Airway responsiveness after a single dose of salmeterol and during four months of treatment in children with asthma

The burden of exacerbations in mild asthma: a systematic review

Background

Although most patients with asthma have mild disease, data on how mild asthma is defined, and how frequently exacerbations occur in this patient population are scarce, so we aimed to redress this.

Methods

We searched Medline and Medline In-Process (PubMed), and Embase in OVID for English-language publications containing “mild asthma” plus at least one relevant therapy and outcome/keyword, limited to randomised controlled trials (RCTs) and observational studies published between January 1990 and February 2019. Publications were filtered to ensure appropriate data extraction. The main outcomes were the definitions of mild asthma and exacerbations, baseline exacerbation rates and exacerbation data for placebo recipients in prospective studies. Meta-analysis of exacerbation rates was planned.

Findings

Of 4064 articles identified, 64 were included in our review (49 743 subjects); 54 RCTs and 10 observational/other studies. Six main types of definitions of mild asthma were identified. While care was taken to ensure inclusion only of patients with mild asthma, marked heterogeneity was revealed in the definitions of mild asthma and hence the study populations. Reporting of exacerbations also varied widely between studies, precluding meta-analysis. Between 0–22% of patients were hospitalised for asthma or had a severe exacerbation in the previous year, according to baseline data from prospective studies. In RCTs, severe exacerbation rates in placebo recipients taking only short-acting β₂-agonist therapy ranged from 0.20–2.88 per year.

Conclusions

These data provide new evidence of the burden of exacerbations in mild asthma and highlight the need for standardised definitions of mild asthma and of exacerbations to progress further research.

This comprehensive literature review highlights the risk of exacerbations for patients with mild asthmahttps://bit.ly/3cauSb3

Pharmacogenomics of long-acting β2-agonists

INTRODUCTION

Long-acting β2-agonists are an effective class of drugs, when combined with inhaled corticosteroids, for reducing symptoms and exacerbations in patients with asthma that is not adequately controlled by inhaled corticosteroids alone. However, because this class of drugs has been associated with severe adverse events, including hospitalization and death in small numbers of patients, efforts to identify a pharmacogenetic profile for patients at risk has been diligently investigated.

AREAS COVERED

The PubMed search engine of the National Library of Medicine was used to identify English-language and non-English language articles published from 1947 to March 2015 pertinent to asthma, pharmacogenomics, and long-acting β2-agonists. Keywords and topics included: asthma, asthma control, long-acting β2-agonists, salmeterol, formoterol, pharmacogenetics, and pharmacogenomics. This strategy was also used for the Cochrane Library Database and CINAHL. Reference types were randomized controlled trials, reviews, and editorials. Additional publications were culled from reference lists. The publications were reviewed by the authors and those most relevant were used to support the topics covered in this review.

EXPERT OPINION

Children, who carry the ADRB2 Arg16Arg genotype, may be at greater risk than adults for severe adverse events. Rare ADRB2 variants appear to provide better clues for identifying the at-risk population of asthmatics.

Effect of montelukast or salmeterol added to inhaled fluticasone on exercise-induced bronchoconstriction in children

OBJECTIVES

To evaluate the effect of montelukast, 5 mg, or inhaled salmeterol, 50 microg, added to inhaled fluticasone in reducing the maximum percentage decrease in forced expiratory volume in 1 second (FEV1) after a standardized exercise challenge and response to rescue bronchodilation with albuterol in children aged 6 to 14 years with persistent asthma and exercise-induced bronchoconstriction (EIB).

METHODS

Randomized, double-blind, double-dummy, multicenter, 2-period, 4-week, crossover study conducted between December 22, 2005 and November 14, 2008 at 30 centers in Europe, Asia, Mexico, and South America. Patients with asthma receiving inhaled corticosteroids demonstrated an FEV1 of 70% or higher of the predicted value and EIB (defined as a decrease in FEV1 > or = 15% compared with preexercise baseline FEV1 on 2 occasions before randomization). Standardized exercise challenges were performed at baseline (prerandomization) and at the end of each active treatment period.

RESULTS

Of 154 patients randomized, 145 completed the study. Montelukast, compared with salmeterol, significantly reduced the mean maximum percentage decrease in FEV1 (10.6% vs 13.8%; P = .009), mean area under the curve for the first 20 minutes after exercise (116.0% x min vs 168.8% x min; P = .006), and median time to recovery (6.0 vs 11.1 minutes; P = .04). Response to albuterol rescue after exercise challenge was significantly greater (P < .001) with montelukast. Montelukast and salmeterol were generally well tolerated.

CONCLUSIONS

Attenuation and response of EIB to albuterol rescue after exercise challenge were significantly better with montelukast than with salmeterol after 4 weeks of treatment.

Use and safety of long-acting β2-agonists for pediatric asthma

Asthma guidelines recommend the use of long-acting β2-agonists (LABAs) as the preferred add-on therapy for adults and children over 5 years of age when asthma is inadequately controlled by inhaled corticosteroids alone. It has been suggested that LABA use may be associated with an increased risk of morbidity and mortality; however, this view is controversial since study findings have been inconsistent. While the safety profile of LABA monotherapy has been questioned, the value of concomitant inhaled corticosteroids to eliminate possible risks remains unproven. There is a paucity of efficacy and safety data for LABA use in children, and existing evidence is not sufficiently convincing to demonstrate a clear position for LABAs in the management of childhood asthma. The main aims of this article are to place LABAs in context in the management of childhood asthma and evaluate the current evidence for safety and efficacy.

