Inhaled beta2 -agonist, formoterol, enhances intense exercise performance, and sprint ability in elite cyclists

PURPOSE

Many athletes use long-acting beta2 -agonist formoterol in treatment of asthma. However, studies in non-athlete cohorts demonstrate that inhaled formoterol can enhance sprint performance calling into question whether its use in competitive sports should be restricted. We investigated whether formoterol at upper recommended inhaled doses (54 μg) would enhance sprint ability and intense exercise performance in elite cyclists.

METHODS

Twenty-one male cyclists (V̇O2max : 70.4 ± 4.3 mL × min-1  × kg-1 , mean ± SD) completed two 6-s all-out sprints followed by 4-min all-out cycling after inhaling either 54 μg formoterol or placebo. We also assessed cyclists' leg muscle mass by dual-energy X-ray absorptiometry and muscle fiber type distribution of vastus lateralis biopsies.

RESULTS

Peak and mean power output during the 6-s sprint was 32 W (95% CI, 19-44 W, p < 0.001) and 36 W (95% CI, 24-48 W, p < 0.001) higher with formoterol than placebo, corresponding to an enhancing effect of around 3%. Power output during 4-min all-out cycling was 9 W (95% CI, 2-16 W, p = 0.01) greater with formoterol than placebo, corresponding to an enhancing effect of 2.3%. Performance changes in response to formoterol were unrelated to cyclists' VO2max and leg lean mass, whereas muscle fiber Type I distribution correlated with change in sprinting peak power in response to formoterol (r2  = 0.314, p = 0.012).

CONCLUSION

Our findings demonstrate that an inhaled one-off dose of 54 μg formoterol has a performance-enhancing potential on sprint ability and short intense performance in elite male cyclists, which is irrespective of training status but partly related to muscle fiber type distribution for sprint ability.

Dietary Exposure and Risk Assessment of Beta-Agonist Residues in Commercial Beef and Pork in Taiwan

Beta-agonists (β-agonists) in meat products in one's diet raise concerns about the possibility of foodborne illness. It may also lead to discomfort, such as headaches and occasional irregular heartbeats, which might be linked to a heightened concern for cardiovascular issues. Taiwan's high demand for meat and reliance on imported meat products from certain countries where β-agonists are permitted has raised concerns. Recent import border checks and monitoring of meat products in the market have revealed the concentration of non-compliance with β-agonist residue regulations, which is ten ppb. This study aims to analyze the concentration of β-agonist residues in meat products sold in Taiwan and assess the current levels of exposure and dietary risk for consumers. The study analyzed 1415 samples of domestically produced and imported livestock products from supermarkets, traditional markets, and bulk stores in New Taipei City between 2019 and 2023. The samples were analyzed using the method for detecting 21 β-agonists based on the Taiwan Food and Drug Administration's specifications. Estimated daily intake (EDI) of β-agonists for different age groups and the target hazard quotient (THQ) were used to assess dietary exposure and risk. The results showed that all 1415 samples were compliant with regulations. Among them, 43 beef samples showed residues of ractopamine originating from the United States, with residue concentrations ranging from 1 to 10 μg/kg and an average residue concentration of 3.3 ± 1.9 μg/kg. Under average consumption, the highest EDI for the exposed population was observed in the 6-12 age group, with values of 0.1469 μg/kg/day, 0.0734 μg/kg/day, and 0.0242 μg/kg/day for the three residue concentrations (maximum detected residue, maximum allowable residue, and average detected residue, respectively). The THQs for ractopamine in imported beef samples were all less than 1, indicating no health hazards at the current intake levels of each age group and the residue concentrations in commercially available beef. Despite the findings, traders need to acknowledge regulatory variations between Taiwan and exporting countries when importing meat products. Traders should provide inspection reports to monitor β-agonist residue levels in imports or explore sourcing beef from countries with β-agonist bans.

Respiratory Syncytial Virus is the Most Common Causative Agent of Viral Bronchiolitis in Young Children: An Updated Review

BACKGROUND

Viral bronchiolitis is a common condition and a leading cause of hospitalization in young children.

OBJECTIVE

This article provides readers with an update on the evaluation, diagnosis, and treatment of viral bronchiolitis, primarily due to RSV.

