Metered dose inhaler salbutamol treatment of asthma in the ED: comparison of two doses with plasma levels

Targeting mucus barrier in respiratory diseases by chemically modified advanced delivery systems

Mucus gel constitutes of heavily cross-linked mucin fibers forming a viscoelastic, dense porous network that coats all the exposed epithelia not covered with the skin. The layer provides protection to the underlying gastrointestinal, respiratory, and female reproductive tracts, in addition to the organs such as the surface of eye by trapping the pathogens, irritants, environmental fine particles, and potentially hazardous foreign matter. However, this property of mucus gel poses a substantial challenge for realizing the localized and sustained drug delivery across the mucosal surfaces. The mucus permeating particles that spare the protective properties of mucus gel improve the therapeutic potency of the drugs aimed at the management of diseases, including sexually transmitted infections, lung cancer, irritable bowel disease, degenerative eye diseases and infections, and cystic fibrosis. As such, the mucoadhesive materials conjugated with drug molecules display a prolonged retention time in the mucosal gel that imparts a sustained release of the deliberated drug molecules across the mucosa. The contemporarily developed mucus penetrating materials for drug delivery applications comprise of a finer size, appreciable hydrophilicity, and a neutral surface to escape the entrapment within the cross-inked mucus fibers. Pertaining to the mucus secretion as a first line of defence in respiratory tract in response to the invading physical, chemical, and biological pathogens, the development of mucus penetrating materials hold promise as a stalwart approach for revolutionizing the respiratory drug delivery paradigm. The present review provides an epigrammatic collation of the mucus penetrating/mucoadhesive materials for achieving a controlled/sustained release of the cargo pharmaceutics and drug molecules across the respiratory mucus barrier.

Effectiveness of Spacer Devices on Preventing Undesirable Cardiovascular Effects of Inhaled Salbutamol

Background: Currently, there are no regulatory guidelines indicating spacer devices/valved holding chamber (VHC) should be used routinely during pulmonary function tests, and few studies evaluated if spacer devices reduce beta-agonist bronchodilators' side effects. Methods: A prospective study compared salbutamol's cardiovascular effects and bronchodilation response during spirometry tests with and without a spacer device/VHC. Heart rate (HR), the corrected QT interval (QTc), and systolic and diastolic blood pressure were measured 10 minutes after the first spirometry test, before the drug administration, and 20 minutes after inhalation in both groups. Spirometric parameters (forced expiratory volume in the first second [FEV1], forced vital capacity [FVC], and FEV1/FVC) were also measured for both groups. Results: HR and QTc increase were significantly higher in the pressurized meter dose inhalers alone group versus the VHC group [mean SD] [73.1 ± 10 bpm to 74.3 + 10 bpm, p = 0.021] and [median (25%-75% interquartile range)] [389 ms (381-404) to 398 ms (387-407), p = 0.045] vs. [mean SD] [75.4 ± 9 to 73.8 + 8 bpm, p = 0.4] and [median (25%-75% interquartile range)] [388 ms (347-408) to 385 ms (366-408), p = 0.35], respectively. FEV1 variation before and after salbutamol were similar between both groups. Discussion: Although VHC significantly reduces HR and QTc variation when using beta-agonist bronchodilators in healthy patients, no clinical repercussions of this variation were found in this study, since no event of tachycardia or pathological QTc was recorded. Conclusion: VHC has a diminished clinical impact for healthy patients when considering cardiovascular effects and spirometric parameters. Beta-agonist bronchodilators may be administrated despite the use of spacer devices in patients without known cardiovascular diseases. Its significance for other populations still needs to be determined.

The Saudi Initiative for Asthma - 2019 Update: Guidelines for the diagnosis and management of asthma in adults and children

This is the fourth version of the updated guidelines for the diagnosis and management of asthma, developed by the Saudi Initiative for Asthma (SINA) group, a subsidiary of the Saudi Thoracic Society. The main objective of the SINA is to have guidelines that are up to date, simple to understand, and easy to use by healthcare workers dealing with asthma patients. To facilitate achieving the goals of asthma management, the SINA panel approach is mainly based on the assessment of symptom control and risk for both adults and children. The approach to asthma management is now more aligned for different age groups. The guidelines have focused more on personalized approaches reflecting better understanding of disease heterogeneity with integration of recommendations related to biologic agents, evidence-based updates on treatment, and role of immunotherapy in management. The medication appendix has also been updated with the addition of recent evidence, new indications for existing medication, and new medications. The guidelines are constructed based on the available evidence, local literature, and current situation at national and regional levels. There is also an emphasis on patient–doctor partnership in the management that also includes a self-management plan.

Holding chambers (spacers) versus nebulisers for beta-agonist treatment of acute asthma

BACKGROUND

In acute asthma inhaled beta(2)-agonists are often administered by nebuliser to relieve bronchospasm, but some have argued that metered-dose inhalers with a holding chamber (spacer) can be equally effective. Nebulisers require a power source and need regular maintenance, and are more expensive in the community setting.

