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

Intolerance to Angiotensin Converting Enzyme Inhibitors in Asthma and the General Population: A UK Population-Based Cohort Study

BACKGROUND

Angiotensin converting enzyme inhibitor (ACEI) intolerance commonly occurs, requiring switching to an angiotensin-II receptor blocker (ARB). Angiotensin converting enzyme inhibitor intolerance may be mediated by bradykinin, potentially affecting airway hyperresponsiveness.

OBJECTIVE

To assess the risk for switching to ARBs in asthma.

METHODS

We conducted a new-user cohort study of ACEI initiators identified from electronic health records from the UK Clinical Practice Research Datalink. The risk for switching to ARBs in people with asthma or chronic obstructive pulmonary disease and the general population was compared. Adjusted hazard ratios (HRs) were calculated using Cox regression, stratified by British Thoracic Society (BTS) treatment step and ACEI type.

RESULTS

Of 642,336 new users of ACEI, 6.4% had active asthma. The hazard of switching to ARB was greater in people with asthma (HR = 1.16; 95% confidence interval [CI], 1.14-1.18; P ≤ .001) and highest in those at BTS step 3 or greater (HR = 1.35, 95% CI, 1.32-1.39; and HR = 1.18, 95% CI, 1.15-1.22, P ≤ .001 for patients aged ≥60 and <60 years, respectively). Hazard was highest with enalapril (HR = 1.25, 95% CI, 1.18-1.34, P ≤ .001; HR = 1.44, 95% CI, 1.32-1.58, P ≤ .001 for BTS step 3 or greater asthma). No increased hazard was observed in chronic obstructive pulmonary disease or those younger than age 60 years at BTS step 1/2. The number needed to treat varied by age, sex, and body mass index (BMI), ranging between 21 and 4, and was lowest in older women with a BMI of 25 or greater.

CONCLUSIONS

People with active asthma are more likely to switch to ARBs after commencing ACEI therapy. The number needed to treat varies by age, sex, BMI, and BTS step. Angiotensin-II receptor blocker could potentially be considered first-line in people with asthma and in those with high-risk characteristics.

The leukotriene receptor antagonist pranlukast attenuates airway remodeling by suppressing TGF-β signaling

BACKGROUND/OBJECTIVE

Asthma is a chronic airway disease characterized by airway eosinophilic inflammation and remodeling, which are associated with a loss in lung function. Although both contribute significantly to asthma pathogenesis, mechanistic studies and drug discovery have focused on inflammatory targets. In this study, we investigated the effect of the leukotriene receptor antagonist pranlukast on allergic airway inflammation and remodeling in vivo and in vitro.

METHOD

Four groups of female BALB/c mice (control; ovalbumin [OVA]-sensitized and -challenged; dimethyl sulfoxide [DMSO]-treated OVA; and pranlukast-treated OVA) were examined. Lung pathology, cytokine production, and airway hyperresponsiveness (AHR) measurements were compared among these groups. A human fetal lung fibroblast HFL-1 cell line was used in the peribranchial fibrosis analysis.

RESULTS

OVA-sensitized and -challenged mice exhibited allergic airway inflammation and significant increases in Th2 cytokines. Pranlukast-treated mice showed significant attenuation of allergic airway inflammation. The pranlukast treatment decreased AHR and attenuated airway remodeling to goblet cell hyperplasia, collagen deposition, α-smooth muscle actin expression, and pro-fibrotic gene expression. We further demonstrated that pranlukast not only inhibited transforming growth factor-beta 1 (TGF-β1)-induced Smad signaling in human fetal lung fibroblast cells but also simultaneously reduced collagen synthesis and pro-fibrotic gene expression.

CONCLUSIONS

The leukotriene receptor antagonist pranlukast can reduce airway inflammation and remodeling by inhibiting TGF-β/Smad signaling in an OVA-sensitized and -challenged asthma mouse model, thus suppressing AHR.

The leukotriene receptor antagonist montelukast and its possible role in the cardiovascular field

BACKGROUND

Cysteinyl leukotrienes (LTC4, LTD4, and LTE4) are pro-inflammatory mediators of the 5-lipooxygenase (5-LO) pathway, that play an important role in bronchoconstriction, but can also enhance endothelial cell permeability and myocardial contractility, and are involved in many other inflammatory conditions. In the late 1990s, leukotriene receptor antagonists (LTRAs) were introduced in therapy for asthma and later on, approved for the relief of the symptoms of allergic rhinitis, chronic obstructive pulmonary disease, and urticaria. In addition, it has been shown that LTRAs may have a potential role in preventing atherosclerosis progression.

