A comparison of the speeds of action of salmeterol and salbutamol in reversing methacholine-induced bronchoconstriction

Measuring short-term changes in specific ventilation using dynamic specific ventilation imaging

Specific ventilation imaging (SVI) measures the spatial distribution of specific ventilation (SV) in the lung with MRI by using inhaled oxygen as a contrast agent. Because of the inherently low signal to noise ratio in the technique, multiple switches between inspiring air and O₂ are utilized, and the high spatial resolution SV distribution determined as an average over the entire imaging period (~20 minutes). We hypothesized that a trade-off between spatial and temporal resolution could allow imaging at a higher temporal resolution, at the cost of a coarser, yet acceptable, spatial resolution. The appropriate window length and spatial resolution compromise was determined by generating synthetic data with signal- and contrast-to-noise characteristics reflective of that in previously published experimental data, with a known and unchanging distribution of SV, and showed that acceptable results could be obtained in an imaging period of ~7 minutes (80 breaths), with a spatial resolution of ~1cm³. Previously published data were then reanalyzed. The average heterogeneity of the temporally resolved maps of SV were not different to the previous overall analysis, however the temporally resolved maps were less effective at detecting the amount of bronchoconstriction resulting from methacholine administration. The results further indicated that the initial response to inhaled methacholine and subsequent inhalation of albuterol were largely complete within ~22 minutes and ~9 minutes respectively, although there was a tendency for an ongoing developing effect in both cases. These results suggest that it is feasible to use a shortened SVI protocol, with a modest sacrifice in spatial resolution, in order to measure temporally dynamic processes.

Inhaled steroids with and without regular formoterol for asthma: serious adverse events

BACKGROUND

Epidemiological evidence has suggested a link between beta₂-agonists and increases in asthma mortality. There has been much debate about whether regular (daily) long-acting beta₂-agonists (LABA) are safe when used in combination with inhaled corticosteroids (ICS). This updated Cochrane Review includes results from two large trials that recruited 23,422 adolescents and adults mandated by the US Food and Drug Administration (FDA).

OBJECTIVES

To assess the risk of mortality and non-fatal serious adverse events (SAEs) in trials that randomly assign participants with chronic asthma to regular formoterol and inhaled corticosteroids versus the same dose of inhaled corticosteroid alone.

SEARCH METHODS

We identified randomised trials using the Cochrane Airways Group Specialised Register of trials. We checked websites of clinical trial registers for unpublished trial data as well as FDA submissions in relation to formoterol. The date of the most recent search was February 2019.

SELECTION CRITERIA

We included randomised clinical trials (RCTs) with a parallel design involving adults, children, or both with asthma of any severity who received regular formoterol and ICS (separate or combined) treatment versus the same dose of ICS for at least 12 weeks.

DATA COLLECTION AND ANALYSIS

We used standard methodological procedures expected by Cochrane. We obtained unpublished data on mortality and SAEs from the sponsors of the studies. We assessed our confidence in the evidence using GRADE recommendations. The primary outcomes were all-cause mortality and all-cause non-fatal serious adverse events.

MAIN RESULTS

We found 42 studies eligible for inclusion and included 39 studies in the analyses: 29 studies included 35,751 adults, and 10 studies included 4035 children and adolescents. Inhaled corticosteroids included beclomethasone (daily metered dosage 200 to 800 µg), budesonide (200 to 1600 µg), fluticasone (200 to 250 µg), and mometasone (200 to 800 µg). Formoterol metered dosage ranged from 12 to 48 µg daily. Fixed combination ICS was used in most of the studies. We judged the risk of selection bias, performance bias, and attrition bias as low, however most studies did not report independent assessment of causation of SAEs.DeathsSeventeen of 18,645 adults taking formoterol and ICS and 13 of 17,106 adults taking regular ICS died of any cause. The pooled Peto odds ratio (OR) was 1.25 (95% confidence interval (CI) 0.61 to 2.56, moderate-certainty evidence), which equated to one death occurring for every 1000 adults treated with ICS alone for 26 weeks; the corresponding risk amongst adults taking formoterol and ICS was also one death (95% CI 0 to 2 deaths). No deaths were reported in the trials on children and adolescents (4035 participants) (low-certainty evidence).In terms of asthma-related deaths, no children and adolescents died from asthma, but three of 12,777 adults in the formoterol and ICS treatment group died of asthma (both low-certainty evidence).Non-fatal serious adverse eventsA total of 401 adults experienced a non-fatal SAE of any cause on formoterol with ICS, compared to 369 adults who received regular ICS. The pooled Peto OR was 1.00 (95% CI 0.87 to 1.16, high-certainty evidence, 29 studies, 35,751 adults). For every 1000 adults treated with ICS alone for 26 weeks, 22 adults had an SAE; the corresponding risk for those on formoterol and ICS was also 22 adults (95% CI 19 to 25).Thirty of 2491 children and adolescents experienced an SAE of any cause when receiving formoterol with ICS, compared to 13 of 1544 children and adolescents receiving ICS alone. The pooled Peto OR was 1.33 (95% CI 0.71 to 2.49, moderate-certainty evidence, 10 studies, 4035 children and adolescents). For every 1000 children and adolescents treated with ICS alone for 12.5 weeks, 8 had an non-fatal SAE; the corresponding risk amongst those on formoterol and ICS was 11 children and adolescents (95% CI 6 to 21).Asthma-related serious adverse eventsNinety adults experienced an asthma-related non-fatal SAE with formoterol and ICS, compared to 102 with ICS alone. The pooled Peto OR was 0.86 (95% CI 0.64 to 1.14, moderate-certainty evidence, 28 studies, 35,158 adults). For every 1000 adults treated with ICS alone for 26 weeks, 6 adults had an asthma-related non-fatal SAE; the corresponding risk for those on formoterol and ICS was 5 adults (95% CI 4 to 7).Amongst children and adolescents, 9 experienced an asthma-related non-fatal SAE with formoterol and ICS, compared to 5 on ICS alone. The pooled Peto OR was 1.18 (95% CI 0.40 to 3.51, very low-certainty evidence, 10 studies, 4035 children and adolescents). For every 1000 children and adolescents treated with ICS alone for 12.5 weeks, 3 had an asthma-related non-fatal SAE; the corresponding risk on formoterol and ICS was 4 (95% CI 1 to 11).

AUTHORS' CONCLUSIONS

We did not find a difference in the risk of death (all-cause or asthma-related) in adults taking combined formoterol and ICS versus ICS alone (moderate- to low-certainty evidence). No deaths were reported in children and adolescents. The risk of dying when taking either treatment was very low, but we cannot be certain if there is a difference in mortality when taking additional formoterol to ICS (low-certainty evidence).We did not find a difference in the risk of non-fatal SAEs of any cause in adults (high-certainty evidence). A previous version of the review had shown a lower risk of asthma-related SAEs in adults taking combined formoterol and ICS; however, inclusion of new studies no longer shows a difference between treatments (moderate-certainty evidence).The reported number of children and adolescents with SAEs was small, so uncertainty remains in this age group.We included results from large studies mandated by the FDA. Clinical decisions and information provided to patients regarding regular use of formoterol and ICS need to take into account the balance between known symptomatic benefits of formoterol and ICS versus the remaining degree of uncertainty associated with its potential harmful effects.