OBJECTIVES

To assess the effects of holding chambers (spacers) compared to nebulisers for the delivery of beta(2)-agonists for acute asthma.

SEARCH METHODS

We searched the Cochrane Airways Group Trial Register and reference lists of articles. We contacted the authors of studies to identify additional trials. Date of last search: February 2013.

SELECTION CRITERIA

Randomised trials in adults and children (from two years of age) with asthma, where spacer beta(2)-agonist delivery was compared with wet nebulisation.

DATA COLLECTION AND ANALYSIS

Two review authors independently applied study inclusion criteria (one review author for the first version of the review), extracted the data and assessed risks of bias. Missing data were obtained from the authors or estimated. Results are reported with 95% confidence intervals (CIs).

MAIN RESULTS

This review includes a total of 1897 children and 729 adults in 39 trials. Thirty-three trials were conducted in the emergency room and equivalent community settings, and six trials were on inpatients with acute asthma (207 children and 28 adults). The method of delivery of beta(2)-agonist did not show a significant difference in hospital admission rates. In adults, the risk ratio (RR) of admission for spacer versus nebuliser was 0.94 (95% CI 0.61 to 1.43). The risk ratio for children was 0.71 (95% CI 0.47 to 1.08, moderate quality evidence). In children, length of stay in the emergency department was significantly shorter when the spacer was used. The mean duration in the emergency department for children given nebulised treatment was 103 minutes, and for children given treatment via spacers 33 minutes less (95% CI -43 to -24 minutes, moderate quality evidence). Length of stay in the emergency department for adults was similar for the two delivery methods. Peak flow and forced expiratory volume were also similar for the two delivery methods. Pulse rate was lower for spacer in children, mean difference -5% baseline (95% CI -8% to -2%, moderate quality evidence), as was the risk of developing tremor (RR 0.64; 95% CI 0.44 to 0.95, moderate quality evidence).

AUTHORS' CONCLUSIONS

Nebuliser delivery produced outcomes that were not significantly better than metered-dose inhalers delivered by spacer in adults or children, in trials where treatments were repeated and titrated to the response of the participant. Spacers may have some advantages compared to nebulisers for children with acute asthma.

Tremor and β(2)-adrenergic agents: is it a real clinical problem?

Tremor is one of the most characteristic adverse effects following administration of β(2)-adrenergic agonists. It is reported by around 2-4% of patients with asthma taking a regular β(2)-adrenergic agonist and is induced by both short-acting and long-acting agents. Tremor associated with β(2)-adrenergic agonists is dose-related and may occur more commonly with oral dosing. The exact mechanism for tremor induction by β(2)-adrenergic agonists is still unknown, but there is some evidence that β(2)-adrenergic agonists act directly on muscle. An early explanation of the tremor was that β(2)-adrenoceptor stimulation shortens the active state of skeletal muscle, which leads to incomplete fusion and reduced tension of tetanic contractions. More recently, tremor has been correlated closely with hypokalaemia. A possible diverse impact of different modes of administration of β(2)-adrenergic agonists on tremorogenic responses has been suggested but solid evidence is still lacking. In any case, the desensitization of β(2)-adrenoceptors that occurs during the first few days of regular use of a β(2)-adrenergic agonist accounts for the commonly observed resolution of tremor after the first few doses. Therefore, tremor is not a really important adverse effect in patients under regular treatment with a β(2)-adrenergic agonist.

Safety of daily albuterol in infants with a history of bronchospasm: a multi-center placebo controlled trial

Introduction:

Inhaled short-acting bronchodilators are recommended for the quick relief of bronchospasm symptoms in children including those less than five years of age. However, limited safety data is available in this young population.

Methods:

Safety data were analyzed from a randomized, double-blind, parallel group, placebo-controlled multicenter, study evaluating albuterol HFA 90µg or 180µg versus placebo three times a day for 4 weeks using a valved holding chamber, Aerochamber Plus and facemask in children birth ≤24 months old with a history of bronchospasm.

Results:

The overall incidence of adverse events (AE) during treatment was: albuterol 90µg (59%), albuterol 180µg (76%) and placebo (71%). The most frequently reported AEs were pyrexia in 7 (24%), 2 (7%), and 3 (11%) subjects in the albuterol 180µg, albuterol 90µg, and placebo groups, respectively. Upper respiratory tract infection (URTI) occurred in 5 (17%) and 3 (11%) subjects in the albuterol 180µg and placebo groups, respectively. Sinus tachycardia occurred in 5 (17%), 2 (7%) and 2 (7%) subjects receiving albuterol 180µg, albuterol 90µg and placebo, respectively. One subject in each of the albuterol treatment groups experienced drug related agitation and/or restlessness or mild sinus arrhythmia. No drug-related QT prolongation or abnormal serum potassium and glucose levels were reported in the albuterol treatment groups.

Conclusion:

This study provides additional albuterol HFA safety information for the treatment of children aged birth ≤24 months with a history of bronchospasm.

