title: Low-dose levalbuterol in children with asthma: safety and efficacy in comparison with placebo and racemic albuterol.
abstract: BACKGROUND
  Racemic albuterol (RAC) is an equal mixture of (R)-albuterol and (S)-albuterol. Only the (R)-isomer, levalbuterol (LEV), is therapeutically active. Lower doses of LEV, devoid of (S)-albuterol, have demonstrated efficacy comparable to that of higher doses of the (R)-isomer administered as a component of RAC.
  
  
  OBJECTIVE
  The purpose of this study was to determine whether LEV results in improved safety and efficacy in children.
  
  
  METHODS
  Asthmatic children aged 4 to 11 years (n = 338; FEV(1), 40% to 85% of predicted) participated in this multicenter, randomized, double-blinded study and received 21 days of 3-times-a-day treatment with nebulized LEV (0.31 or 0.63 mg), RAC (1.25 or 2.5 mg), or placebo. The primary endpoint was FEV(1) (peak percent change). Adverse events, clinical laboratory test results, vital signs, and electrocardiograms were evaluated for safety.
  
  
  RESULTS
  All active treatments significantly improved the primary endpoint in comparison with placebo (P < .001). Significant differences in FEV(1) were noted immediately after nebulization (median change, 2.0%, 19.0%, 18.1%, 12.4%, and 15.6% for placebo, LEV 0.31 and 0.63, RAC 1.25 and 2.5 mg, respectively; P < .05 vs placebo; P < .05 for LEV 0.31 and 0.63 vs RAC 1.25 mg). LEV 0.31 mg was the only treatment not different from placebo for changes in ventricular heart rate, QT(c) interval, and glucose (P > .05). All active treatments decreased serum potassium (range, -0.3 to -0.6; P < .002 vs placebo), and RAC 2.5 mg caused the greatest change (P < .005 vs other actives). In a patient subset with severe asthma, a dose-response relationship was observed for levalbuterol, indicating that higher doses were more effective.
  
  
  CONCLUSIONS
  LEV was clinically comparable to 4- to 8-fold higher doses of RAC, and it demonstrated a more favorable safety profile. LEV 0.31 mg should be used as the starting dose in 4-11 year old children with mild to moderate persistent asthma. Patients with severe disease might benefit from higher doses.
authors.affiliation: National Jewish Medical and Research Center, Denver, Colorado, USA.
authors.forename: H
authors.initials: H
authors.lastname: Milgrom
authors.forename: D P
authors.initials: DP
authors.lastname: Skoner
authors.forename: G
authors.initials: G
authors.lastname: Bensch
authors.forename: K T
authors.initials: KT
authors.lastname: Kim
authors.forename: R
authors.initials: R
authors.lastname: Claus
authors.forename: R A
authors.initials: RA
authors.lastname: Baumgartner
mesh_terms: D000318:Adrenergic beta-Agonists / Q000627:therapeutic use*; D000420:Albuterol / Q000009:adverse effects / Q000493:pharmacokinetics / Q000627:therapeutic use*; D001249:Asthma / Q000188:drug therapy* / Q000503:physiopathology; D001993:Bronchodilator Agents / Q000627:therapeutic use*; D002648:Child; D002675:Child, Preschool; D004311:Double-Blind Method; D005260:Female; D005541:Forced Expiratory Volume / Q000187:drug effects; D006801:Humans; D008297:Male; D013237:Stereoisomerism
chemical_list: D000318:Adrenergic beta-Agonists; D001993:Bronchodilator Agents; D000420:Albuterol