Regional airflow obstruction after bronchoconstriction and subsequent bronchodilation in subjects without pulmonary disease

Some subjects with asthma have ventilation defects that are resistant to bronchodilator therapy, and it is thought that these resistant defects may be due to ongoing inflammation or chronic airway remodeling. However, it is unclear whether regional obstruction due to bronchospasm alone persists after bronchodilator therapy. To investigate this, six young, healthy subjects, in whom inflammation and remodeling were assumed to be absent, were bronchoconstricted with a PC₂₀ [the concentration of methacholine that elicits a 20% drop in forced expiratory volume in 1 s (FEV₁)] dose of methacholine and subsequently bronchodilated with a standard dose of albuterol on three separate occasions. Specific ventilation imaging, a proton MRI technique, was used to spatially map specific ventilation across 80% of each subject's right lung in each condition. The ratio between regional specific ventilation at baseline and after intervention was used to classify areas that had constricted. After albuterol rescue from methacholine bronchoconstriction, 12% (SD 9) of the lung was classified as constricted. Of the 12% of lung units that were classified as constricted after albuterol, approximately half [7% (SD 7)] had constricted after methacholine and failed to recover, whereas half [6% (SD 4)] had remained open after methacholine but became constricted after albuterol. The incomplete regional recovery was not reflected in the subjects' FEV₁ measurements, which did not decrease from baseline (P = 0.97), nor was it detectable as an increase in specific ventilation heterogeneity (P = 0.78).NEW & NOTEWORTHY In normal subjects bronchoconstricted with methacholine and subsequently treated with albuterol, not all regions of the healthy lung returned to their prebronchoconstricted specific ventilation after albuterol, despite full recovery of integrative lung indexes (forced expiratory volume in 1 s and specific ventilation heterogeneity). The regions that remained bronchoconstricted following albuterol were those with the highest specific ventilation at baseline, which suggests that they may have received the highest methacholine dose.

Inhaled steroids with and without regular salmeterol for asthma: serious adverse events

BACKGROUND

Epidemiological evidence has suggested a link between use of beta₂-agonists and increased asthma mortality. Much debate has surrounded possible causal links for this association, and whether regular (daily) long-acting beta₂-agonists (LABAs) are safe, particularly when used in combination with inhaled corticosteroids (ICSs). This is an update of a Cochrane Review that now includes data from two large trials including 11,679 adults and 6208 children; both were mandated by the US Food and Drug Administration (FDA).  OBJECTIVES: To assess risks of mortality and non-fatal serious adverse events (SAEs) in trials that randomised participants with chronic asthma to regular salmeterol and ICS versus the same dose of ICS.

SEARCH METHODS

We identified randomised trials using the Cochrane Airways Group Specialised Register of trials. We checked websites of clinical trials registers for unpublished trial data. We also checked FDA submissions in relation to salmeterol. The date of the most recent search was 10 October 2018.

SELECTION CRITERIA

We included parallel-design randomised trials involving adults, children, or both with asthma of any severity who were randomised to treatment with regular salmeterol and ICS (in separate or combined inhalers) versus the same dose of ICS of at least 12 weeks in duration.

DATA COLLECTION AND ANALYSIS

We conducted the review according to standard procedures expected by Cochrane. We obtained unpublished data on mortality and SAEs from the sponsors, from ClinicalTrials.gov, and from FDA submissions. We assessed our confidence in the evidence according to current GRADE recommendations.

MAIN RESULTS

We have included in this review 41 studies (27,951 participants) in adults and adolescents, along with eight studies (8453 participants) in children. We judged that the overall risk of bias was low for all-cause events, and we obtained data on SAEs from all study authors. All except 542 adults (and none of the children) were given salmeterol and fluticasone in the same (combination) inhaler.DeathsEleven of a total of 14,233 adults taking regular salmeterol and ICS died, as did 13 of 13,718 taking regular ICS at the same dose. The pooled Peto odds ratio (OR) was 0.80 (95% confidence interval (CI) 0.36 to 1.78; participants = 27,951; studies = 41; I² = 0%; moderate-certainty evidence). In other words, for every 1000 adults treated for 25 weeks, one death occurred among those on ICS alone, and the corresponding risk among those taking salmeterol and ICS was also one death (95% CI 0 to 2 deaths).No children died, and no adults or children died of asthma, so we remain uncertain about mortality in children and about asthma mortality in any age group.Non-fatal serious adverse eventsA total of 332 adults receiving regular salmeterol with ICS experienced a non-fatal SAE of any cause, compared to 282 adults receiving regular ICS. The pooled Peto OR was 1.14 (95% CI 0.97 to 1.33; participants = 27,951; studies = 41; I² = 0%; moderate-certainty evidence). For every 1000 adults treated for 25 weeks, 21 adults on ICS alone had an SAE, and the corresponding risk for those on salmeterol and ICS was 23 adults (95% CI 20 to 27).Sixty-five of 4229 children given regular salmeterol with ICS suffered an SAE of any cause, compared to 62 of 4224 children given regular ICS. The pooled Peto OR was 1.04 (95% CI 0.73 to 1.48; participants = 8453; studies = 8; I² = 0%; moderate-certainty evidence). For every 1000 children treated for 23 weeks, 15 children on ICS alone had an SAE, and the corresponding risk for those on salmeterol and ICS was 15 children (95% CI 11 to 22).Asthma-related serious adverse eventsEighty and 67 adults in each group, respectively, experienced an asthma-related non-fatal SAE. The pooled Peto OR was 1.15 (95% CI 0.83 to 1.59; participants = 27,951; studies = 41; I² = 0%; low-certainty evidence). For every 1000 adults treated for 25 weeks, five receiving ICS alone had an asthma-related SAE, and the corresponding risk among those on salmeterol and ICS was six adults (95% CI 4 to 8).Twenty-nine children taking salmeterol and ICS and 23 children taking ICS alone reported asthma-related events. The pooled Peto OR was 1.25 (95% CI 0.72 to 2.16; participants = 8453; studies = 8; I² = 0%; moderate-certainty evidence). For every 1000 children treated for 23 weeks, five receiving an ICS alone had an asthma-related SAE, and the corresponding risk among those receiving salmeterol and ICS was seven children (95% CI 4 to 12).

AUTHORS' CONCLUSIONS

We did not find a difference in the risk of death or serious adverse events in either adults or children. However, trial authors reported no asthma deaths among 27,951 adults or 8453 children randomised to regular salmeterol and ICS or ICS alone over an average of six months. Therefore, the risk of dying from asthma on either treatment was very low, but we remain uncertain about whether the risk of dying from asthma is altered by adding salmeterol to ICS.Inclusion of new trials has increased the precision of the estimates for non-fatal SAEs of any cause. We can now say that the worst-case estimate is that at least 152 adults and 139 children must be treated with combination salmeterol and ICS for six months for one additional person to be admitted to the hospital (compared to treatment with ICS alone). These possible risks still have to be weighed against the benefits experienced by people who take combination treatment.However more than 90% of prescribed treatment was taken in the new trials, so the effects observed may be different from those seen with salmeterol in combination with ICS in daily practice.