[Severe acute asthma: its management in emergency visits and intensive care]

All patients with asthma are at risk of suffering an acute asthma attack over their lifetime, and these may finally be fatal. Hospitalizations and emergency department visits and intensive care account for a large proportion of the health-care cost burden of asthma. Thus, it is especially important to establish plans for prevention, education and therapeutic rationalization of primary care that establishes the disease and decreases its worsening. The severity of the exacerbations may vary from a mild to life threatening. The mortality is basically linked to inadequate assessment of the patient's severity. This leads to inadequate treatment in the emergency and delay in the patient's hospitalization. This review describes the epidemiology, costs, pathophysiology, mortality and management of adult acute asthma patients in the emergency department and intensive care, especially that related to non-invasive mechanical ventilation and conventional forms of mechanical respiratory care, with the current changes in its operational strategy.

Comparison between nebulized adrenaline and beta2 agonists for the treatment of acute asthma. A meta-analysis of randomized trials

OBJECTIVE

To evaluate the efficacy of aerosolized adrenaline compared to inhaled beta(2) agonists in the treatment of acute asthma in the emergency setting.

DATA SOURCES

MEDLINE, EMBASE, CINAHI, and Cochrane databases, review articles, and references of included trials.

REVIEW METHODS

Published (1966-2005) randomized controlled trials with pulmonary function as primary outcome.

RESULTS

Six studies met the criteria for inclusion in the meta-analysis. They included 161 adults and 121 children and adolescents. Patients who received inhaled adrenaline showed a nonsignificant improvement in pulmonary function (standardized mean difference = 0.20, 95% confidence interval -0.22 to 0.63, P = .35) compared to patients getting inhaled beta(2) agonists. Moderate heterogeneity was identified between studies (I(2) = 47.2%). Homogeneity was achieved when studies that reported pulmonary function were stratified by intensity of adrenaline treatment. The use of more than 2 mg of adrenaline per dose was equivalent to 5 mg of salbutamol or terbutaline per dose. On the contrary, 2 mg or less of adrenaline per dose was inferior to 2.5 or 5 mg of salbutamol per dose. In addition, there were no differences in heart rate and Pao(2) between treatments.

CONCLUSIONS

There was no statistically significant benefit of nebulized adrenaline over salbutamol or terbutaline in the treatment of children and adults with moderate-severe acute asthma.

Holding chambers (spacers) versus nebulisers for beta-agonist treatment of acute asthma

BACKGROUND

In acute asthma inhaled beta2-agonists are often administered to relieve bronchospasm by wet nebulisation, but some have argued that metered-dose inhalers with a holding chamber (spacer) can be equally effective. Nebulisers require a power source and need regular maintenance, and are more expensive in the community setting.

OBJECTIVES

To assess the effects of holding chambers (spacers) compared to nebulisers for the delivery of beta2-agonists for acute asthma.

SEARCH STRATEGY

We last searched the Cochrane Airways Group trials register in January 2006 and the Cochrane Central Register of Controlled Trials (The Cochrane Library, Issue 4, 2005).

SELECTION CRITERIA

Randomised trials in adults and children (from two years of age) with asthma, where spacer beta2-agonist delivery was compared with wet nebulisation.

DATA COLLECTION AND ANALYSIS

Two reviewers independently applied study inclusion criteria (one reviewer for the first version of the review), extracted the data and assessed trial quality. Missing data were obtained from the authors or estimated. Results are reported with 95% confidence intervals (CI).

MAIN RESULTS

This review has been updated in January 2006 and four new trials have been added. 2066 children and 614 adults are now included in 25 trials from emergency room and community settings. In addition, six trials on in-patients with acute asthma (213 children and 28 adults) have been reviewed. Method of delivery of beta2-agonist did not appear to affect hospital admission rates. In adults, the relative risk of admission for spacer versus nebuliser was 0.97 (95% CI 0.63 to 1.49). The relative risk for children was 0.65 (95% CI: 0.4 to 1.06). In children, length of stay in the emergency department was significantly shorter when the spacer was used, with a mean difference of -0.47 hours (95% CI: -0.58 to -0.37). Length of stay in the emergency department for adults was similar for the two delivery methods. Peak flow and forced expiratory volume were also similar for the two delivery methods. Pulse rate was lower for spacer in children, mean difference -7.6% baseline (95% CI: -9.9 to -5.3% baseline).

AUTHORS' CONCLUSIONS

Metered-dose inhalers with spacer produced outcomes that were at least equivalent to nebuliser delivery. Spacers may have some advantages compared to nebulisers for children with acute asthma.

Drug-induced tremors

Tremor is a common complaint for many patients. Caffeine and beta-adrenergic agonists are well-recognised drugs that cause or exacerbate tremors. Other tremorogenic drugs, such as selective serotonin reuptake inhibitors and tricyclic antidepressants, are less well recognised. Recognition of the drugs that can cause or exacerbate tremors can help prompt diagnosis, avoids unnecessary tests, and allows clinicians to quickly take corrective action (usually by discontinuing the tremor-inducing drugs). The aim of this review is to provide clinicians with current information on drugs that are associated with tremor and the correct treatment of these drug-induced tremors.