METHODS

A PubMed search was conducted in December 2021 in Clinical Queries using the key terms "acute bronchiolitis" OR "respiratory syncytial virus infection". The search included clinical trials, randomized controlled trials, case control studies, cohort studies, meta-analyses, observational studies, clinical guidelines, case reports, case series, and reviews. The search was restricted to children and English literature. The information retrieved from the above search was used in the compilation of this article.

RESULTS

Respiratory syncytial virus (RSV) is the most common viral bronchiolitis in young children. Other viruses such as human rhinovirus and coronavirus could be etiological agents. Diagnosis is based on clinical manifestation. Viral testing is useful only for cohort and quarantine purposes. Cochrane evidence-based reviews have been performed on most treatment modalities for RSV and viral bronchiolitis. Treatment for viral bronchiolitis is mainly symptomatic support. Beta-agonists are frequently used despite the lack of evidence that they reduce hospital admissions or length of stay. Nebulized racemic epinephrine, hypertonic saline and corticosteroids are generally not effective. Passive immunoprophylaxis with a monoclonal antibody against RSV, when given intramuscularly and monthly during winter, is effective in preventing severe RSV bronchiolitis in high-risk children who are born prematurely and in children under 2 years with chronic lung disease or hemodynamically significant congenital heart disease. Vaccines for RSV bronchiolitis are being developed. Children with viral bronchiolitis in early life are at increased risk of developing asthma later in childhood.

CONCLUSION

Viral bronchiolitis is common. No current pharmacologic treatment or novel therapy has been proven to improve outcomes compared to supportive treatment. Viral bronchiolitis in early life predisposes asthma development later in childhood.

Asthma severity and impact on perinatal outcomes: an updated systematic review and meta-analysis

BACKGROUND

Large-scale studies exploring the associations of asthma severity, exacerbations and medication use with adverse perinatal outcomes have been published in recent years.

OBJECTIVES

To update evidence on the associations of asthma severity, exacerbations and medication use with the adverse perinatal outcomes of preterm delivery (PD), low birthweight (LBW) and small-for-gestational-age (SGA).

SEARCH STRATEGY

PubMed, Embase, Wanfang, and China National Knowledge Infrastructure (CNKI) from inception to 1 January 2021.

SELECTION CRITERIA

Cohort studies comparing the likelihood of adverse perinatal outcomes in groups of asthmatic women stratified by asthma severity, asthma exacerbations or medication use, or comparing the likelihood of adverse perinatal outcomes between non-asthmatic women and asthmatics of various levels of severity and exacerbation.

DATA COLLECTION AND ANALYSIS

Two authors independently extracted data and assessed risk of bias. Random-effects models were used to meta-analyse the results.

MAIN RESULTS

Twenty studies met the inclusion criteria. The odds of delivering SGA babies increased with maternal asthma severity. Pregnant women with an asthma exacerbation had higher odds of delivering LBW babies and SGA babies, compared with pregnant women with asthma but without an exacerbation (pooled adjusted odds ratio [OR] 1.15, 95% CI 1.02-1.29 for LBW; number of studies with adjusted OR 3; I²  = 0%) (pooled adjusted OR 1.13, 95% CI 1.04-1.23 for SGA; number of studies with adjusted OR 4; I²  = 0%) and compared to pregnant women without asthma. Oral corticosteroids use during pregnancy was associated with increased odds of LBW, but not PD.

CONCLUSIONS

The available data suggest that maternal asthma severity and exacerbations are associated with increased odds of LBW and SGA babies.

TWEETABLE ABSTRACT

A systematic review and meta-analysis found that maternal asthma severity and exacerbations are associated with increased odds of delivering low birthweight and small-for-gestational-age babies.

Asthma and COVID-19: In Defense of Evidence-Based SABA

There have recently been major objections to the use of short-acting beta-agonist (SABA) in episodic acute asthma culminating in a call for replacing SABA with combination of inhaled corticosteroids and long-acting beta-agonists despite little evidence supporting this point of view. It is regrettable to note that this attack on SABA occurs in the midst of an unprecedented demand for, and shortage of, SABA inhalers during the current COVID-19 pandemic, and the worldwide efforts to increase SABA supplies. In this commentary, we defend the well-established role of SABA and argue that the call for the phase out of SABA is inappropriate, since it is not solidly evidence based.