Regular treatment with formoterol and inhaled steroids for chronic asthma: serious adverse events

BACKGROUND

Epidemiological evidence has suggested a link between beta2-agonists and increases in asthma mortality. Much debate has surrounded possible causal links for this association and whether regular (daily) long-acting beta2-agonists are safe when used alone or in conjunction with inhaled corticosteroids. This is an updated Cochrane Review.

OBJECTIVES

To assess the risk of fatal and non-fatal serious adverse events in people with chronic asthma given regular formoterol with inhaled corticosteroids versus the same dose of inhaled corticosteroids alone.

SEARCH METHODS

Trials were identified using the Cochrane Airways Group Specialised Register of trials. Web sites of clinical trial registers were checked for unpublished trial data; Food and Drug Administration (FDA) submissions in relation to formoterol were also checked. The date of the most recent search was August 2012.

SELECTION CRITERIA

Controlled clinical trials with a parallel design were included if they randomly allocated people of any age and severity of asthma to treatment with regular formoterol and inhaled corticosteroids for at least 12 weeks.

DATA COLLECTION AND ANALYSIS

We used standard methodological procedures expected by The Cochrane Collaboration. Unpublished data on mortality and serious adverse events were obtained from the sponsors. We assessed the quality of evidence using GRADE recommendations.

MAIN RESULTS

Following the 2012 update, we have included 20 studies on 10,578 adults and adolescents and seven studies on 2788 children and adolescents. We found data on all-cause fatal and non-fatal serious adverse events for all studies, and we judged the overall risk of bias to be low.Six deaths occurred in participants taking regular formoterol with inhaled corticosteroids, and one in a participant administered regular inhaled corticosteroids alone. The difference was not statistically significant (Peto odds ratio (OR) 3.56, 95% confidence interval (CI) 0.79 to 16.03, low-quality evidence). All deaths were reported in adults, and one was believed to be asthma-related.Non-fatal serious adverse events of any cause were very similar for each treatment in adults (Peto OR 0.98, 95% CI 0.76 to 1.27, moderate-quality evidence), and weak evidence suggested an increase in events in children on regular formoterol (Peto OR 1.62, 95% CI 0.80 to 3.28, moderate-quality evidence).In contrast with all-cause serious adverse events, the addition of new trial data means that asthma-related serious adverse events associated with formoterol are now significantly fewer in adults taking regular formoterol with inhaled corticosteroids (Peto OR 0.49, 95% CI 0.28 to 0.88, moderate-quality evidence). Although a greater number of asthma-related events were reported in children receiving regular formoterol, this finding was not statistically significant (Peto OR 1.49, 95% CI 0.48 to 4.61, low-quality evidence).

AUTHORS' CONCLUSIONS

From the evidence in this review, it is not possible to reassure people with asthma that regular use of inhaled corticosteroids with formoterol carries no risk of increasing mortality in comparison with use of inhaled corticosteroids alone. On the other hand, we have found no conclusive evidence of serious harm, and only one asthma-related death was registered during more than 4200 patient-years of observation with formoterol.In adults, no significant difference in all-cause non-fatal serious adverse events was noted with regular formoterol with inhaled corticosteroids, but a significant reduction in asthma-related serious adverse events was observed in comparison with inhaled corticosteroids alone.In children the number of events was too small, and consequently the results too imprecise, to allow determination of whether the increased risk of all-cause non-fatal serious adverse events found in a previous meta-analysis on regular formoterol alone is abolished by the additional use of inhaled corticosteroids.We await the results of large ongoing surveillance studies mandated by the Food and Drug Administration (FDA) for more information. Clinical decisions and information provided to patients regarding regular use of formoterol have to take into account the balance between known symptomatic benefits of formoterol and the degree of uncertainty associated with its potential harmful effects.

Regular treatment with salmeterol and inhaled steroids for chronic asthma: serious adverse events

BACKGROUND

Epidemiological evidence has suggested a link between beta2-agonists and increased asthma mortality. There has been much debate about possible causal links for this association, and whether regular (daily) long-acting beta2-agonists are safe. This is an updated systematic review.

OBJECTIVES

To assess the risk of mortality and non-fatal serious adverse events in trials which randomised patients with chronic asthma to regular salmeterol and inhaled corticosteroids in comparison to the same dose of inhaled corticosteroids.

SEARCH METHODS

We identified randomised trials using the Cochrane Airways Group Specialised Register of trials. We checked websites of clinical trial registers for unpublished trial data. Food and Drug Administration (FDA) submissions in relation to salmeterol were also checked. The date of the most recent search is August 2012.

SELECTION CRITERIA

We included parallel design controlled clinical trials on patients of any age and severity of asthma if they randomised patients to treatment with regular salmeterol and inhaled corticosteroids (in separate or combined inhalers), and were of at least 12 weeks duration.

DATA COLLECTION AND ANALYSIS

We conducted the review according to standard procedures expected by the Cochrane Collaboration. We obtained unpublished data on mortality and serious adverse events from the sponsors, and from FDA submissions. We assessed the quality of evidence according to GRADE recommendations.

MAIN RESULTS

We have included 35 studies (13,447 participants) in adults and adolescents, and 5 studies (1862 participants) in children in this review. We judged that the overall risk of bias was low, and we obtained data on serious adverse events from all studies. All except 542 adults (and none of the children) who were randomised to salmeterol were given fluticasone in the same (combination) inhaler.Seven deaths occurred in 6986 adults on regular salmeterol with inhaled corticosteroids (ICS), and seven deaths in 6461 adults on regular inhaled corticosteroids at the same dose. The difference was not statistically significant (Peto odds ratio (OR) 0.90; 95% confidence interval (CI) 0.31 to 2.60, moderate quality evidence). The risk of dying from any cause in adults on ICS was 10 per 10,000, and on salmeterol and ICS we would expect between 3 and 26 deaths per 10,000. No deaths were reported in 1862 children, and no deaths were reported to be asthma-related in adults or children.Non-fatal serious adverse events of any cause were reported in 167 adults on regular salmeterol with ICS, compared to 135 adults on regular ICS; again this was not a statistically significant increase (Peto OR 1.15; 95% CI 0.91 to 1.44, moderate quality evidence). The frequency of serious adverse events was 21 per 1000 in the adults treated with ICS and 24 per 1000 in those treated with salmeterol and ICS. The absolute difference in the risk of non-fatal serious adverse events was an increase of 3 per 1000, that was not statistically significant (risk difference (RD) 0.003; 95% CI -0.002 to 0.008).There were 6 of 930 children with serious adverse events on regular salmeterol with ICS, compared to 5 out of 932 on regular ICS: there was no significant difference between treatments (Peto OR 1.20; 95% CI 0.37 to 3.91, moderate quality evidence).Asthma-related serious adverse events were reported in 29 and 23 adults in each group respectively, a non-significant difference (Peto OR 1.12; 95% CI 0.65 to 1.94, moderate quality evidence), and only 1 asthma-related event was reported in children in each treatment group.