Childhood evaluation of salmeterol tolerance--a double-blind randomized controlled trial

Long acting beta(2)-agonists (LABA) are widely used in children with asthma. Data from adults suggest that there is tachyphylaxis particularly to the bronchoprotective effects of LABA. There are no data in children. To determine whether LABA are subject to tachyphylaxis in school-aged children. Children were eligible for participation if they remained symptomatic on 400 microg of beclometasone dipropionate equivalent/day. Participants undertook a 4-wk run in period with open-label fluticasone 100 microg BD via Diskus. Children were then randomized to receive fluticasone 100 microg BD or salmeterol/fluticasone 50/100 microg BD via Diskus in a double-blind manner. Children underwent spirometry, cold air challenge and salbutamol reversibility testing at baseline, 4 and 8 wk. 37/42 children completed the study. There were significant improvements in basal FEV1 (% predicted) in the salmeterol/fluticasone group (n = 21) (+6.4% (95% CI: 2.4-10.5) p = 0.0033) but not in the fluticasone group (n = 16) [+1.2 (95% CI: -3.4 to 5.8) p = 0.5900]. There was a non-significant reduction in fall in FEV1 provoked by cold air in both groups. There was a significant lessening in the acute salbutamol response after 8 wk in the salmeterol/fluticasone group [-11.4% (95% CI: -17.6 to -5.2) p = 0.0010] but not in the fluticasone group [-1.6% (95% CI: -9.8 to 6.6) p = 0.6827]. Salmeterol/fluticasone therapy significantly improves basal FEV(1) in asthmatic children however, there is negligible additional bronchoprotection by week 4 of treatment and there is significant attenuation of salbutamol responsiveness when compared with fluticasone alone. Some of this reduction in salbutamol response may relate to the concurrent improvements in baseline lung function.

Asthma

Asthma has been recognized as a disease since the earliest times. In the Corpus Hippocraticum, Hippocrates used the term “ασθμα” to indicate any form of breathing difficulty manifesting itself by panting. Aretaeus of Cappadocia, a well-known Greek physician (second century A.D.), is credited with providing the first detailed description of an asthma attack [13], and to Celsus it was a disease with wheezing and noisy, violent breathing. In the history of Rome, we find many members of the Julio-Claudian family affected with probable atopic respiratory disorders: Caesar Augustus suffered from bronchoconstriction, seasonal rhinitis as well as a highly pruritic skin disease. Claudius suffered from rhinoconjunctivitis and Britannicus was allergic to horse dander [529]. Maimonides (1136–1204) warned that to neglect treatment of asthma could prove fatal, whereas until the 19th century, European scholars defined it as “nervous asthma,” a term that was given to mean a defect of conductivity of the ninth pair of cranial nerves.

Long-acting beta2-agonists for chronic asthma in adults and children where background therapy contains varied or no inhaled corticosteroid

BACKGROUND

Asthma is a common respiratory disease among both adults and children and short acting inhaled beta-2 agonists are used widely for 'reliever' bronchodilator therapy. Long acting beta-2 agonists (LABA) were introduced as prospective 'symptom controllers' in addition to inhaled corticosteroid 'preventer' therapy (ICS). In this updated review we have included studies in which patients were either not on ICS as a group, or in which some patients, but not all, were on ICS to complement previous systematic reviews of studies where LABA was given in patients uniformly receiving ICS. We have focussed particularly on serious adverse events, given previous concerns about potential risks, especially of death, from regular beta-2 agonist use.

OBJECTIVES

This review aimed to determine the benefit or detriment on the primary outcome of asthma control with the regular use of LABA compared with placebo, in mixed populations in which only some were taking ICS and in populations not using ICS therapy.

SEARCH STRATEGY

We carried out searches using the Cochrane Airways Group trial register, most recently in October 2005. We searched bibliographies of identified RCTs for additional relevant RCTs and contacted authors of identified RCTs for other published and unpublished studies.

SELECTION CRITERIA

All randomised studies of at least four weeks duration, comparing a LABA given twice daily with a placebo, in chronic asthma. Selection criteria to this updated review have been altered to accommodate recently published Cochrane reviews on combination and addition of LABA to ICS therapy. Studies in which all individuals were uniformly taking ICS were excluded from this review.

DATA COLLECTION AND ANALYSIS

Two reviewers performed data extraction and study quality assessment independently. We contacted authors of studies for missing data.

MAIN RESULTS

Sixty-seven studies (representing 68 experimental comparisons) randomising 42,333 participants met the inclusion criteria. Salmeterol was used as long-acting agent in 50 studies and formoterol fumarate in 17. The treatment period was four to nine weeks in 29 studies, and 12 to 52 weeks in 38 studies. Twenty-four studies did not permit the use of ICS, and forty permitted either inhaled corticosteroid or cromones (in three studies this was unclear). In these studies between 22% and 92% were taking ICS, with a median of 62%. There were significant advantages to LABA treatment compared to placebo for a variety of measurements of airway calibre including morning peak expiratory flow (PEF), evening PEF and FEV1. They were associated with significantly fewer symptoms, less use of rescue medication and higher quality of life scores. This was true whether patients were taking LABA in combination with ICS or not. Findings from SMART (a recently published surveillance study) indicated significant increases in asthma related deaths, respiratory related deaths and combined asthma related deaths and life threatening experiences. The absolute increase in asthma-related mortality was consistent with an increase of around one per 1250 patients treated with LABA for six months, but the confidence intervals are wide (from 700 to 10,000). Post-hoc exploratory subgroups suggested that African-Americans and those not on inhaled corticosteroids were at particular risk for the primary end-point of death or life-threatening asthma event. There was also a suggestion of an increase in exacerbation rate in children. Pharmacologically predicted side effects such as headache, throat irritation, tremor and nervousness were more frequent with LABA treatment.

