Comparison of racemic albuterol and levalbuterol for treatment of acute asthma

Asthma pathophysiology and evidence-based treatment of severe exacerbations

PURPOSE

The pathogenesis of asthma and the treatment approach for acute exacerbations are described. The pharmacology, efficacy, safety, and cost of the beta2 agonist, albuterol, a racemic mixture of equal amounts of R- and S-enantiomers, and levalbuterol, the R-enantiomer, are compared.

SUMMARY

Asthma symptoms are the result of bronchial hyperresponsiveness, bronchospasm, and chronic airway inflammation. Short-acting, inhaled beta2 agonists; oxygen; intravenous fluids; and corticosteroids are the mainstays of treatment for acute exacerbations. The R-enantiomer of albuterol is responsible for bronchodilation. The S-enantiomer exhibits broncho-constricting activity in vitro, which may be mediated by muscarinic receptors and may be opposed by adding the anticholinergic agent ipratropium bromide. Levalbuterol improves pulmonary function to a greater extent than racemic albuterol and reduces the need for costly hospitalizations in patients with acute asthma exacerbations.

CONCLUSION

Levalbuterol is an alternative to racemic albuterol with the potential to improve patient outcomes and reduce costs in the treatment of acute asthma exacerbations.

Levosalbutamol in the treatment of asthma

With the exception of levosalbutamol, all of the beta2-agonists that are currently in use are racemic mixtures that are composed in equal amounts of (R)- and (S)-enantiomers. Clinical and mechanistic studies have demonstrated that (R)-salbutamol alone provides the beta2-agonist activity that is needed for the relief of bronchoconstriction, as well as the beta2-adrenergically mediated side effects. (S)-Salbutamol, on the other hand, has minimal binding affinity for the beta2-receptor, indicating that its effects are likely to be mediated through another site. Furthermore, there is evidence that (S)-salbutamol opposes the desirable effects of (R)-salbutamol in the racemic mixture and contributes to the development of characteristic features of asthma, such as airway obstruction, bronchial hyperresponsiveness and airway inflammation. Evidence from clinical studies shows delayed recovery from exacerbation of asthma by patients who are exposed to high concentrations of (S)-salbutamol.

Genetic aspects of the etiology and treatment of asthma

This article provides a clinical review of the genetic aspects of the etiology and treatment of asthma for pediatric practitioners who are experienced in asthma diagnosis and management but lack expertise in genetics and immunology. Asthma is caused by the interaction of genetic susceptibility with environmental factors. The asthmatic response is characterized by elevated production of IgE, cytokines, and chemokines; mucus hypersecretion; airway obstruction; eosinophilia; and enhanced airway hyperreactivity to spasmogens. The genes most clearly associated with asthma include disintegrin and metalloprotease ADAM-33, dipeptidyl peptidase 10, PHD finger protein 11, and the prostanoid DP1 receptor. Within a few years, practitioners may apply sophisticated knowledge of cell and molecular biology to expand pharmacotherapeutic approaches and to personalize diagnosis and management.

A comparison of levalbuterol with racemic albuterol in the treatment of acute severe asthma exacerbations in adults

This multicenter, randomized, double-blind trial compared nebulized levalbuterol (Lev) and racemic albuterol (Rac) in the treatment of acute asthma.

METHODS

Adults with acute asthma exacerbations (FEV(1) 20%-55% predicted) received prednisone and either Lev (1.25 mg, n = 315) or Rac (2.5 mg, n = 312). Nebulized treatments were administered every 20 minutes in the first hour, then every 40 minutes for 3 additional doses, then as necessary for up to 24 hours. The primary end point was time to meet discharge criteria. Secondary end points included changes in lung function and hospitalization rates. A subset of 160 patients had plasma (S)-albuterol concentrations determined at study entry.