AUTHORS' CONCLUSIONS

We found no statistically significant differences in fatal or non-fatal serious adverse events in trials in which regular salmeterol was randomly allocated with ICS, in comparison to ICS alone at the same dose. Although 13,447 adults and 1862 children have now been included in trials, the frequency of adverse events is too low and the results are too imprecise to confidently rule out a relative increase in all cause mortality or non-fatal adverse events with salmeterol used in conjunction with ICS. However, the absolute difference between groups in the risk of serious adverse events was very small. We could not determine whether the increase in all cause non-fatal serious adverse events reported in the previous meta-analysis on regular salmeterol alone is abolished by the additional use of regular ICS. We await the results of large ongoing surveillance studies mandated by the FDA to provide more information. There were no asthma-related deaths and few asthma-related serious adverse events. Clinical decisions and information for patients regarding regular use of salmeterol have to take into account the balance between known symptomatic benefits of salmeterol and the degree of uncertainty and concern associated with its potential harmful effects.

Bronchial reversibility with a short-acting β2-agonist predicts the FEV1 response to administration of a long-acting β2-agonist with inhaled corticosteroids in patients with bronchial asthma

A long-acting β2-agonist (LABA) combined with an inhaled corticosteroid (ICS) is frequently prescribed as initial therapy in steroid-naïve asthma patients because of its effective control of symptoms and improvement of pulmonary function. However, it is unclear which patients will be responsive to LABAs and whether bronchial responsiveness to LABAs is similar to that to short-acting β2-agonists (SABAs) in a clinical setting. Therefore, the goal of the present study was to compare the changes in spirometric parameters after SABA (salbutamol) inhalation to those after 1-month LABA/ICS (salmeterol/fluticasone propionate) therapy. Spirometric changes were evaluated as absolute values, as the percentage of predicted normal values and as the percentage of baseline values after salbutamol inhalation or 1-month LABA/ICS therapy in 45 patients with asthma. Compared to SABA inhalation, LABA/ICS therapy produced significant improvements in forced expiratory volume in 1 sec (FEV1), peak expiratory flow (PEF), forced expiratory flow at 50% of vital capacity expired (FEF50%) from baseline (expressed as the percentage predicted) in all patients. FEV1 and the FEV1/forced vital capacity (FVC) ratio after SABA or LABA/ICS therapy were inversely related to the corresponding baseline values. Analysis of spirometric changes after SABA inhalation showed that FEV1 was the best among spirometric parameters, such as PEF, correlated with responsiveness to LABA/ICS therapy. Reversibility of FEV1 with SABA inhalation predicts the spirometric response to LABA/ICS as initial therapy in patients with bronchial asthma. LABA/ICS therapy had a greater effect on bronchial reversibility in asthmatic patients, compared to SABA inhalation. This suggested that evaluation of bronchial reversibility after LABA/ICS therapy would be superior to that after SABA inhalation.

Regular treatment with formoterol and an inhaled corticosteroid versus regular treatment with salmeterol and an inhaled corticosteroid for chronic asthma: serious adverse events

BACKGROUND

An increase in serious adverse events with both regular formoterol and regular salmeterol in chronic asthma has been demonstrated in comparison with placebo in previous Cochrane reviews. This increase was significant in trials that did not randomise participants to an inhaled corticosteroid, but less certain in the smaller numbers of participants in trials that included an inhaled corticosteroid in the randomised treatment regimen.

OBJECTIVES

We set out to compare the risks of mortality and non-fatal serious adverse events in trials which have randomised patients with chronic asthma to regular formoterol versus regular salmeterol, when each are used with an inhaled corticosteroid as part of the randomised treatment.

SEARCH STRATEGY

Trials were identified using the Cochrane Airways Group Specialised Register of trials. Manufacturers' web sites of clinical trial registers were checked for unpublished trial data and Food and Drug Administration (FDA) submissions in relation to formoterol and salmeterol were also checked. The date of the most recent search was July 2009.

SELECTION CRITERIA

Controlled clinical trials with a parallel design, recruiting patients of any age and severity of asthma were included if they randomised patients to treatment with regular formoterol versus regular salmeterol (each with a randomised inhaled corticosteroid), and were of at least 12 weeks duration.

DATA COLLECTION AND ANALYSIS

Two authors independently selected trials for inclusion in the review and extracted outcome data. Unpublished data on mortality and serious adverse events were sought from the sponsors and authors.

MAIN RESULTS

Eight studies met the eligibility criteria of the review recruiting 6,163 adults and adolescents. There were seven studies (involving 5,935 adults and adolescents) comparing formoterol and budesonide to salmeterol and fluticasone. All but one study administered the products as a combined inhaler, and most used formoterol 50 mcg and budesonide 400 mcg twice daily versus salmeterol 50 mcg and fluticasone 250 mcg twice daily. There were two deaths overall (one on each combination) and neither were thought to be related to asthma.There was no significant difference between treatment groups for non-fatal serious adverse events, either all-cause (Peto OR 1.14; 95% CI 0.82 to 1.59, I(2) = 26%) or asthma-related (Peto OR 0.69; 95% CI 0.37 to 1.26, I(2) = 33%). Over 23 weeks the rates for all-cause serious adverse events were 2.6% on formoterol and budesonide and 2.3% on salmeterol and fluticasone, and for asthma-related serious adverse events, 0.6% and 0.8% respectively.There was one study (228 adults) comparing formoterol and beclomethasone to salmeterol and fluticasone, but there were no deaths or hospital admissions.No studies were found in children.

AUTHORS' CONCLUSIONS

The seven identified studies in adults did not show any significant difference in safety between formoterol and budesonide in comparison with salmeterol and fluticasone. Asthma-related serious adverse events were rare, and there were no reported asthma-related deaths. There was a single small study comparing formoterol and beclomethasone to salmeterol and fluticasone in adults, but no serious adverse events occurred in this study. No studies were found in children.Overall there is insufficient evidence to decide whether regular formoterol and budesonide or beclomethasone have equivalent or different safety profiles from salmeterol and fluticasone.

[Long-acting beta(2)-adrenoceptor agonists for asthma and COPD]

The introduction of long-acting beta(2)-adrenoceptor agonists such as salmeterol and formoterol has opened new perspectives for the treatment of asthma and, possibly, also COPD. These drugs are particularly useful in bronchial asthma and meet the requirements of several treatment guidelines to combine long-acting bronchodilator therapy with inhaled corticosteroids in patients with persistent asthma. The role of long-acting beta(2)-adrenoceptor agonists for management of COPD is less clear. While effects on lung function will be small, parameters of improved quality of life and exercise tolerance may verify the clinical role of long-acting beta(2)-adrenoceptor agonists for COPD treatment in the future.

Molecular mechanisms for the persistent bronchodilatory effect of the beta 2-adrenoceptor agonist salmeterol

BACKGROUND

Beta(2)-adrenoceptor agonists are effective bronchodilators. In vitro studies demonstrated long-lasting airway smooth muscle relaxation by salmeterol after washout, the quick disappearance of this effect in presence of antagonists and its recovery after antagonist removal. Current explanations invoke salmeterol accumulation in the membrane ('diffusion microkinetic' model) or the existence of salmeterol-binding 'exosites'. An alternative model based on 'rebinding' of a dissociated ligand to the receptor molecules also produces an apparent decrease in the ligand's dissociation rate in the absence of competing ligands. PURPOSE AND APPROACH: Computer-assisted simulations were performed to follow the receptor-occupation by a salmeterol-like ligand and a competing ligand as a function of time. The aptness of the models to describe the above in vitro findings was evaluated.

