Antiinflammatory effects of long-acting beta2-agonists in patients with asthma: a systematic review and metaanalysis

Drug-Drug Interactions and Synergy: From Pharmacological Models to Clinical Application

This review explores the concept of synergy in pharmacology, emphasizing its importance in optimizing treatment outcomes through the combination of drugs with different mechanisms of action. Synergy, defined as an effect greater than the expected additive effect elicited by individual agents according to specific predictive models, offers a promising approach to enhance therapeutic efficacy while minimizing adverse events. The historical evolution of synergy research, from ancient civilizations to modern pharmacology, highlights the ongoing quest to understand and harness synergistic interactions. Key concepts, such as concentration-response curves, additive effects, and predictive models, are discussed in detail, emphasizing the need for accurate assessment methods throughout translational drug development. Although various mathematical models exist for synergy analysis, selecting the appropriate model and software tools remains a challenge, necessitating careful consideration of experimental design and data interpretation. Furthermore, this review addresses practical considerations in synergy assessment, including preclinical and clinical approaches, mechanism of action, and statistical analysis. Optimizing synergy requires attention to concentration/dose ratios, target site localization, and timing of drug administration, ensuring that the benefits of combination therapy detected bench-side are translatable into clinical practice. Overall, the review advocates for a systematic approach to synergy assessment, incorporating robust statistical analysis, effective and simplified predictive models, and collaborative efforts across pivotal sectors, such as academic institutions, pharmaceutical companies, and regulatory agencies. By overcoming critical challenges and maximizing therapeutic potential, effective synergy assessment in drug development holds promise for advancing patient care. SIGNIFICANCE STATEMENT: Combining drugs with different mechanisms of action for synergistic interactions optimizes treatment efficacy and safety. Accurate interpretation of synergy requires the identification of the expected additive effect. Despite innovative models to predict the additive effect, consensus in drug-drug interactions research is lacking, hindering the bench-to-bedside development of combination therapies. Collaboration among science, industry, and regulation is crucial for advancing combination therapy development, ensuring rigorous application of predictive models in clinical settings.

Budesonide promotes airway epithelial barrier integrity following double-stranded RNA challenge

Airway epithelial barrier dysfunction is increasingly recognized as a key feature of asthma and other lung diseases. Respiratory viruses are responsible for a large fraction of asthma exacerbations, and are particularly potent at disrupting epithelial barrier function through pattern recognition receptor engagement leading to tight junction dysfunction. Although different mechanisms of barrier dysfunction have been described, relatively little is known about whether barrier integrity can be promoted to limit disease. Here, we tested three classes of drugs commonly prescribed to treat asthma for their ability to promote barrier function using a cell culture model of virus-induced airway epithelial barrier disruption. Specifically, we studied the corticosteroid budesonide, the long acting beta-agonist formoterol, and the leukotriene receptor antagonist montelukast for their ability to promote barrier integrity of a monolayer of human bronchial epithelial cells (16HBE) before exposure to the viral mimetic double-stranded RNA. Of the three, only budesonide treatment limited transepithelial electrical resistance and small molecule permeability (4 kDa FITC-dextran flux). Next, we used a mouse model of acute dsRNA challenge that induces transient epithelial barrier disruption in vivo, and studied the effects budesonide when administered prophylactically or therapeutically. We found that budesonide similarly protected against dsRNA-induced airway barrier disruption in the lung, independently of its effects on airway inflammation. Taken together, these data suggest that an under-appreciated effect of inhaled budesonide is to maintain or promote airway epithelial barrier integrity during respiratory viral infections.

State-of-the-art beta-adrenoreceptor agonists for the treatment of asthma

INTRODUCTION

Asthma, a heterogeneous disease, is characterized by chronic airway inflammation and hyperreactivity. β₂-adrenoreceptor agonists (β₂-agonists) remain pivotal for asthma management. Short-acting β₂-agonists (SABAs) result in rapid symptomatic alleviation and bronchospasm prevention. Patients experience significant clinical benefits from therapy with long-acting β₂-agonists (LABAs) with efficacy to bronchodilate, and prolonged lung function betterment. Recently discovered β₂-agonists with longer half-lives offer once-daily dosing.

AREAS COVERED

The authors provide a thorough review of the pharmacokinetics, pharmacodynamics, efficacy, tolerability, classification, and safety of β₂-agonists through an in-depth review of current literature using these databases: U.S. National Institutes of Health's National Library of Medicine (NIH/NLM), PubMed Central, and NLM clinical trials.

