotriene receptor antagonists have emerged as a useful oral nonsteroidal anti-inflammatory adjunct both as monotherapy and in combination with other classes of drugs. Monitoring their effects in terms of lung function alone may result in clinicians missing beneficial effects on inflammatory biomarkers, airway hyperresponsiveness, and exacerbations.

Effect of montelukast on symptoms and exhaled nitric oxide levels in 7- to 14-year-old children with seasonal allergic rhinitis

BACKGROUND

Cysteinyl leukotrienes have been found to exert potent inflammatory effects in the upper airways and play a fundamental role in the pathogenesis of allergic rhinitis. Previous studies have reported increased levels of exhaled nitric oxide (eNO) in patients with allergic rhinitis without asthma symptoms.

OBJECTIVE

To investigate the role of treatment with montelukast on symptoms, eNO levels, and peripheral eosinophil counts of children with seasonal allergic rhinitis during pollen season.

METHODS

A randomized, double-blind, parallel-group study performed between April and June 2005 in 57 children aged 7 to 14 years with seasonal allergic rhinitis was performed. The study comprised a 1-week screening period, a 1-week run-in period, and a 2-week treatment period with once daily montelukast, 5 mg, or matching placebo.

RESULTS

No significant difference at baseline was found in symptom scores, eNO levels, and blood eosinophil counts between the treatment and placebo groups. After 2 weeks of montelukast treatment, improvements from the baseline in the daytime nasal, composite, and daytime eye symptoms scores were significantly greater in the montelukast group compared with the placebo group (P < .001, P < .001, and P < .01, respectively). A significant decrease was also found in eosinophil counts (P < .001) in the montelukast group compared with the placebo group after treatment. Montelukast treatment did not produce a significant effect on eNO levels compared with placebo (P = .96).

CONCLUSION

Montelukast treatment provided significant improvement in symptoms and peripheral eosinophil counts of school-age children with seasonal allergic rhinitis; however, it did not show a significant effect on eNO levels.

Combined mediator blockade or topical steroid for treating the unified allergic airway

BACKGROUND

Asthma and allergic rhinitis are manifestations of a single unified allergic airway, for which the best treatment is uncertain.

OBJECTIVE

To compare the anti-inflammatory efficacy in the unified allergic airway of combined oral mediator antagonism and combined topical steroid.

METHODS

Subjects with asthma and perennial allergic rhinitis entered a randomized double blind crossover study comparing montelukast 10 mg and cetirizine 10 mg to extra-fine inhaled beclomethasone 400 mcg/day and intranasal beclomethasone 200 mcg/day, each taken once daily for 2 months, after 2-week placebo washouts. Measurements were made after each washout and randomized treatment, comprising: methacholine PC20, exhaled and nasal nitric oxide, blood eosinophils and eosinophilic cationic protein, symptoms, lung and nasal function tests.

RESULTS

Seventeen patients completed per protocol. For PC20 and exhaled nitric oxide, only combined topical steroid produced improvements (P < 0.005) from placebo baseline. Combined steroid was superior by a 0.93 (95% CI 0.14-0.93, P < 0.05) doubling dilution difference for PC20 and a 0.99 (95% CI 0.9-15.1, P < 0.01) doubling difference for exhaled nitric oxide. Both treatments attenuated eosinophils and eosinophilic cationic protein, and reduced nasal symptoms (P < 0.05). Only steroid improved nasal nitric oxide (P=0.05) and asthma symptoms (P < 0.05). Neither treatment affected lung or nasal function tests.

CONCLUSION

Combined topical steroid and combined mediator antagonism both attenuated systemic inflammation in the unified allergic airway, but only the former reduced bronchial and nasal inflammatory markers. The relevance of this to exacerbations and airway remodelling needs to be defined.

Effects of intranasal corticosteroid on nasal adenosine monophosphate challenge in persistent allergic rhinitis

BACKGROUND

Response to a single dose nasal adenosine monophosphate challenge has been used as a surrogate inflammatory marker for allergic rhinitis. Attenuation of response following intranasal corticosteroid would further validate the challenge.