PURPOSE

The aims of this short review are to delineate the potential cardiovascular protective role of a LTRA, montelukast, beyond its traditional use, and to foster the design of appropriate clinical trials to test this hypothesis.

RESULTS AND CONCLUSIONS

What it is known about leukotriene receptor antagonists? •Leukotriene receptor antagonist, such as montelukast and zafirlukast, is used in asthma, COPD, and allergic rhinitis. • Montelukast is the most prescribed CysLT₁ antagonist used in asthmatic patients. • Different in vivo animal studies have shown that leukotriene receptor antagonists can prevent the atherosclerosis progression, and have a protective role after cerebral ischemia. What we still need to know? • Today, there is a need for conducting clinical trials to assess the role of montelukast in reducing cardiovascular risk and to further understand the mechanism of action behind this effect.

Bronchoprotection and bronchorelaxation in asthma: New targets, and new ways to target the old ones

Despite over 50years of inhaled beta-agonists and corticosteroids as the default management or rescue drugs for asthma, recent research suggests that new therapeutic options are likely to emerge. This belief stems from both an improved understanding of what causes and regulates airway smooth muscle (ASM) contraction, and the identification of new targets whose inhibition or activation can relax ASM. In this review we discuss the recent findings that provide new insight into ASM contractile regulation, a revolution in pharmacology that identifies new ways to "tune" G protein-coupled receptors to improve therapeutic efficacy, and the discovery of several novel targets/approaches capable of effecting bronchoprotection or bronchodilation.

Leukotriene-receptor antagonists versus placebo in the treatment of asthma in adults and adolescents: a systematic review and meta-analysis

BACKGROUND

Leukotriene-receptor antagonists (LTRAs) are recommended as an alternative treatment in patients with mild asthma, but their effect compared with placebo is unclear.

PURPOSE

To determine the benefits and harms of LTRAs as monotherapy or in combination with inhaled corticosteroids compared with placebo in adults and adolescents with asthma.

DATA SOURCES

MEDLINE and the Cochrane Central Register of Controlled Trials from inception through June 2015.

STUDY SELECTION

Peer-reviewed, English-language, randomized, controlled trials in patients with asthma that reported the effect of LTRAs versus placebo on measures of asthma control.

DATA EXTRACTION

Three researchers extracted data on study population, interventions, outcome measures, and adverse events. One researcher assessed risk of bias.

DATA SYNTHESIS

Of the 2008 abstracts that were screened, 50 trials met eligibility criteria. Random-effects meta-analyses of 6 trials of LTRA monotherapy showed that LTRAs reduced the risk for an exacerbation (summary risk ratio [RR], 0.60 [95% CI, 0.44 to 0.81]). In 4 trials of LTRAs as add-on therapy to inhaled corticosteroids, the summary RR for exacerbation was 0.80 (CI, 0.60 to 1.07). Leukotriene-receptor antagonists either as monotherapy or as add-on therapy to inhaled corticosteroids increased FEV1, whereas FEV1 percentage of predicted values was improved only in trials of LTRA monotherapy. Adverse event rates were similar in the intervention and comparator groups.

LIMITATION

Variation in definitions and reporting of outcomes, high risk of bias in some studies, heterogeneity of findings, possible selective outcome reporting bias, and inability to assess the effect of asthma severity on summary estimates.

CONCLUSION

Leukotriene-receptor antagonists as monotherapy improved asthma control compared with placebo, but which patients are most likely to respond to treatment with LTRAs remains unclear.

PRIMARY FUNDING SOURCE

National Institutes of Health.