EXPERT OPINION

β₂- agonists act primarily on airway smooth muscle cells and are quintessential for adequate asthma management. Given their pharmacodynamic and pharmacokinetic properties, SABAs are used as rescue medication. Notably, the current Global Initiative for Asthma (GINA) strategy document recommends using LABA/inhaled corticosteroid combinations both as a daily controller and as a rescue medication. Clinicians should assess this new treatment plan on a per-case basis, making sure to evaluate inhaler adherence and treat modifiable risk factors. The development of next-generation β₂- agonists is an exciting research area that could significantly improve patients' adherence to treatment regimens and, consequently, asthma control and quality of life.

Mechanisms and therapeutic strategies for non-T2 asthma

Non-T2 asthma is traditionally defined as asthma without features of T2 asthma. The definition is arbitrary and is generally based on the presence of neutrophils in sputum, or the absence (or normal levels) of eosinophils or other T2 markers in sputum (paucigranulocytic), airway biopsies or in blood. This definition may be imprecise as we gain more knowledge from applying transcriptomics and proteomics to blood and airway samples. The prevalence of non-T2 asthma is also difficult to estimate as most studies are cross-sectional and influenced by concomitant treatment with glucocorticosteroids, and by the presence of recognized or unrecognized airway infections. No specific therapies have shown any clinical benefits in patients with asthma that is associated with a non-T2 inflammatory process. It remains to be seen if such an endotype truly exists and to identify treatments to target that endotype. Meanwhile, identifying intense airway neutrophilia as an indicator of airway infection and airway hyperresponsiveness as an indicator of smooth muscle dysfunction, and treating them appropriately, and not increasing glucocorticosteroids in patients who do not have obvious T2 inflammation, seem reasonable.

Subdiuretic dose of furosemide enhances albuterol effects in asthmatic mice rather than bumetanide

BACKGROUND

One of the loop diuretics, furosemide, was found useful in bronchial asthma. It enhanced anti-asthmatic effects of albuterol. The underlying mechanism is still unclear.

OBJECTIVE

This study was planned to investigate whether the enhancing effect of furosemide for albuterol in ovalbumin-induced asthmatic BALB/c mice is diuretic-related or not.

METHODS

Two sets of experiments were performed. In the first, effects of inhaled subdiuretic doses of furosemide and bumetanide (another loop diuretic) were compared. Treatments (mg/mL) were given as 15 minute-inhalation before final ovalbumin provocation as follows: albuterol (2.5), furosemide (0.08), bumetanide (0.005), (albuterol+furosemide, 2.5+0.08), and (albuterol+bumetanide, 2.5+0.005). Airway hyperreactivity (AHR) to inhaled methacholine, levels of IL-6, TNF-α, and differential white blood cells in bronchoalveolar lavage fluid (BALF), and lung histopathology were evaluated. In the second set, effects of oral diuretic doses (mg/kg) of furosemide (10) and bumetanide (0.25) were given before final ovalbumin provocation. Urine volume and asthma parameters were measured.

RESULTS

Ovalbumin-asthmatic mice showed significant increases in AHR, levels of IL-6, TNF-α, and inflammatory cells in BALF, and lung inflammatory cell infiltration. Inhaled furosemide significantly decreased these changes while inhaled bumetanide failed. Albuterol and albuterol+bumetanide significantly decreased these changes more than furosemide while albuterol+furosemide produced the most significant decreases. Both oral furosemide and bumetanide exerted equivalent diuretic effects but failed to improve asthma.

CONCLUSIONS

Inhaled subdiuretic dose of furosemide enhanced effects of albuterol more in ovalbumin-asthmatic mice rather than bumetanide, while oral diuretic doses of both drugs failed to improve asthma, indicating that this enhancing effect is not diuretic-related.

Glucocortiosteroid subsensitivity and asthma severity

PURPOSE OF REVIEW

Glucocorticosteroids (GCSs) remain the cornerstone of therapy for treating the inflammatory component of asthma. Clinical response to GCS is heterogeneous, varying both within asthma 'endotypes', as well as the same individual. Different factors and micro-environment can alter the canonical GCS-induced signalling pathways leading to reduced efficacy, collectively termed as GCS subsensitivity, which includes the entire spectrum of steroid insensitivity and steroid resistance.

RECENT FINDINGS

In the past, steroid subsensitivity has been associated with dysregulated expression of glucocorticoid-receptor isoforms, neutrophilic inflammation and Th17 cytokines, oxidative stress-inducing factors and their downstream effect on histone deacetylase activities and gene expression. The review highlights recent observations, such as GCS-induced dysregulation of key transcription factors involved in host defence, role of airway infections altering expression of critical regulatory elements like the noncoding microRNAs, and the importance of interleukin (IL)-10 in reinstating steroid response in key immune cells. Further, emerging concepts of autoimmunity triggered because of delayed resolution of eosinophilic inflammation (due to GCS subsensitivity) and observed lymphopenia (plausibly a side-effect of continued GCS use) are discussed.