OBJECTIVE

To assess the effect of 4 weeks of 200 mcg once daily mometasone furoate nasal spray on a simplified (single 160 mg dose) nasal adenosine monophosphate challenge.

METHODS

Twenty participants with persistent allergic rhinitis completed a double blind placebo-controlled crossover study. Outcome measures were the peak nasal inspiratory flow and total nasal symptoms score responses to nasal adenosine monophosphate challenge, as well as domiciliary peak nasal inspiratory flow and patient symptom diary cards.

RESULTS

Mometasone significantly (P < 0.05) attenuated response time profiles vs. placebo for peak nasal inspiratory flow but not total nasal symptom scores. For the maximum percentage fall this amounted to a mean difference of 9.6% (95% confidence interval 1.3-17.9%). The coefficient of variation for repeatability was 48.7%. Improvements were seen in prechallenge and domiciliary measurements of peak nasal inspiratory flow (both P < 0.05) and total nasal symptom scores (both P < 0.01).

CONCLUSIONS

Mometasone attenuates the peak nasal inspiratory flow response to a single 160 mg nasal adenosine monophosphate challenge. Such challenges have been shown to be sensitive to the effects of antihistamines, antileukotrienes and now nasal steroids. This further supports their application as surrogate inflammatory markers for therapeutic trials in allergic rhinitis, potentially as 20 min challenges which can be conducted in a non-hospital setting.

Montelukast exerts no acute direct effect on NO synthases

The cysteinyl leukotrienes (CysLTs) LTC(4), LTD(4) and LTE(4) are potent proinflammatory lipid mediators that play a central role in inflammation, contraction and remodelling of airways observed in asthmatics. Montelukast, a competitive inhibitor of the cysteinyl leukotriene-1 (CysLT(1)) receptor attenuates asthmatic airway inflammation, contraction and remodelling. As a number of studies have shown that montelukast reduced exhaled nitric oxide (NO) levels, a marker of inflammation that correlates with the severity of asthma, we investigated whether or not a direct inhibition of NO synthase (NOS) by montelukast takes place. In an ex vivo rat lung perfusion and ventilation model the NOS-dependent vasodilation effect after lipopolysaccharide (LPS) infusion was assessed with and without montelukast. Functional organ bath studies using isolated aortic rings from the same species aimed to assess effects of montelukast on the inducible and endothelial NOS isoenzymes (i- and eNOS) as well as on iNOS expression. Neuronal NOS (nNOS) was assessed by field stimulated rabbit corpus cavernosum, and isolated human iNOS enzyme activity was assessed for potential inhibition. Montelukast failed to cause vasoconstriction in LPS challenged rat lung, or to inhibit i- and eNOS activity as well as iNOS expression in aortic rings from the same species. Also the assays for nNOS in rabbit corpus cavernosum and on isolated human iNOS enzyme gave no evidence for a direct inhibition by montelukast in physiological and supraphysiological concentrations up to 10(-4)M. We therefore conclude that montelukast has no acute NOS inhibitor action. Its effect on exhaled NO is therefore probably indirectly mediated by a modulation of the asthmatic airway inflammation.

Emerging anti-inflammatory agents for allergic rhinitis

Allergic rhinitis (AR) is a high-prevalence disease, affecting 10-15% of the general population. AR is sustained by an IgE-mediated reaction, and by a complex inflammatory network of cells, mediators and cytokines that becomes chronic when exposure to allergen persists. A T helper 2 (TH2)-biased immune response is the basis for the allergic inflammation. The current therapeutic strategy is mainly based on drugs (antihistamines, nasal corticosteroids, cromones, decongestants) and allergen immunotherapy. Drugs are overall effective in controlling symptoms, but do not modify the immune background that leads to allergic inflammation, and safety concerns may be present especially for prolonged treatments. Immunotherapy can modify the allergic response, but there is still space for improvement. Nowadays, several approaches are under investigation to optimise the management of AR. On one hand, new drugs and antimediators are being developed; on the other hand, attempts are made to selectively block relevant signal pathways of allergic reaction. Finally, one of the major goals is to modify the TH2-biased immune response by improving the characteristics and modes of action of allergen immunotherapy.