AUTHORS' CONCLUSIONS

LABA are effective in the control of chronic asthma in the "real-life" subject groups included. However there are potential safety issues which call into question the safety of LABA, particularly in those asthmatics who are not taking ICS, and it is not clear why African-Americans were found to have significant differences in comparison to Caucasians for combined respiratory-related death and life threatening experiences, but not for asthma-related death.

Benefit-risk assessment of long-acting beta2-agonists in asthma

The use of a regular long-acting beta2-adrenoceptor agonists (beta2-agonists; LABA) is now established in asthma guidelines as the preferred option for second-line controller therapy in addition to inhaled corticosteroids. This has been driven by data showing beneficial effects of LABAs on exacerbation rates, in turn suggesting a putative corticosteroid-sparing effect. As LABAs are devoid of any clinically meaningful anti-inflammatory activity in vivo, their effects on exacerbations are presumably due to a diurnal stabilising effect on airway smooth muscle. LABAs have marked effects on symptoms and lung function, and this may make it difficult to assess anti-inflammatory control with inhaled corticosteroids when used in a combination inhaler such as fluticasone propionate/salmeterol or budesonide/formoterol. The use of fixed-dose combination inhalers is in many respects counter-intuitive to conventional teaching regarding flexible dosage titration with inhaled corticosteroids. It would therefore seem prudent first to gain optimal control of inflammation with inhaled corticosteroids before considering adding a LABA. Increasing the dosage of inhaled corticosteroids will have a relatively greater effect on exacerbations than on symptoms and lung function, whereas the converse applies when adding a LABA. Another option is to add a leukotriene receptor antagonist, which confers additional anti-inflammatory activity and is as effective on exacerbations as adding a LABA. Despite in vitro and ex vivo data showing a ligand-independent effect of LABAs on glucocorticoid receptor activation, clinical data do not indicate any relevant synergy between LABAs and inhaled corticosteroids when used together in the same inhaler. In particular, there is no evidence of potentiation by LABAs of the in vivo anti-inflammatory activity of inhaled corticosteroids that would suggest any genuine corticosteroid-sparing activity. Nonetheless, the data support the additive effects of inhaled corticosteroids and LABAs when used together due to their separate effects on inflammation and smooth muscle, respectively. Tolerance with LABAs is a predictable pharmacological phenomenon that occurs despite concomitant therapy with inhaled corticosteroids. Moreover, cross-tolerance also develops to short-acting beta2-agonists used for protection against bronchoconstrictor stimuli as a result of LABA-induced down-regulation, desensitisation and prolonged occupancy of beta2-adrenoceptors. The exact role of beta2-adrenoceptor polymorphism in determining tolerance with LABAs requires further prospective clinical studies evaluating long-term effects on outcomes such as exacerbations in patients with relevant genotypes and haplotypes. The next decade will provide challenging issues for clinicians with respect to defining further the role of LABAs as add-on controller therapy, particularly in evaluating the long-term effects of combination inhalers on inflammatory outcomes and airway remodelling.

Treatment of childhood asthma: how do the available options compare?

The National Asthma Council of Australia suggests that "the aim of preventive therapy should be to enable patients to enjoy a normal life (comparable with that of non-asthmatic children), with the least amount of medication and at minimal risk of adverse events. The level of maintenance therapy should be determined by symptom control and lung function in the interval periods." The British Thoracic Society/Scottish Intercollegiate Guidelines Network states that the aims of the pharmacological treatment of asthma should be to control symptoms, prevent exacerbations and achieve the best possible lung function with minimal adverse effects. We have used the current published international guidelines to highlight the international differences in management recommendations, and compared the possible pharmacological options with a focus on the above ideals. Cromones have been used for many years in childhood asthma. Most evidence suggests they now have little role. Regarding inhaled corticosteroids (ICS), beclomethasone and budesonide are essentially similar in their efficacy. Fluticasone propionate is equally as effective at one-half the equivalent dose of budesonide or beclomethasone. Adverse effects are rare in dosages <400 microg/day of budesonide and beclomethasone or <200 microg/day of fluticasone propionate, but may occur in individual patients. Relevant clinical adverse effects are rare and pharmacological systemic effects are less noticeable with budesonide and fluticasone propionate than with beclomethasone, but data are conflicting. Long-acting beta2-adrenoceptor agonists (beta2-agonists) are recommended once low-dose ICS have failed to control symptoms. The main pharmacological difference between the agents is that formoterol is a full beta2-adrenergic agonist, whereas salmeterol is a partial agonist at the beta2-adrenoceptor and has a unique pharmacological action. The main clinical distinction between these two agents is that their onset of bronchodilation differs. Bronchodilation begins at about 3 minutes after inhalation of formoterol, which is similar to the short-acting agents, whereas salmeterol has a much slower onset of action at about 15-30 minutes. The many in vitro differences between the two drugs are probably not clinically relevant. There are no comparative pediatric data on the leukotriene modifiers to make clear recommendations.

Inhaled long acting beta agonists for stable chronic asthma

BACKGROUND

Asthma is a common respiratory disease among both adults and children and short acting inhaled beta-2 agonists are used widely for 'reliever' bronchodilator therapy. Long acting beta-2 agonists were introduced as prospective 'symptom controllers' in addition to inhaled corticosteroid 'preventer' therapy (ICS).

OBJECTIVES

This review aimed to determine the benefit or detriment on the primary outcome of asthma control with the regular use of long acting inhaled beta-2 agonists compared with placebo.

SEARCH STRATEGY

We carried out searches using the Cochrane Airways Group trial register, most recently in October 2002. We searched bibliographies of identified RCTs for additional relevant RCTs and contacted authors of identified RCTs for other published and unpublished studies.