SUMMARY

This review bridges concepts that have been known, and those under current investigation, providing both molecular and clinical insights to aid therapeutic strategies for optimal management of asthmatics with varying degree of steroid subsensitivity and disease severity, with particular emphasis on the PI3 kinase pathways.

Sputum cell counts to manage prednisone-dependent asthma: effects on FEV1 and eosinophilic exacerbations

Background

Prednisone dependence in asthma is usually described based on clinical and spirometric characteristics. It is generally believed that these patients have frequent exacerbations and lose lung function rapidly because of uncontrolled airway eosinophilia.

Objectives

The objectives of this study are to report the effect on asthma exacerbations and the change in lung function over time in prednisone-dependent asthma when severe asthma is managed using a protocol that aims to maintain normal sputum cell counts.

Methods

A retrospective survey of patients prospectively assessed in a university tertiary care asthma clinic.

Results

52 patients (30 males, mean age 51 years, 64% non-atopic) were followed for a median period of 5.4 years (min–max: 0.2–35.2). Monitoring with the aim of keeping sputum eosinophils below 3% resulted in higher doses of corticosteroids (median daily dose of prednisone was 10 mg and for inhaled corticosteroids was 1500 μg of fluticasone equivalent) than at baseline and this was associated with predictable adverse effects. Despite the disease severity, 10 patients (19%) did not require LABA for symptom control. Most importantly, over the period of follow-up, there were only 0.3 eosinophilic exacerbations/patient/year. Overall, there was an increase in FEV1 over the period of follow-up (mean +84.6 ml/year) rather than an expected decline.

Conclusions

Monitoring of eosinophils in sputum enables to maintain symptom control and preserve FEV1 in patients with severe prednisone-dependent asthma.

Co-inhalation of roflumilast, rather than formoterol, with fluticasone more effectively improves asthma in asthmatic mice

Roflumilast is approved as an add-on therapy for chronic obstructive pulmonary disease. The inflammation in chronic obstructive pulmonary disease is mainly neutrophilic, while in asthma it is mainly eosinophilic, studies addressing role of roflumilast in eosinophilic inflammation are recommended. Also in severe asthma, the dominant inflammatory cells are neutrophils. Thus, roflumilast has a potential off-label use in the treatment of asthma. This study was designed to evaluate the effects of co-inhalation of roflumilast and fluticasone compared to that of formoterol and fluticasone in ovalbumin-sensitized and-challenged BALB/c mice. Besides normal control group, the ovalbumin-asthmatic mice were randomly divided into seven groups (n = 8): positive control, vehicle-treated, and five drug-treated groups. Treatments (µg/kg) were given as 15 min-inhalation once/day for five days as follows: roflumilast (500), formoterol (50), fluticasone (1000), roflumilast + fluticasone (500 + 1000), and formoterol + fluticasone (50 + 1000). Penh values were measured in conscious unrestrained mice using the single-chamber whole-body plethysmography. Airway hyperreactivity to inhaled methacholine was evaluated. Bronchoalveolar lavage fluid was used for the measurements of levels of IL-4, IL-5, TNF-α, OVA-specific IgE, and total and differential white cells. Lung sections were stained with hematoxylin and eosin and periodic acid-Schiff. The asthmatic mice showed significant increases in airway hyperreactivity which were significantly reversed by the combination treatments. The asthmatic mice showed significant increases in levels of IL-4, IL-5, TNF-α, ovalbumin-specific IgE, and total and differential white cells in bronchoalveolar lavage fluid. All treatments (except formoterol) significantly reversed these changes mainly with roflumilast + fluticasone. The asthmatic mice showed severe inflammatory infiltration and goblet cell hyperplasia which were maximally reversed by roflumilast + fluticasone, while minimally reversed by formoterol. In conclusion, co-inhalation of roflumilast + fluticasone more significantly improved inflammation and histopathological changes than co-inhalation of formoterol + fluticasone in ovalumin-asthmatic mice. Further studies are needed to help confirm the potential off-label add-on use of roflumilast in typical and atypical asthma and asthma-chronic obstructive pulmonary disease overlap syndrome. Impact statement Roflumilast, a selective phosphodiesterase-4 inhibitor, was approved for the treatment of chronic obstructive pulmonary disease (COPD). This study showed that co-inhalation of roflumilast and fluticasone significantly decreased airway hyperresponsiveness in ovalumin-asthmatic mice. Also, it more significantly improved inflammation and histopathological changes than co-inhalation of formoterol and fluticasone. The current results showed that inhaled roflumilast reduced counts of eosinophils, neutrophils, and macrophages in bronchoalveolar lavage fluid. Consequently, inhaled roflumilast might be of potential off-label benefit in treatment of eosinophilic and neutrophilic asthma and asthma-COPD overlap syndrome (ACOS). These results could also support other experimental and clinical studies addressing the same issue.