RESULTS

Time to meet discharge criteria did not differ between the 2 treatments. FEV(1) improvement was greater following Lev compared with Rac, both after dose 1 and cumulatively over the entire treatment period (dose 1 in intent to treat [ITT] group: Lev 0.50 +/- 0.43 L, Rac 0.43 +/- 0.37 L; P = .02), particularly among the 60% of patients not on recent steroid therapy (dose 1: Lev 0.58 +/- 0.47 L, Rac 0.44 +/- 0.37 L; P < .01), and patients whose entry (S)-albuterol concentrations were in the highest quartile of those measured. A small and similar proportion of Lev-treated (7.0%) and Rac-treated (9.3%) patients required hospitalization (P = .28). Among patients not on steroids, fewer Lev- than Rac-treated patients required admission (3.8% vs 9.3%, P = .03), as was also the case for patients with high plasma (S)-albuterol concentrations. Asthma relapses (5% in 30 days) were lower than in previous reports and did not differ between groups.

CONCLUSIONS

This study suggests that early, regular nebulized beta(2)-agonist and systemic corticosteroid therapy may reduce hospitalization and relapse rates in patients with acute severe asthma. Lev was well tolerated and compared favorably with Rac in improving airway function, particularly in those who were not on inhaled or oral corticosteroids and in those who had high plasma (S)-albuterol concentrations at presentation.

Evaluation of levalbuterol metered dose inhaler in pediatric patients with asthma: a double-blind, randomized, placebo- and active-controlled trial

OBJECTIVE

To evaluate the efficacy and safety of levalbuterol metered dose inhaler (MDI) in children aged 4-11 years (n = 173).

RESEARCH DESIGN AND METHODS

Multicenter, randomized, double-blind 28-day study of QID levalbuterol 90 microg, racemic albuterol 180 mug, and placebo (2:1:1 ratio). Serial spirometry was performed on Days 0, 14, and 28. The primary endpoint was the double-blind average peak percent (%) change in FEV(1) from visit pre-dose; the primary comparison was with placebo. Secondary endpoints included the area under the FEV(1) percent change from pre-dose curve and peak % predicted FEV(1). Safety endpoints included adverse events, laboratory tests, rescue medication use, and electrocardiograms.

RESULTS

Levalbuterol significantly improved the least square mean peak percent change in FEV(1) compared with placebo (levalbuterol 25.6% +/- 1.3% [p < 0.001]; racemic albuterol 21.8% +/- 1.8% [p = ns]; placebo 16.8% +/- 1.9%). Results for levalbuterol were similar for the other spirometry endpoints (p < 0.05 vs. placebo). No levalbuterol-treated patients had a peak percent change in FEV(1) < 10% (compared with 15.8% of racemic albuterol-treated patients and 30.3% of placebo-treated patients). The incidence of adverse events was 43.4% for levalbuterol, 56.4% for racemic albuterol, and 51.4% for placebo. The rate of discontinuation was 1.3% for levalbuterol, 2.6% for racemic albuterol, and 8.6% for placebo. The rate of asthma attacks (10.5%, 12.8%, 14.3%, respectively) was similar among treatments. Levalbuterol and racemic albuterol both reduced rescue medication use (p < 0.01 vs. placebo) and produced changes in ventricular heart rate and QT(c-F) that were similar to placebo.

CONCLUSIONS

In this study, levalbuterol administered via MDI significantly improved airway function in comparison with placebo in asthmatic children aged 4-11 years with a safety profile that was similar to placebo.

Current management of status asthmaticus in the pediatric ICU

Status asthmaticus (SA) in the pediatric ICU (PICU) can progress to a life-threatening emergency. The goal of management is to improve hypoxemia, improve bronchoconstriction, and decrease airway edema through the administration of continuous nebulized beta2 adrenergic agonist with intermittent anticholinergics, corticosteroids, and oxygen. Adjunctive therapies, such as magnesium, methylxanthines, intravenous beta-agonists, heliox, and noninvasive ventilation should be considered in the child who fails to respond to initial therapies. The restoration of adequate pulmonary functions, resolution of airway obstruction, and avoidance of mechanical ventilation should guide management. This article reviews the pathophysiology, assessment, and management of the child who has SA in the PICU to provide the critical care nurse with current information to facilitate optimal care.

Clinical efficacy of racemic albuterol versus levalbuterol for the treatment of acute pediatric asthma

STUDY OBJECTIVE

An efficacy treatment study is conducted comparing levalbuterol to racemic albuterol for acute pediatric asthma in the emergency department (ED).