Arachidonic acid intake and asthma risk in children and adults: a systematic review of observational studies

The effect of arachidonic acid (ARA) intake on asthma risk is unclear. The objective of the present review was to systematically evaluate available observational studies on the relationship between ARA exposure and asthma risk in children and adults. A PubMed search was conducted on 22 October 2013 and seventy-three publications were checked against predefined criteria for eligibility. To identify additional eligible publications, potentially relevant articles were searched from bibliographies of articles on ARA and asthma. A total of 2924 citations were scrutinised. Finally, fourteen articles were included. A quality assessment was conducted based on the reporting and methodological quality. A meta-analysis was not conducted; therefore, a qualitative assessment is presented. Three high-, two medium- and ten low-quality studies were reviewed. Eleven studies, including two high- and two medium-quality studies, did not find a significant association between ARA exposure and asthma risk. In contrast, one high-quality study indicated a significant trend toward reducing asthma risk in children with decreasing maternal ARA intake (P trend = 0·025), and one low-quality study reported a significant trend of increasing asthma risk with higher blood ARA levels (P trend = 0·007). In two low-quality studies, asthma patients had significantly lower blood ARA levels than controls (both P < 0·05). These studies did not sufficiently demonstrate any relationships between ARA exposure and asthma risk because of the limited number of studies and their methodological limitations. They seem to suggest that ARA exposure is not consistently associated with asthma risk. Nevertheless, further evidence is required to prove or disprove the association.

Leukotriene receptor antagonists for small-airway abnormalities in asthmatics: a systematic review and meta-analysis

BACKGROUND

Airway inflammation that occurs in asthma is mainly distributed in the small airways. Leukotriene receptor antagonists (LTRAs) are systemically active drugs that may act on the small airways.

OBJECTIVES

The aim of our study was to assess the efficacy of LTRAs for small-airway abnormalities in asthmatics.

METHODS

We searched the databases of Cochrane Central, MEDLINE, and EMBASE from the time of the establishment of the databases to December 2012. The data were extracted using a pooled mean difference (MD) or standardized mean difference (SMD) with a 95% confidence interval (CI).

RESULTS

Eight studies were included. The outcomes were the conventional parameters for the detection of small-airway abnormalities. Eight studies were included. The outcomes were the conventional parameters for the detection of small-airway abnormalities. LTRAs compared to placebo improved small-airway abnormalities, as indicated by a number of radiological and physiological parameters, such as lung attenuation (MD, 61.00; 95% CI, 26.32 to 95.68) and residual volume (SMD, -0.85; 95% CI, -1.29 to -0.42). Conventional inhaled corticosteroids (ICSs) compared to LTRAs improved small-airway abnormalities, as indicated by the reactance area (p = 0.028). Compared with conventional treatment alone, a combination of LTRAs and conventional treatment improved small-airway abnormalities, as indicated by a number of radiological and physiological parameters, such as airway wall thickness (p < 0.05), alveolar nitric oxide concentration (p = 0.04), a decrease in resistance from 5 to 20 hertz (p = 0.032), reactance area (p = 0.014), eosinophil cationic protein levels (p = 0.045) and number of eosinophils (p = 0.035) in the late-phase induced sputum. However, there was no significant improvement in forced expiratory flow between 25% and 75% of forced vital capacity in any of the comparisons.

CONCLUSIONS

LTRAs may improve most of the conventional parameters for the detection of small-airway abnormalities in asthmatics. However, there is no evidence of the superiority of LTRAs over ICSs in improving functional parameters related to the small airways.

Montelukast in asthma: a review of its efficacy and place in therapy

Many studies have been published in the last 10 years on the efficacy and safety of montelukast in asthma since this drug entered the market. Experimental studies, in vitro and in vivo, and clinical studies on large numbers of patients with asthma of different severity have clearly demonstrated that montelukast is able to modify the pathophysiological mechanisms of the disease, and to improve to some extent the clinical and functional manifestations of asthma. Studies of montelukast as monotherapy or in combination with other drugs, mainly inhaled corticosteroids (ICS), versus different comparator drugs have contributed to the positioning of montelukast in the different levels of asthma treatment, according to the Global Initiative for Asthma Guidelines. Montelukast may be used as monotherapy as an alternative to low-dose ICS (particularly in a step-down strategy) or in addition to ICS for improving clinical manifestations by an increase in anti-inflammatory effects and a sparing of corticosteroids. The heterogeneity of asthma has received a large amount of attention in the last few years in order to better tailor treatment according to the different clinical and biological phenotypes of asthma. Montelukast has proven to be particularly effective in exercise-induced asthma and in asthma associated with allergic rhinitis. Other phenotypes where montelukast is effective include asthma in obese patients, asthma in smokers, aspirin-induced asthma and viral-induced wheezing episodes. The safety profile of montelukast is very good, and the suspicions of increased risk of Churg-Strauss syndrome or suicide have not been confirmed.