Concerns with beta2-agonists in pediatric asthma - a clinical perspective

Beta2-adrenoreceptor agonists (β2-agonists) are extensively used in the treatment of childhood asthma. However, there have been concerns regarding their adverse effects and safety. In 2005, the FDA commissioned a "Black Box Warning" communicating the potential for an increased risk for serious asthma exacerbations or asthma related deaths, with the regular use of LABAs. In a meta-analysis of controlled clinical trials, the incidence of severe adverse events appeared to be highest in the 4-11 year age group. Several mechanisms have been proposed regarding the risk of regular use of β2-agonists, such as masking patients' perception of worsening asthma, desensitization and downregulation of the β2-adrenoreceptor, pro-inflammatory effects of β2-agonists, pharmacogenetic effects of β2-adrenoreceptor polymorphisms and age related differences in pathophysiology of asthma. In this paper, we review β2-receptor pharmacology, discuss the concerns regarding treatment with β2-agonists in childhood asthma, and provide suggestions for clinical pediatric practice in the light of current literature.

Bronchodilators, receptors and cross-talk: Together is better?

The most widely used maintenance therapies in chronic obstructive pulmonary disease (COPD) are long-acting muscarinic antagonists (LAMAs), and a number of these drugs are now available in combination with long-acting β2-agonists (LABAs). LAMAs inhibit the parasympathetic muscarinic pathway, while LABAs, as sympathomimetics, reduce airway smooth muscle (ASM) tone. As well as directly controlling the constriction and relaxation of ASM, muscarinic and adrenergic receptors are found on inflammatory cells, and drugs that target these receptors may also reduce inflammation in COPD. Evidence suggests that the muscarinic and adrenergic pathways cross-talk at the level of neuronal input to the ASM via second-messenger pathways within ASM cells. Although the cross-talk is not completely understood, pharmacologically targeting both pathways in COPD can maximize bronchodilation. Combining LAMAs and LABAs demonstrated improved efficacy compared with the individual therapies and so, for greater convenience, several fixed-dose combinations for once-daily use have been developed. These fixed-dose combinations demonstrate improvements in both lung-function and patient-reported outcomes compared with well-established monotherapies, with similar tolerability profiles to the individual agents.

Inhaled corticosteroid and long-acting β2-agonist pharmacological profiles: effective asthma therapy in practice

Fixed-dose combinations of inhaled corticosteroids (ICSs) and long-acting β2-agonists (LABAs) have been used to manage asthma for several years. They are the preferred therapy option for patients who do not achieve optimal control of their asthma with low-dose ICS monotherapy. In Europe, four ICS/LABA products are commercially available for asthma maintenance therapy (fluticasone propionate/formoterol fumarate, fluticasone propionate/salmeterol xinafoate, budesonide/formoterol fumarate and beclometasone dipropionate/formoterol fumarate), and other combinations are likely to be developed over the next few years (e.g. mometasone/formoterol fumarate, fluticasone furoate/vilanterol, mometasone/indacaterol). Data from randomized, controlled, clinical trials do not demonstrate a clear overall efficacy difference among ICS/LABA combinations approved for asthma therapy. Conversely, pharmacological data indicate that there may be certain advantages to using one ICS or LABA over another because of the specific pharmacodynamic and pharmacokinetic profiles associated with particular treatments. This review article summarizes the pharmacological characteristics oft he various ICSs and LABAs available for the treatment of asthma, including the potential for ICS and LABA synergy, and gives an insight into the rationale for the development of the latest ICS/LABA combination approved for asthma maintenance therapy.

Dose-dependent anti-inflammatory effect of inhaled mometasone furoate/formoterol in subjects with asthma

OBJECTIVE

A well-controlled study in patients with allergic asthma was warranted to assess dose-dependency between fractional concentration of exhaled nitric oxide (FeNO) and sputum eosinophils to a combination of an inhaled corticosteroid plus a long-acting β2-agonist. We sought to characterize the dose-dependency of mometasone furoate/formoterol (MF/F) using FeNO and sputum eosinophil percentage as surrogates of airway inflammation in subjects with allergic asthma.