METHODS

This was a prospective, double-blind, randomized, controlled study involving 129 children (2 to 14 years), presenting to a pediatric ED with an acute moderate or severe asthma exacerbation. Children were treated using a standard ED asthma pathway. Primary outcomes were changes from baseline in clinical asthma score and the percentage of predicted forced expiratory volume in 1 second after the first, third, and fifth treatment. Secondary outcomes included number of treatments, length of ED care, rate of hospitalization, and changes in pulse rate, respiratory rate, and oxygen saturation. Occurrence of adverse events was recorded.

RESULTS

Sixty-four children in the racemic albuterol and 65 children in the levalbuterol group completed the study. There were no differences between groups in primary outcomes, secondary outcomes, or adverse events.

CONCLUSION

There was no difference in clinical improvement in children with acute moderate to severe asthma exacerbations treated with either racemic albuterol or levalbuterol.

Comparison of racemic albuterol and levalbuterol in the treatment of acute asthma in the ED

BACKGROUND

Acute asthma is often treated with racemic albuterol, a 1:1 mixture of (R)-albuterol and (S)-albuterol. Levalbuterol is the single-isomer agent comprised (R)-albuterol, an active bronchodilator, without any effects of (S)-albuterol.

OBJECTIVE

To compare emergency department (ED) admission rates of patients presenting with acute asthma who were treated with either racemic albuterol or levalbuterol.

SETTING

Suburban community teaching hospital.

DESIGN

Retrospective observational case review.

METHODS

Emergency department patients presenting with acute asthma at 2 different sites were reviewed over 9- and 3-month consecutive periods. Outcome measures included ED hospital admission rate, length of stay, arrival acuity, and treatment costs. Patients were excluded if younger than 1 year or if no treatment of acute asthma was rendered.

RESULTS

Of the initial 736 consecutive cases, significantly fewer admissions (4.7% vs 15.1%, respectively; P = .0016) were observed in the levalbuterol vs racemic albuterol group. Of the subsequent 186 consecutive cases, significantly fewer admissions were also observed (13.8% vs 28.9%, respectively; P = .021) in the levalbuterol vs racemic albuterol group. Treatment costs were lower with levalbuterol mainly because of a decrease in hospital admissions.

CONCLUSION

Levalbuterol treatment in the ED for patients with acute asthma resulted in higher patient discharge rates and may be a cost-effective alternative to racemic albuterol.

Advances in the management of pediatric asthma: a review of recent FDA drug approvals and label updates

Children have the highest prevalence of asthma of any age group. In the United States during 2001, there were 12.6 million physician and hospital outpatient visits for asthma treatment, of which almost 5 million involved children 18 years and younger. Therapeutic advances in pediatric asthma could improve patient outcomes and potentially reduce the burden on health care systems. Efforts to obtain efficacy and safety data in pediatric populations and develop pediatric formulations of asthma treatments have been encouraged by the FDA and clinicians. This article reviews the newest additions to asthma therapies approved for use in children, including an inhaled corticosteroid, some long-acting beta2-agonists, some leukotriene-receptor blockers, and a single-isomer, short-acting beta2-agonist.

The reading, writing, and arithmetic of the medical literature, part 2: critical evaluation of statistical reporting

OBJECTIVE

To offer suggestions to help improve clinicians' understanding of the statistical analyses in the literature and their use of these methods in their own medical writings.

DATA SOURCES

Literature searches began at the National Library of Medicine's online database and were traced to primary sources.

STUDY SELECTION

All referenced information in this article was cited from primary sources.

RESULTS

Physicians should be able to determine the variables studied and how they were measured, the comparisons that were made, the difference (with 95% confidence interval) between the groups, the exact P value for the difference, the statistical test used in the analysis, whether the data conformed to the assumptions of the test, whether the study had adequate statistical power, and the clinical importance of the difference.

CONCLUSION

Clinicians should know how to interpret statistical results so that they can use medical science to its full extent in treating patients.