Comparison of leukotriene receptor antagonists and anti-histamines as an add-on therapy in patients with asthma complicated by allergic rhinitis

Patients with asthma are often complicated by allergic rhinitis, and the intimate pathophysiological association between allergic rhinitis and asthma often imposes a significant morbidity on affected individuals. The present study was conducted to assess the clinical efficacies of leukotriene receptor antagonists (LTRAs) and anti-histamines on asthma as an add-on therapy in patients with asthma complicated by allergic rhinitis. Consecutive patients with asthma were recruited to fill in systematic self-administered questionnaires concerning symptoms and conditions related to asthma and allergic rhinitis. The questionnaire was conducted twice, one month apart, and the attending physicians gave detailed information on disease control and medications on both occasions. In the study 3,140 patients with asthma participated, and 634 had concomitant allergic rhinitis (mean age: 53.1, 389 female). The second survey disclosed that treatment with LTRAs or anti-histamines had been added in 26 patients and 19 patients, respectively, without any changes in other medications. There were no significant differences in age, gender, severity of disease, or baseline treatments. The initial survey indicated that the patients who were treated with LTRAs had significantly more severe asthma-related symptoms (i.e. wheeze, cough and sleep disturbance) and experienced greater dissatisfaction with the treatment than did those who were treated with anti-histamines. The second survey disclosed significant reductions in sneezing (p=0.03), rhinorrhea (p=0.01), dyspnea (p=0.046), sleep disturbance (p=0.02), over-all asthma symptoms (p=0.013), and an improvement in satisfaction with treatment (p=0.019) in patients to whom LTRAs were added-on, whereas the patients receiving anti-histamines reported no significant changes in these symptoms. These results suggest that LTRAs are more effective than anti-histamines as an add-on therapy in symptomatic patients with asthma complicated by allergic rhinitis.

[Montelukast in the treatment of mild to moderate persistent asthma]

INTRODUCTION

Anti-inflammatory preventive treatment is recommended in cases of persistent asthma. Besides inhaled corticosteroids (ICS), which represent the mainstay of treatment, other therapeutic options are available, of which only antileukotrienes are approved for all age groups.

BACKGROUND

Given as a substitute of low-dose ICS, montelukast prevents exacerbations as efficiently and for a longer period than long-acting β2-agonists. Montelukast is as efficient as doubling the dose of ICS on asthma symptoms in cases of inadequate control with low-dose ICS. Combined with ICS, it can lead to better control of asthma and potentially to ICS sparing.

CONCLUSIONS

Given the efficacy, tolerance and long-term treatment compliance of montelukast in mild persistent asthma in adults and children, montelukast, given as a substitute or combined with ICS, could contribute to enhanced control of asthma, especially in children.

Levalbuterol versus albuterol

Albuterol has been used for more than 40 years to treat acute asthma exacerbations as a racemic mixture of isomers: the active form, (R)-albuterol, or levalbuterol, and (S)-albuterol, classically considered inert. The single-isomer formulation, levalbuterol, has been synthesized recently and used therapeutically when the racemate is deemed less desirable. Basic investigations indicate that racemic albuterol and levalbuterol can produce effects that favor asthma remediation, including corticosteroid amplification and reduction of inflammatory mediators; in contrast, (S)-albuterol produces opposite effects. With inhalation of racemic albuterol, circulating (S)-albuterol persists 12 times longer than levalbuterol, suggesting potential for paradoxical effects observed clinically. Although mainly consistent with basic findings, clinical studies suggest no overwhelming superiority of levalbuterol over racemic albuterol; however, levalbuterol's effects may be greatest in moderate to severe asthma patients, especially with racemic albuterol overuse. Recent adoption of the hydrofluoroalkane formulation has narrowed the cost gap between levalbuterol and racemic albuterol metered-dose inhalers, but it remains for the nebulized formulations. Thus, physician selection of these drugs has remained dependent on experience, pharmaceutical knowledge, and established prescribing habits combined with cost factors, formulary structures, and availability, such that racemic albuterol is still used significantly compared with levalbuterol to treat acute asthma exacerbations.