Efficacy of montelukast during the allergy season in patients with chronic asthma and seasonal aeroallergen sensitivity

BACKGROUND

Montelukast has proven efficacy in the treatment of chronic asthma and seasonal allergic rhinitis, but it has not been evaluated in the subpopulation of asthmatic patients with seasonal asthma symptoms.

OBJECTIVE

To determine the effectiveness of montelukast treatment in improving the control of asthma symptoms during the allergy season in patients with active asthma and seasonal aeroallergen sensitivity.

METHODS

Adults with a history of chronic asthma who are also symptomatic during the allergy season and with skin test sensitivity to seasonal aeroallergens were enrolled in a randomized, parallel-group, multicenter study with a 1-week, single-blind, placebo run-in period followed by 3 weeks of double-blind treatment during the spring of 2004. After the run-in period, eligible patients were randomly assigned to receive either oral montelukast (10 mg) or placebo. Daytime and nighttime asthma symptom scores, beta-agonist use, and morning and evening peak expiratory flow rates were recorded daily using an electronic diary. The primary end point was mean change from baseline to week 3 in the daytime asthma symptom score.

RESULTS

Of 455 randomized patients, 433 completed the study. Compared with placebo, treatment with montelukast resulted in a significant improvement from baseline in the daytime asthma symptom score (-0.54 vs -0.34; P = .002) and in beta-agonist use, nighttime symptoms, and peak expiratory flow rates. Few patients in the montelukast and placebo groups discontinued study participation because of asthma (1.3% and 3.0%, respectively).

CONCLUSION

In patients with chronic asthma and seasonal aeroallergen sensitivity, montelukast treatment provided significant asthma control during the allergy season compared with placebo.

Treating asthma: is there a place for leukotriene receptor antagonists?

Asthma is a chronic disorder, characterized by airway hyperresponsiveness (AHR), airway inflammation and airway remodelling. Evidence has been provided for a relationship between pathophysiology, airway inflammation and remodelling. Moreover, these asthma features have been shown to respond to anti-inflammatory therapy. According to current guidelines, monitoring of asthma is predominantly based on symptoms and lung function data. However, these parameters appeared as poor indices for asthma control. Alternatively, asthma control relates well to exacerbations and (anamnestic) surrogate biomarkers of airway inflammation. Hence, appropriate treatment of asthma should primarily target the airway inflammation. According to current guidelines for asthma management, anti-inflammatory therapy with inhaled corticosteroids (ICS) is the cornerstone in the treatment of persistent asthma. To further optimize asthma control, add-on therapy with long-acting beta2-agonists (LABA) or leukotriene receptor antagonists (LTRA) should be combined with low to high doses of ICS. While the first combination focuses on optimal control of symptoms and lung function, the second provides a more complete suppression of the airway inflammation. In this paper we discuss treatment of asthma according to current guidelines versus new insights, addressing practical issues.

Relationship between Asthma and Rhinitis: Epidemiologic, Pathophysiologic, and Therapeutic Aspects

Over the last few years, the evidence of links between rhinitis and asthma has been strengthened. This has led to the introduction of the concept of united airway disease. Rhinitis and asthma appear to be interrelated at the epidemiologic level and at the pathophysiologic level. This article reviews current epidemiologic and pathophysiologic evidence of the relationship between rhinitis and asthma and discusses the effect of treatment of one site on the other site.

Evaluation of an intranasal house dust mite provocation model as a tool in clinical research

BACKGROUND

As a result of the all-year-round exposure to house dust mite (HDM), perennial rhinitis patients never have a clear symptom-free period. In this study, we investigated whether, despite these symptoms, we can still use nasal HDM provocations to study perennial allergic rhinitis and the effects of treatment.