Elevated plasma lactate level associated with high dose inhaled albuterol therapy in acute severe asthma

BACKGROUND

Lactic acidosis is a recognised event in adult patients with status asthmaticus, particularly in the setting of intensive care. However, it has been infrequently studied in patients attending the emergency departments (ED).

METHODS

We conducted a prospective and descriptive study to assess levels of lactate and effects on bronchodilator response in adult patients with acute severe asthma treated with high doses of albuterol in the ED. In total, 18 subjects (mean (SD) age 42.9 (2.7) years, FEV1 = 32.2 (10.9)% of predicted) who presented to an emergency department were enrolled in the study. All patients were treated with albuterol; four puffs (100 microg/puff) at 10 minute intervals, delivered by a pressurised metered dose inhaler into a spacer device over a 2 hour period.

RESULTS

At the end of treatment, mean (SD) plasma lactate level (2.94 (2.1) mmol/l) was significantly higher (p = 0.001) than baseline. Of the 18 patients, nine (50%) showed lactate levels > or = 2.5 mmol/l (four patients presented values > 4 mmol/l); these patients had a shorter duration of attack prior to ED presentation (p = 0.01), a higher pretreatment heart rate (p = 0.005), a lower pretreatment SpO2 (p = 0.03), a lower pretreatment PO2 (p = 0.009), a higher pretreatment PCO2, and a lower pretreatment serum potassium (p = 0.005). However, there were no significant differences in the airway response between groups.

CONCLUSIONS

This study confirmed previous observations that high lactate concentrations can develop during the first hours of inhaled beta agonist treatment. The presence of a previous hyperadrenergic state may predispose to the development of this condition. A significant improvement in lung function was associated with elevated lactate levels.

Acute asthma in adults: a review

All patients with asthma are at risk of having exacerbations. Hospitalizations and emergency department (ED) visits account for a large proportion of the health-care cost burden of asthma, and avoidance or proper management of acute asthma (AA) episodes represent an area with the potential for large reductions in health-care costs. The severity of exacerbations may range from mild to life threatening, and mortality is most often associated with failure to appreciate the severity of the exacerbation, resulting in inadequate emergency treatment and delay in referring to hospital. This review describes the epidemiology, costs, pathophysiology, mortality, and management of adult AA in the ED and in the ICU.

A comparison of salmeterol and formoterol in attenuating airway responses to short-acting beta2-agonists

In vitro data suggest that salmeterol, contrary to formoterol, can partly antagonise the effect of short-acting beta(2)-agonist rescue medication. To explore whether this occurs in vivo, we compared the effects of increasing doses (200-3200 microg) of fenoterol on the recovery of methacholine induced bronchoconstriction as well as PD(20) methacholine in 23 asthmatic patients, during two-week treatment periods with placebo, and standard doses of salmeterol or formoterol in a double blind, double-dummy, crossover study. Salmeterol showed a slightly higher propensity for the development of bronchodilator tolerance. The recovery of methacholine induced bronchoconstriction was more complete during regular use of formoterol relative to salmeterol. During regular use of both long-acting beta(2)-agonists the bronchoprotective efficacy of fenoterol was attenuated, but this was more pronounced during salmeterol than during formoterol. The mean maximum increase in PD(20) metacholine after the highest dose of fenoterol was 3.97 DD during placebo, 2.47 DD during formoterol (p<0.001) and 1.81 DD during salmeterol treatment (p<0.001). We conclude that in asthmatic patients the efficacy of short-acting beta(2)-adrenoceptor agonists can be significantly attenuated during regular use of long-acting beta(2)-agonists. In this respect, differences were observed between salmeterol and formoterol that may represent the expression of partial antagonism by salmeterol.

Spacers and nebulisers for the delivery of beta-agonists in non-life-threatening acute asthma

BACKGROUND

In asthma exacerbations, higher doses of inhaled beta-agonists are used to overcome acute bronchoconstriction. Traditionally, wet nebulisation has been used, but metered-dose inhaler with a spacer device is an alternative delivery method.

OBJECTIVE

To compare the clinical outcomes in adults and children with acute asthma, presenting in emergency departments or in the community, who have been randomised to beta-agonists given by two different delivery.

METHODS

a metered-dose inhaler with spacer or a nebuliser.

RESULTS

A Cochrane review has found no important differences between the two delivery methods in adults. Children may suffer fewer side effects with spacer delivery.

CONCLUSIONS

Individual response to treatment cannot be predicted, but many studies overcame this problem by using frequent repeated doses of beta-agonists (one respule via nebuliser or four separate actuations of a metered-dose inhaler through a spacer) every 10-15 min, titrated against the clinical response of the patients. This approach is advocated in clinical practice.

Inhaled therapy for acute adult asthma

PURPOSE OF REVIEW

To evaluate recent developments on emergency department inhalotherapy in non-intubated acute adult asthma patients.