The Saudi Initiative for Asthma

The Saudi Initiative for Asthma (SINA) provides up-to-date guidelines for healthcare workers managing patients with asthma. SINA was developed by a panel of Saudi experts with respectable academic backgrounds and long-standing experience in the field. SINA is founded on the latest available evidence, local literature, and knowledge of the current setting in Saudi Arabia. Emphasis is placed on understanding the epidemiology, pathophysiology, medications, and clinical presentation. SINA elaborates on the development of patient-doctor partnership, self-management, and control of precipitating factors. Approaches to asthma treatment in SINA are based on disease control by the utilization of Asthma Control Test for the initiation and adjustment of asthma treatment. This guideline is established for the treatment of asthma in both children and adults, with special attention to children 5 years and younger. It is expected that the implementation of these guidelines for treating asthma will lead to better asthma control and decrease patient utilization of the health care system.

Leukotriene pathway genetics and pharmacogenetics in allergy

Leukotrienes (LT) are biologically active lipid mediators known to be involved in allergic inflammation. Leukotrienes have been shown to mediate diverse features of allergic conditions including inflammatory cell chemotaxis/activation and smooth muscle contraction. Cysteinyl leukotrienes (LTC(4), LTD(4) and, LTE(4)) and the dihydroxy leukotriene LTB(4) are generated by a series of enzymes/proteins constituting the LT synthetic pathway or 5-lipoxygenase (5-LO) pathway. Their function is mediated by interacting with multiple receptors. Leukotriene receptor antagonists (LTRA) and LT synthesis inhibitors (LTSI) have shown clinical efficacy in asthma and more recently in allergic rhinitis. Despite growing knowledge of leukotriene biology, the molecular regulation of these inflammatory mediators remains to be fully understood. Genes encoding enzymes of the 5-LO pathway (i.e. ALOX5, LTC4S and LTA4H) and encoding for LT receptors (CYSLTR1/2 and LTB4R1/2) provide excellent candidates for disease susceptibility and severity; however, their role remains unclear. Preliminary data also suggest that 5-LO pathway/receptor gene polymorphism can predict patient responses to LTSI and LTRA; however, the exact mechanisms require elucidation. The aim of this review was to summarize the recent advances in the knowledge of these important mediators, focusing on genetic and pharmacogenetic aspects in the context of allergic phenotypes.

Complementary therapy in asthma: inhaled corticosteroids and what?

PURPOSE OF REVIEW

For optimal asthma control, complementary strategies are advocated to cover several aspects of the disease. This mini-review highlights different complementary strategies with special focus on the combined use of inhaled corticosteroids (ICSs) and long-acting beta2 agonists and as an alternative, the combination of ICSs and antileukotrienes.

RECENT FINDINGS

New data show that combinations of ICSs/long-acting beta2 agonists or ICSs with antileukotrienes improve disease stability with concomitant control of the underlying airway inflammation. Moreover, there is some evidence that combination therapy may prevent some aspects of airway remodelling. The use of a fixed combination of both a reliever and a controller medication may have certain advantages compared with a fixed dose regime with as-needed separate reliever therapy. Alternatively, in some asthma phenotypes, such as combined allergic rhinitis and asthma syndrome, the combination of ICSs with antileukotrienes offers a complementary anti-inflammatory treatment in combination with controller effects on both airway compartments.

SUMMARY

This review compares different strategies of complementary therapy in asthma with special focus on how to achieve the best clinical control also aimed at controlling the underlying airway inflammation. We have chosen to focus on two major topics: the use of ICSs and long-acting beta2 agonists in two different strategies, that is, a symptom-driven versus a fixed symptom-preventive approach; and the use of ICSs with a long-acting beta2 agonist versus ICSs and a leukotriene receptor antagonist. What regime should be chosen is highly dependent on the individual phenotype and defined treatment goal.

Evaluating combination therapies for asthma: pros, cons, and comparative benefits

Combination therapies with inhaled corticosteroids (ICS) and either long-acting beta2 agonists (LABA) or leukotriene receptor antagonists (LTRA) are commonly used to help patients maintain control of their asthma. LABA and LTRA have different mechanisms of action and both provide complementary benefits when combined with ICS. This paper compares the two regimens based on recent clinical trial data, evaluates their efficacy on various clinical and quality of life outcomes, and discusses the importance of therapy choice in people with specific asthma phenotypes. The potential of new dosing strategies, including adjustable maintenance therapy and single-inhaler maintenance and reliever therapy is also reviewed. Given the variety of outcomes, phenotypes, and treatment strategies that must be considered, the importance of individualized management is emphasized.

