Antitussive effects of the leukotriene receptor antagonist montelukast in patients with cough variant asthma and atopic cough

One-step fabrication of 3D-aligned human skeletal muscle tissue and measurement of contractile force for preclinical drug testing

Human muscle tissue models are critical to understanding the complex physiology of skeletal muscle in studies of drug discovery, development, and toxicity profiling in the human body. However, due to the challenges in in vitro maturation of human muscle cells, few research groups developing their own tissue engineering techniques have succeeded in producing contractile human muscle tissues. Moreover, a more sophisticated method is necessary to measure contractile forces generated by the muscle tissues for preclinical studies in muscle physiology and drug discovery. Although a few research groups have established their own tissue model systems that measure contractile force, they require multi-step fabrication processes to produce human muscle tissues sufficiently functional to be able to measure the contractile forces. To improve the usability of our tissue model system, this study focused on simplifying the tissue engineering approach to produce a practical muscle tissue model. In this study, muscle satellite cells were simply mixed with a combination of fibrinogen, thrombin, and Matrigel before gel formation. The presence of muscle satellite cells induces gel compaction and spontaneously induces unidirectional stretching of the gel, resulting in the muscle satellite cells being aligned three-dimensionally with the direction of stretching. Furthermore, this gel environment promotes the maturation of the human muscle progenitor cells into aligned myofibers, also provides the tissue with an elastic platform for muscle contraction, and allows the attachment of the muscle tissue to a device for measurement of contractile force. Therefore, this one-step tissue fabrication allowed us to produce 3D-aligned human muscle tissues and this tissue model is ready to use for the measurement of contractile forces. In fact, the muscle contractions created by electrical and chemical stimulation were quantitatively determined using our measurement system. In addition, the impact of some representative drugs on this muscle tissue were able to be monitored in real-time throughout the changes in contractile forces. In conclusion, our tissue model system, produced by a simple fabrication method, can be used for preclinical in vitro studies in muscle physiology and drug discovery.

Guidelines for the management of chronic cough in adults. Endorsed by the French speaking society of respiratory diseases (Société de Pneumologie de Langue Française, SPLF), the Société Française d'Oto-Rhino-Laryngologie et de Chirurgie de la Face et du Cou (SFORL), the Société Française de Phoniatrie et de Laryngologie (SFPL), the Société Nationale Française de Gastro-entérologie (SNFGE)

Patients with chronic cough experience a high alteration of quality of life. Moreover, chronic cough is a complex entity with numerous etiologies and treatments. In order to help clinicians involved in the management of patients with chronic cough, guidelines on chronic cough have been established by a group of French experts. These guidelines address the definitions of chronic cough and the initial management of patients with chronic cough. We present herein second-line tests that might be considered in patients with cough persistence despite initial management. Experts also propose a definition of unexplained or refractory chronic cough (URCC) in order to better identify patients whose cough persists despite optimal management. Finally, these guidelines address the pharmacological and non-pharmacological interventions useful in URCC. Thus, amitryptilline, pregabalin, gabapentin or morphine combined with speech and/or physical therapy are a mainstay of treatment strategies in URCC. Other treatment options, such as P2 × 3 antagonists, are being developed.

[Guidelines for the management of chronic cough in adults]

Patients with chronic cough experience major alteration in their quality of life. Given its numerous etiologies and treatments, this disease is a complex entity. To help clinicians involved in patient management of patients, guidelines have been issued by a group of French experts. They address definitions of chronic cough and initial management of patients with this pathology. We present herein the second-line tests that might be considered in patients whose coughing has persisted, notwithstanding initial management. The experts have also put forward a definition of unexplained or refractory chronic cough (URCC), the objective being to more precisely identify those patients whose cough persists despite optimal management. Lastly, these guidelines indicate the pharmacological and non-pharmacological interventions of use in URCC. Amitriptyline, pregabalin, gabapentin or morphine combined with speech and/or physical therapy are mainstays in treatment strategies. Other treatment options, such as P2X3 antagonists, are being developed and have generated high hopes among physicians and patients alike.