METHODS

In a parallel-group study, after 1 week treatment with either fluticasone propionate aqueous nasal spray (FPANS) or placebo, 20 patients, allergic to HDM, registered symptoms (nasal obstruction, rhinorrhoea, sneezing, pruritus and eye symptoms) using three different scoring methods [Lebel, categorical and visual analogue scale (VAS)] and peak nasal inspiratory flow (PNIF) after HDM provocations. Provocations were performed with 1000 biological units/ml and 24 h later with 10,000 biological units/ml of HDM. Before and after the provocations, nasal mucosa biopsies were taken for immunohistochemical staining to determine the number of eosinophils.

RESULTS

House dust mite provocations resulted in an increase in symptoms and a decrease in PNIF. Even at high-dose provocation, the FPANS group registered significantly lower symptoms than the placebo group for nasal blockage, sneezing, eye symptoms, and PNIF in both early and late phases. FPANS also suppressed rhinorrhoea during the late phase and the influx of eosinophils in the lamina propria.

CONCLUSION

Despite the high background of symptoms, allergic responses can be induced in this perennial rhinitis model. The VAS score seems most suited to detect these changes and the suppression of symptoms by 7 days of FPANS treatment. Epithelial eosinophilia at baseline was correlated positively with the severity of the reaction after the first provocation.

The linkage between Churg-Strauss syndrome and leukotriene receptor antagonists: fact or fiction?

Epidemiologic evidence has shown that the worldwide prevalence of asthma is increasing. The leukotriene receptor antagonists (LTRAs) represent a new class of therapy for asthma. They have been developed in the last decade and play a pivotal steroid-sparing role in treating the inflammatory component of asthma. Consequently, reports of Churg-Strauss syndrome (CSS), a rare form of systemic vasculitis, have been recognized as a potential side effect in individuals with moderate to severe asthma on LTRA therapy. The serious nature of this disorder is worthy of prompt recognition by clinicians and aggressive therapy to avoid the subsequent longstanding effects of vasculitis. To validate the postulated linkage between the LTRAs and CSS, this review comprehensively evaluates reported cases in the literature and supports a pathophysiological relationship between the LTRAs and the development of CSS.

Second-generation antihistamines in asthma therapy: is there a protective effect?

Second-generation histamine H(1) receptor antagonists are recognized as being highly effective treatments for allergic-based disease and are among the most frequently prescribed drugs in the world. The newer antihistamines represent a heterogeneous group of compounds with markedly different chemical structures, a spectrum of antihistaminic properties, adverse effects, half-life, tissue distribution, metabolism and varying degrees of anti-inflammatory effects. Histamine is an important mast cell- and basophil-derived mediator that has been implicated in the pathogenesis of asthma, resulting in smooth muscle contraction, mucus hypersecretion, and increased vascular permeability leading to mucosal edema. Antihistamines should never be used as monotherapy for asthma but there is evidence that these drugs give a measure of protection in histamine-induced bronchoconstriction. Furthermore, several studies have demonstrated that the use of second-generation antihistamines, as adjunct therapy, may benefit those patients whose allergic asthma co-exists with allergic rhinitis. Indeed, many patients present with both allergic rhinitis and asthma. The link between the upper and lower respiratory airways is now well established and there is increasing evidence that allergic rhinitis is a risk factor for the development of asthma. More recently, a number of novel antihistamines have been developed which are either metabolites of active drugs or enantiomers and there is emerging evidence that at least one of these drugs, desloratadine, may give significant symptomatic benefit in some types of asthma. It is of interest to note that cetirizine provides a primary pharmacological intervention strategy to prevent the development of asthma in specifically-sensitized high risk groups of infants. Moreover, the documented anti-inflammatory activities of antihistamines may provide a novel mechanism of action for the therapeutic control of virus-induced asthma exacerbations by inhibiting the expression of intercellular adhesion molecule-1 (ICAM-1) by airway epithelial cells. Finally, several well-conducted studies suggest that combination therapy with antihistamines and antileukotrienes may be as effective as corticosteroid use in patients with allergic asthma and seasonal allergic rhinitis.