The Brussels Declaration: the need for change in asthma management

Asthma is a highly prevalent condition across Europe and numerous guidelines have been developed to optimise management. However, asthma can be neither cured nor prevented, treatment choices are limited and many patients have poorly controlled or uncontrolled asthma. The Brussels Declaration on Asthma, sponsored by The Asthma, Allergy and Inflammation Research Charity, was developed to call attention to the shortfalls in asthma management and to urge European policy makers to recognise that asthma is a public health problem that should be a political priority. The Declaration urges recognition and action on the following points: the systemic inflammatory component of asthma should be better understood and considered in assessments of treatment efficacy; current research must be communicated and responded to quickly; the European Medicines Agency guidance note on asthma should be updated; "real world" studies should be funded and results used to inform guidelines; variations in care across Europe should be addressed; people with asthma should participate in their own care; the impact of environmental factors should be understood; and targets should be set for improvement. The present paper reviews the evidence supporting the need for change in asthma management and summarises the ten key points contained in the Brussels Declaration.

Critical appraisal of antileukotriene use in asthma management

PURPOSE OF REVIEW

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 asthma treatment to become available since the introduction of inhaled corticosteroids. Nevertheless, despite their widespread use in clinical practice, the role of leukotriene modifiers in the management of asthma remains controversial. In the present article the clinical applications of this class of drugs have been critically reviewed based on recent evidence.

RECENT FINDINGS

In an effort to try and establish the proper place of antileukotrienes in the management of asthma, important systematic reviews have been carried out over these recent years in three critical areas: antileukotrienes as second choice first line agents after inhaled corticosteroids; antileukotrienes as add-on therapy to inhaled corticosteroids; add-on antileukotrienes versus long acting beta-agonists to patients not controlled by inhaled corticosteroids. In addition, novel and useful clinical targets for this class of drugs have been recently explored and include: patients with severe asthma; aspirin-intolerant asthma; asthmatic patients with allergic rhinitis.

SUMMARY

Use of antileukotrienes is not recommended as first-line monotherapy in patients with asthma, except those who have aspirin intolerant asthma. Patients with concomitant allergic rhinitis may be a good target population for therapy with antileukotrienes. Addition of leukotriene modifiers to inhaled corticosteroids produces only a modest improvement in the clinical response, and is not greater to that of add-on long acting beta-agonists. The exact role of antileukotrienes in asthma management guidelines still continues to evolve.

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.

Biological effects of montelukast, a cysteinyl-leukotriene receptor-antagonist, on T lymphocytes

BACKGROUND

Montelukast (MNT), a cysteinyl-leukotriene receptor (Cys-LTR) antagonist, has anti-inflammatory activity in the treatment of allergic diseases. If this effect is due only to blocking leukotrienes or also owing to inhibiting proliferation and survival of inflammatory cells, is actually unknown.

OBJECTIVE

Testing the hypothesis that MNT could influence T lymphocyte functional behaviour in vitro.

METHODS

Normal T lymphocytes were analysed for surface expression of Cys-LTR(1) and Cys-LTR(2) by means of monoclonal antibodies (mAbs), in the resting state and after activation with T helper type 2 cytokine or T cell receptor (TcR) stimulation. Proliferative activity, as well as IL-4 andIFN-gamma production, were simultaneously determined in samples exposed to molar concentrations of MNT from 10(-8) to 10(-5). Programmed cell death in cultured samples was evaluated by means of propidium iodide and fluorescein isothiocyanate-conjugated anti-Annexin V mAb staining. The complementary DNA microarray technique was adopted to identify gene products involved in apoptosis induction.

RESULTS

Resting T cells expressed low levels of Cys-LTR. Upon anti-CD3 mAb activation, a progressive increase in Cys-LTR(1) and -LTR(2) expression was observed. Exposure to MNT reduced proliferative response to TcR engagement, increased IFN-gamma production and led to apoptosis at minimal concentrations of 10(-6) M. A progressive loss in BAD and B cell lymphoma/leukaemia-2 activities, and an increase in the expression of CD27, TRAF3, TRAIL, p53 and Fas genes were also observed.

