***TASK*** the task is to summarize an input biomedical literature in six sentences 
    ***INPUT*** the input is a biomedical literature 
    ***OUTPUT*** the output is the summary of an input biomedical literature in six sentences 
    ***DOCUMENTATION*** 
    ***EXAMPLES*** 
    Input: 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 prospect i ve , double-blind , r and omized , 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 st and ard 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 The (R)-enantiomer of racemic albuterol produces bronchodilation , whereas the (S)-enantiomer may increase airway reactivity . After oral or intravenous administration of racemic albuterol , the (R)- enantiomer is metabolized several times faster than the (S)-enantiomer ; however , enantiomer disposition after inhaling racemic albuterol with a metered-dose inhaler ( MDI ) is not known . Accordingly , 10 healthy subjects inhaled racemic albuterol with a MDI alone and with a MDI and holding chamber . We measured plasma levels of unchanged (R)- and (S)-albuterol  before and up to 4 h after inhalation of racemic albuterol , and determined the unchanged R/S ratio in urine before and at 0.5 , 4 , 8 , and 24 h later . The disposition of albuterol 's enantiomers with a MDI and holding chamber was similar to that with a MDI alone . The area under the curve ( AUC ) of the plasma levels over time was significantly lower for the (S)- than for the (R)-enantiomer-395.5 + /- 141.0 ( SE ) versus 882.7 + /- 126.4 ng . ml(-)(1 ) . min ( p < 0.05)-indicating preferential retention of (S)-albuterol in the lung . The R/S ratio in urine at 0 . 5 h after albuterol was > 1 , reflecting the higher plasma level of the (R)-enantiomer . In conclusion , preferential retention of the (S)- compared with the (R)-enantiomer in the lung could lead to accumulation of the (S)-enantiomer after long-term use of racemic albuterol Objective To compare efficacy and tolerability of levosalbutamol ( Group 1 ) and racemic salbutamol ( Group 2 ) for the treatment of acute exacerbation of asthma in children age 5 to 18 yr . Methods A r and omized double blind clinical study involving 60 children was undertaken between October ’ 06 to December ’ 07 . Results The following baseline clinical characteristic were recorded initially and after giving 3 nebulizations at 20 min intervals in the Ist hour of presentation viz respiratory rate ( RR ) , heart rate ( HR ) , oxygen saturation in room air SPO2 , PEFR ( peak expiratory flow rate ) , serum K+ level and asthma score . In Group 1 patients ( levosalbutamol ) , there was significant increment in SPO2 and PEFR ( P<0.05 ) values with decrease in tachypnea and asthma score while no significant difference was found in pre and post treatment HR & Serum K+ levels . In Group 2 patients although there was clinical improvement in terms of SPO2 , PEFR , RR and asthma score , it result ed in significant tachycardia and decrease in K+ levels .  Conclusion Levosalbutamol appears to be more efficacious than racemic salbutamol in terms of improvement in PEFR , SPO2 and asthma score while deleterious effects of tachycardia and fall in serum K+ were seen with racemic salbutamol Objective : To compare levalbuterol and racemic albuterol for the treatment of acute exacerbation of asthma in pediatric population . Design : Prospect i ve , double-blind , r and omized 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 r and omization 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 Objective . To compare racemic albuterol ( RAC ) with levalbuterol ( LEV ) in continuous form for the treatment of acute pediatric asthma exacerbations in the emergency department . Study design . Children between the ages of 6 and 17 inclusive were enrolled if they had a history of asthma , presented to the emergency department with an acute asthma exacerbation , and had an initial forced expiratory volume in 1 second ( FEV1 ) < 70 % predicted . Patients were then r and omized to receive either 7.5 mg of RAC or 3.75 mg of LEV over 1 hour , in addition to st and ard asthma therapies . Spirometry and asthma scoring were performed at the end of the first hour , and a second hour-long nebulization with the same drug was administered if deemed necessary . Spirometry and asthma scoring were again performed and the final disposition was recorded . As a second , optional part of the study , baseline serum albuterol levels were collected on some patients before treatment . Results . A total of 99 patients completed the study ( 44 RAC and 55 LEV ) . Baseline characteristics were similar except that the RAC group had a higher baseline asthma score . Children in the RAC group had a greater improvement in their FEV1 ( p = .043 ) as well as in their asthma scores ( p = .01 ) after 1 hour of continuous treatment compared to the LEV group . The greater improvement in asthma scores was maintained after the second hour of continuous therapy in the RAC group ( p = .008 ) but not for FEV1 measurements ( p = .57 ) . There were no differences between groups for changes in heart rate , respiratory rate , oxygen saturation , or rates of admission . Conclusions . At the doses used , RAC appears to be superior to LEV with respect to changes in FEV1 and asthma score . There was no significant difference between the drugs with respect to admission rates or side-effect profile Objectives of this study were to compare the pharmacokinetics , pharmacodynamics and safety of single cumulative doses of active (R)-salbutamol given either as the single enantiomer or racemic mixture by inhalation to subjects with mild to moderate asthma . This was a double-blind , crossover , cumulative-dose , r and omized study where all subjects received either four doses of 1.25 mg of (R)-salbutamol or 2.5 mg of racemic ( RS- ) salbutamol by nebulization . The pharmacokinetic parameters were determined by noncompartmental analysis and model-fitting . Changes in FEV(1 ) , plasma potassium , plasma glucose , heart rate , and QTc interval were measured . The potassium and glucose data were fitted to indirect response pharmacodynamic models . The heart rate and QTc data were evaluated using data descriptors . No significant differences in pharmacokinetics of (R)-salbutamol given as either (R)- or (RS)-salbutamol were found with AUC values of 11.90 + /- 4.37 and 11 . 47 + /- 2.88 ng.h/ml . The t(max)of about 2 h reflected serial dosing rather than delayed absorption . The t(1/2)averaged about 3.5 h. The (S)-salbutamol showed AUC of 48.46 + /- 12.11 ng.h/ml with a t(1/2)of about 5 h. The changes in FEV(1)reached a plateau after an initial increase and did not return to pre-drug values for 10 h. All pharmacodynamic parameters were similar whether (R)- or (RS)-salbutamol was given . The exposure to (R)-salbutamol was identical after inhalation of ( R ) - and (RS)-salbutamol by subjects with asthma . Several pharmacological responses including FEV(1)were also similar and there were no unique safety concerns with either treatment UNLABELLED This multicenter , r and omized , 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 
    Output:
    
There were no significant differences in side effects between groups .
Levalbuterol was not superior to albuterol regarding efficacy and safety in subjects with acute asthma .
We suggest that levalbuterol should not be used over albuterol for acute asthma