Pharmacogenetic Factors Affecting Asthma Treatment Response. Potential Implications for Drug Therapy

Asthma is a frequent disease, mainly characterized by airway inflammation, in which drug therapy is crucial in its management. The potential of pharmacogenomics testing in asthma therapy has been, to date, little explored. In this review, we discuss pharmacogenetic factors affecting asthma treatment, both related to drugs used as controller medications for regular maintenance, such as inhaled corticosteroids, anti-leukotriene agents, long-acting beta-agonists, and the new biologic agents used to treat severe persistent asthma. In addition, we discuss current pharmacogenomics knowledge for rescue medications provided to all patients for as-needed relief, such as short-acting beta-agonists. Evidence for genetic variations as a factor related to drugs response has been provided for the following genes and groups of drugs: Inhaled corticosteroids: FCER2; anti-leukotriene agents: ABCC1, and LTC4S; beta-agonists: ADRB2. However, the following genes require further studies confirming or rejecting association with the response to asthma therapy: ADCY9, ALOX5, ARG1, ARG2, CRHR1, CRHR2, CYP3A4, CYP3A5, CYSLTR1, CYSLTR2, GLCCI1, IL4RA, LTA4H, ORMDL3, SLCO2B1, SPATS2L, STIP1, T, TBX21, THRA, THRB, and VEGFA. Although only a minority of these genes are, at present, listed as associated with drugs used in asthma therapy, in the Clinical Pharmacogenomics Implementation Consortium gene-drug pair list, this review reveals that sufficient evidence to start testing the potential of clinical pharmacogenomics in asthma therapy already exists. This evidence supports the inclusion in pilot pharmacogenetics tests of at least four genes. Hopefully these tests, if proven useful, will increase the efficiency and the safety of asthma therapy.

TMT-Based Proteomics Profiling of Bovine Liver Underscores Protein Markers of Anabolic Treatments

Illegal use of growth promoter compounds in food production exposes consumers to health risk. Surveillance of such practices is based on direct detection of drugs or related metabolites by HPLC-MS/MS. Screening strategies focusing on indirect biological responses are considered promising tools to improve surveillance. In this study, an untargeted shotgun proteomics approach based on tandem mass tags (TMTs) is carried out to identify proteins altered in bovine liver after different anabolic treatments. Three controlled pharmacological treatments with dexamethasone, a combination of dexamethasone and clenbuterol, or a combination of sexual steroids (trenbolone and estradiol) are analyzed. Untargeted TMT analysis of liver digests by high resolution MS allowed for the relative quantification of proteins. Thanks to partial least squarediscriminant analysis, a set of proteins capable to classify animals treated with dexamethasone alone (11 proteins), or in combination with clenbuterol (13 proteins) are identified. No significant difference is found upon administration of sexual steroids. After relative quantification of candidate markers by parallel reaction monitoring (PRM), two predictive models are trained to validate protein markers. Finally, an independent animal set of control bulls and bulls treated with dexamethasone is analyzed by PRM to further validate a predictive model giving an accuracy of 100%.

Beta2 -adrenoceptor agonist salbutamol increases protein turnover rates and alters signalling in skeletal muscle after resistance exercise in young men

KEY POINTS

Animal models have shown that beta₂ -adrenoceptor stimulation increases protein synthesis and attenuates breakdown processes in skeletal muscle. Thus, the beta₂ -adrenoceptor is a potential target in the treatment of disuse-, disease- and age-related muscle atrophy. In the present study, we show that a few days of oral treatment with the commonly prescribed beta₂ -adrenoceptor agonist, salbutamol, increased skeletal muscle protein synthesis and breakdown during the first 5 h after resistance exercise in young men. Salbutamol also counteracted a negative net protein balance in skeletal muscle after resistance exercise. Changes in protein turnover rates induced by salbutamol were associated with protein kinase A-signalling, activation of Akt2 and modulation of mRNA levels of growth-regulating proteins in skeletal muscle. These findings indicate that protein turnover rates can be augmented by beta₂ -adrenoceptor agonist treatment during recovery from resistance exercise in humans.