KEY RESULTS

The 'diffusion microkinetic' model is sufficient to explain a long-lasting beta(2)-adrenoceptor stimulation and reassertion as long as the membrane harbors a high concentration of the agonist. At lower concentration, 'rebinding' and, in second place, 'exosite' binding are likely to become operational.

CONCLUSIONS AND IMPLICATIONS

The 'rebinding' and 'exosite' binding mechanisms take place at a sub-cellular/molecular scale. Pending their demonstration by experiments on appropriate, simple models such as intact cells or membranes thereof, these mechanisms remain hypothetical in the case of salmeterol. Airway smooth muscle contraction could also be governed by additional mechanisms that are particular to this macroscopic approach.

Regular treatment with salmeterol and inhaled steroids for chronic asthma: serious adverse events

BACKGROUND

Epidemiological evidence has suggested a link between beta(2)-agonists and increased asthma mortality. There has been much debate about possible causal links for this association, and whether regular (daily) long-acting beta(2)-agonists are safe.

OBJECTIVES

The aim of this review is to assess the risk of fatal and non-fatal serious adverse events in trials that randomised patients with chronic asthma to regular salmeterol with inhaled corticosteroids versus the same dose of inhaled corticosteroids alone.

SEARCH STRATEGY

Trials were identified using the Cochrane Airways Group Specialised Register of trials. Web sites of clinical trial registers were checked for unpublished trial data and Food and Drug Administration (FDA) submissions in relation to salmeterol were also checked. The date of the most recent search was October 2008.

SELECTION CRITERIA

Controlled parallel design clinical trials on patients of any age and severity of asthma were included if they randomised patients to treatment with regular salmeterol and inhaled corticosteroids (in separate or combined inhalers), and were of at least 12 weeks duration.

DATA COLLECTION AND ANALYSIS

Two authors independently selected trials for inclusion in the review. Outcome data were independently extracted by two authors. Unpublished data on mortality and serious adverse events were obtained from the sponsors, and from FDA submissions.

MAIN RESULTS

The review included 30 studies (10,873 participants) in adults and adolescents, and three studies (1,173 participants) in children. The overall risk of bias was low and data on serious adverse events were obtained from all studies.Six deaths occurred in 5,710 adults on regular salmeterol with inhaled corticosteroids, and five deaths in 5,163 adults on regular inhaled corticosteroids at the same dose. The difference was not statistically significant (Peto OR 1.05; 95% CI 0.32 to 3.47) and the absolute difference between groups in risk of death of any cause was 0.00005 (95% CI -0.002 to 0.002). No deaths were reported in 1,173 children, and no deaths were reported to be asthma-related.Non-fatal serious adverse events of any cause were reported in 134 adults on regular salmeterol with inhaled corticosteroids, compared to 103 adults on regular inhaled corticosteroids; again this was not a significant increase (Peto OR 1.17; 95% CI 0.90 to 1.52). The absolute difference in the risk of non-fatal serious adverse events was 0.003 (95% CI -0.002 to 0.009).There were three of 586 children with serious adverse events on regular salmeterol with inhaled corticosteroids, compared to four out of 587 on regular inhaled corticosteroids: there was no significant difference between treatments (Peto OR 0.75; 95% CI 0.17 to 3.31).Asthma-related serious adverse events were reported in 23 and 21 adults in each group respectively, a non-significant difference (Peto OR 0.95; 95% CI 0.52 to 1.73), and only one event was reported in children.

AUTHORS' CONCLUSIONS

No significant differences have been found in fatal or non-fatal serious adverse events in trials in which regular salmeterol has been randomly allocated with inhaled corticosteroids, in comparison to inhaled corticosteroids at the same dose. Although 10,873 adults and 1,173 children have been included in trials, the number of patients suffering adverse events is too small, and the results are too imprecise to confidently rule out a relative increase in all-cause mortality or non-fatal adverse events. It is therefore not possible to determine whether the increase in all-cause non-fatal serious adverse events reported in the previous meta-analysis on regular salmeterol alone is abolished by the additional use of regular inhaled corticosteroids. The absolute difference between groups in the risk of serious adverse events was small. There were no asthma-related deaths and few asthma-related serious adverse events. Clinical decisions and information for patients regarding regular use of salmeterol have to take into account the balance between known symptomatic benefits of salmeterol and the degree of uncertainty and concern associated with its potential harmful effects.

Regular treatment with formoterol and inhaled steroids for chronic asthma: serious adverse events

BACKGROUND

Epidemiological evidence has suggested a link between beta(2)-agonists and increases in asthma mortality. There has been much debate about possible causal links for this association, and whether regular (daily) long-acting beta(2)-agonists are safe when used alone or in conjunction with inhaled corticosteroids.

OBJECTIVES

The aim of this review is to assess the risk of fatal and non-fatal serious adverse events in trials that randomised patients with chronic asthma to regular formoterol with inhaled corticosteroids versus the same dose of inhaled corticosteroids alone.

SEARCH STRATEGY

Trials were identified using the Cochrane Airways Group Specialised Register of trials. Web sites of clinical trial registers were checked for unpublished trial data and Food and Drug Administration (FDA) submissions in relation to formoterol were also checked. The date of the most recent search was October 2008.

SELECTION CRITERIA

Controlled parallel design clinical trials on patients of any age and severity of asthma were included if they randomised patients to treatment with regular formoterol and inhaled corticosteroids, and were of at least 12 weeks duration.

DATA COLLECTION AND ANALYSIS

Two authors independently selected trials for inclusion in the review. Outcome data were independently extracted by two authors. Unpublished data on mortality and serious adverse events were obtained from the sponsors.

MAIN RESULTS

The review included 14 studies on adults and adolescents (8,028 participants) and seven studies on children and adolescents (2,788 participants). Data on all cause fatal and non-fatal serious adverse events were found for all studies, and the overall risk of bias was low.Four deaths occurred on regular formoterol with inhaled corticosteroids, and none on regular inhaled corticosteroids alone. All the deaths were in adults, and one was reported to be asthma-related. The difference was not statistically significant.Non-fatal serious adverse events of any cause were very similar in adults [Peto Odds Ratio 0.99 (95% CI 0.74 to 1.33)], and an increase in events in children on regular formoterol was not statistically significant [Peto Odds Ratio 1.62 (95% CI 0.80 to 3.28)].Asthma related serious adverse events on formoterol were lower in adults [Peto Odds Ratio 0.53 (95% CI 0.28 to 1.00)] and although they were higher in children [Peto Odds Ratio 1.49 (95% CI 0.48 to 4.61)], this was not statistically significant.