RECENT FINDINGS

There is evidence that high-flow oxygen can be associated with hypercarbia, and that full humidification of the inspired gases should be recommended. On the contrary, there is a lack of evidence to support the role of heliox in the initial treatment of acute asthma. Specific short-acting inhaled beta(2)-agonists are the drugs of choice. A more rapid and profound bronchodilatation with fewer side effects and less time of treatment can be achieved when sufficient doses are given using pressurized meter dose inhalers and large-volume valved-spacers, particularly in patients with the most severe obstruction. Findings argue against the routine use of continuous nebulization. High and repetitive doses of ipratropium bromide in combination with beta(2)-agonists are indicated as first line treatment of severe acute asthma. There is insufficient evidence that inhaled corticosteroids alone are as effective as systemic corticosteroids. Finally, the combination of nebulized magnesium and albuterol provides no benefit in addition to that provided by therapy with albuterol in patients with mild-to-moderate asthma exacerbations.

SUMMARY

According to the latest evidence, the goals of treatment may be summarized as follows: maintenance of adequate arterial oxygen saturation with supplemental oxygen, relief of airflow obstruction by administration of inhaled beta-agonists and anticholinergics, and reduction of airway inflammation and prevention of future relapses by using early administration of systemic corticosteroids.

Holding chambers versus nebulisers for beta-agonist treatment of acute asthma

BACKGROUND

In acute asthma inhaled beta-2-agonists are often administered to relieve bronchospasm by wet nebulisation, but some have argued that metered-dose inhalers with a holding chamber (spacer) can be equally effective. In the community setting nebulisers are more expensive, require a power source and need regular maintenance.

OBJECTIVES

To assess the effects of holding chambers compared to nebulisers for the delivery of beta-2-agonists for acute asthma.

SEARCH STRATEGY

We last searched the Cochrane Airways Group trials register in November 2002 and the Cochrane Central Register of Controlled Trials (The Cochrane Library, Issue 3, 2002).

SELECTION CRITERIA

Randomised trials in adults and children (from two years of age) with asthma, where holding chamber beta-2-agonist delivery was compared with wet nebulisation.

DATA COLLECTION AND ANALYSIS

Two reviewers independently applied study inclusion criteria (one reviewer for the first version of the review), extracted the data and assessed trial quality. Missing data were obtained from the authors or estimated. Results are reported with 95% confidence intervals (CI).

MAIN RESULTS

This review has been updated in 2003 and has now analysed 1076 children and 444 adults included in 22 trials from emergency room and community settings. In addition, five trials on in-patients with acute asthma (184 children and 28 adults) have been added to the review. Method of delivery of beta-2-agonist did not appear to affect hospital admission rates. In adults, the relative risk of admission for holding chamber versus nebuliser was 0.88 (95% CI 0.56 to 1.38). The relative risk for children was 0.65 (95% CI 0.4 to 1.06). In children, length of stay in the emergency department was significantly shorter when the holding chamber was used, with a weighted mean difference of -0.47 hours, (95% CI -0.58 to -0.37 hours). Length of stay in the emergency department for adults was similar for the two delivery methods. Peak flow and forced expiratory volume were also similar for the two delivery methods. Pulse rate was lower for holding chamber in children, weighted mean difference -7.6% baseline (95% CI -9.9 to -5.3% baseline).

REVIEWER'S CONCLUSIONS

Metered-dose inhalers with holding chamber produced outcomes that were at least equivalent to nebuliser delivery. Holding chambers may have some advantages compared to nebulisers for children with acute asthma.

Comparison of single 7.5-mg dose treatment vs sequential multidose 2.5-mg treatments with nebulized albuterol in the treatment of acute asthma

STUDY OBJECTIVE

s: The purpose of the current trial was to compare the relief of airway obstruction from treatment with a single dose of albuterol,7.5 mg (single-dose group), with that from three sequential doses of albuterol, 2.5 mg, spaced 20 min apart (multidose group).

DESIGN

Randomized clinical trial designed to test equivalence.

SETTING

Urban county hospital emergency department.

PATIENTS OR PARTICIPANTS

Adult patients between the ages of 18 and 60 years presenting to the emergency department with acute asthma, as defined by the American Thoracic Society criteria, with FEV (1) on presentation to the emergency department of < or = 75% of predicted were included in the study.

INTERVENTIONS

After the initial evaluation, patients were administered either albuterol, 2.5 mg via nebulizer every 20 min for a total of three doses, or albuterol 7.5 mg via nebulizer in a single dose.

MEASUREMENTS AND RESULTS

Ninety-four patients participated, 46 in the single-dose group and 48 in the multidose group. Patients in both groups had severe obstruction on presentation to the emergency department (single-dose group pretreatment FEV(1), 45% of predicted [SD, 16% of predicted]; multidose group pretreatment FEV(1), 47% of predicted [SD, 17% of predicted]; p = 0.62). The primary outcome measure was the change in FEV(1) percent predicted over time. The secondary outcome measures were disposition after treatment (ie, hospitalization or discharge to home) and the incidence of side effects. We noted a 44.5% improvement (SD, 56.2%) in pretreatment to posttreatment FEV(1) values in the single-dose group and a 38.1% improvement (SD, 37.3%) in the multidose group (p = 0.52). A similar proportion of patients in both groups required hospitalization (single-dose group, 48%; multidose group, 41%; p = 0.51). There was a trend for the patients in the single-dose group to experience more side effects than patients in the multidose group (patients in the single-dose group patients, 40% [SD, 19%]; multidose group patients, 22% [SD, 10%]; p = 0.06).