METHODS

Following a 2-week, open-label run-in, 93 subjects (≥12 y) using only short-acting beta agonist reliever medication as needed, were randomized to twice daily (BID) placebo; MF/F 100/10 μg, 200/10 μg, or 400/10 μg (via pressurized metered-dose inhaler [MDI]); MF-MDI 200 μg; or MF 200 μg via dry powder inhaler (DPI) during a 2-week, double-blind treatment period.

RESULTS

All active treatments demonstrated significant percentage reductions from baseline in FeNO compared with placebo at all time points (P ≤ 0.034). At endpoint, mean MF/F treatment group FeNO reductions ranged from -35.3% to -61.4%. Sputum eosinophil percentage reductions from baseline were significant compared with placebo for the MF/F 200/10 μg, MF/F 400/10 μg, and MF-DPI 200 μg groups at endpoint (P ≤ 0.023). Escalating MF/F doses significantly reduced both FeNO (P ≤ 0.001) and sputum eosinophil (P ≤ 0.022) levels in a dose-dependent manner at all time points. All treatments were well tolerated; no serious adverse events were observed.

CONCLUSION

All 3 MF/F doses demonstrated pronounced, clinically meaningful, dose-dependent reductions in FeNO, with reduced sputum eosinophil levels for MF/F 200/10 μg and MF/F 400/10 μg. These findings suggest both inflammatory markers may be useful in assessing corticosteroid responsiveness in asthma patients, and perhaps identifying the same asthma subphenotype. Clinical Trials.gov: NCT00635882.

Salmeterol and fluticasone in young children with multiple-trigger wheeze

BACKGROUND

Treatment guidelines recommend using an inhaled corticosteroid (ICS) plus a long-acting β(2)-agonist (LABA) for childhood asthma when the symptoms are not controlled by ICS alone, but the appropriate use of LABAs in children continues to be debated.

OBJECTIVE

To compare the efficacy of an inhaled salmeterol and fluticasone propionate combination, 50/100 μg twice daily, with fluticasone propionate, 100 μg twice daily, or salmeterol, 50 μg twice daily, in children with multiple-trigger wheeze.

METHODS

A total of 105 children 4 to 7 years of age with multiple-trigger wheezing based on respiratory symptoms and bronchodilator responsiveness and/or exercise-induced bronchoconstriction without a viral cold were randomized to salmeterol-fluticasone, fluticasone propionate alone, or salmeterol alone via a metered-dose inhaler and a spacer device for 8 weeks. The primary efficacy outcome was exhaled nitric oxide level. Secondary outcomes were lung function measurements via impulse oscillometry, respiratory symptoms, and rescue medication use.

RESULTS

The exhaled nitric oxide levels decreased after all treatments, significantly more so after salmeterol-fluticasone and fluticasone than with salmeterol (adjusted geometric means at 8 weeks: salmeterol-fluticasone, 9.4 ppb; fluticasone, 9.3 ppb; salmeterol, 13.9 ppb; salmeterol-fluticasone vs salmeterol, P = .02; fluticasone vs salmeterol, P = .01). No treatment differences were found with respect to respiratory symptoms or median rescue use. Salmeterol-fluticasone resulted in a small but statistically significant improvement in baseline lung function compared with fluticasone. All treatments were equally well tolerated.

CONCLUSION

The effects of salmeterol-fluticasone and fluticasone were comparable, although lung function improvement was better with salmeterol-fluticasone than with fluticasone alone. There is no obvious benefit in initiation therapy with salmeterol-fluticasone rather than fluticasone alone in the treatment of steroid-naive children with multiple-trigger wheeze.

TRIAL REGISTRATION

Pathway of clinical trial registry of Helsinki University:http://www.hus.fi/?Path=1;28;2530;9899;9900;23618;23903;33578.

Controversies regarding long-acting β2-agonists

PURPOSE OF REVIEW

This review examines the literature regarding the efficacy and safety of long-acting β2-agonists as add-on therapy to inhaled corticosteroids.

RECENT FINDINGS

The Global Initiative for Asthma (GINA) 2009 guidelines and the National Heart, Lung, and Blood Institute (NHLBI) 2007 asthma guidelines recommend adding long-acting β2-agonists to patients inadequately controlled on inhaled corticosteroids. These recommendations must be balanced against published data which demonstrate a signal of increased morbidity and mortality with use of long-acting β2-agonists. These conflicting data raise the question of whether or not there may be genotypic or phenotypic discriminators leading to disparate responses to long-acting β2-agonists.

SUMMARY

The combination of long-acting β2-agonists and inhaled corticosteroids demonstrates improvement in asthma control and exacerbation rates; however, long-acting β2-agonists are not recommended for use as monotherapy or without optimization of inhaled corticosteroid dose. Although the majority of asthmatic patients appear to benefit from the addition of long-acting β2-agonists, there are concerns that a small proportion of patients, including steroid-naïve patients and African Americans, may not obtain such benefits. Thus far, studies have not clearly demonstrated genotypic or phenotypic differences explaining the variability in response.