CONCLUSIONS

Biological effects of MNT delineate a complex picture of gene activation and repression, probably induced by Cys-LTR blockade. The induction of apoptosis in allergen-specific T cell population, as a final result, appears fundamental in the treatment of asthma.

Effects of dual therapy with corticosteroids plus long acting beta2-agonists in asthma

Asthma is a common condition characterised by inflammation, airway hyperresponsiveness and reversible airflow obstruction. Effective pharmacotherapy must therefore be aimed at attenuating these underlying hallmark features. Despite the use of regular low-to-moderate doses of inhaled corticosteroids, many patients remain symptomatic and require further 2nd line controller therapy. The addition of a concomitant long acting beta2-agonist provides an effective means in which to alleviate symptoms and reduce exacerbation frequency. Moreover, both agents can be combined in a single inhaler, and provide patients with a more convenient and effective way in which to deliver treatment to the endobronchial tree. This evidenced-based review article discusses the effects of such combination inhalers upon a variety of outcome parameters and their effects upon asthmatics across a range of severities.

Does bronchial hyperresponsiveness in asthma matter?

Bronchial hyperresponsiveness is a fundamental component of the asthmatic inflammatory process causing airway narrowing on exposure to a bronchoconstrictor stimulus. This in turn causes patients to experience symptoms of breathlessness, chest tightness, cough and wheeze. Bronchial challenge tests can be performed in the laboratory to establish the degree of bronchial hyperresponsiveness to both direct and indirect stimuli. The extent to which asthma pharmacotherapy attenuates bronchial hyperresponsiveness is therefore an important measure of efficacy. This review article discusses the effects of inhaled and oral asthma treatment upon bronchial hyperresponsiveness and highlights how, in conjunction with conventional measures of asthma control, it can be used as an aid to optimally manage patients.

Pharmacology of airway inflammation in asthma and COPD

The current asthma therapies are not cures and symptoms return soon after treatment is stopped even after long term treatment. Although inhaled glucocorticoids are highly effective in controlling airway inflammation in asthma, they are ineffective in the small group of patients with glucocorticoid-dependent and -resistant asthma. With very few exceptions, COPD is caused by tobacco smoking, and smoking cessation is the only truly effective treatment of COPD available. Current pharmacological treatment of COPD is unsatisfactory, as it does not significantly influence the severity of the disease or its natural course. Glucocorticoids are scarcely effective in COPD patients without concomitant asthma. Bronchodilators improves symptoms and quality of life, in COPD patients, but, with the exception of tiotropium, they do not significantly influence the natural course of the disease. Theophylline is the only drug which has been demonstrated to have a significant effect on airway inflammation in patients with COPD. Here we review the pharmacology of currently used antiinflammatory therapies for asthma and COPD and their proposed mechanisms of action. Recent understanding of disease mechanisms in severe steroid-dependent and -resistant asthma and in COPD, has lead to the development of novel compounds, which are in various stages of clinical development. We review the current status of some of these new potential drugs.

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.

Pranlukast: a review of its use in the management of asthma

Pranlukast (Onon, Azlaire), is an orally administered, selective, competitive antagonist of the cysteinyl leukotrienes (LT) C(4), LTD(4) and LTE(4). It is indicated for the prophylactic treatment of chronic bronchial asthma in paediatric and adult patients. The efficacy of pranlukast 225mg twice daily in adults with mild to moderate asthma was demonstrated in double-blind, placebo- or azelastine-controlled studies of 4 or 8 weeks' duration. The drug at this dosage was superior to both comparators in improving mean attack scores and morning and/or evening peak expiratory flow rates, and decreasing the use of rescue bronchodilators (p < 0.05). In limited clinical studies, pranlukast 225mg twice daily appeared to be as effective as montelukast 10mg once daily and zafirlukast 40mg twice daily in adults with mild to moderate asthma. Tachyphylaxis was absent when the drug was administered for up to 4 years. In patients requiring high-dose inhaled corticosteroid therapy, pranlukast 225 mg twice daily plus a halved dosage of inhaled corticosteroid was as effective as the original dosage of inhaled corticosteroid. Pranlukast was also effective in patients with mild to severe asthma in a clinical practice setting. In a double-blind trial, greater improvements in most outcome measures were observed with pranlukast than with oxatomide in children and adolescents with asthma. In clinical trials, pranlukast was well tolerated in adult and paediatric patients with asthma, with an adverse event profile similar to that of placebo. Gastrointestinal events and hepatic function abnormalities were the most commonly reported adverse events. No clinically significant differences in adverse event profiles between pranlukast, zafirlukast or montelukast were shown in limited comparisons. Although Churg-Strauss syndrome has been noted in pranlukast recipients, a direct causal relationship is unlikely.