Evaluation of the safety and efficacy of levalbuterol in 2-5-year-old patients with asthma

The purpose of this study was to evaluate the safety and efficacy of single-isomer (R)-albuterol (levalbuterol, LEV) in children aged 2-5 years. Children aged 2-5 years (n = 211) participated in this multicenter, randomized, double-blind study of 21 days of t.i.d. LEV (0.31 mg or 0.63 mg without regard to weight), racemic albuterol (RAC, 1.25 mg for children <33 pounds (lb); 2.5 mg for children >/=33 lb), or placebo (PBO). Endpoints included adverse-event (AE) reporting, safety parameters, peak expiratory flow (PEF), the Pediatric Asthma Questionnaire(c) (PAQ), and the Pediatric Asthma Caregiver's Quality of Life Questionnaire (PACQLQ). Baseline disease severity was generally mild in all groups, as defined by PAQ scores that ranged from 6.3-7.3 on a scale of 0-27 and 1.5 days/week of uncontrolled asthma. After treatment, the PAQ decreased in all groups (P = NS). In the subset of subjects able to perform PEF (51.7%), all active treatments improved in-clinic PEF after the first dose (mean +/- SD: PBO, 1.4 +/- 20.8; LEV 0.31 mg, 12.4 +/- 12; LEV 0.63 mg, 16.7 +/- 15.4; RAC, 18.0 +/- 16.5 l/min; P < 0.01). PACQLQ measurements improved more than the minimally important difference only in the LEV-treated groups, and were significant in children <33 lb (P < 0.05). Asthma exacerbations occurred primarily in children >/=33 lb, and one serious asthma exacerbation occurred in the 2.5-mg RAC group. RAC and LEV 0.63 mg, but not LEV 0.31 mg or placebo, led to significant increases in ventricular heart rate. In this study of levalbuterol in children aged 2-5 years with asthma, LEV was generally well-tolerated, and in children able to perform PEF, led to significant bronchodilation compared with placebo.

Comparison of levalbuterol and racemic albuterol combined with ipratropium bromide in acute pediatric asthma: a randomized controlled trial

Our study compared levalbuterol (LEV) to the combination of racemic albuterol (RAC) and ipratropium bromide (IB) in 140 patients aged 6-18 years presenting to a tertiary hospital Emergency Department with acute asthma and a peak expired flow rate (PEF)<80% predicted. Patients were randomized to: LEV (<or=6 nebs LEV 1.25 mg); or RAC/IB (<or=3 nebs RAC 5.0 mg+IB 0.25 mg followed as needed by <or=3 nebs RAC 5.0 mg). No difference was noted in the study population (mean age 11.6 years and initial mean predicted PEF 49.5%) between LEV (n=72) and RAC/IB (n=68) for study outcomes except for measures of heart rate (HR). Median % HR increase for RAC/IB (26%) exceeded LEV (9%) (p<0.001). In a sample of children with acute asthma and initial mean PEF<50% predicted, LEV was associated with less tachycardia but had no other advantage over RAC combined with IB.

Respiratory distress

Preparation for pediatric pulmonary emergencies in the office setting includes adequate training for all medical staff, properly sized and working equipment, and medications to help alleviate respiratory distress when indicated. Status asthmaticus, viral bronchiolitis, and croup account for the vast majority of respiratory emergencies encountered in the pediatric office setting. Timely application of proven approaches to assessment and treatment of these illnesses can prevent hospitalization, decrease length of hospitalizations, and save lives.

Automatic replacement of albuterol nebulizer therapy by metered-dose inhaler and valved holding chamber

PURPOSE

Evidence supporting the delivery of bronchodilators with a metered-dose inhaler and a valved holding chamber (MDI+VHC) in place of a small-volume nebulizer (SVN) is discussed, and the steps taken to accomplish such a conversion program at one institution are described.