AUTHORS' CONCLUSIONS

It is not possible, from the data in this review, to reassure people with asthma that inhaled corticosteroids with regular formoterol carries no risk of increasing mortality in comparison to inhaled corticosteroids alone as all four deaths occurred among 6,594 people using inhaled corticosteroids with formoterol. On the other hand, we have found no conclusive evidence of harm and there was only one asthma related death registered during over 3,000 patient year observation on formoterol. In adults, the decrease in asthma-related serious adverse events on regular formoterol with inhaled corticosteroids was not accompanied by a decrease in all cause serious adverse events. In children the number of events was too small, and consequently the results too imprecise, to determine whether the increase in all cause non-fatal serious adverse events found in the previous meta-analysis on regular formoterol alone is abolished by the additional use of inhaled corticosteroids. Clinical decisions and information for patients regarding regular use of formoterol have to take into account the balance between known symptomatic benefits of formoterol and the degree of uncertainty and concern associated with its potential harmful effects.

Regular treatment with salmeterol for chronic asthma: serious adverse events

BACKGROUND

Epidemiological evidence has suggested a link between beta-agonists and increases in asthma mortality. There has been much debate about possible causal links for this association, and whether regular (daily) long-acting beta(2)-agonists are safe.

OBJECTIVES

The aim of this review is to assess the risk of fatal and non-fatal serious adverse events in trials that randomised patients with chronic asthma to regular salmeterol versus placebo or regular short-acting beta(2)-agonists.

SEARCH STRATEGY

Trials were identified using the Cochrane Airways Group Specialised Register of trials. Web sites of clinical trial registers were checked for unpublished trial data and FDA submissions in relation to salmeterol were also checked. The date of the most recent search was October 2007.

SELECTION CRITERIA

Controlled parallel design clinical trials on patients of any age and severity of asthma were included if they randomised patients to treatment with regular salmeterol and were of at least 12 weeks duration. Concomitant use of inhaled corticosteroids was allowed, as long as this was not part of the randomised treatment regimen.

DATA COLLECTION AND ANALYSIS

Two authors independently selected trials for inclusion in the review. Outcome data was extracted by one author and checked by the second author. Unpublished data on mortality and serious adverse events was sought.

MAIN RESULTS

The review includes 26 trials comparing salmeterol to placebo and 8 trials comparing with salbutamol. These included 62,630 participants with asthma (including 2,380 children). In 6 trials (2,766 patients), no serious adverse event data could be obtained. All cause mortality was higher with regular salmeterol than placebo but the increase was not significant, Odds Ratio 1.33 [95% CI: 0.85, 2.10]. Non-fatal serious adverse events were significantly increased when regular salmeterol was compared with placebo, Odds Ratio 1.14 [95% CI: 1.01, 1.28]. One extra serious adverse event occurred over 28 weeks for every 188 people treated with regular salmeterol [95% CI: 95 to 2606]. There is insufficient evidence to assess whether the risk in children is higher or lower than in adults. No significant increase in fatal or non-fatal serious adverse events was found when regular salmeterol was compared with regular salbutamol. Individual patient data from the SNS study have been combined with the results of the SMART study; in patients who were not taking inhaled corticosteroids, compared to regular salbutamol or placebo, there was a significant increase in risk of asthma-related death with regular salmeterol, Odds Ratio 9.52 [95% CI: 1.24, 73.09]. The confidence interval for patients taking inhaled corticosteroids is too wide to rule out an increase in asthma mortality in this group.

AUTHORS' CONCLUSIONS

In comparison with placebo, we have found an increased risk of serious adverse events with regular salmeterol. There is also a clear increase in risk of asthma-related mortality in patients not using inhaled corticosteroids in the two large surveillance studies. Although the increase in asthma-related mortality was smaller in patients taking inhaled corticosteroids at baseline, the confidence interval is wide, so it cannot be concluded that the inhaled corticosteroids abolish the risks of regular salmeterol. The adverse effects of regular salmeterol in children remain uncertain due to the small number of children studied.

Tolerance and rebound with zafirlukast in patients with persistent asthma

BACKGROUND

The potential for tolerance to develop to zafirlukast, a cysteinyl leukotriene (CysLT) receptor antagonist (LRA) in persistent asthma, has not been specifically examined.

OBJECTIVE

To look for any evidence of tolerance and potential for short-term clinical worsening on LRA withdrawal. Outcome measures included changes in; airway hyperresponsiveness to inhaled methacholine (PD20FEV1), daily symptoms and peak expiratory flows (PEF), sputum and blood cell profiles, sputum CysLT and prostaglandin (PG)E2 and exhaled nitric oxide (eNO) levels.

METHODS

A double blind, placebo-controlled study of zafirlukast, 20 mg twice daily over 12 weeks in 21 asthmatics taking beta2-agonists only (Group I), and 24 subjects treated with ICS (Group II).

RESULTS

In Group I, zafirlukast significantly improved morning PEF and FEV1compared to placebo (p < 0.01), and reduced morning waking with asthma from baseline after two weeks (p < 0.05). Similarly in Group II, FEV1 improved compared to placebo (p < 0.05), and there were early within-treatment group improvements in morning PEF, beta2-agonist use and asthma severity scores (p < 0.05). However, most improvements with zafirlukast in Group I and to a lesser extent in Group II deteriorated toward baseline values over 12 weeks. In both groups, one week following zafirlukast withdrawal there were significant deteriorations in morning and evening PEFs and FEV1 compared with placebo (p < or = 0.05) and increased nocturnal awakenings in Group II (p < 0.05). There were no changes in PD20FEV1, sputum CysLT concentrations or exhaled nitric oxide (eNO) levels. However, blood neutrophils significantly increased in both groups following zafirlukast withdrawal compared to placebo (p = 0.007).

CONCLUSION

Tolerance appears to develop to zafirlukast and there is rebound clinical deterioration on drug withdrawal, accompanied by a blood neutrophilia.

Same efficacies of ipratropium and salbutamol in reversing methacholine-induced bronchoconstriction

Efficacy of salbutamol (S) was compared to that of ipratropium (I) or to their association, after methacholine challenge testing (MCT). MCT was performed in 4 groups of 10 patients suspected to suffer from asthma; mean changes in FEV1, maximal midexpiratory flow rate (MMFR), and airway resistance (Raw) were the same in all groups. After MCT, the group 1 patients inhaled S and then I, 10 min later; both drugs were given in the reverse order to the group 2 patients. The group 3 patients inhaled a mixture of both drugs just after MCT; the group 4 patients were not given any bronchodilator till the 20th min after MCT, when they inhaled S. Short-term (10 min) bronchodilator effects of S, I or S + I on spirometric variables were of the same magnitude and Raw returned to its baseline value. Further improvement (10-20 min) in FEV1 was mainly due to spontaneous recovery, whereas further increase in MMFR was due also to bronchodilator actions of drugs. It is concluded that ipratropium could be proposed as an alternative bronchodilator to salbutamol after MCT.

Speed of onset of bronchodilator response to salbutamol inhaled via different devices in asthmatics: a bioassay based on functional antagonism

AIMS

To evaluate the speed of onset of bronchodilation following salbutamol administered via a metered-dose inhaler with a spacer (pMDI + Volumatic) and a dry-powder inhaler (Diskus), as well as the relative potencies of these devices in asthmatic patients with methacholine-induced bronchoconstriction.