Emerging drugs in the treatment of chronic cough

INTRODUCTION

Chronic cough is a debilitating condition that is among the most common reasons for seeking medical attention yet remains challenging to manage. Identifying an underlying respiratory, nasal or upper gastrointestinal disease triggering cough is the first step in assessment, but once this has been ruled out or adequately treated, many patients remain troubled with chronic cough.

AREAS COVERED

This narrative review discusses the role of existing treatments and describes the current research landscape for the development of new therapies for chronic cough greater than 8 weeks that is refractory (RCC) or unexplained (UCC). The literature search includes published studies found on pubmed and conference abstracts until 2023.

EXPERT OPINION

RCC/UCC can occur due to neuronal dysregulation of the vagus nerve or central nervous system. Hence, novel anti-tussives have targeted ion channels involved in the neuronal signaling which triggers cough. Although some therapies targeting receptors such as TRPV1 have failed to show efficacy, P2X3 antagonists have emerged as the most promising therapy for patients impacted by chronic cough. Disease specific therapies such as for idiopathic pulmonary fibrosis are in early development.

A case of atopic cough with aphonia showed a prominent response to a histamine H1 receptor antagonist

A 33-year-old woman admitted to our hospital for further examination of severe non-productive cough lasting for about two months. Her symptom did not ameliorate by treatments including long acting β2 agonists. She had a medical history of drug allergy to non-steroidal anti-inflammatory drugs. At the initial visit, she could not speak at all and communicated with us in writing. Chest auscultation revealed no wheezes, rhonchi and other crackles. Laboratory findings showed a mild eosinophilia with normal total and specific serum immunoglobulin E. The results of an electrocardiogram, a chest X-ray and a chest CT were unremarkable. A fractional exhaled nitric oxide value was within normal limit. Based on these observations, a diagnosis of atopic cough (AC) was suspected, and we started treatment with a histamine H1 receptor antagonist (H1-RA). She had become able to speak again in association with complete disappearance of cough by eight-weeks after treatment initiation, and her symptoms did not recur even after cessation of treatment. By the confirmation of remarkable clinical improvement in response to a H1-RA, a diagnosis of AC was made. To the best of our knowledge, this is the first report of an AC patient who presented severe cough with aphonia. J. Med. Invest. 70 : 281-284, February, 2023.

Chronic cough in adults: recommendations from an Italian intersociety consensus

BACKGROUND

Chronic cough (CC) is a burdensome health problem in adult and older people, with a major impact on quality of life. Its management is often troublesome, and many guidelines have been released. Notwithstanding, a proportion of cases still do not reach a definite diagnosis and resolutive treatment. A coordinated approach between different specialists would be highly recommended, but its implementation in clinical practice suffers from the lack of shared protocols and poor awareness of the problem. The present consensus document has been implemented to address these issues.

AIMS

To develop evidence-based recommendations for the management of adults with CC.

METHODS

A 12-member expert task force of general practitioners, geriatricians, pneumologists, allergologists, otorhynolaringologists and gastroenterologists was established to develop evidence-based recommendations for the diagnostic and therapeutic approach to subjects with CC. A modified Delphi approach was used to achieve consensus, and the US Preventive Services Task Force system was used to rate the strength of recommendations and the quality of evidence.

RESULTS

A total of 56 recommendations were proposed, covering 28 topics and concerning definitions and epidemiology, pathogenesis and etiology, diagnostic and therapeutic approach along with the consideration of specific care settings.

CONCLUSION

These recommendations should ease the management of subjects with CC by coordinating the expertise of different specialists. By providing a convenient list of topics of interest, they might assist in identifying unmet needs and research priorities.

Upper airway cough syndrome may be the main cause of chronic cough in Japan: a cohort study

BACKGROUND

Upper airway cough syndrome (UACS) is generally considered a common cause of chronic cough but remains poorly recognised in Japan.

OBJECTIVE

This study aimed to assess whether UACS was a common cause of chronic cough in Japan, as is true in other countries. Interview and examination items were evaluated for their potential use in UACS diagnosis.