SUMMARY

Double-blind, randomized studies in patients with acute exacerbations of asthma have demonstrated that higher doses of albuterol delivered by MDI+VHC (4-10 puffs per dose) are as effective as 2.5 mg of albuterol sulfate delivered by SVN. Three double-blind studies support the conclusion that the two methods are equivalent with respect to both efficacy and adverse effects in patients with chronic obstructive pulmonary disease. MDI+VHC offers practical advantages over SVN, including the capacity for home use by the patient, portability, less setup time, and no need for daily disinfection. Pharmacists and respiratory therapists obtained approval through the pharmacy and therapeutics committee for respiratory therapists to convert orders for bronchodilators delivered by SVN to administration by MDI+VHC. The conversion policy allows physicians to override it, but none have exercised this option. On intensive care units (ICUs), the policy resulted in a 53% increase in the use of MDI+VHC during the six-month period after it went into effect. Respiratory therapists have been less thorough in implementing the policy for non-ICU patients.

CONCLUSION

Delivery of bronchodilators by MDI+VHC is as effective as delivery by SVN but offers several advantages. A policy to switch patients from SVN to MDI+VHC for bronchodilator administration met with limited success.

Levalbuterol versus racemic albuterol in the treatment of acute exacerbation of asthma in children

OBJECTIVE

To compare levalbuterol and racemic albuterol for the treatment of acute exacerbation of asthma in pediatric population.

DESIGN

Prospective, double-blind, randomized research trial in a pediatric emergency department of an urban tertiary care hospital.

PARTICIPANTS

Children 5 to 21 years with a history of asthma presenting to the emergency department in acute exacerbation.

INTERVENTIONS

As per a computer-generated randomization sequence, patients received either 1.25 mg of levalbuterol or albuterol 2.5 mg via nebulization along with ipratropium hydrochloride. Patients received 3 back-to-back treatments as needed every 20 minutes, maximum of 3; 2 mg/kg of oral prednisone was administered to the patients after the second treatment. Baseline respiratory parameters such as oxygen saturations, respiratory rates, and peak flow rates were measured and repeated after every treatment.The decision for further treatments and or hospitalization was made by the treating emergency department physician as per his/her clinical judgement of the respiratory parameters at the end of 3 treatments.

RESULTS

Seventy patients completed the study. Most of the patients were in moderate severity of asthma exacerbation. All patients in both groups showed improvement in oxygen saturations, respiratory rates, and peak flow rates. However, no statistically significant difference was observed in the 2 groups regarding the respiratory parameters (P > 0.05).

CONCLUSION

Levalbuterol is not more efficacious than racemic albuterol in improving respiratory parameters in children presenting with acute exacerbation of asthma.

Past, present and future--beta2-adrenoceptor agonists in asthma management

The beta-adrenoceptor agonists (beta-agonists) have been used to relieve bronchoconstriction for at least 5000 years. beta-agonists are based on adrenaline and early forms, such as isoprenaline, Lacked bronchial selectivity and had unpleasant side effects. Modern beta-agonists are more selective for the beta2-adrenoceptors (beta2-receptors) located in bronchial smooth muscle and have less cardiotoxicity. Traditional beta2-adrenoceptor agonists (beta2-agonists), such as salbutamol, terbutaline and fenoterol, were characterised by a rapid onset but relatively short duration of action. While valuable as reliever medication, their short duration gave inadequate night-time relief and limited protection from exercise-induced bronchoconstriction. beta2-agonists with longer durations of action, formoterol and salmeterol, were subsequently discovered or developed. When combined with inhaled corticosteroids they improved lung function, and reduced symptoms and exacerbations more than an increased dose of corticosteroids. However, tolerance to the bronchprotective effects of long-acting beta2-agonists and cross-tolerance to the bronchodilator effects of short-acting beta2-agonists is apparent despite use of inhaled corticosteroids. The role of beta2-receptor polymorphisms in the development of tolerance has yet to be fully determined. Formoterol is unique in having both a long-lasting bronchodilator effect (> 12 h) and a fast onset of action (1-3min from inhalation), making it effective both as maintenance and reliever medication. The recent change in classification from short- and long-acting beta2-agonists to rapid-acting and/or long-acting agents reflects the ongoing evolution of beta2-agonist therapy.