SELECTION CRITERIA

All randomised studies of at least two weeks duration, comparing a long acting inhaled beta-agonist given twice daily with a placebo, in chronic asthma.

DATA COLLECTION AND ANALYSIS

Two reviewers performed data extraction and study quality assessment independently. We contacted authors of studies for missing data.

MAIN RESULTS

Eighty five studies met the inclusion criteria, 56 parallel group and 29 cross over design. Salmeterol xinafoate was used as long acting agent in 60 studies and formoterol fumarate in 25. The treatment period was two to four weeks in 32 studies, and 12 to 52 weeks in 53 studies. 34 study groups used concurrent inhaled corticosteroid treatment, 21 studies did not permit their use and 35 permitted either inhaled corticosteroid or cromones. There were significant advantages to long acting beta-2 agonist treatment compared to placebo for a variety of measurements of airway calibre including morning peak expiratory flow (PEF) (weighted mean difference (WMD) 26.78 L/min 95%CI 20.36 to 33.20), evening PEF (WMD 19.17 L/min 95%CI 11.63 to 26.73). They were associated with significantly fewer symptoms, less use of rescue medication and higher quality of life scores. The risk of exacerbation was lower in adults using regular inhaled corticosteroids.

REVIEWER'S CONCLUSIONS

Long acting beta-2 agonists are effective in the control of chronic asthma, and the evidence supports their use in addition to inhaled corticosteroids, as emphasised in current guidelines. Further research is needed on their use in children under 12 and in mild asthmatics not taking ICS.

Antagonism of long-acting beta2-adrenoceptor agonism

The established place of regular long-acting beta2-adrenoceptor agonists at step 3 in asthma management guidelines has evolved as a consequence of evidence showing additive effects of salmeterol and formoterol on exacerbation rates, resulting in a putative inhaled corticosteroid sparing effect. There is however, evidence to show that although long-acting beta2-adrenoceptor agonists facilitate using a lower dose of inhaled corticosteroid, this may occur at the expense of suboptimal anti-inflammatory control. This is likely to be the case especially with fixed dose combination inhalers where it is not possible to properly titrate anti-inflammatory therapy with inhaled corticosteroids without also inadvertently overtreating with unnecessarily high doses of long-acting beta2-adrenoceptor agonists. Most patients with mild to moderate persistent asthma can be adequately controlled on monotherapy with inhaled corticosteroid in low or medium dosage, which is considerably cheaper than concomitant use of a long-acting beta2-adrenoceptor agonist. Subsensitivity to long-acting beta2-adrenoceptor agonists is a predictable pharmacological phenomenon which occurs despite concomitant inhaled corticosteroid therapy and occurs more readily for bronchoprotective than bronchodilator effects. Subsensitivity of salbutamol protection against bronchoconstrictor stimuli occurs in patients receiving concomitant long-acting beta2-adrenoceptor agonists, which may be due to beta2-adrenoceptor down-regulation or prolonged receptor occupancy. Prospective large scale long-term studies are required to further define the clinical relevance of beta2-adrenoceptor polymorphisms, to look at clinical control outcomes as well as propensity for subsensitivity. It would therefore make more sense to first of all optimize the dose of anti-inflammatory therapy with inhaled corticosteroid and to then consider adding a long-acting beta2-adrenoceptor agonist for patients who are poorly controlled.

Regular treatment with long acting beta agonists versus daily regular treatment with short acting beta agonists in adults and children with stable asthma

BACKGROUND

Selective beta-adrenergic agonists for use in asthma are: short acting (2-6 hours) and long acting (>12 hours). There has been little controversy about using short acting beta-agonists intermittently, but long acting beta-agonists are used regularly, and their regular use has been controversial.

OBJECTIVES

To determine the benefit or detriment of treatment with regular short- or long acting inhaled beta-agonists in chronic asthma.

SEARCH STRATEGY

A search was carried out using the Cochrane Airways Group register. Bibliographies of identified RCTs were searched for additional relevant RCTs. Authors of identified RCTs were contacted for other published and unpublished studies.

SELECTION CRITERIA

All randomised studies of at least two weeks duration, comparing a long acting inhaled beta-agonist given twice daily with any short acting inhaled beta-agonist of equivalent bronchodilator effectiveness given regularly in chronic asthma.

DATA COLLECTION AND ANALYSIS

Two reviewers performed data extraction and study quality assessment independently. Authors of studies were contacted for missing data.

MAIN RESULTS

31 studies met the inclusion criteria, 24 of parallel group and 7 cross over design. Salmeterol xinafoate was used as long acting agent in 22 studies and formoterol fumarate in 9. Salbutamol was the short acting agent used in 27 studies and terbutaline in 5. The treatment period was over 2 weeks in 29 studies, and at least 12 weeks in 20. 25 studies permitted a variety of co-intervention treatments, usually inhaled corticosteroid or cromones. One study did not permit inhaled corticosteroid. Long acting beta-agonists were significantly better than short acting for a variety of lung function measurements including morning PEF (Weighted Mean Difference (WMD) 33 l/min 95% CI 25, 42) or evening PEF (WMD 26 l/min 95% CI 18, 33); and had significantly lower scores for day and night time asthma symptom scores and percentage of days and nights without symptoms. They were also associated with a significantly lower use of rescue medication both during the day and night. Risk of exacerbations was not different between the two types of agent, but most studies were of short duration which limits the power to test for such differences.

REVIEWER'S CONCLUSIONS

Long acting inhaled beta-agonists have advantages across a wide range of physiological and clinical outcomes for regular treatment.