Fluticasone/Salmeterol combination confers benefits in people with asthma who smoke

BACKGROUND

Smoking induces airway inflammation and relative resistance to inhaled steroids. The objective of this study was to evaluate the effects on airway hyperresponsiveness of adding salmeterol to fluticasone vs doubling the dose of fluticasone in patients with asthma who smoked and patients with asthma who did not smoke.

METHODS

Sixteen patients with mild to moderate persistent asthma who did not smoke and 15 such patients who smoked completed a double-blind, randomized, placebo-controlled crossover study. They received either a fluticasone/salmeterol combination (FP/SM) (125/25 μg) two puffs bid (plus fluticasone placebo), or active fluticasone (250 μg) two puffs bid (plus FP/SM placebo), for 2 weeks each, with baselines after 1-week to 2-week run-in and washout periods. The primary outcome was the change from baseline in the provocative concentration of methacholine required to produce a 20% fall in FEV(1) (PC(20)).

RESULTS

In the patients who did not smoke, there were similar improvements in the methacholine PC(20) with the use of fluticasone and FP/SM. The patients who smoked gained a benefit from FP/SM but not fluticasone, amounting to a PC(20) difference of 1.6 doubling dilutions (95% CI, 1.0-2.2), P < .01. The provocative dose of mannitol required to produce a 15% fall in FEV(1) (PD(15)) showed greater improvements with FP/SM than fluticasone in both patients who smoked and did not smoke. Similar differences in airway caliber between those who smoked and did not smoke were observed in FEV(1) and airway resistance.

CONCLUSIONS

FP/SM confers greater improvements in airway hyperresponsiveness and airway caliber in patients with asthma who smoke compared with double the dose of fluticasone. We hypothesize that in the presence of relative steroid resistance, the smooth muscle stabilization conferred by salmeterol is of greater clinical importance in patients who smoke than in those who do not smoke.

TRIAL REGISTRY

ClinicalTrials.gov: No.: NCT00830505; URL: www.clinicaltrials.gov.

Safe use of long-acting β-agonists: what have we learnt?

INTRODUCTION

Long-acting β-agonists (LABAs) added to inhaled corticosteroids (ICS) reduce symptoms, improve lung function and enhance overall asthma control. However, several studies have indicated an increased risk of asthma mortality and asthma-related serious adverse events and the FDA recently mandated restrictions to the use of LABAs in asthma.

AREAS COVERED

This review highlights the clinical studies on which safety analyses pertaining to salmeterol and formoterol have been based and then focuses on recent meta-analyses of safety outcomes with and without consideration of concomitant ICS.

EXPERT OPINION

The phenomenon of masking of inflammation by LABA if ICS dose is insufficient underscores the potential for confounding in determining real safety risks. Under-treatment with ICS and differential dosing of ICS in many trials are major factors driving the LABA safety concern. The FDA meta-analysis, when stratified for mandatory ICS use, found no significant increase in the composite outcome of asthma mortality, intubations and hospitalizations. Add-on therapy with LABA is effective and safe if the dose of ICS is adequate to treat airway inflammation. LABA and ICS given in a single device will negate the possibility of LABA monotherapy which is contraindicated. The FDA has recommended that LABAs be withdrawn when control is achieved with combination therapy but recent evidence suggests this may result in loss of symptom control.

The addition of long-acting beta-agonists to inhaled corticosteroids in asthma

PURPOSE OF REVIEW

although long-acting beta-agonists (LABAs) have been used for two decades, with many studies showing benefit versus increasing inhaled corticosteroid (ICS), controversy regarding safety has resulted in the United States Food and Drug Administration (FDA) recently mandating label changes restricting LABA use. This review addresses these safety concerns together with clinical studies and meta-analyses assessing the appropriate use of LABAs.

RECENT FINDINGS

effective use of LABAs requires sufficient ICS to control inflammation. Underuse of ICS, which is often manifest by exacerbations, may reflect undue emphasis on alleged steroid-sparing effects of LABAs. The FDA meta-analysis found that LABA with mandatory ICS was not associated with increased risks of serious adverse events. The role of LABA with ICS as initial therapy in steroid-naïve patients is debated, as is LABA use in children, with data indicating less benefit than in adults. The FDA recommendation that LABA be withdrawn once control is achieved remains problematic, as greater ICS reduction can be achieved when LABA is continued.