ABSTRACT

The effect of beta₂ -adrenoceptor stimulation on skeletal muscle protein turnover and intracellular signalling is insufficiently explored in humans, particularly in association with exercise. In a randomized, placebo-controlled, cross-over study investigating 12 trained men, the effects of beta₂ -agonist (6 × 4 mg oral salbutamol) on protein turnover rates, intracellular signalling and mRNA response in skeletal muscle were investigated 0.5-5 h after quadriceps resistance exercise. Each trial was preceded by a 4-day lead-in treatment period. Leg protein turnover rates were assessed by infusion of [¹³ C₆ ]-phenylalanine and sampling of arterial and venous blood, as well as vastus lateralis muscle biopsies 0.5 and 5 h after exercise. Furthermore, myofibrillar fractional synthesis rate, intracellular signalling and mRNA response were measured in muscle biopsies. The mean (95% confidence interval) myofibrillar fractional synthesis rate was higher for salbutamol than placebo [0.079 (95% CI, 0.064 to 0.093) vs. 0.066 (95% CI, 0.056 to 0.075%) × h^-1 ] (P < 0.05). Mean net leg phenylalanine balance 0.5-5 h after exercise was higher for salbutamol than placebo [3.6 (95% CI, 1.0 to 6.2 nmol) × min^-1  × 100 g_{Leg Lean Mass}^-1 ] (P < 0.01). Phosphorylation of Akt2, cAMP response element binding protein and PKA substrate 0.5 and 5 h after exercise, as well as phosphorylation of eEF2 5 h after exercise, was higher (P < 0.05) for salbutamol than placebo. Calpain-1, Forkhead box protein O1, myostatin and Smad3 mRNA content was higher (P < 0.01) for salbutamol than placebo 0.5 h after exercise, as well as Forkhead box protein O1 and myostatin mRNA content 5 h after exercise, whereas ActivinRIIB mRNA content was lower (P < 0.01) for salbutamol 5 h after exercise. These observations suggest that beta₂ -agonist increases protein turnover rates in skeletal muscle after resistance exercise in humans, with concomitant cAMP/PKA and Akt2 signalling, as well as modulation of mRNA response of growth-regulating proteins.

Chronic β2 -adrenoceptor agonist treatment alters muscle proteome and functional adaptations induced by high intensity training in young men

KEY POINTS

While several studies have investigated the effects of exercise training in human skeletal muscle and the chronic effect of β₂ -agonist treatment in rodent muscle, their effects on muscle proteome signature with related functional measures in humans are still incompletely understood. Herein we show that daily β₂ -agonist treatment attenuates training-induced enhancements in exercise performance and maximal oxygen consumption, and alters muscle proteome signature and phenotype in trained young men. Daily β₂ -agonist treatment abolished several of the training-induced enhancements in muscle oxidative capacity and caused a repression of muscle metabolic pathways; furthermore, β₂ -agonist treatment induced a slow-to-fast twitch muscle phenotype transition. The present study indicates that chronic β₂ -agonist treatment confounds the positive effect of high intensity training on exercise performance and oxidative capacity, which is of interest for the large proportion of persons using inhaled β₂ -agonists on a daily basis, including athletes.