Therapeutic responses in asthma and COPD. Bronchodilators

The presence of acute reversibility to bronchodilators does not distinguish asthma from COPD. Patients with either condition can benefit from bronchodilators, and should be given a trial to assess their response. Some respond with a change in lung volume with less hyperinflation; others improve their forced inspiratory flow and become much more comfortable. The combination of long-acting beta-agonists (LABAs) and inhaled steroids is useful in both conditions. While anticholinergics seem to yield the best results in COPD, some patients with asthma benefit from their use. Tiotropium may be the most effective agent as monotherapy in COPD, but the combination of an inhaled steroid and a LABA may produce similar results in improving lung function. Long-acting bronchodilators are effective agents as monotherapy in COPD, but in asthma should be combined with a controller medication. Short-acting beta-agonists should be used intermittently in asthma, but may be used regularly or combined with an anticholinergic in COPD. The roles of stereoisomers, leukotriene receptor antagonists, and type 4 phosphodiesterase inhibitors in asthma and COPD remain uncertain at this time.

Severe exacerbations of asthma

All asthmatics regardless of their perceived severity, are at risk of exacerbation, particularly if they are suboptimally treated in the outpatient arena. Fortunately most patients recover after administration of bronchodilators and anti-inflammatory medications, but preventable deaths continue to occur and refractory cases result in hospitalization and need for mechanical ventilation. We begin this article by reviewing the pathophysiology of acute exacerbations to build a foundation for the assessment of clinical status and to provide the rationale for a carefully contemplated and evidence-based therapeutic approach. We end this article with an in-depth examination of the particular problems that are encountered during mechanical ventilation and offer a strategy that helps minimize complications. In the final analysis, however, the greatest gains in the field of acute asthma will come not from its treatment but from its prevention by enhanced educational and environmental efforts and by the delivery of optimal medications at home.

Current concepts in asthma treatment in children

PURPOSE OF REVIEW

The purpose of this review is to present current literature related to the management of childhood asthma.

RECENT FINDINGS

Persistent asthma is now considered an inflammatory airways disease. Inhaled corticosteroids are recognized as the preferred long-term control medication. New classes of medications have been introduced during the last 5 years, including leukotriene modifiers, long-acting beta-adrenergic agonists, combination inhaled corticosteroids with long-acting beta-adrenergic agonists, and anti-IgE. Research is also being directed to understand the early onset of asthma.

SUMMARY

Management of childhood asthma is now being directed to early recognition and early intervention. Recent updates in the asthma guidelines prompt clinicians to consider intervention with antiinflammatory therapy, preferably inhaled corticosteroids, in children who have frequent asthma exacerbations and a risk profile for persistent asthma. In children with persistent asthma, inhaled corticosteroids are recognized as the preferred antiinflammatory therapy. Health care systems that have adapted this approach have recognized the benefits of reduced hospitalizations and urgent care visits. Continued research is needed to identify asthma at a very early stage so that interventions can be directed to interrupting the development of this disease.

Levalbuterol compared with racemic albuterol in the treatment of acute asthma: results of a pilot study

This was a prospective, open-label, nonrandomized pilot study to evaluate efficacy and tolerability of levalbuterol (LEV) in acute asthma. Asthmatics (forced expiratory volume in 1 second [FEV1], 20-55% predicted) were sequentially enrolled into cohorts of 12 to 14 and received 0.63, 1.25, 2.5, 3.75, or 5.0 mg LEV or 2.5 or 5.0 mg racemic albuterol (RAC) every 20 minutes x 3. After the first dose, FEV1 changes were 56% (0.6 L) for 1.25 mg LEV and 6% (0.07 L) and 14% (0.21 L) for 2.5 and 5 mg RAC respectively. After three doses, FEV1 changes were 74% (0.9 L), 39% (0.5 L), and 37% (0.6 L) for 1.25 mg, LEV 2.5 mg, RAC and 0.63 mg LEV respectively. LEV doses greater than 1.25 mg did not further improve bronchodilation. Baseline plasma (S)-albuterol levels were negatively correlated with baseline FEV1 (R = - 0.3, P = .004) and percent change in FEV1 (R = -0.3, P = .006). LEV at a dose of 1.25 mg produced effective bronchodilation that was greater than both RAC doses. The negative correlation between (S)-albuterol levels and FEV1 could suggest a deleterious effect of (S)-albuterol. Larger comparative studies are warranted.