METHODS

All patients with chronic cough were preliminarily diagnosed with bronchial asthma, UACS, gastroesophageal reflux disease, or postinfectious prolonged cough, based on interviews and examinations. Treatment centred on nasal steroids was administered to the UACS group and standard treatment to the other groups. The observation period lasted 4 weeks. The subjective cough score at first diagnosis was set at 10, and the final diagnosis was made based on the treatment administered at the time the cough score had decreased to ≤2. The associations between the presence or absence of UACS and interview and examination items were statistically evaluated.

RESULTS

Among 230 patients with chronic cough, 146 were diagnosed with UACS-only. Multivariate logistic regression revealed that the assessment items 'awareness of mucus accumulating in the back of the throat', 'presence of abnormal echography findings', 'absence of associated coughing when exercising' and 'presence of coughing persisting after onset' were significantly correlated with the presence or absence of UACS (p < 0.05).

CONCLUSIONS

UACS may be the most common cause of chronic cough in Japan and may be effectively treated with nasal corticosteroids. Diagnosing UACS might be possible by selecting appropriate interview and examination items.

lncRNA PCGEM1 strengthens anti-inflammatory and lung protective effects of montelukast sodium in children with cough-variant asthma

Montelukast sodium is an effective and well-tolerated anti-asthmatic drug. Long non-coding RNAs (lncRNAs) are involved in the treatment of asthma. Therefore, this study aimed to investigate the effect of montelukast sodium on children with cough-variant asthma (CVA) and the role of lncRNA prostate cancer gene expression marker 1 (PCGEM1) in drug efficacy. The efficacy of montelukast sodium was evaluated by assessing the release of inflammatory factors and pulmonary function in CVA children after a 3-month treatment. An ovalbumin (OVA)-sensitized mouse model was developed to simulate asthmatic conditions. PCGEM1 expression in clinical peripheral blood samples and lung tissues of asthmatic mice was determined. Asthmatic mice experienced nasal inhalation of PCGEM1 overexpression with simultaneous montelukast sodium to investigate the roles of PCGEM1 in asthma treatment. The NF-κB axis after PCGEM1 overexpression was detected to explore the underling mechanisms. Consequently, montelukast sodium contributed to reduced levels of pro-inflammatory factors and improved pulmonary function in CVA children. PCGEM1 was poorly expressed in OVA-sensitized asthmatic mice and highly expressed in CVA children with response to the treatment. PCGEM1 overexpression enhanced the anti-inflammatory effects and promoted effects on pulmonary function of montelukast sodium in CVA children and OVA-sensitized asthmatic mice. Furthermore, PCGEM1 inhibited the activation of the NF-κB axis. This study demonstrated the anti-inflammatory and lung-protective effects of montelukast sodium on CVA, which was strengthened by overexpression of PCGEM1. Findings in this study highlighted a potential anti-asthmatic target of montelukast sodium.

Repeated bronchoconstriction attenuates the cough response to bronchoconstriction in naïve guinea pigs

BACKGROUND

Cough variant asthma (CVA) is recognized as a precursor of bronchial asthma (BA). However, the cough response to bronchoconstriction differs between these similar diseases. Repeated bronchoconstriction and the resulting imbalance of endogenous lipid mediators may impact the cough response.

METHODS

We investigated the influence of repeated bronchoconstriction on the cough response to bronchoconstriction using naïve guinea pigs. Bronchoconstriction was induced for 3 consecutive days and changes in the cough response and lipid mediators, such as PGE₂, PGI₂, and cysteinyl-LTs (Cys-LTs), in BAL fluid (BALF) were assessed. We investigated the effect of endogenous PGI₂ on the cough response by employing a PGI₂ receptor antagonist. In order to investigate the cough response over a longer period, we re-evaluated the cough response 2 weeks after repeated bronchoconstriction.

RESULTS

The number of coughs induced by bronchoconstriction were significantly decreased by repeated bronchoconstriction. The levels of PGE₂, PGI₂, and Cys-LTs, and the ratio of PGI₂/PGE₂ were significantly increased, following repeated bronchoconstriction. This decrease in the cough response was suppressed by pretreatment with a PGI₂ receptor antagonist. Two weeks after repeated bronchoconstriction, the cough response returned to the same level as before repeated bronchoconstriction along with a concomitant return of lipid mediators, such as PGE₂, PGI₂, and Cys-LTs and the ratio of PGI₂/PGE₂.