ABSTRACT

Although the effects of training have been studied for decades, data on muscle proteome signature remodelling induced by high intensity training in relation to functional changes in humans remains incomplete. Likewise, β₂ -agonists are frequently used to counteract exercise-induced bronchoconstriction, but the effects β₂ -agonist treatment on muscle remodelling and adaptations to training are unknown. In a placebo-controlled parallel study, we randomly assigned 21 trained men to 4 weeks of high intensity training with (HIT+β₂ A) or without (HIT) daily inhalation of β₂ -agonist (terbutaline, 4 mg dose^-1 ). Of 486 proteins identified by mass-spectrometry proteomics of muscle biopsies sampled before and after the intervention, 32 and 85 were changing (false discovery rate (FDR) ≤5%) with the intervention in HIT and HIT+β₂ A, respectively. Proteome signature changes were different in HIT and HIT+β₂ A (P = 0.005), wherein β₂ -agonist caused a repression of 25 proteins in HIT+β₂ A compared to HIT, and an upregulation of 7 proteins compared to HIT. β₂ -Agonist repressed or even downregulated training-induced enrichment of pathways related to oxidative phosphorylation and glycogen metabolism, but upregulated pathways related to histone trimethylation and the nucleosome. Muscle contractile phenotype changed differently in HIT and HIT+β₂ A (P ≤ 0.001), with a fast-to-slow twitch transition in HIT and a slow-to-fast twitch transition in HIT+β₂ A. β₂ -Agonist attenuated training-induced enhancements in maximal oxygen consumption (P ≤ 0.01) and exercise performance (6.1 vs. 11.6%, P ≤ 0.05) in HIT+β₂ A compared to HIT. These findings indicate that daily β₂ -agonist treatment attenuates the beneficial effects of high intensity training on exercise performance and oxidative capacity, and causes remodelling of muscle proteome signature towards a fast-twitch phenotype.

Electronic Adherence Monitoring in a High-Utilizing Pediatric Asthma Cohort: A Feasibility Study

BACKGROUND

Inner-city, minority children with asthma have the highest rates of morbidity and death from asthma and the lowest rates of asthma controller medication adherence. Some recent electronic medication monitoring interventions demonstrated dramatic improvements in adherence in lower-risk populations. The feasibility and acceptability of such an intervention in the highest-risk children with asthma has not been studied.

OBJECTIVE

Our objective was to assess the feasibility and acceptability of a community health worker-delivered electronic adherence monitoring intervention among the highest utilizers of acute asthma care in an inner-city practice.

METHODS

This was a prospective cohort pilot study targeting children with the highest frequency of asthma-related emergency department and hospital care within a local managed care Medicaid plan. The 3-month intervention included motivational interviewing, electronic monitoring of controller and rescue inhaler use, and outreach by a community health worker for predefined medication alerts. We measured acceptability by using a modified technology acceptability model and changes in asthma control using the Asthma Control Test (ACT). Given prominent feasibility issues, we describe qualitative patterns of medication use at baseline only.

RESULTS

We enrolled 14 non-Hispanic black children with a median age of 3.5 years. Participants averaged 7.8 emergency or hospital visits in the year preceding enrollment. We observed three distinct patterns of baseline controller use: 4 patients demonstrated sustained use, 5 patients had periodic use, and 5 patients lapsed within 2 weeks. All participants initiated use of the electronic devices; however, no modem signal was transmitted for 5 or the 14 participants after a mean of 45 days. Of the 9 (64% of total) caregivers who completed the final study visit, all viewed the electronic monitoring device favorably and would recommend it to friends, and 5 (56%) believed that the device helped to improve asthma control. ACT scores improved by a mean of 2.7 points (P=.05) over the 3-month intervention.

CONCLUSIONS

High-utilizer, minority families who completed a community health worker-delivered electronic adherence intervention found it generally acceptable. Prominent feasibility concerns, however, such as recruitment, data transmission failure, and lost devices, should be carefully considered when designing interventions in this setting.

Sympathetic innervation controls homeostasis of neuromuscular junctions in health and disease

The distribution and function of sympathetic innervation in skeletal muscle have largely remained elusive. Here we demonstrate that sympathetic neurons make close contact with neuromuscular junctions and form a network in skeletal muscle that may functionally couple different targets including blood vessels, motor neurons, and muscle fibers. Direct stimulation of sympathetic neurons led to activation of muscle postsynaptic β2-adrenoreceptor (ADRB2), cAMP production, and import of the transcriptional coactivator peroxisome proliferator-activated receptor γ-coactivator 1α (PPARGC1A) into myonuclei. Electrophysiological and morphological deficits of neuromuscular junctions upon sympathectomy and in myasthenic mice were rescued by sympathicomimetic treatment. In conclusion, this study identifies the neuromuscular junction as a target of the sympathetic nervous system and shows that sympathetic input is crucial for synapse maintenance and function.