Photoacoustic detection of nitric oxide by use of a quantum-cascade laser

A photoacoustic trace-gas sensor for the measurement of nitric oxide with a detection limit of 500 parts in 10(9) has been demonstrated. The radiation source was a thermoelectrically cooled distributed-feedback quantum-cascade laser operating in pulsed mode near 5.3 microm with an average laser power of 8 mW. A resonant photoacoustic cell was excited in its first longitudinal mode by the modulated laser light. Preliminary measurements have been performed to test the performance of our photoacoustic sensor; possible improvements to reach lower detection limits are discussed.

Therapeutic modulation of allergic airways disease with leukotriene receptor antagonists

Although asthma is one of the most common chronic respiratory conditions, it often remains unrecognized and undertreated, while patients are often reluctant to comply with regular inhaled anti-inflammatory and bronchodilator therapy. Allergic rhinitis co-exists with asthma in as many as 40% of patients, and can be regarded as a continuum of the same inflammatory disease process. Corticosteroids are the 'gold standard' first-line treatment for both conditions, and have a significant impact upon underlying inflammation, symptoms and long-term outcome. Cysteinyl leukotrienes are potent airway inflammatory mediators, suggesting that treatment antagonizing their effects could play a role in disease management. In recent years, leukotriene receptor antagonists have provided a further therapeutic option in the management of allergic airways disease. These drugs are orally active, can be administered once daily, and provide a systemic approach to the management of patients with asthma and allergic rhinitis. We review the pharmacology of leukotriene receptor antagonists, their potential role in clinical practice in patients with allergic airways disease, and likely areas for further research.

5-Lipoxygenase inhibition by N-hydroxycarbamates in dual-function compounds

A series of N-hydroxycarbamates containing a histaminergic H(1) receptor antagonist pharmacophore was synthesized. In vitro assays determined the compounds had both histaminergic binding and 5-lipoxygenase inhibiting activities comparable to the corresponding N-hydroxyurea analog. Animal models demonstrated antihistaminergic and the 5-lipopxygenase inhibitory activity, with the N-hydroxyurea analog having a better overall profile.

Second-Generation Antihistamines

Antihistamines are useful medications for the treatment of a variety of allergic disorders. Second-generation antihistamines avidly and selectively bind to peripheral histamine H1 receptors and, consequently, provide gratifying relief of histamine-mediated symptoms in a majority of atopic patients. This tight receptor specificity additionally leads to few effects on other neuronal or hormonal systems, with the result that adverse effects associated with these medications, with the exception of noticeable sedation in about 10% of cetirizine-treated patients, resemble those of placebo overall. Similarly, serious adverse drug reactions and interactions are uncommon with these medicines. Therapeutic interchange to one of the available second-generation antihistamines is a reasonable approach to limiting an institutional formulary, and adoption of such a policy has proven capable of creating substantial cost savings. Differences in overall efficacy and safety between available second-generation antihistamines, when administered in equivalent dosages, are not large. However, among the antihistamines presently available, fexofenadine may offer the best overall balance of effectiveness and safety, and this agent is an appropriate selection for initial or switch therapy for most patients with mild or moderate allergic symptoms. Cetirizine is the most potent antihistamine available and has been subjected to more clinical study than any other. This agent is appropriate for patients proven unresponsive to other antihistamines and for those with the most severe symptoms who might benefit from antihistamine treatment of the highest potency that can be dose-titrated up to maximal intensity.

5-lipoxygenase inhibitors with histamine H(1) receptor antagonist activity

A series of novel compounds with both 5-lipoxygenase (5-LO) inhibitory and histamine H(1) receptor antagonist activity were designed for the treatment of asthma. These dual-function compounds were made by connecting 5-LO and H(1) pharmacophores,N-hydroxyureas and benzhydryl piperazines, respectively. A range of in vitro activities was observed, with the furan analog 10 demonstrating both activities in an animal model. The activities observed were compared to single-function drugs.

An update on the asthma-rhinitis link

PURPOSE OF REVIEW

For the present article we collected and reviewed the more relevant experimental results concerning the asthma-rhinitis link in allergic diseases, published since January 2002.