CONCLUSIONS

Our results suggest that repeated bronchoconstriction and the resulting imbalance of endogenous lipid mediators contribute to the difference in cough responses to bronchoconstriction in CVA and BA.

Managing Chronic Cough Due to Asthma and NAEB in Adults and Adolescents: CHEST Guideline and Expert Panel Report

BACKGROUND

Asthma and non-asthmatic eosinophilic bronchitis (NAEB) are among the commonest causes of chronic cough in adults. We sought to determine the role of non-invasive measurements of airway inflammation, including induced sputum and fractional exhaled nitric oxide, in the evaluation of cough associated with asthma, and what the best treatment is for cough due to asthma or NAEB.

METHODS

We undertook three systematic reviews of randomized controlled trials and observational trials of adults and adolescents > 12 years of age with a chronic cough due to asthma or NAEB. Eligible studies were identified in MEDLINE, CENTRAL, and SCOPUS and assessed for relevance and quality. Guidelines were developed and voted upon using CHEST guideline methodology.

RESULTS

Of the citations reviewed, 3/1,175, 53/656, and 6/134 were identified as being eligible for inclusion in the three systematic reviews, respectively. In contrast to established guidelines for asthma therapies in general and the inclusion in some guidelines for a role of biomarkers of airway inflammation to guide treatment in severe disease, the evidence of specific benefit related to the use of non-invasive biomarkers in patients with chronic cough due to asthma was weak. The best therapeutic option for cough in asthma or NAEB is inhaled corticosteroids followed by leukotriene receptor antagonism.

CONCLUSIONS

This guideline offers recommendations on the role of non-invasive measurements of airway inflammation and treatment for cough due to asthma or NAEB based on the available literature, and identifies gaps in knowledge and areas for future research.

ERS guidelines on the diagnosis and treatment of chronic cough in adults and children

These guidelines incorporate the recent advances in chronic cough pathophysiology, diagnosis and treatment. The concept of cough hypersensitivity has allowed an umbrella term that explains the exquisite sensitivity of patients to external stimuli such a cold air, perfumes, smoke and bleach. Thus, adults with chronic cough now have a firm physical explanation for their symptoms based on vagal afferent hypersensitivity. Different treatable traits exist with cough variant asthma (CVA)/eosinophilic bronchitis responding to anti-inflammatory treatment and non-acid reflux being treated with promotility agents rather the anti-acid drugs. An alternative antitussive strategy is to reduce hypersensitivity by neuromodulation. Low-dose morphine is highly effective in a subset of patients with cough resistant to other treatments. Gabapentin and pregabalin are also advocated, but in clinical experience they are limited by adverse events. Perhaps the most promising future developments in pharmacotherapy are drugs which tackle neuronal hypersensitivity by blocking excitability of afferent nerves by inhibiting targets such as the ATP receptor (P2X3). Finally, cough suppression therapy when performed by competent practitioners can be highly effective. Children are not small adults and a pursuit of an underlying cause for cough is advocated. Thus, in toddlers, inhalation of a foreign body is common. Persistent bacterial bronchitis is a common and previously unrecognised cause of wet cough in children. Antibiotics (drug, dose and duration need to be determined) can be curative. A paediatric-specific algorithm should be used.

Montelukast and budesonide combination for children with chronic cough-variant asthma

This study investigated the effectiveness and safety of montelukast combined budesonide (MCB) treatment for children with chronic cough-variant asthma (CCVA).In total, 82 cases of children with CCVA, aged 4 to 11 years were included in this study. All cases received either MCB or budesonide alone between May 2015 and April 2017. The primary outcome was lung function, measured by the peak expiratory flow rates (PEFRs) and forced expiratory volume in 1 second (FEV1). The secondary outcome was measured by the clinical assessment score. Furthermore, adverse events (AEs) were also recorded in this study. All outcomes were measured after 8-week treatment.After 8-week treatment, MCB showed greater effectiveness than did budesonide alone in improving the lung function, measured by PEFR V1 (P = .02), and FEV1 (P < .01). Similarly, the clinical assessment score also demonstrated significant difference between the 2 groups (P < .05). In addition, no serious AEs occurred in both groups.The results of this study demonstrate that the effectiveness of MCB is superior to budesonide alone in the treatment of children with CCVA.