CONCLUSION

A single dose of 7.5 mg nebulized albuterol and sequential doses of 2.5 mg nebulized albuterol are clinically equivalent in the treatment of patients with moderate-to-severe acute asthma and result in similar dispositions from the emergency department.

Clinical pharmacokinetics of salmeterol

Salmeterol is an inhaled long-acting selective beta(2)-adrenoceptor agonist that is commercially available as the xinafoate (1-hydroxy-2-naphthoic acid) salt of the racemic mixture of the two optical isomers, (R)- and (S)-, of salmeterol. It acts locally in the lung through action on beta2 receptors. Limited data have been published on the pharmacokinetics of salmeterol. Moreover, there are no data on the extent to which inhaled salmeterol undergoes first-pass metabolism. This lack of information is most likely due to the very low plasma concentrations reached after inhalation of therapeutic doses of salmeterol and the problems in developing an analytical method that is sensitive enough to determine these concentrations. When salmeterol is inhaled, plasma concentrations of the drug often cannot be detected, even at 30 minutes after administration of therapeutic doses. Larger inhaled doses give approximately proportionally increased blood concentrations. Plasma salmeterol concentrations of 0.1 to 0.2 and 1 to 2 microg/L have been attained in healthy volunteers about 5 to 15 minutes after inhalation of a single dose of 50 and 400 microg, respectively. In patients who inhaled salmeterol 50microg twice daily for 10 months, a second peak concentration of 0.07 to 0.2 microg/L occurred 45 to 90 minutes after inhalation, probably because of the gastrointestinal absorption of the swallowed drug. Salmeterol xinafoate dissociates in solution to salmeterol and 1-hydroxy-2-naphthoic acid. These two compounds are then absorbed, distributed, metabolised and excreted independently. The xinafoate moiety has no apparent pharmacological activity, is highly protein bound (>99%), largely to albumin, and has a long elimination half-life of about 12 to 15 days in healthy individuals. For this reason, it accumulates in plasma during repeated administration, with steady-state concentrations reaching about 80 to 90 microg/L in patients treated with salmeterol 50microg twice daily for several months. The cytochrome P450 (CYP) isoform 3A4 is responsible for aliphatic oxidation of salmeterol base, which is extensively metabolised by hydroxylation with the major metabolite being alpha-hydroxysalmeterol, with subsequent elimination predominantly in the faeces. It has been demonstrated that 57.4% of administered radioactivity is recovered in the faeces and 23% in the urine; most is recovered between 24 and 72 hours after administration. Unchanged salmeterol accounts for <5% of the excreted dose in the urine. Since the therapeutic dose of salmeterol is very low, it is unlikely that any clinically relevant interactions will be observed as a consequence of the coadministration of salmeterol and other drugs, such as fluticasone propionate, that are metabolised by CYP3A. All the available data clearly show that at the recommended doses of salmeterol, systemic concentrations are low or even undetectable. This is an important point, because it has been demonstrated that the systemic effects of salmeterol are more likely to occur with higher doses, which lead to approximately proportionally increased blood concentrations.

Acute asthma

OBJECTIVE: Asthma is the most common medical emergency in children. It is associated with significant morbidity and mortality rates and poses a tremendous societal burden worldwide. Management of the acute attack involves a stepwise approach that includes beta-agonist and steroid therapy, the mainstay of emergency treatment. Most patients will respond to this regime and can be discharged from the emergency department. Failure to respond to treatment necessitates hospital admission and sometimes admission to the intensive care unit (ICU). Management in the ICU involves intensification of pharmacologic therapy, including nonstandard therapies, in an attempt to avoid intubation and ventilation. When needed, mechanical ventilatory support can be rendered fairly safe with little morbidity if the likely cardiorespiratory physiologic derangements are appreciated and if appropriate ventilatory strategies are used. In the past two decades, the availability of newer potent medications and changes in approach to monitoring and ventilatory strategies have resulted in a decrease in ICU morbidity and mortality rates. Research endeavors are presently underway to further characterize the underlying mechanisms of the disease and are likely to lead to novel therapies. This article reviews the approach to management of acute severe asthma.