RECENT FINDINGS

During the last 2 years, particular attention has been devoted to the behaviour of the immune response in the two compartments of the airways. The recent experimental data, mainly obtained with specific nasal or bronchial allergen challenges, have confirmed that the link between the nose and the bronchi is bidirectional, and that a systemic cross-talk occurs. Furthermore, the pathogenic role of paranasal sinus infections in respiratory allergy has been better elucidated. It was shown that, in sinusitis, a T helper type 2 polarization exists, which can be reverted by proper therapy. On the other hand, despite the abundant experimental evidence, our view of the united airways is still not complete, and several points need to be developed.

SUMMARY

The new findings on the asthma-rhinitis link have confirmed the current pathogenic view of respiratory allergy. These findings have important implications from a therapeutic point of view, and therefore encourage and promote the search for novel integrated treatment strategies.

Cetirizine and loratadine-based antihistamines with 5-lipoxygenase inhibitory activity

A series of compounds possessing both H(1) histamine receptor antagonist and 5-lipoxygenase (5-LO) inhibitory activities was synthesized. The H(1)-binding scaffolds of cetirizine, efletirizine, and loratadine were linked to a lipophilic N-hydroxyurea, the 5-LO inhibiting moiety of zileuton. Both activities were observed in vivo, as was increased CYP3A4 inhibition compared to their respective single-function drugs. Selected analogs in the series were shown to be orally active in guinea pig models.

Clinical implications of the allergic rhinitis-asthma link

A possible link between allergic rhinitis (AR) and allergic asthma has long been a subject of debate. Surveys report that up to 78% of asthma patients have AR and 38% of patients with AR have asthma. Evidence points to a causal or coincidental relation between these upper and lower airway diseases. Various agents used to manage one entity have shown benefit in treating the other. The 2001 Allergic Rhinitis and Its Impact on Asthma guidelines call for patients with either condition to be assessed for the other. Medical therapy for AR or asthma should be chosen with awareness of the probable coexistence of these diseases. We present the case for and against the united airway theory proposed to explain the association between these diseases. The roles of various therapies for dually afflicted patients are evaluated, including topical corticosteroids, antihistamines, leukotriene modifiers, anti-immunoglobulin E monoclonal antibody, theophylline, and immunotherapy.

Effect of montelukast pretreatment on inducible nitric oxide synthase mRNA expression in the lungs of antigen-challenged allergic mice

BACKGROUND

Growing evidence suggests that inducible nitric oxide synthase (iNOS) is the main source of the high output of exhaled nitric oxide (NO) in asthma. Treatment of asthmatic patients with glucocorticoids reduces high levels of exhaled NO mainly by inhibiting the transcription of iNOS. A similar reduction in exhaled NO was recently observed in patients treated with the leukotriene receptor antagonists, but the exact interaction between these drugs and iNOS remains obscure.

OBJECTIVE

The purpose of this study was to evaluate the effect of a leukotriene receptor antagonist, montelukast, on the expression and activity of iNOS in a murine model of allergic asthma.

METHODS

Twenty-four BALB/c mice were sensitized to OVA and were equally divided into 3 groups (Groups 1-3). Eight additional mice were sham sensitized and served as a negative control group (Group 4). Group 1 received montelukast 1 mg/kg/day in their drinking water, Group 2 received dexamethasone 1 mg/kg/day in their drinking water and Groups 3 and 4 received plain tap water. After 1 week, the animals were challenged by inhalation of OVA and, 3 h later, they were killed and their lung cells were isolated by enzymatic tissue digestion. NO generation was measured by a Griess assay, and iNOS mRNA was studied by RT-PCR.

RESULTS

A significant increase in iNOS mRNA expression and in NO generation was evident after allergen challenge compared with the controls. Pretreatment with montelukast mildly decreased NO production without producing a concomitant significant decrease in iNOS mRNA expression.

CONCLUSION

Unlike pretreatment with glucocorticoids, we failed to find compelling evidence for a major role for montelukast treatment in the modulation of iNOS mRNA in a murine model of acute asthma.

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.