The Emerging Role of The Eosinophil and Its Measurement in Chronic Cough

Although the aetiology of chronic cough in guidelines is clearly stated as asthma and related syndromes, gastro-oesophageal reflux disease (GORD), and upper airways disease, the inflammatory mechanisms underlying these conditions differ. Recent studies on asthma have increasingly focused on its molecular phenotypes instead of clinical characteristics. Here, we proposed the hypothesis that divides cough into two groups; the eosinophilic and neutrophilic. This division will enhance our ability to recognise the type of airway inflammation which, as a consequence will lead us to more targeted and personalized treatment approaches.

Montelukast, current indications and prospective future applications

INTRODUCTION

Montelukast is recommended for the treatment of asthma, exercise -induced bronchospasm and allergic rhinitis. Several trials demonstrated potential therapeutic effects in other respiratory conditions, and different animal-model-based studies explored potential pharmacological actions in non-respiratory conditions.

AREAS COVERED

Clinical investigations on the pharmacotherapeutic effects of montelukast, in addition to in-vivo studies on animal models of non-respiratory diseases. The data discussed in this review were mainly obtained from clinical randomized trials, real-life studies, and studies based on animal models as approve of concept. As a condition, all of the discussed articles were published in journals cited by Pubmed. Expert commentary: The current clinical data are in favor of montelukast use in the management of chronic asthma as an add-on or alternative therapy to the inhaled corticosteroids. Further clinical trials are required to confirm the effectiveness and feasibility of montelukast for the treatment of conditions other than the current clinical indications.

Cough hypersensitivity as a neuro-immune interaction

Cough is an intrinsic protective reflex. However, chronic cough affects a considerable proportion of general population and has a major impact on quality of life. A recent paradigm shift to ‘cough hypersensitivity syndrome’ suggests that chronic cough arises from hypersensitivity of the airway sensory nerves. As cough reflex is determined by interaction of the nervous system with immune system, persistent dysregulation of one or both of these systems may lead to chronic cough hypersensitivity. Here we review the current evidence for the neuro-immune interactions that underlie cough hypersensitivity and discuss future therapeutic strategies.

Antitussive drugs--past, present, and future

Cough remains a serious unmet clinical problem, both as a symptom of a range of other conditions such as asthma, chronic obstructive pulmonary disease, gastroesophageal reflux, and as a problem in its own right in patients with chronic cough of unknown origin. This article reviews our current understanding of the pathogenesis of cough and the hypertussive state characterizing a number of diseases as well as reviewing the evidence for the different classes of antitussive drug currently in clinical use. For completeness, the review also discusses a number of major drug classes often clinically used to treat cough but that are not generally classified as antitussive drugs. We also reviewed a number of drug classes in various stages of development as antitussive drugs. Perhaps surprising for drugs used to treat such a common symptom, there is a paucity of well-controlled clinical studies documenting evidence for the use of many of the drug classes in use today, particularly those available over the counter. Nonetheless, there has been a considerable increase in our understanding of the cough reflex over the last decade that has led to a number of promising new targets for antitussive drugs being identified and thus giving some hope of new drugs being available in the not too distant future for the treatment of this often debilitating symptom.

A real - life observational pilot study to evaluate the effects of two-week treatment with montelukast in patients with chronic cough

Background

Different conditions make the proximal airways susceptible to tussigenic stimuli in the chronic cough (CC) syndrome. Leukotrienes can be implicated in the inflammatory mechanism at play in it. Montelukast is a selective cysteinyl-leukotriene receptor antagonist with proven effectiveness in patients with asthma. The aim of our real-life pilot study was to use montelukast to relieve cough symptoms in patients with CC allegedly due to the two frequent causes other than asthma – upper airway cough syndrome and gastroesophageal reflux (GER).