First-line therapy for adult patients with acute asthma receiving a multiple-dose protocol of ipratropium bromide plus albuterol in the emergency department

We designed a larger, double-blind, randomized, prospective trial to test our hypothesis that patients with acute asthma given combination high dose therapy with ipratropium bromide (IB) and beta(2)-agonists will have greater improvement in pulmonary function and fewer hospital admissions than those given beta(2)-agonists alone. One hundred eighty patients (mean age +/- SD, 34.3 +/- 10.5 yr) who presented to an emergency department (ED) for treatment of an exacerbation of asthma (baseline FEV(1) < 50% of predicted) were assigned in a randomized, double-blind fashion to receive albuterol and placebo (n = 92) or albuterol and IB (n = 88). Both drugs were administered through a metered-dose inhaler and spacer at 10-min intervals for 3 h (24 puffs or 2,880 microg of albuterol and 504 microg of IB each hour). Primary outcome measures were improvement in pulmonary function (FEV(1) or peak expiratory flow [PEF]), and hospital admission rates. In both groups, pulmonary function improved significantly over baseline values (p < 0.01). Subjects who received IB had an overall 20.5% (95% CI: 2.6 to 38.4%) (p = 0.02) greater improvement in PEF and a 48.1% (95% CI: 19.8 to 76.4%) (p = 0.001) greater improvement in FEV(1) from the control group. At the end of protocol (3 h), 39% (n = 36) of patients in the control group and 20% (n = 18) in the IB group were admitted (p = 0.01). The use of high doses of IB reduced the risk of hospital admission 49% (relative risk = 0.51, 95% CI: 0.31 to 0.83). Five (95% CI: 3 to 17) patients would need to be treated with high doses of IB to prevent a single admission. Kaplan-Meier-estimated curves of the proportion of patients who reached the discharge threshold during the 3 h of treatment, showed a significant difference in favor of the IB group (log-rank test = 0.005). A subgroup analysis showed that patients most likely to benefit from the addition of high doses of IB were those with more severe obstruction (FEV(1) </= 30% of predicted) and long duration of symptoms before the ED presentation (>/= 24 h). On the contrary, previous use of inhaled beta(2)-agonists did not modify the admission rate and the pulmonary function response to IB. In conclusion, our data support a substantial therapeutic benefit from the addition of IB to albuterol administered in high doses through MDI plus spacer, particularly in patients with FEV(1) less than 30%, and with long duration of symptoms before the ED presentation (>/= 24 h).

Comparison of 2.5 vs 7.5 mg of inhaled albuterol in the treatment of acute asthma

PURPOSE

The optimal dose of albuterol to use in the treatment of acute asthma has yet to be established. The National Asthma Education and Prevention Program (NAEPP) recommends a starting dose of 2.5 to 5 mg of aerosolized albuterol every 20 min, although European authorities recommend higher doses. The purpose of this study was to compare 2.5 vs 7.5 mg of nebulized albuterol for the treatment of acute asthma.

SUBJECTS

We studied 160 patients presenting to the emergency department with acute asthma.

METHODS

On enrollment, patients underwent baseline testing, including initial spirometry. All patients received prednisone, 60 mg, orally. Patients then received in a randomized, double-blinded fashion, nebulized albuterol either 2.5 or 7.5 mg every 20 min for a total of three doses. Spirometry was repeated after each of the first two treatments and again 40 min after completion of the three treatments.

RESULTS

The pretreatment FEV1 was 36.9+/-16.6% of predicted normal in the low-dose group vs 41.5+/-15.4% of predicted normal in the high-dose group (not significant [NS]). The patients in the low-dose group had a 50.3+/-62.6% improvement in FEV1 pretreatment to post-treatment, whereas those in the high-dose group had a 44.6+/-48.2% improvement in FEV1 (NS). There was no difference in the admission rate in the low-dose group (43%) as compared with that of the high-dose group (39%; NS).

CONCLUSION

We conclude that there is no advantage to the routine administration of doses of albuterol higher than 2.5 mg every 20 min. It is possible that there may be an advantage in the most severely obstructed patients, although this study did not enroll enough patients with very severe asthma to evaluate this. As has been previously demonstrated, patients who subsequently require admission have a diminished response to albuterol. This decreased responsiveness is seen with the first aerosol administration and is unaffected by increasing the dose.

Salbutamol treatment of acute severe asthma in the ED: MDI versus hand-held nebulizer

The objectives of this study were to compare the efficacy of salbutamol delivered by either metered-dose inhaler plus spacer (MDI-spacer) or by wet nebulization (NEB), and to determine the relationships between physiologic responses and plasma salbutamol concentrations. Asthmatic patients presenting to the emergency department (ED) with acute severe asthma (forced expiratory volume in the first second [FEV1] less than 50% of predicted) were enrolled in a randomized, double-blind, parallel-group study. The MDI-spacer group received salbutamol, delivered via MDI into a spacer device, in four puffs actuated in rapid succession at 10-minute intervals (2.4 mg/h). The NEB group was treated with nebulized salbutamol, 1.5 mg, via nebulizer at 15-minute intervals (6 mg/h). Doses were calculated on the basis of the percentage of total dose that reaches the lower airway with both methods. The protocol involved 3 hours of this treatment. Mean peak expiratory flow rate (PEFR) and FEV1 improved significantly over baseline values for both groups (P=.01). However, there were no significant differences between both groups for PEFR and FEV1 at any point studied. The examination of the relationships between cumulative dose of salbutamol and change in FEV1 showed a significant linear relationship (P=.01) for both methods (MDI r=.97; NEB r=.97). The regression equations showed that for every 1 mg of salbutamol by MDI-spacer, 2.5 mg are needed from nebulization to have equal therapeutic response. At the end of treatment, the salbutamol plasma levels were 10.1+/-1.6 ng/ml for the MDI-spacer group and 14.4+/-2.3 ng/ml for the NEB group (P=.0003). Both groups showed a nonsignificant heart rate decrease. A significant group-by-time interaction means that differences between groups increased with time (P=.04). Additionally, the NEB group presented a higher incidence of tremor (P=.03) and anxiety (P=.04), reflecting larger systemic absorption of salbutamol. These data indicate that when doses used are calculated on the basis of the percentage of total drug that reaches the lower airway, there was equivalent bronchodilatation after salbutamol administered by either MDI-spacer or nebulization in patients with acute severe asthma. However, nebulizer therapy produced greater side effects related to the increase in salbutamol absorption and higher plasma level.