Beta2-adrenoceptors: mechanisms of action of beta2-agonists

The human beta2-adrenoceptor is a member of the 7 transmembrane family of receptors. It is encoded by a gene on chromosome 5 and is widely distributed in the respiratory tract. Following beta2-adrenoceptor activation, intracellular signalling is mainly produced by inducing cyclic AMP. This produces airway relaxation through phosphorylation of muscle regulatory proteins and modification of cellular Ca2+concentrations. Beta2-agonists have been characterised into those which directly activate the receptor (salbutamol/terbutaline), those which are taken up into a membrane depot (formoterol) and those which interact with a receptor-specific, auxiliary binding site (salmeterol). These differences in mechanism of action are reflected in the kinetics of airway smooth muscle relaxation and bronchodilation in asthmatic patients. Beta-adrenoceptor desensitisation is associated with beta2-agonist activation and differs depending on the cell type. It is reflected in the different profiles of clinical tolerance to chronic beta2-agonist therapy. A number of polymorphisms of the beta2-receptor have been described which appear to alter the behaviour of the receptor, including the degree of downregulation and response to beta2-agonists.

Salmeterol in paediatric asthma

BACKGROUND

The addition of long acting inhaled beta(2) agonists is recommended at step 3 of the British guidelines on asthma management but a recent study suggested no additional benefit in children with asthma.

METHODS

The aim of this study was to compare, in a double blind, three way, crossover study, the effects of the addition of salmeterol 50 microg bd, salmeterol 100 microg bd, and salbutamol 200 microg qds in asthmatic children who were symptomatic despite treatment with inhaled corticosteroids in a dose of at least 400 microg/day over a one month period. Symptom scores, morning and evening peak expiratory flow (PEF) rates, use of rescue medication, spirometric indices, and histamine challenge were measured.

RESULTS

Forty five children aged 5-14 years were enrolled. All three treatments improved asthma control, morning and evening PEF rates, and spirometric indices with no change in bronchial hyperreactivity. Mean morning PEF was significantly better during the salmeterol treatment periods than with salbutamol treatment (p<0.05). The analysis of mean morning PEF gave an estimated treatment difference of 9.6 l/min for salmeterol 50 microg bd versus salbutamol 200 microg qds (95% confidence interval (CI) 2.1 to 17.1), and an estimated treatment difference of 13.8 l/min for salmeterol 100 microg bd versus salbutamol 200 microg qds (95% CI 6.0 to 21.5). There were no significant differences between the two doses of salmeterol and all treatments were well tolerated.

CONCLUSIONS

In this population of moderate to severe asthmatic children on inhaled corticosteroids, salmeterol in a dose of either 50 microg bd or 100 microg bd is significantly more effective at increasing the morning PEF rate over a one month period than salbutamol 200 microg qds. The data provided no significant evidence of a difference in efficacy between the two doses of salmeterol, 50 microg and 100 microg. A trial of salmeterol 100 microg bd may be worth considering in those still symptomatic on the lower dose.

Long-acting beta(2)-agonists in management of childhood asthma: A critical review of the literature

This review assesses the evidence regarding the use of long-acting beta(2)-agonists in the management of pediatric asthma. Thirty double-blind, randomized, controlled trials on the effects of formoterol and salmeterol on lung function in asthmatic children were identified. Single doses of inhaled salmeterol or formoterol cause prolonged bronchodilatation (>12 h) and extended bronchoprotection against exercise-induced bronchoconstriction in children, some children achieving full protection for more than 12 h. Heterogeneity in bronchoprotection has been observed, and individual dose-titration may be attempted. The onset of action of formoterol is comparable to salbutamol, while salmeterol has a slower onset of action. Partial tolerance develops when long-acting beta(2)-agonists are used as regular treatment, including cross-tolerance to short-acting beta(2)-agonists. Regular treatment with salmeterol in children with or without corticosteroids provides statistically significant bronchodilatation, but the degree of improvement in lung function or bronchoprotection against exercise and nonspecific irritants is small with regular use. There is no evidence of anti-inflammatory effects from inhaled long-acting beta(2)-agonists, which is reflected by unchanged or increased bronchial hyperreactivity and no reduction of exacerbation rates. The evidence does not support a recommendation for long-acting beta(2)-agonists as monotherapy, nor does it support their general use as regular add-on therapy. In conclusion, long-acting beta(2)-agonists provide effective bronchodilatation and bronchoprotection when used as intermittent, single-dose treatment of asthma in children, but not when used as regular treatment. Future studies should examine the positioning of long-acting beta(2)-agonists as an "as needed" rescue medication instead of short-acting beta(2)-agonists for pediatric asthma management.

Sustained bronchoprotection, bronchodilatation, and symptom control during regular formoterol use in asthma of moderate or greater severity. The Canadian FO/OD1 Study Group

BACKGROUND

Recent studies have raised concern that regular inhalation of beta2 -agonists may cause a worsening of asthma control compared with on-demand dosing regimens.

OBJECTIVE

The objective of this study was to compare the effect of twice daily formoterol (Foradil), 4 times daily albuterol, and on-demand albuterol on bronchial hyperresponsiveness (BHR), lung function measurements, symptoms, and other indicators of disease control over 6 months inpatients with asthma of moderate or greater severity receiving concomitant inhaled corticosteroids. We also looked for occurrence of rebound BHR on discontinuation of treatment.

METHODS

This was a multicenter, parallel-group, double-blind, clinical trial. Methacholine PC20 was the primary outcome variable. Other outcome variables included symptom scores, use of rescue medication, morning peak expiratory flow (PEF), serial FEV1 measurements, and asthma exacerbations.