Methods

14 consecutive patients with CC were evaluated before and after 2 weeks of treatment with montelukast 10 mg daily. Cough was assessed by validated cough questionnaire. Questionnaires regarding the presence of gastroesophageal reflux were also completed. Cough reflex sensitivity to incremental doubling concentrations of citric acid and capsaicin was measured. Lung function, airway hyperresponsiveness and exhaled breath temperature (EBT), a non-invasive marker of lower airway inflammation, were evaluated to exclude asthma as an underlying cause. Thorough upper-airway examination was also conducted. Cell counts, eosinophil cationic protein (ECP), lactoferrin, myeloperoxidase (MPO) were determined in blood to assess systemic inflammation.

Results

Discomfort due to cough was significantly reduced after treatment (P < 0.001). Cough threshold for capsaicin increased significantly (P = 0.001) but not for citric acid. The values of lactoferrin and ECP were significantly reduced, but those of MPO rose. EBT and pulmonary function were not significantly affected by the treatment.

Conclusion

Patients with CC due to upper airway cough syndrome or gastroesophageal reflux (GER) but not asthma reported significant relief of their symptoms after two weeks of treatment with montelukast. ECP, lactoferrin, MPO altered significantly, highlighting their role in the pathological mechanisms in CC. Clinical trial ID at Clinicaltrials.gov is NCT01754220.

Urine Leukotriene E4 Levels in Children with Nonspecific Isolated Chronic Dry Cough

Chronic cough is the most common complaint during childhood. Various pathophysiologic mechanisms may cause cough. Knowledge of the mechanisms underlying chronic cough plays an important role in the choice of treatment to evaluate the role of leukotrienes in children with nonspecific isolated chronic dry cough. The patient group consisted of children with isolated chronic dry cough persisting for >4 weeks and the control group included healthy children. Medical histories were elicited and physical examinations were performed, then respiratory function testing was done and chest X-rays were obtained. Patients were given inhaled corticosteroid. The urine leukotriene E4 (uLTE4) levels in the patient and control groups was measured by enzyme immunoassay. The patient group included 55 patients, 25 of them were males between 6 and 12 years old. The control group included 25 healthy children between 6 and 12 years old, 12 of them were males. There were no pathologic findings on physical examinations, pulmonary function testing, and chest X-rays. The complaints of cough in 50 patients were resolved after treatment. The median level of uLTE4 was 73.1 ng/mmol creatinine (range, 15.59-787.55 ng/mmol creatinine) in the patient group, and 64.2 ng/mmol creatinine (range, 12-282 ng/mmol creatinine) in the control group. No significant difference was detected between the 2 groups with respect to age, gender, and uLTE4 levels. Different pathophysiologic mechanisms are known to influence nonspecific isolated chronic dry cough. Various mechanisms, other than leukotrienes, may also give rise to dry cough.

Cough, asthma, and cysteinyl-leukotrienes

Asthma is a chronic inflammatory disease of the lower airways, involving various cells such as eosinophils, and cytokines and mediators. Cyteinyl-leukotrienes (cys-LTs) are one of the chemical mediators that play major pathophysiological roles in asthma. They are produced by eosinophils and mast cells, and induce bronchoconstriction, mucous hypersecretion, microvascular leakage, eosinophil chemotaxis and airway remodeling. Anti-leukotrienes, including leukotriene receptor antagonists (LTRAs) which block cysLT1 receptors, exert both bronchodilatory and anti-inflammatory effects and are utilized as second- to third-line controller medication of persistent asthma. Cough is a major symptom of asthma, and cough variant asthma (CVA) is an asthma phenotype that solely presents with coughing. Sputum levels of cys-LTs are increased in patients with CVA. Antitussive effects of monotherapy with LTRAs in patients with CVA have been reported. We have recently demonstrated that 4 weeks' treatment with an LTRA montelukast exerted anti-inflammatory effect as proved by a decrease of sputum eosinophils, in addition to attenuation of cough VAS and capsaicin cough sensitivity, as reported previously. Spirometry, airway responsiveness, and impulse oscillation indices (respiratory resistance and reactance) were unchanged. These results suggested that the antitussive effect of montelukast in CVA might be attributable to its anti-inflammatory ability rather than bronchodilation. The treatment did not affect sputum levels of mediators (cys-LTs, LTB4, PGD2, PGE2, PGF2α, and TXB2). Since inhaled corticosteroid does not seem to affect cough sensitivity while attenuating cough in patients with CVA, LTRAs may involve different mechanism(s) from that of corticosteroid. LTRAs must theoretically be effective against cough of asthmatic subjects through its "anti-asthma" effects, while evidence supporting direct antitussive effects of cys-LTs on "cough receptors" is scarce. An important clinical question is that whether LTRAs involve non-specific antitussive effects. While a definite answer is not available yet, this possibility seems unlikely at the moment, although some secondary anti-inflammatory properties have been reported for montelukast. This issue needs to be clarified by future research to avoid overuse of this expensive class of medication.