Management of patients during and after exacerbations of chronic obstructive pulmonary disease: the role of primary care physicians

Current treatments have failed to stem the continuing rise in health care resource use and fatalities associated with exacerbations of chronic obstructive pulmonary disease (COPD). Reduction of severity and prevention of new exacerbations are therefore important in disease management, especially for patients with frequent exacerbations. Acute exacerbation treatment includes short-acting bronchodilators, systemic corticosteroids, and antibiotics if bacterial infections are present. Oxygen and/or ventilatory support may be necessary for life-threatening conditions. Rising health care costs have provided added impetus to find novel therapeutic approaches in the primary care setting to prevent and rapidly treat exacerbations before hospitalization is required. Proactive interventions may include risk reduction measures (eg, smoking cessation and vaccinations) to reduce triggers and supplemental pulmonary rehabilitation to prevent or delay exacerbation recurrence. Long-term treatment strategies should include individualized management, addressing coexisting nonpulmonary conditions, and the use of maintenance pharmacotherapies, eg, long-acting bronchodilators as monotherapy or in combination with inhaled corticosteroids to reduce exacerbations. Self-management plans that help patients recognize their symptoms and promptly access treatments have the potential to prevent exacerbations from reaching the stage that requires hospitalization.

Asthma treatment through the beta receptor: lessons from animal models

Asthma is a significant health problem worldwide with a prevalence that continues to rise and for which there is no cure. Animal models have been used for decades to investigate the cause and cures of asthma, and while they do not always mimic many of the facets of this syndrome, mechanistic animal studies are still nevertheless very useful. Animal studies with beta-agonists suggest much broader and perhaps more important roles for beta-agonists since beta-agonists reduce aspects of inflammation and may affect structural remodeling. Studies using enantiomers of beta-agonists provide a confusing picture of the degree and mechanism of the deleterious effects of racemic mixtures and/or the S-enantiomer or other classes of beta-agonists. Neural mechanisms are implicated. The future holds a promise of even more insight into the mechanisms of the acute and chronic role of the beta-adrenoceptor, asthma therapeutics, in particular, beta-agonists that will lead to a better understanding of the pathogenesis and treatment of asthma.

Effect of beta2-adrenergic receptor polymorphism on response to longacting beta2 agonist in asthma (LARGE trial): a genotype-stratified, randomised, placebo-controlled, crossover trial

BACKGROUND

Some studies suggest that patients with asthma who are homozygous for arginine at the 16th amino acid position of the beta2-adrenergic receptor (B16 Arg/Arg) benefit less from treatment with longacting beta2 agonists and inhaled corticosteroids than do those homozygous for glycine (B16 Gly/Gly). We investigated whether there is a genotype-specific response to treatment with a longacting beta2 agonist in combination with inhaled corticosteroid.

METHODS

In this multicentre, randomised, double-blind, placebo-controlled trial, adult patients with moderate asthma were enrolled in pairs matched for forced expiratory volume in 1 s and ethnic origin, according to whether they had the B16 Arg/Arg (n=42) or B16 Gly/Gly (n=45) genotype. Individuals in a matched pair were randomly assigned by computer-generated randomisation sequence to receive inhaled longacting beta2 agonist (salmeterol 50 microg twice a day) or placebo given in a double-blind, crossover design for two 18-week periods. Open-label inhaled corticosteroid (hydrofluoroalkane beclometasone 240 microg twice a day) was given to all participants during the treatment periods. The primary endpoint was morning peak expiratory flow (PEF). Analysis was by intention to treat. This trial is registered with ClinicalTrials.gov, number NCT00200967.