Therapeutic response patterns to high and cumulative doses of salbutamol in acute severe asthma

STUDY OBJECTIVES

To examine the main therapeutic response patterns to high doses of salbutamol and to determine the factors that contribute to outcome in acute severe asthma.

SETTING

The emergency department (ED) of a large, urban hospital with primary and referral care responsibilities.

PATIENTS AND DESIGN

One hundred sixteen consecutive patients with acute exacerbations of asthma were enrolled in the trial, using a prospective sequential design.

INTERVENTIONS

All patients were treated with salbutamol delivered with a metered-dose inhaler into a spacer device in four puffs (400 microg) at 10-min intervals. The protocol involved 3 h of this treatment (1,200 microg each 30 min).

MEASURES AND RESULTS

A dose-response increase in pulmonary function was found, but only 70% improved sufficiently to be discharged. Of these, almost 70% required < or =2.4 mg of the drug within 1 h to reach the discharge threshold, whereas the remainder 30% need > or =3.6 mg. In 30% of subjects, salbutamol was ineffective. These patients were characterized by a more severe disease as judged by previous beta2-agonist use, larger duration of attack before ED visit, and a more severe obstruction at presentation. However, the most important predictors of outcome were peak expiratory flow rate (PEFR) as percent of predicted, PEFR as liters per minute, and PEFR variation over baseline value, all at 30 min.

CONCLUSIONS

This study described two different therapeutic response patterns to salbutamol. Almost 70% of patients were sensitive to salbutamol (good response pattern), and in this group, 2.4 to 3.6 mg represents optimal treatment. In the remainder 30% of patients (poor response pattern), salbutamol in high doses had little effect. However, the outcome was not determined by the intensity of the initial symptoms or by the value of the presenting PEFR, but rather by the early (30 min) short-term response to treatment.

Inhaled flunisolide for acute severe asthma

This randomized, double-blind trial was designed to determine the benefit of high and cumulative doses of flunisolide added to salbutamol in patients with acute asthma in the emergency room (ER). Ninety-four patients who presented to an ER for treatment of an acute exacerbation of asthma were assigned in a randomized, double-blind fashion to receive salbutamol and placebo (n = 47) or salbutamol combined with flunisolide (n = 47). Both drugs were administered successively through a metered-dose inhaler and spacer at 10-min intervals for 3 h (400 microg of salbutamol and 1 mg of flunisolide every 10 min). In both groups, FEV1 and peak expiratory flow rate (PEFR) improved significantly over baseline values (p < 0.01). Results in the flunisolide group were significantly different from those in the placebo group at 90, 120, 150, and 180 min. Data analyzed separately in accord with the duration of the attack before presenting at the ER (< 24 or > or = 24 h) showed that the placebo > or = 24 h group produced a significantly lower FEV1 at 120, 150, and 180 min (p = 0.041) than did the remaining groups. Our data support the theory that high and cumulative doses of inhaled flunisolide administered by metered-dose inhaler with spacer and added to salbutamol are an effective therapy for patients with acute asthma and a prolonged duration of symptoms before ER presentation.

Effect of age on bronchodilator response in acute severe asthma treatment

STUDY OBJECTIVES

This study was designed to evaluate the effects of age on bronchodilator response to salbutamol in patients with acute severe asthma in the emergency department.

SUBJECTS AND METHODS

Sixty-four sequential patients (mean age, 34.2+/-10.7 years) with acute asthma were enrolled in the trial. Using age as a major criterion, we divided the sample in two groups: the young one (age < or = 35 years, n=30) and the older (> 35 years, n=34). All patients were treated with salbutamol delivered with metered-dose inhaler into a spacer device, in a dose of four puffs every 10 min (100 microg per actuation) during 3 h.

RESULTS

Mean FEV1 improved significantly over baseline values for both groups (p=0.001). At final disposition, the mean percent of predicted FEV1 was 55.1+/-16.3% in the young group and 58.0+/-20.9% in the older group. There were no significant differences between both groups for FEV1 percent response at any point studied. A significant increase in heart rate over baseline was seen in the older group (p=0.001). Older patients also presented a higher incidence in nausea and tremor. Young and older patients with acute asthma achieved equivalent bronchodilation response to salbutamol.

CONCLUSIONS

We concluded that age is not a predictor of response to beta-agonists.