Add-on montelukast vs double-dose budesonide in nonasthmatic eosinophilic bronchitis: a pilot study

BACKGROUND

Budesonide at 800 μg/d is generally suggested for treatment of nonasthmatic eosinophilic bronchitis (NAEB). In asthma, adjunctive therapy with montelukast has been shown to confer addictive anti-inflammatory effects to inhaled corticosteroid (ICS). However, whether such effects could be extrapolated to NAEB is not known.

OBJECTIVES

To study the efficacy and tolerability of add-on therapy with montelukast as compared to double-dose ICS in suppressing airway eosinophilia and decreasing cough severity in NAEB.

METHODS

In a randomized controlled trial, 26 nonsmoking, steroid-naïve NAEB patients presenting with chronic cough were treated with 800 μg/d budesonide or 400 μg/d budesonide plus montelukast 10 mg/d for 4 weeks. Cough visual analogue scale (CVAS) and eosinophil differential ratio in induced sputum (Eos) were monitored at baseline, Week 1, 2 and 4. Adverse events during treatment were recorded.

RESULTS

The two groups were comparable in age, gender distribution, cough duration, FEV(1)% predicted, FEV(1)/FEV ratio, baseline CVAS and geometric mean of Eos. Both regimens significantly reduced Eos and CVAS throughout the treatment course, with abrogation of sputum eosinophilia at end of therapy. There was no significant difference between the two groups in reduction of Eos and CVAS at all time points. Both regimens were well tolerated.

CONCLUSIONS

This preliminary study demonstrated that add-on montelukast might be an effective and well tolerated alternative to the generally suggested dose of ICS in treating steroid-naive NAEB, with suppression of eosinophilic inflammation, reduction of cough severity and sparing of ICS doses. (NCT01121016).

Clinical, physiological and anti-inflammatory effect of montelukast in patients with cough variant asthma

BACKGROUND

Cough variant asthma (CVA) is a phenotype of asthma presenting solely with coughing, characterized by airway hyperresponsiveness, eosinophilic inflammation and a cough response to bronchodilators. Leukotriene receptor antagonists (LTRAs) are antiasthma medications with anti-inflammatory and bronchodilatory properties. Although LTRAs exert antitussive effects in CVA, the mechanisms involved are unknown.

OBJECTIVES

This study aimed to clarify the antitussive mechanisms of LTRAs in CVA patients.

METHODS

We prospectively observed the effect of montelukast (10 mg) daily for 4 weeks in 23 consecutive nonsmoking adults with anti-inflammatory treatment-naive CVA. We evaluated, before and after treatment, the cough visual analogue scale (VAS), pulmonary function (spirometry and impulse oscillation), methacholine airway responsiveness, cough receptor sensitivity, expressed by the concentration of capsaicin inducing 2 or more (C2) and 5 or more (C5) coughs, sputum eosinophil counts and levels of inflammatory mediators, including cysteinyl leukotrienes, leukotriene B(4), prostaglandin (PG) D(2), PGE(2), PGF(2)(α) and thromboxane B(2). We compared the baseline characteristics of the patients based on the symptomatic response to montelukast, defined as a decrease in the cough VAS of >25% (n = 15) or ≤25% (n = 8).