Effect of montelukast on time-course of exhaled nitric oxide in asthma: influence of LTC4 synthase A(-444)C polymorphism

Leukotrienes (LT) mediate inflammation in asthma. The fraction of exhaled nitric oxide (FE(NO)) is thought to be a sensitive and reproducible method for assessing airway inflammation in asthmatics and the anti-inflammatory effects of drugs. A number of factors are known to contribute to intrapatient variation in FE(NO) which can confound interpretation. The aims of this study were to characterize the time-course of FE(NO), determine the effect of montelukast on the time-course of FE(NO), and evaluate the influence of the LTC(4) synthase A(-444)C polymorphism on montelukast-evoked changes in FE(NO). Following a 2-week run-in, 7 males and 5 females with asthma, 10-16 years old, received 5 or 10 mg of montelukast or an identical placebo at bedtime for 7 days in double-blind, crossover fashion, followed by a 7-day washout. FE(NO)was quantified every 30 min for 3 or 6 hr at baseline and on days 1, 2, 3, and 7 of treatment. A time-averaged value for FE(NO) was calculated (FE(NO)*), and % changes in FE(NO)* relative to baseline vs. time following placebo and montelukast were compared. The genotype of the A(-444)C polymorphism was determined by PCR and RFLP. FE(NO) varied markedly as a function of time in each patient. Time-averaged values of FE(NO) (FE(NO)*) during placebo and montelukast treatment were similar. Montelukast significantly reduced the slope of the % change in FE(NO)* vs. time curve in heterozygotes (n = 4), but not in A/A homozygotes (n = 8). These data suggest that heterozygotes respond better to montelukast compared to A/A homozygotes, at least with respect to changes in FE(NO). We conclude that assessment of inflammation or the anti-inflammatory effects of drugs in asthma based on single determinations of FE(NO) can be misleading. We further conclude that the A(-444)C polymorphism in the LTC(4) synthase gene probably contributes to interpatient variability in montelukast-evoked changes in FE(NO)* and warrants further study.

Allergen sensitization and bronchial hyper-responsiveness to adenosine monophosphate in asthmatic patients

BACKGROUND

Indirect bronchoprovocation using adenosine monophosphate (AMP) is related to atopic phenotype expression.

OBJECTIVE

To evaluate the putative relationship between skin prick allergen sensitization and bronchial hyper-responsiveness to AMP in a retrospective cross-sectional database analysis.

METHODS

We retrospectively evaluated two groups of non-smoking asthmatics (forced expiratory volume in 1 s (FEV)1>/=60% predicted) who were reactive (responders) or unreactive (controls) to inhaled AMP. The main outcome measure was the difference in sensitization to individual allergens and the total atopic load according to the presence or absence of bronchial hyper-responsiveness.

RESULTS

We initially identified 180 (44%) non-smoking asthmatics with PC20</=200 mg/mL, while 233 (56%) had PC20>/=1600 mg/mL. For those who had a skin prick test, the responders (n=151) and controls (n=151) were found to be matched for age, sex, inhaled corticosteroid dose and number of patients using inhaled corticosteroids. There were significant differences in the number of responders vs. controls in terms of sensitization to house dust mite (77% vs. 62%, P=0.004), aspergillus (19% vs. 9%, P=0.014), cat (61% vs. 48%, P=0.028), total atopic load (493 vs. 380 positive tests, P<0.001) and forced mid-expiratory flow (60% vs. 68% predicted, P<0.001).

CONCLUSION

Sensitization to common aeroallergens increased the likelihood of bronchial inflammation as reflected by bronchial hyper-responsiveness to inhaled AMP, independently of both FEV1 or inhaled corticosteroid use. This in turn suggests an association between allergen exposure and AMP responsiveness in asthmatics. Further prospective long-term evaluation is indicated to assess whether allergen avoidance strategies can modify the airway response.

Leukotriene C4 synthase polymorphisms and responsiveness to leukotriene antagonists in asthma

AIM

Cysteinyl leukotrienes are important pro-inflammatory mediators in the pathogenesis of asthma, while leukotriene C4 synthase is a key enzyme in their biosynthesis. Our aim is to evaluate whether responsiveness to leukotriene receptor antagonists was determined by expression of the variant (C) or wild-type (A) polymorphism of this enzyme.