METHODS

Eighteen patients inhaled methacholine (MCh) until FEV(1) decreased by 35% of control. Following administration of placebo, 200 microg salbutamol or 400 microg salbutamol through the pMDI + Volumatic or the Diskus, we calculated the time elapsed from drug administration and the appearance of a 90% increase in post-MCh forced vital capacity (FVC), FEV(1) and volume-adjusted mid-expiratory flow (recovery times). The salbutamol doses to be delivered by the two inhalation devices to achieve similar recovery times and the relative potencies of the devices were calculated by using the 2-by-2 Finney parallel regression method.

RESULTS

For all functional variables, recovery times were significantly (P < 0.01) shorter in pMDI + Volumatic than Diskus trials. The salbutamol doses to be delivered by the Diskus to achieve recovery times for FVC, FEV(1) and volume-adjusted mid-expiratory flow similar to those obtained with 200 microg salbutamol administered via the pMDI + Volumatic were 558 (95% CI 537, 579) microg, 395 (95% CI 388, 404) microg and 404 (95% CI 393, 415) microg, respectively, and corresponded to relative potencies of 2.79 (95% CI 2.68, 2.90), 1.98 (95% CI 1.94, 2.02), and 2.02 (95% CI 1.96, 2.07).

CONCLUSIONS

Administration of salbutamol via the pMDI + Volumatic provides faster reversal of induced bronchoconstriction than via the Diskus. The salbutamol dose targeting the lungs with the pMDI + Volumatic is approximately twice that with the Diskus.

Long-acting beta2-agonists: comparative pharmacology and clinical outcomes

Salmeterol and formoterol are both long-acting beta(2)-adrenoceptor agonists (beta(2)-agonists). They both provide excellent bronchodilating and bronchoprotective effects in patients with asthma but their are some differences between these two long-acting beta(2)-agonists in vitro and in vivo. Formoterol has a greater potency and intrinsic activity than salmeterol, which can become especially apparent at higher doses than that clinically recommended, and in contracted bronchi. Long-term use of long-acting beta(2)-agonists can induce tolerance, which can be partially reversed with corticosteroids. Long-acting beta(2)-agonists have some anti-inflammatory effects in vitro, but data in vivo are less convincing. Compared with doubling the dose of inhaled corticosteroids, the addition of inhaled long-acting beta(2)-agonists to inhaled corticosteroids improves symptom control in patients with asthma and reduces both the exacerbation rate of asthma and hospital admission rate. No enhanced airway responsiveness or loss of perception of dyspnea has been observed with the use of inhaled long-acting beta(2)-agonists. Monotherapy with long-acting beta(2)-agonists is not recommended.

A comparison of the onset of action of salbutamol and formoterol in reversing methacholine-induced bronchoconstriction

This single-centre, randomized, double-blind, double-dummy four-way cross-over study in 24 moderately severe asthmatic patients compared the speed of onset of recommended doses of salbutamol (200 micrograms) and formoterol (12 micrograms) delivered by metered-dose inhaler in reversing the bronchoconstriction induced by a cumulative dose of methacholine to produce a 20% decrease (PD20) in forced expiratory volume in 1 s (FEV1). Specific airway conductance (SGAW) and airway resistance (RAW) were measured in baseline condition, immediately after challenge and 0.5, 1.5, 3, 5, 10, 15, 30, 60 min and every hour up to 4 h after inhalation of the trial drug. FEV1 was measured in baseline condition, after challenge and 15, 30 and 60 min and then every 30 min up to 4 h after inhalation of the study drug. The primary efficacy parameter was the change in SGAW. Salbutamol produced a two-fold increase in SGAW within 4 min and a maximum increase after 79.3 min. Formoterol produced a two-fold increase in SGAW after 5 min and a maximum increase after 119.6 min. Changes in SGAW were slightly, but consistently, higher during the first 2 h after inhalation of salbutamol, both in absolute values and as a percentage of the maximum response. Differences were significant at 10, 15 and 30 min time points. There was no significant difference between the maximum values of SGAW after the two drugs. Changes in RAW and FEV1 reflected the differences in SGAW. It was concluded that in methacholine-induced bronchoconstriction both formoterol and salbutamol have a very fast onset of action, achieving prechallenge values of SGAW within 3 min, salbutamol being slightly faster than formoterol.

Acute bronchodilatory effect of salmeterol on methacholine-induced bronchoconstriction in childhood asthma

A review of the literature highlights the need for research, particularly on the acute bronchodilatory effect of salmeterol on bronchoconstriction in the pediatric age group. The present study attempted to evaluate the acute bronchodilatory effect of salmeterol on methacholine-induced bronchoconstriction in childhood asthma and to compare it with the effect of salbutamol. Forty-four asymptomatic children with mild-to-moderate asthma (23 boys and 21 girls; aged 7-17 years) were studied. At the beginning, the baseline forced expiratory volume in 1 s (FEV1) was measured, and the methacholine challenge was performed by doubling the dose to determine PC20 (provocative concentration of inhaled methacholine required to reduce FEV1 by 20%). At the same time, the transcutaneous arterial oxygen saturation (SaO2) was also measured. Each subject inhaled a single dose of 25 micrograms salmeterol (n: 23, group I) or 100 micrograms salbutamol (n: 21, group II) following the SaO2 measurement. The same measurements (FEV1, SaO2) were repeated 5 and 20 min after the inhalation. After inhalation of salmeterol or salbutamol, the differences between the values of FEV1 and SaO2 after 5 and 20 min were insignificant in both group I and group II (P > 0.05), although there was a significant improvement in both FEV1 and SaO2 after 5 and 20 min (P < 0.005). From these findings it was concluded that salmeterol can be considered as effective as salbutamol on methacholine-induced bronchoconstriction.

The interaction between salmeterol and beta 2-adrenoceptor agonists with higher efficacy on guinea-pig trachea and human bronchus in vitro

1. In guinea-pig tracheal preparations precontracted with 1 mumol l-1 carbachol, formoterol, procaterol, fenoterol, salmefamol, salbutamol and terbutaline (in that order of potency) caused a concentration-dependent and almost complete, relaxation. However, under these conditions, the maximum relaxation by salmeterol was approximately 30% of the maximum attainable relaxation. 2. We have therefore explored the ability of salmeterol to inhibit the relaxant response to beta 2-adrenoceptor agonists of different chemical structure and relatively higher efficacy in smooth muscle preparations from guinea-pig trachea and human bronchus. 3. With 1 mumol l-1 salmeterol in the organ bath, the concentration-effect curves for the other agonists were shifted to the right in a variable way by 1.8-2.8 log units, fenoterol and salbutamol being the extremes. 4. When 20 mumol l-1 sulfonterol, another low efficacy beta 2-adrenoceptor agonist, was substituted for salmeterol, the difference in the magnitude of the rightward shift between fenoterol and salbutamol was eliminated. 5. In the human bronchus, formoterol and terbutaline had a higher apparent efficacy than salmeterol. With 1 mumol l-1 salmeterol in the organ bath, the concentration-effect curve for formoterol was shifted 2.7 log units to the right. 6. Salmeterol inhibits, competitively, relaxant responses to beta 2-adrenoceptor agonists with higher efficacy. The degree of inhibition seems to be dependent on the agonist used. This contrasts with results obtained with sulfonterol and suggests that salmeterol interacts with the beta 2-adrenoceptor in a complex way.