SUMMARY

the safe use of LABAs, which are clearly effective in many patients with moderate to severe asthma, requires high compliance with ICS therapy, which is best assured if ICS and LABA are provided in a single inhaler.

Harnessing the clinical efficacy of phosphodiesterase 4 inhibitors in inflammatory lung diseases: dual-selective phosphodiesterase inhibitors and novel combination therapies

Phosphodiesterase (PDE) 4 inhibitors have been in development as a novel anti-inflammatory therapy for more than 20 years, with asthma and chronic obstructive pulmonary disease (COPD) being primary indications. Despite initial optimism, only one selective PDE4 inhibitor, roflumilast (Daxas (®)), has been approved for use in humans and available in Canada and the European Union in 2011 for the treatment of a specific population of patients with severe COPD. In many other cases, the development of PDE4 inhibitors of various structural classes has been discontinued due to lack of efficacy and/or dose-limiting adverse events. Indeed, for many of these compounds, it is likely that the maximum tolerated dose is either subtherapeutic or at the very bottom of the efficacy dose-response curve. Thus, a significant ongoing challenge that faces the pharmaceutical industry is to synthesize compounds with therapeutic ratios that are superior to roflumilast. Several strategies are being considered, but clinically effective compounds with an optimal pharmacophore have not, thus far, been reported. In this chapter, alternative means of harnessing the clinical efficacy of PDE4 inhibitors are described. These concepts are based on the assumption that additive or synergistic anti-inflammatory effects can be produced with inhibitors that target either two or more PDE families or with a PDE4 inhibitor in combination with other anti-inflammatory drugs such as a glucocorticoid.

Annual change of respiratory functions in adult patients with asthma: the potential of antiasthma treatments for many years to repair irreversible changes of the airway

BACKGROUND

Little is known regarding annual changes of respiratory functions among patients with asthma after asthma symptoms enter remission.

OBJECTIVE

Annual changes of respiratory function and influence of patient characteristics and treatment variables on these changes were assessed in patients with adult asthma.

METHODS

Respiratory function (pre- and postbronchodilator forced expiratory volume in one second [FEV₁] and reversibility by short-acting β₂-agonist) and their changes were retrospectively investigated and relationships between these changes, after symptomatic remission, and patient characteristics and treatments were analyzed in adult outpatients with asthma who had undergone spirometry (including a reversibility test) ≥5 times in >5 years.

RESULTS

In patients ≥40 years old, or with disease duration ≥10 years or receiving treatment for severe asthma (steps 4-5, high-dose inhaled glucocorticosteroids, or addition of other medications), both pre- and postbronchodilator FEV₁ values were significantly lower (p < .05). Mean annual change of prebronchodilator FEV₁ (Δpre-FEV₁), annual change of postbronchodilator FEV₁ (Δpost-FEV₁), and annual change of reversibility (Δ reversibility) were -13.8 ± 59.7 ml/year, -25.9 ± 51.0 ml/year, and -0.56% ± 1.89%/year, respectively. Multivariate analysis after stepwise selection for variables in patient characteristics or treatments showed that disease duration ≥10 years contributed to annual improvement of respiratory functions (Δpre-FEV₁: odds ratio [OR] 1.57, 95% confidence interval [CI] 1.01-2.46; Δpost-FEV₁: OR 2.13, 95% CI 1.25-3.66), treatment with long-acting β₂-agonists (LABAs) contributed to annual improvement of respiratory function (Δpre-FEV₁: OR 2.05, 95% CI 1.23-3.16; Δpost-FEV₁: OR 1.78, 95% CI 1.11-2.87), and poor compliance contributed to annual worsening of respiratory functions (Δpre-FEV₁: OR 0.43, 95% CI 0.24-0.76; Δpost-FEV₁: OR 0.39, 95% CI 0.22-0.70). In addition, duration of disease ≥10 years and severe treatment (steps 4-5) from the beginning contributed to decreasing Δreversibility (OR 0.55, 95% CI 0.34-0.87 and OR 0.50, 95% CI 0.29-0.83, respectively).

CONCLUSIONS

Long-term treatments for asthma are expected to normalize respiratory dysfunction, which cannot be repaired in the short term. Treatment with LABAs and patient compliance may be the most important factors associated with annual improvement of respiratory functions.

Prescribing practices and asthma control with hydrofluoroalkane-beclomethasone and fluticasone: a real-world observational study

BACKGROUND

Long-term randomized trials comparing asthma outcomes between inhaled corticosteroids in real-world populations are lacking. As such, rigorously conducted observational studies to complement the findings of randomized trials are needed.

OBJECTIVE

We sought to compare asthma-related outcomes over 1 year as recorded in a large primary care database for patients aged 5 to 60 years receiving a first prescription (initiation population) or dose increase (step-up population) of hydrofluoroalkane (HFA)-beclomethasone or fluticasone.