METHODS

We carried out a retrospective analysis of 8 randomised, placebo-controlled trials performed in our department in mild-to-moderate asthmatics. In all trials, effect of leukotriene receptor antagonist was compared to placebo, where the primary outcome was bronchial hyperresponsiveness to adenosine monophosphate or methacholine. Secondary outcomes were forced expiratory volume in 1 second, exhaled nitric oxide and peripheral blood eosinophils.

RESULTS

For the primary outcome of attenuation of bronchial hyperresponsiveness by leukotriene receptor antagonist vs placebo, there were significant effects within each genotype on adenosine monophosphate (AMP) (n = 78): 2.21 and 2.07-fold improvements for AA and AC/CC, respectively; while for methacholine (n = 81) there were 1.39 and 1.36-fold improvements, respectively. There were no significant differences between genotypes (i.e. AA vs AC/CC): geometric mean fold-differences of 1.07 (95%CI 0.63-1.81) and 1.02 (95%CI 0.70-1.50) for AMP and methacholine, respectively. There were also no differences between genotypes for all secondary outcomes.

CONCLUSION

Polymorphisms of leukotriene C4 synthase did not determine responsiveness, in terms of attenuation of bronchial hyperresponsiveness, to leukotriene receptor antagonists in mild-to-moderate asthmatics. Further prospective large pharmacogenetic studies are required in more severe patients, where there may be greater improvements in pharmacodynamic outcome measures such as bronchial hyperresponsiveness and exhaled nitric oxide.

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.

The role of allergy in chronic rhinosinusitis

Issues surrounding the cause and pathogenesis of chronic rhinosinusitis (CRS) remain controversial. Various models involving physiologic factors and anatomic obstruction have been offered to explain the pathogenesis of this common disease. More recently, the role of chronic inflammatory processes has been demonstrated. These findings may modify the current paradigm of this disease and transform the diagnosis and management of patients with CRS. This review focuses on the role of allergy and inflammation in the pathogenesis of CRS.

Allergic Rhinitis: Broader Disease Effects and Implications for Management

Allergic rhinitis is a burdensome disease for a significant part of the population in both adults and children. Poorly controlled allergic rhinitis can trigger exacerbations of asthma, sinusitis, and otitis media, diseases with which it shares common pathophysiologic elements. Consequently, early diagnosis and treatment should be a priority for patients and physicians, not only to control the symptoms of allergic rhinitis but also to improve the management of associated diseases. Several pharmacologic therapies can be considered in an armamentarium that includes antihistamines (intranasal and systemic), intranasal cromolyn, intranasal anticholinergic agents, intranasal steroids, systemic steroids, immunotherapy, and, most recently, leukotriene receptor antagonists. Often, combinations of these treatments are used to maximize control of refractory symptoms.

Dose response of inhaled corticosteroids on bronchial hyperresponsiveness: a meta-analysis

BACKGROUND

There is a relatively steep dose-response curve for effects of inhaled corticosteroids on conventional airway markers of asthmatic disease control.

OBJECTIVE

We sought to determine whether a dose-response effect exists for bronchial hyperresponsiveness.

METHODS

A meta-analysis of placebo-controlled trials in asthmatic patients was performed using a computerized systematic review of databases. Doubling dose/dilution protection of inhaled corticosteroid was compared with placebo. Studies which used direct (methacholine and histamine) and indirect (adenosine monophosphate) bronchial challenge stimuli were eligible for inclusion.

RESULTS

Twenty-five studies fulfilled eligibility criteria (963 patients). Values for doubling dose/dilution protection categorized by low/medium dose (< 1,000 microg) and high dose (> or = 1,000 microg) of inhaled corticosteroid amounted to a 1.25 (95% confidence interval 1.08 to 1.42) and 2.16 (95% confidence interval 1.88 to 2.44) shift, respectively.

CONCLUSIONS

High doses of inhaled corticosteroids conferred greater improvements in bronchial hyperresponsiveness than low doses.

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.