FINDINGS

After 18 weeks of treatment, mean morning PEF in Arg/Arg participants was 21.4 L/min (95% CI 11.8-31.1) higher when participants were assigned to receive salmeterol than when assigned to receive placebo (p<0.0001). In Gly/Gly participants, morning PEF was 21.5 L/min (11.0-32.1) higher when participants were assigned to receive salmeterol than when assigned to receive placebo (p<0.0001). The improvement in PEF did not differ between genotypes (difference [Arg/Arg-Gly/Gly] -0.1, -14.4 to 14.2; p=0.99). In Gly/Gly participants, methacholine PC20 (20% reduction in forced expiratory volume in 1 s; a prespecified secondary outcome) was 2.4 times higher when participants were assigned to salmeterol than when assigned to placebo (p<0.0001). Responsiveness to methacholine did not differ between salmeterol and placebo in Arg/Arg participants (p=0.87). The 2.5 times higher genotype-specific difference in responsiveness to methacholine was significant (1.32 doubling dose difference between genotypes, 0.43-2.21, p=0.0038). Seven Arg/Arg participants (placebo, n=5; salmeterol, n=2) and six Gly/Gly participants (placebo, n=3; salmeterol, n=3) had an asthma exacerbation. Five serious adverse events were reported, one each during the pre-match and run-in phases on open-label inhaled corticosteroid, two during double-blind treatment with salmeterol/inhaled corticosteroid, and one during double-blind treatment with placebo/inhaled corticosteroid. None of the serious events was asthma-related or related to study drugs or procedures.

INTERPRETATION

In asthma patients with B16 Arg/Arg and B16 Gly/Gly genotypes, combination treatment with salmeterol and inhaled corticosteroid improved airway function when compared with inhaled corticosteroid therapy alone. These findings suggest that patients should continue to be treated with longacting beta2 agonists plus moderate-dose inhaled corticosteroids irrespective of B16 genotype. Further investigation is needed to establish the importance of the genotype-specific difference in responsiveness to methacholine.

FUNDING

National Institutes of Health.

Combination therapy with a long-acting beta-agonist and a leukotriene antagonist in moderate asthma

RATIONALE

Long-acting beta-agonists (LABAs) and inhaled corticosteroids administered together appear to be complementary in terms of effects on asthma control. The elements of asthma control achieved by LABAs (improved lung function) and leukotriene receptor antagonists (LTRAs; protection against exacerbations) may be complementary as well.

OBJECTIVE

We sought to determine whether the combination of the LTRA montelukast and the LABA salmeterol could provide an effective therapeutic strategy for asthma.

METHODS AND MEASUREMENTS

In a randomized, placebo-controlled, crossover study of 192 subjects with moderate asthma, we compared the clinical efficacy of regular treatment over 14 weeks with the combination of montelukast and salmeterol to that with the combination of beclomethasone and salmeterol in moderate asthma. The primary efficacy outcome was time to treatment failure.

MAIN RESULTS

Three months after the randomization of the last subject, the Data and Safety Monitoring Board determined that the primary research question had been answered and terminated the trial. The combination of montelukast and salmeterol was inferior to the combination of beclomethasone and salmeterol as judged by protection against asthma treatment failures (p = 0.0008), lung function (26 L/min difference in a.m. peak expiratory flow rate, p = 0.011), asthma control score (0.22 difference in Asthma Control Questionnaire score, p = 0.038), and markers of inflammation and airway reactivity.

CONCLUSIONS

Patients with moderate asthma similar to those we studied should not substitute the combination of an LTRA and an LABA for the combination of inhaled corticosteroid and an LABA.

Mechanisms of beta-receptor stimulation-induced improvement of acute lung injury and pulmonary edema

Acute lung injury (ALI) and the acute respiratory distress syndrome are complex syndromes because both inflammatory and coagulation cascades cause lung injury. Transport of salt and water, repair and remodeling of the lung, apoptosis, and necrosis are additional important mechanisms of injury. Alveolar edema is cleared by active transport of salt and water from the alveoli into the lung interstitium by complex cellular mechanisms. Beta-2 agonists act on the cellular mechanisms of pulmonary edema clearance as well as other pathways relevant to repair in ALI. Numerous studies suggest that the beneficial effects of beta-2 agonists in ALI include at least enhanced fluid clearance from the alveolar space, anti-inflammatory actions, and bronchodilation. The purposes of the present review are to consider the effects of beta agonists on three mechanisms of improvement of lung injury: edema clearance, anti-inflammatory effects, and bronchodilation. This update reviews specifically the evidence on the effects of beta-2 agonists in human ALI and in models of ALI. The available evidence suggests that beta-2 agonists may be efficacious therapy in ALI. Further randomized controlled trials of beta agonists in pulmonary edema and in acute lung injury are necessary.