RESULTS

Of the 271 randomized patients, 217 completed the study. Formoterol was significantly superior to on-demand albuterol with regard to methacholine PC20, FEV1, PEF, symptom scores, and use of rescue medication at each measured time point/interval. Regular albuterol was superior to on-demand albuterol with regard to PC20 and FEV1, but not PEF or various clinical scores. After a small drop in the magnitude of bronchoprotection and bronchodilatation occurring shortly after randomization, there was no evidence of progressive tolerance to either regular treatment for any of the measured variables or of rebound increase in BHR 2 days after the end of treatment. The formoterol group had the lowest number of exacerbation days, as defined by high intake of rescue bronchodilator and/or symptom scores, whereas the number of exacerbations requiring increased corticosteroid coverage was similar in the 3 groups.

CONCLUSION

In patients with asthma of moderate or greater severity receiving inhaled corticosteroids, formoterol taken twice daily resulted in superior bronchoprotection, bronchodilatation, and clinical control compared with on-demand albuterol over 6 months. Four times daily albuterol was superior to on-demand albuterol for only some of the end points. Progressive tolerance and a rebound increase in BHR on discontinuation of beta-agonists were not found

Effects of theophylline on tolerance to the bronchoprotective actions of salmeterol in asthmatics in vivo

Long-term treatment with salmeterol produces tolerance for its protective effects against bronchoconstrictor stimuli in patients with asthma. There is human in vitro evidence that theophylline may prevent beta2-adrenoceptor downregulation. Therefore, we investigated the effect of theophylline on the tolerance to the protective effect of salmeterol against histamine challenge in asthma in vivo. In a parallel 6-wk study, 25 asthmatics were treated with theophylline (mean serum level +/- SEM: 9.9 +/- 1.1 mg/L, Days 1 to 40) or placebo, combined with inhaled salmeterol (50 microgram twice daily, Days 8 to 36). Histamine challenges were carried out by tidal breathing method at entry, and at Days 4, 8, 22, 36, and 40. The response was measured by PC20. There was no significant change in PC20 after 4 d monotherapy with theophylline or placebo (mean difference +/- SEM: 0.54 +/- 0.39 and -0.02 +/- 0.41 doubling dose [DD], respectively; p > 0.15). One hour after the first dose, salmeterol afforded significant protection against histamine, as shown by an increase in PC20 in both the theophylline and placebo group (by 3.49 +/- 0.28 and 3.36 +/- 0.32 DD, respectively; p < 0. 001). However, after 2 and 4 wk salmeterol treatment, the improvements in PC20 by salmeterol were significantly reduced to 1. 80 +/- 0.35 and 1.69 +/- 0.36 DD, respectively, in the theophylline group (p < 0.001), and to 1.55 +/- 0.47 and 1.52 +/- 0.56 DD, respectively, in the placebo group (p < 0.002). These changes were not significantly different between the groups (p > 0.80). After cessation of salmeterol treatment, PC20 was not significantly different from the values at entry in either group (p > 0.90). We conclude that regular theophylline treatment neither prevents, nor worsens, the development of tolerance to the bronchoprotective effect of salmeterol in asthmatics in vivo.

Influence of beclomethasone and salmeterol on the perception of methacholine-induced bronchoconstriction

BACKGROUND

Patient evaluation of asthma severity and medication needs is mostly based on respiratory symptoms and may be influenced by changes in perception of bronchoconstriction-induced sensations. However, the influence of asthma medication on the ability to perceive symptoms is still to be documented. This study evaluated the effects of short-term and regular use of salmeterol on the perception of methacholine-induced bronchoconstriction (MIB) in subjects with mild asthma, using inhaled salbutamol on an "as required" basis (n=15), and in subjects with moderate asthma, using daily inhaled beclomethasone (mean daily dose, 640 microg; n=15) in addition to salbutamol to control their asthma.

METHODS

Methacholine challenges (MC) were performed at entry into the study, and then before, 1, and 12 h following inhalation of 50 microg of salmeterol or a placebo, after a 15-day baseline period; and after 4 weeks of twice daily use of those treatments. The measurements were then repeated with the alternate treatment after a 15-day washout period. Finally, a last MC was performed after another 15-day washout period. For each MC, the perception score of bronchoconstriction-associated breathlessness at 20% fall in FEV1 (PS20) was evaluated on a modified Borg scale from 0 to 10.

RESULTS

Subjects using regular beclomethasone had a higher baseline PS20 than those using only salbutamol (means: 3.06 0.06 and 2.01+/-0.07, p=0.0001). Short- and long-term use of salmeterol did not change significantly the PS20 compared with placebo (p>0.05) in either group (with or without corticosteroid). Although there were some intraindividual variations, mean PS20 did not vary significantly throughout the study.

CONCLUSION

These observations show that the perception of bronchoconstriction-associated breathlessness is not influenced by regular use of salmeterol. Patients using inhaled corticosteroids show a greater perception of MIB.

Short-term effects of budesonide, nedocromil sodium and salmeterol on bronchial hyperresponsiveness in childhood asthma

BACKGROUND

The effects of budesonide, nedocromil sodium and salmeterol on bronchial hyperresponsiveness were determined over a period of 3 weeks.

METHODS

Forty-three asymptomatic children (22 male, 21 female, aged 7-17 years) with mild-to-moderate asthma were evaluated. The study was placebo-controlled and double-blind. At the beginning the forced expiratory volume in 1 second (FEV1) was measured and a methacholine challenge was performed to determine PC20 (provocative concentration of inhaled methacholine required to reduce FEV1 by 20%). The patients in group I (n = 12), group II (n = 10), group III (n = 11), and group IV (n = 10) inhaled 200 micrograms of budesonide, 2 mg of nedocromil sodium, 25 micrograms of salmeterol and a placebo, respectively, twice a day over the period of 3 weeks. Then the methacholine PC20 values of all patients were measured again and the results were compared statistically with their previous values.