Salmeterol: a novel, long-acting beta 2-agonist

OBJECTIVE

The clinical pharmacology, pharmacokinetics, clinical efficacy, and adverse effects of the long-acting beta 2-agonist salmeterol are reviewed.

DATA SOURCES

A MEDLINE search was performed to identify English-language publications pertaining to salmeterol.

STUDY SELECTION

Open and controlled trials were reviewed in assessing clinical efficacy. Only the results of controlled, randomized trials were considered in the effectiveness evaluation.

DATA EXTRACTION

The primary measures of effectiveness in the clinical trials were bronchodilator activity and reduction of hyperresponsiveness that may reflect antiinflammatory activity. Bronchodilator activity was measured as changes in pulmonary function; reduction of hyperresponsiveness was evaluated using respiratory challenge with methacholine, histamine, allergen, or cold air. Secondary measures included symptom scores, need for rescue doses, and patient preference.

DATA SYNTHESIS

Salmeterol is a selective, beta 2-agonist that has been studied in the treatment of exercise-induced, nocturnal, and allergen-induced asthma. Salmeterol interacts with the traditional beta-receptor in a similar manner as other beta-agonists, and it exhibits potent in vitro antiinflammatory effects as an inhibitor of inflammatory mediator release. Less evidence exists for its in vivo antiinflammatory activity. Salmeterol demonstrates prolonged receptor occupancy, which is thought to contribute to its long duration of action. The recommended dose is 50 micrograms via metered-dose inhaler or dry-powdered inhalation. In the published clinical trials, salmeterol was more effective than albuterol in treating asthma, including exercise and allergen-induced asthma. Salmeterol's major advantage over other inhaled beta-agonists is its long duration of action (12 hours), making it an excellent choice for treatment of nocturnal asthma. A potential disadvantage is delayed onset of action. Tachyphylaxis to salmeterol's bronchodilator effects has not been shown, but tolerance to its protective effects against methacholine-induced bronchoconstriction has occurred. Adverse effects reported have been mild and have included headache, tremor, and palpitations.

CONCLUSIONS

Salmeterol is an effective beta 2-agonist in the treatment of asthma. However, several issues require further investigation regarding its long-term effects on disease control, significance of antiinflammatory activity, and role as a rescue medication.

Salmeterol, formoterol, and salbutamol in the isolated guinea pig trachea: differences in maximum relaxant effect and potency but not in functional antagonism

BACKGROUND

Formoterol and salmeterol are new long acting beta 2 adrenoceptor agonists. The maximum relaxant effect, potency and functional antagonism against carbachol induced contraction for salmeterol, formoterol and salbutamol have been compared in the guinea pig isolated trachea. In addition, the possibility of inducing a non-beta adrenoceptor mediated relaxation by salmeterol was studied.

METHODS

Concentration response experiments were conducted with isolated tracheal preparations (n = 4-6 in all experiments), precontracted by carbachol to cause either 40% (60 nmol/l), 80% (0.3 mumol/l) or 100% (3 mumol/l, supramaximal) of the maximum contraction. Each beta agonist was added cumulatively at each level of precontraction. Additional cumulative concentration response experiments were conducted for salmeterol alone at the highest level of precontraction, with and without beta blockade by sotalol (1 mmol/l). With the drug concentrations which produced the maximum response and the highest level of precontraction, the relaxation of formoterol (10 nmol/l) and salmeterol (1 mumol/l) was also compared non-cumulatively. Finally, with the corresponding drug concentrations and precontraction, the relaxant effect was compared for formoterol (10 nmol/l) in salmeterol relaxed airways with that of salmeterol (1 mumol/l) in formoterol relaxed airways.

RESULTS

The increase in carbachol concentration from 60 nmol/l to 3 mumol/l induced a rightward shift in the mean (SE) concentration (log steps) causing 50% maximum relaxation for salmeterol (0.73 (0.17)), formoterol (0.85 (0.18)), and salbutamol (1.13 (0.11)). Significant differences in the maximum relaxant effect were shown at the highest level of precontraction only, with a remaining active tension of percentage precontraction of 27% (4%) for 1 mumol/l salbutamol and 35% (3%) for 10 nmol/l formoterol compared with 50% (2%) for 1 mumol/l salmeterol. The rank order of potency was: formoterol > salbutamol approximately salmeterol at all levels of precontraction (-log EC50: 9.32 (0.05) for formoterol, 7.82 (0.08) for salbutamol, and 7.50 (0.13) for salmeterol at 80% maximum precontraction). Beta blockade by sotalol (1 mmol/l) significantly inhibited the relaxation induced by salmeterol (1 mumol/l) (remaining active tension: 104% (1%) v 71% (11%) of precontraction) but not the relaxation induced by salmeterol (10 mumol/l) (remaining active tension: 75% (5%) v 71% (12%) of precontraction). In the non-cumulative experiments, formoterol displayed more relaxant effect than salmeterol (remaining active tension: 51% (6%) v 65% (6%) of precontraction). Finally, formoterol significantly relaxed salmeterol relaxed airways (relaxant effect: 22% (8%) of precontraction) whereas there was no significant response to salmeterol in formoterol relaxed airways (relaxant effect: 5% (12%) of precontraction).

CONCLUSIONS

In the guinea pig isolated trachea, formoterol and salbutamol produce more relaxant effect than salmeterol, suggesting that salmeterol is a partial beta 2 agonist. Very high concentrations of salmeterol may induce non-beta adrenoceptor mediated relaxation. Formoterol is more potent than both salbutamol and salmeterol. There is no pronounced difference in the magnitude of antagonism against carbachol induced contractions between salmeterol, formoterol, and salbutamol.

Long acting inhaled beta-adrenoceptor agonists the comparative pharmacology of formoterol and salmeterol

Formoterol and salmeterol are chemically distinct, highly selective beta-2-adrenoceptor agonists developed to provide sustained (12h+) relief of airway obstruction in diseases such as asthma. Despite their similar long duration of action, these drugs differ. Formoterol has a faster onset of action in both experimental and clinical tests than that of salmeterol. Salmeterol, but not formoterol, behaves as a beta-adrenoceptor antagonist in some experimental models due to its considerably weaker efficacy at the beta 2-adrenoceptor in vitro although their are no established clinical consequences of this antagonism. Both formoterol and salmeterol display a peculiar "reassertion" behaviour in isolated airway smooth muscle subjected to beta-adrenoceptor antagonism and then washed with antagonist-free buffer. Both formoterol and salmeterol are highly efficient inhibitors of a number of indices of acute inflammatory processes in cells and tissues of human or animal origin. However, neither of these drugs has a proven clinical anti-inflammatory effect in chronic asthma in humans. Surprisingly, recent biophysical studies of formoterol and salmeterol have provided strong evidence that their individual patterns of onset speed, duration of action and "reassertion" are due to a common drug-lipid membrane interaction rather than drug-adrenoceptor interactions. A membrane-drug diffusion microkinetic model is presented to describe these phenomena.