CONCLUSIONS

Pranlukast is a well tolerated and effective preventative treatment in adult and paediatric patients with persistent asthma of all severities. In some patients, pranlukast may be beneficial when added to low-dose inhaled corticosteroids; it may also be a viable alternative to increasing inhaled corticosteroid dosages. The efficacy of pranlukast relative to placebo has been confirmed; its efficacy relative to other therapy awaits further investigation. Nonetheless, pranlukast is a useful therapeutic option (with as-required short-acting beta(2)-agonists), either as preventative monotherapy for the treatment of mild persistent asthma or in conjunction with inhaled corticosteroids in the management of moderate or severe persistent 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.

Second-line controller therapy for persistent asthma uncontrolled on inhaled corticosteroids: the step 3 dilemma

The asthma syndrome is characterised by airway inflammation with associated bronchial hyperresponsiveness (BHR) and reversible airflow obstruction. Therapy has benefited from an enhanced understanding of the pathophysiology of asthma and the resulting guidelines that emphasise the pivotal role of anti-inflammatory inhaled corticosteroids (ICS) as first-line therapy. Most patients with mild-to-moderate asthma can be adequately controlled on low-to-medium dosages of ICS alone. For patients with moderate-to-severe asthma who are not adequately controlled by ICS, it is unclear which medication should be added on. The two principal drugs under consideration are long-acting beta(2)-agonists (LABAs) and leukotriene antagonists (LTAs). Although both LABAs and LTAs are both effective at improving lung function, reducing symptoms and decreasing exacerbations, important differences exist that may determine the selection of one over the other in particular circumstances. LABAs and LTAs are equally effective at reducing exacerbations and improving symptoms and quality of life when used as add-on therapy. LABAs tend to be more effective bronchodilators than LTAs. Although LABAs stabilise the airway smooth muscle, they do not affect the underlying inflammatory process. Their long-term use also leads to subsensitivity of response to both LABAs and short-acting beta(2)-agonists (SABAs). The subsensitivity of response to SABAs is more pronounced in the presence of acute bronchoconstriction, which could be relevant during an acute attack. When combined with an ICS, LTAs provide additive non-steroidal anti-inflammatory properties and alleviate associated BHR, but do not induce subsensitivity of response. Not only is the efficacy of LTAs maintained over time, but also they do not affect the response to SABAs as reliever therapy. LTAs also have beneficial effects in patients who have concomitant allergic rhinitis, thus treating the unified airway. The choice between LABA and LTA as add-on therapy will therefore be determined by the needs of the individual patient in terms of providing anti-inflammatory versus bronchodilatory control. For patients with poor lung function where bronchodilatation is required, then an LABA would seem to be a logical choice. For the patient whose lung function is less impaired, with evidence of ongoing BHR where bronchoprotection is needed (e.g. exercise, allergen, cold air), or when there is concomitant allergic rhinitis, then an LTA would be more suitable.

Single-isomer levalbuterol: a review of the acute data

Levalbuterol, the pure (R)-isomer of racemic albuterol, is a new therapeutic option for patients with asthma. Racemic albuterol comprises a 50:50 mixture of (R)- and (S)-albuterol, with (R)-albuterol conferring all of the bronchodilator effects of the racemate. Numerous preclinical and in vitro studies have indicated that (S)-albuterol is not an inert isomer, but may have proinflammatory effects. Results from clinical trials in adults and children with asthma have demonstrated that 0.63 mg levalbuterol provides effective bronchodilation with lower b-mediated side effects compared with 2.5 mg racemic albuterol. In the emergency department, levalbuterol provided greater bronchodilation and significantly reduced hospital admissions compared with racemic albuterol. Recent studies have supported that levalbuterol use in acute settings may reduce the cost of asthma treatment by decreasing the total treatments and subsequent respiratory therapy resources. Levalbuterol provides heath care professionals with a safe, effective, and potentially cost-saving alternative to racemic albuterol for the treatment of patients with asthma.