RESULTS

The statistical data revealed that the methacholine doses in PC20 before and after treatment were different in group I (P < 0.01). However, these differences were not statistically significant in the other groups (P > 0.05).

CONCLUSIONS

The short term usage of budesonide decreases bronchial hyperresponsiveness, but nedocromil sodium and salmeterol in the given dises do not affect bronchial hyperresponsiveness.

An overview of nine clinical trials of salmeterol in an asthmatic population

In an attempt to establish the protection afforded by regular salmeterol use against induced bronchoconstriction in asthmatic patients, a meta-analysis was conducted on nine double-blind clinical trials that fulfilled the inclusion criteria. In each trial, subjects were randomly assigned to receive either salmeterol 50 micrograms twice daily or a comparator (placebo or salbutamol). Two hundred and twenty-five asthmatic subjects had at least one PC20 or PD20 (histamine or methacholine concentration or dose producing 20% fall in forced expiratory volume in 1 s) measurement recorded within 1 h to 16 weeks after the first dose, and up to 31 days after the last dose, of medication. One hour after the first dose of salmeterol, there was a 3.5-fold increase in doubling dose compared to baseline. Within 12 h of the first dose, the level of protection was 1.5 doubling doses, and protection was maintained at 0.5-1.5 doubling doses over 16 weeks' treatment. This level of protection was maintained for up to 60 h after the last dose. At no time during the washout period did the level of protection fall below zero. Salmeterol afforded significantly greater protection at all time points during the treatment period than comparator agents, but there was no significant difference during the washout period. In conclusion, salmeterol affords protection against bronchoconstrictor stimuli, and any reduction in this bronchoprotective effect occurred during the first few days of treatment. During long-term salmeterol treatment, there was maintained significant protection that showed no evidence of attenuation after 16 weeks' treatment. Furthermore, there was no evidence of rebound deterioration in bronchial responsiveness after cessation of salmeterol treatment.

A comparison of beclomethasone, salmeterol, and placebo in children with asthma. Canadian Beclomethasone Dipropionate-Salmeterol Xinafoate Study Group

BACKGROUND

An inhaled glucocorticoid is currently the medication of choice for long-term control of persistent asthma in children. The role of long-acting beta2-adrenergic-receptor agonists, such as salmeterol, needs to be defined.

METHODS

We conducted a randomized, double-blind, placebo-controlled, parallel-group, one-year study of 241 children (mean [+/-SD] age, 9.3+/-2.4 years) with clinically stable asthma and less than one month of prior glucocorticoid use. We compared inhaled beclomethasone dipropionate (200 microg twice daily) with salmeterol xinafoate (50 microg twice daily) and placebo (lactose). The primary outcome measure, airway responsiveness (as assessed with a methacholine challenge) was evaluated before treatment; after 3, 6, 9, and 12 months of treatment (12 and 36 hours after study medications had been withheld); and 2 weeks after the end of treatment. Spirometry, symptoms, use of rescue medication (200 microg of albuterol inhaled as needed), and adverse effects were also assessed.

RESULTS

During months 1 through 12 overall, beclomethasone was associated with significantly less airway hyperresponsiveness than salmeterol (P= 0.003) or placebo (P<0.001). This effect was lost two weeks after treatment had been stopped. As compared with placebo, beclomethasone was associated with less variability between morning and evening in the peak expiratory flow (P=0.002), as was salmeterol (P=0.02). Beclomethasone was also associated with a reduced need for albuterol as rescue therapy (P<0.001) and fewer withdrawals because of asthma exacerbations (P=0.03), but salmeterol was not (P=0.09 and 0.55, respectively). During months 1 through 12, linear growth was 3.96 cm in the children receiving beclomethasone, as compared with 5.40 cm in the salmeterol group (P=0.004) and 5.04 cm in the placebo group (P=0.018). Height was not measured after treatment ended.

CONCLUSIONS

Beclomethasone was effective in reducing airway hyperresponsiveness and in controlling symptoms of asthma, but it was associated with decreased linear growth. Salmeterol was not as effective as beclomethasone in reducing airway hyperresponsiveness or in controlling symptoms; however, it was an effective bronchodilator and was not associated with rebound airway hyperresponsiveness, masking of symptoms, or adverse effects.

One year treatment with salmeterol compared with beclomethasone in children with asthma. The Dutch Paediatric Asthma Study Group

The aim of this study was to compare the effects of salmeterol and beclomethasone on lung function and symptoms in children with mild to moderate asthma. Sixty-seven children not treated with inhaled corticosteroids were randomized in a double-blind parallel study either to salmeterol 50 micrograms b.i.d. or beclomethasone 200 micrograms b.i.d. After one year, FEV1 significantly increased in the beclomethasone group, whereas in the salmeterol group there was a small reduction. Differences between groups were 14.2% predicted (p < 0.0001) and 7.0% predicted (p = 0.007) for pre- and postbronchodilator FEV1 values, respectively. PD20 methacholine decreased by 0.73 DD (p = 0.05) in the salmeterol group and increased by 2.02 DD (p < 0.0001) in the beclomethasone group. Morning and evening PEF and symptom scores improved in both groups, although more in the beclomethasone group. Asthma exacerbations, for which prednisolone was needed, were more frequent in the salmeterol group (17 versus two), as were the number of withdrawals due to exacerbations (six versus one). However, growth was significantly slower in the beclomethasone group (-0.28 SDS) compared with that in the salmeterol group (-0.03 SDS) (p = 0.001). We conclude that treatment with a moderate dose of beclomethasone is superior to salmeterol in children with mild to moderate asthma and recommend that salmeterol should not be used as monotherapy.

