title: Improved bronchodilation with levalbuterol compared with racemic albuterol in patients with asthma.
abstract: BACKGROUND
  Racemic albuterol is an equal mixture of (R)-albuterol (levalbuterol), which is responsible for the bronchodilator effect, and (S)-albuterol, which provides no benefit and may be detrimental.
  
  
  OBJECTIVE
  We sought to compare 2 doses of a single enantiomer, levalbuterol (0.63 mg and 1.25 mg), and equivalent amounts of levalbuterol administered as racemic albuterol with placebo in patients with moderate-to-severe asthma.
  
  
  METHODS
  This was a randomized, double-blind, parallel-group trial. Three hundred sixty-two patients 12 years of age or older were treated with study drug administered by means of nebulization 3 times daily for 28 days. The primary endpoint was peak change in FEV1 after 4 weeks.
  
  
  RESULTS
  The change in peak FEV1 response to the first dose in the combined levalbuterol group was significantly greater compared with the combined racemic albuterol group (0.92 and 0.82 L, respectively; P =.03), with similar but nonsignificant results after 4 weeks (0.84 and 0.74 L, respectively). Improvement in FEV1 was similar for levalbuterol 0.63 mg and racemic albuterol 2.5 mg and greatest for levalbuterol 1.25 mg. Racemic albuterol 1.25 mg demonstrated the weakest bronchodilator effect, particularly after chronic dosing. The greatest increase in FEV1 was seen after levalbuterol 1.25 mg, especially in subjects with severe asthma. All active treatments were well tolerated, and beta-adrenergic side effects after administration of levalbuterol 0.63 mg were reduced relative to levalbuterol 1.25 mg or racemic albuterol 2.5 mg. At week 4, the predose FEV1 value was greatest in patients who received levalbuterol or placebo when compared with those who received racemic albuterol. The difference was more evident and was statistically significant in patients who were not receiving inhaled corticosteroids.
  
  
  CONCLUSIONS
  Levalbuterol appears to provide a better therapeutic index than the standard dose of racemic albuterol. These results support the concept that (S)-albuterol may have detrimental effects on pulmonary function.
authors.affiliation: National Jewish Medical and Research Center, Denver, CO, USA.
authors.forename: H S
authors.initials: HS
authors.lastname: Nelson
authors.forename: G
authors.initials: G
authors.lastname: Bensch
authors.forename: W W
authors.initials: WW
authors.lastname: Pleskow
authors.forename: R
authors.initials: R
authors.lastname: DiSantostefano
authors.forename: S
authors.initials: S
authors.lastname: DeGraw
authors.forename: D S
authors.initials: DS
authors.lastname: Reasner
authors.forename: T E
authors.initials: TE
authors.lastname: Rollins
authors.forename: P D
authors.initials: PD
authors.lastname: Rubin
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000420:Albuterol / Q000009:adverse effects / Q000627:therapeutic use*; D001249:Asthma / Q000188:drug therapy* / Q000503:physiopathology; D001993:Bronchodilator Agents / Q000009:adverse effects / Q000627:therapeutic use*; D002648:Child; D005260:Female; D005541:Forced Expiratory Volume / Q000187:drug effects; D006801:Humans; D008297:Male; D008875:Middle Aged; D018570:Risk Assessment; D013237:Stereoisomerism
chemical_list: D001993:Bronchodilator Agents; D000420:Albuterol