RESULTS

Montelukast significantly decreased the cough VAS (p = 0.0008), sputum eosinophil count (p = 0.013) and cough sensitivity (C2: p = 0.007; C5: p = 0.039), whereas pulmonary function, airway responsiveness and sputum mediator levels remained unchanged. Multivariate analysis showed that a better response to montelukast was associated solely with younger age (p = 0.032).

CONCLUSION

The antitussive effect of montelukast in CVA may be attributed to the attenuation of eosinophilic inflammation rather than its bronchodilatory properties.

Unusual asthma syndromes and their management

Asthma usually presents with symptoms of wheeze, dyspnoea and cough. However, clinicians should be aware of atypical presentation of this disorder when cough is the main or only symptom in conditions such as cough-variant asthma, nonasthmatic eosinophilic bronchitis and atopic cough. Early diagnosis and treatment of these conditions with inhaled corticosteroids improves symptoms in the majority of patients. Up to 10% of patients with asthma remain poorly controlled in spite of optimal standard therapy. These patients have been encompassed under the term 'treatment-refractory asthma' (TRA), have the greatest morbidity and are responsible for more than 50% of healthcare costs. In this review we discuss investigations, management and pathophysiology of the various phenotypes of atypical presentations of asthma as well as novel biological agents licensed and those that have been reported in clinical trials in terms of their efficacy and safety in TRA.

Cough: an unmet clinical need

Cough is among the most common complaints for which patients worldwide seek medical attention. Thus, the evaluation and treatment of cough result in tremendous financial expenditure and consumption of health care resources. Yet, despite the clinical significance of cough, research efforts aimed at improving diagnostic capabilities and developing more effective therapeutic agents have been, to date, disappointing in their limited scope and outcomes. Acute cough due to the common cold represents the most common type of cough. Currently, available medications for the symptomatic management of acute cough are inadequate due to lack of proven efficacy and/or their association with undesirable or intolerable side effects at anti-tussive doses. Subacute cough, often representing a prolonged post-viral response, is typically refractory to standard anti-tussive therapy. Few clinical trials have evaluated therapeutic options for subacute cough. Diagnostic challenges facing the clinician in the management of chronic cough include the determination of whether symptoms of upper airway cough syndrome (formerly, postnasal drip syndrome) or gastro-oesophageal reflux disease are indeed the underlying cause of cough. Chronic, refractory unexplained (formerly, idiopathic) cough must be distinguished from cough that has not been fully evaluated and treated according to current guideline recommendations. Eagerly awaited are new safe and effective anti-tussive agents for use when cough suppression is desired, regardless of underlying aetiology of cough, as well as practical, validated ambulatory cough counters to aid clinical assessment and future research in the field of cough.

Leukotriene receptor antagonist for prolonged non-specific cough in children

BACKGROUND

Non-specific cough is defined as non-productive cough in the absence of identifiable respiratory disease or known aetiology. It is commonly seen in paediatric practice. These children are treated with a variety of therapies including a variety of asthma medications. The leukotriene pathway is reported to be involved in the sensory (neurogenic) pathway, which is a mechanism thought to be involved in the pathogenesis of chronic cough.

OBJECTIVES

To evaluate the effectiveness of leukotriene receptor antagonist (LTRA) in treating children with prolonged non-specific cough.

SEARCH STRATEGY

The Cochrane Register of Controlled Trials (CENTRAL), the Cochrane Airways Group Specialised Register, MEDLINE and EMBASE databases were searched by the Cochrane Airways Group. The latest searches were carried out in September 2005.

SELECTION CRITERIA

All randomised controlled trials comparing LTRA with a placebo medication in children with non-specific cough.

DATA COLLECTION AND ANALYSIS

Results of searches were reviewed against pre-determined criteria for inclusion. One eligible trial was identified but no data was available for analysis. It was not possible to separate results from children with non-specific cough from those without.

MAIN RESULTS

There was no significant difference in all study endpoints between the montelukast and placebo groups (total N=256).

AUTHORS' CONCLUSIONS

With the lack of evidence, the routine use of LRTA in treating children with non-specific cough cannot be recommended.