Salmeterol. A review of its pharmacological properties and clinical efficacy in the management of children with asthma

Salmeterol xinafoate is a selective beta 2-adrenoceptor agonist indicated for the maintenance treatment of adults and children with asthma. When administered as a dry powder or aerosol, salmeterol produces bronchodilation for at least 12 hours and protects against methacholine and exercise-induced bronchoconstriction. Salmeterol is not recommended for the treatment of acute exacerbations of asthma. Recent clinical studies have demonstrated the efficacy and tolerability of inhaled salmeterol in the management of asthma in children. Salmeterol improved symptom control and lung function more effectively than placebo or regularly administered salbutamol. In children who were symptomatic despite regular inhaled corticosteroid therapy, the addition of salmeterol to treatment produced a significant improvement in morning and evening peak expiratory flow and forced expiratory volume in 1 second, and a significant reduction in the incidence of asthma exacerbations compared with placebo. Notably, the long duration of action of salmeterol makes it particularly suitable for the prevention of nocturnal asthma symptoms and exercise-induced asthma (EIA) in children. Current data suggest that salmeterol should not be used as a substitute for corticosteroid therapy in children, but rather as an adjunct to therapy. Thus, salmeterol may be a suitable adjunct to therapy in children with asthma receiving inhaled corticosteroids. In addition, salmeterol also has a potentially important role in the prevention of EIA and nocturnal asthma symptoms.

Airway subsensitivity with long-acting beta 2-agonists. Is there cause for concern?

Regular treatment with both long- and short-acting beta 2-agonists results in tolerance to their bronchoprotective effects, although the relevance of this phenomenon in terms of long term asthma control remains unclear. However, there appears to be no appreciable difference between the 2 long-active beta 2-agonists, salmeterol and formoterol, in their propensity to induce beta 2-adrenoceptor down-regulation and subsensitivity. The degree of subsensitivity appears to be somewhat greater with indirect stimuli such as exercise and allergen challenge, compared with direct stimuli such as histamine and methacholine. This loss of functional antagonism with long-acting beta 2-agonist therapy is partial and is not prevented by concomitant inhaled corticosteroid therapy. However, the protective effects of inhaled corticosteroids on their own appear to be additive to those of long-acting beta 2-agonists when both drugs are concomitantly administered in the long term. The subsensitivity to bronchoprotection may be of clinical relevance in terms of patients who are inadvertently exposed to indirect bronchoconstrictor stimuli such as allergens or exercise, suggesting that long-acting beta 2-agonists should not be taken on a regular basis for this particular indication. There is a greater tendency for bronchodilator subsensitivity to develop with longer-acting, than with shorter-acting beta 2-agonists, and this may reflect the longer duration of beta 2-adrenoceptor occupancy and consequent downregulation. As with the bronchoprotective effects of long-acting beta 2-agonists, the development of bronchodilator subsensitivity is only partial and occurs regardless of whether patients are taking concomitant inhaled corticosteroid therapy. The long-term bronchodilator action of the long-acting beta 2-agonist itself is maintained within the twice daily administration interval. However, subsensitivity occurs in relation to a blunted response to repeated doses of short-acting beta 2-agonists, as in the setting of an acute asthma attack. There is considerable inter-individual variability in the propensity for downregulation and subsensitivity, which is determined by genetic polymorphism of the beta 2-adrenoceptor. Current international asthma management guidelines suggest that long-acting beta 2-agonists should be used on a regular basis in patients who ware inadequately controlled on inhaled corticosteroid therapy, so the addition of long-acting beta 2-agonist therapy is an alternative to using higher doses of inhaled corticosteroids. There are, however, concerns that regular long-acting beta 2-agonists might result in masking of inadequately treated inflammation in patients receiving suboptimal inhaled corticosteroid therapy. Physicians should be aware of the airway subsensitivity that develops with long-acting beta 2-agonist therapy, and patients should be warned that they may have to use higher than conventional dosages of short-acting beta 2-agonists to relieve acute bronchoconstriction in order to overcome this effect. In patients receiving an optimised maintenance dose of inhaled corticosteroid, if long-acting beta 2-agonists are to be used on an as required basis, it would seem rational to use formoterol for this purpose, due to its faster onset of action than salmeterol.

Tolerance to the bronchoprotective effect of salmeterol in adolescents with exercise-induced asthma using concurrent inhaled glucocorticoid treatment

OBJECTIVES

The long-acting beta2-adrenergic agonist salmeterol prevents exercise-induced asthma, but tolerance may develop to its bronchoprotective effect. We wanted to ascertain if the development of tolerance could be prevented by using a low-dose treatment regimen of 50 microg once daily, instead of the usual dose of 50 microg twice daily, in adolescents receiving regular glucocorticoid inhalations. Methods. In a randomized, double-blind, 2x28-day crossover study, we administered salmeterol (50 microg) or placebo once daily via a metered-dose inhaler and Nebulizer Chronolog device to monitor compliance. Exercise challenge tests were performed 1 and 9 hours after salmeterol or placebo inhalation on the 1st and 28th day of each treatment period. The primary outcome variable was the maximum decrease in percent predicted FEV1 postexercise.

RESULTS

Fourteen subjects with a mean age of 13.1 years completed the study. The first dose of salmeterol had an excellent bronchoprotective effect against exercise-induced asthma at 1 and 9 hours. After the 28th consecutive daily dose of salmeterol, the bronchoprotective effect was significantly greater than that of placebo at 1 hour, but not at 9 hours.

CONCLUSIONS

We conclude that a single 50-microg dose of salmeterol has an excellent protective effect against exercise-induced asthma for at least 9 hours, but that this effect may wane during regular once-daily salmeterol treatment, despite the reduced frequency of dosing and despite concomitant use of inhaled glucocorticoids.