METHODS

We used a retrospective matched cohort study in which patients were matched on baseline demographic and disease severity measures. Coprimary outcomes were asthma control (a composite measure comprising no unplanned visit or hospitalization for asthma, oral corticosteroids, or antibiotics for lower respiratory tract infection) and exacerbation rate.

RESULTS

More than 80% of patients in each population achieved asthma control; 10% and 16% of patients in the initiation and step-up populations, respectively, received add-on or combination therapy during the year. Fluticasone was prescribed at significantly higher doses than HFA-beclomethasone for both populations (P <or= .001). In the initiation population (n = 1319 in each cohort) the adjusted odds ratio for achieving asthma control with HFA-beclomethasone was 1.30 (95% CI, 1.02-1.65) relative to fluticasone. In the step-up population (cohorts: n = 250) the adjusted odds ratio for achieving asthma control with HFA-beclomethasone was 1.22 (95% CI, 0.66-2.26). Exacerbation rates were similar between cohorts.

CONCLUSIONS

In a real-world setting patients receiving HFA-beclomethasone had a similar or better chance of achieving asthma control at lower prescribed doses than with fluticasone.

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.

Clinical implications of the intrinsic efficacy of beta-adrenoceptor drugs in asthma: full, partial and inverse agonism

PURPOSE OF REVIEW

beta2-Adrenoceptor (AR) agonists are the most effective bronchodilators known, and play important roles in every step of asthma therapy. Intrinsic efficacy is an important pharmacological property that differentiates the clinical effects and safety profile of beta2-AR agonists. We review the role of beta2-AR agonist intrinsic efficacy in asthma treatment focusing on recent literature.

RECENT FINDINGS

In acute asthma, a full agonist (high intrinsic efficacy) offers a clinical advantage over a partial agonist (low intrinsic efficacy) but with the potential of inducing dose-dependent adverse effects. The chronic use of beta2-AR agonists may be associated with several adverse outcomes including loss of asthma control and even increased mortality. Recently, the role of beta-AR inverse agonists (beta-blockers) which have a negative intrinsic efficacy was studied. Whereas contraindicated in acute asthma, preliminary data suggest that the chronic use of these agents may be associated with attenuation of airway hyper-responsiveness in patients with mild asthma. Studies in a murine model of asthma suggest that such effects may be related to decreased airway inflammation and mucous metaplasia.

SUMMARY

Rational choice among beta2-AR agonists in acute and chronic asthma should be influenced by differences in intrinsic efficacy among these agents. In acute severe asthma, a full agonist offers a clinical advantage over a partial agonist. Whereas the use of inverse agonists in the treatment of asthma is still experimental and needs further exploration in future trials, preliminary studies suggest that their chronic use is well tolerated and is associated with decreased airway hyper-responsiveness.

Pharmacotherapy of asthma: regular treatment or on demand?

Some studies have raised the question of the need for chronic controller therapy in mild persistent asthma as suggested by international guidelines. Although the Improving Asthma Control (IMPACT) and Beclomethasone plus Salbutamol (BEST) studies suggest that on-demand therapy in some patients with mild persistent asthma achieves a similar degree of asthma control based on symptoms and functional outcomes, the IMPACT study indicates that regular and on-demand therapy is not equivalent for controlling airway inflammation. Persistent airway inflammation might lead to airway remodelling with onset or worsening of symptoms, deterioration in lung function, and reduced response to pharmacological therapy. However, the relationships between chronic airway inflammation and airway remodelling need to be clarified. Choosing the 'right' pharmacological strategy (regular versus on-demand treatment) for asthma control is currently difficult due to the fact that (1) inflammatory outcome measures were not generally incorporated into asthma clinical trials; (2) the relationships between chronic airway inflammation and airway remodelling are largely unknown; (3) current clinical asthma trials that are generally based on symptomatic and functional outcome measures are too short to assess the impact of regular anti-inflammatory therapy on natural history of asthma; (4) asthma is an heterogeneous disease and different phenotypes of asthma patients likely requiring a different therapeutic approach can be identified, even in the same class of asthma severity. Guidelines for asthma management are valuable tools, although they are necessarily based on a strategy directed to the best outcome in a group of patients. Asthma phenotyping is becoming central for asthma management. The issue of regular versus on-demand treatment of intermittent and mild persistent asthma would be better addressed if considered within an individualized approach to asthma management and assessment. Identification of clinical, functional, morphological and biochemical phenotypes of patients with asthma and its clinical implications is likely to lead to a tailored, individualized, pharmacological therapy and asthma management.