The object of this study is a post hoc pairwise comparison of
levalbuterol versus racemic
albuterol for
asthma in a multicenter, double-blind, randomized, placebo-controlled clinical trial. The participants are patients > or =12 years of age (n = 362) with FEV1 45-70% of predicted. The patients received nebulized
levalbuterol (0.63 or 1.25 mg), racemic
albuterol (1.25 or 2.5 mg), or placebo t.i.d. for 4 weeks. The primary endpoints, published in Nelson HS, Bensch G, Pleskow WW, et al. Improved bronchodilation with
levalbuterol compared with racemic
albuterol in patients with
asthma. J
Allergy Clin Immunol 102:943-952, 1998, included comparisons of active treatments with placebo and of the combined
levalbuterol with the combined racemic
albuterol groups for pulmonary function and rescue medication use. After the first dose,
levalbuterol 1.25 mg produced a significantly greater increase in the mean peak change in FEV1 compared with both doses of racemic
albuterol (p < 0.03) in all patients and in those with more severe
asthma.
Levalbuterol 1.25 mg also produced a significantly greater (p < 0.05) mean area under the curve (AUC) of the FEV1 versus time plot (AUC FEV1) compared with all other treatments after the first dose in all patients and in the subset with more severe disease, illustrating better overall improvement in FEV1. Active treatment groups demonstrated significant improvements compared with the placebo group (p < 0.05), except for AUC FEV1 in the racemic
albuterol 1.25-mg group at week 4.
Levalbuterol in the absence of the (S)-isomer provided greater bronchodilation than the same quantity of (R)-
albuterol delivered as the racemate. These data suggest that (S)-
albuterol may compromise the efficacy of (R)-
albuterol.