Gly/Gly and Arg/Arg genotype responses to albuterol differed in mild asthma.

M e t h o d s Design: Randomized, placebo-controlled, cross-over trial (Beta-Adrenergic Response by Genotype [BARGE] trial). Allocation: Concealed.* Blinding: Blinded (clinicians and patients).* Follow-up period: 24 weeks. Setting: {6 centers in the United States.}† Patients: 78 patients who were 18 to 55 years of age (mean age 31 y, 68% women) and had physician-diagnosed mild asthma, who reported use of as-needed inhaled β-agonist < 56 puffs/wk as their only treatment, whose FEV1 was ≥ 70% of the predicted value, and who had either the Arg/Arg or Gly/Gly genotype as the locus encoding the 16th amino acid residue of the β2-adrenergic receptor. Intervention: Each patient with the Arg/Arg genotype was matched with a patient with the Gly/Gly genotype by FEV1 (within 10% of predicted) and study center. During a 6-week, single-blind, run-in period, they received 2 puffs 4 times/d of a placebo metered-dose inhaler and open-label ipratropium bromide as rescue medication. Patients were allocated to the active-to-placebo (n = 37) or placebo-to-active (n = 41) crossover sequence and received inhaled albuterol or placebo, 2 puffs, 90 μg/puff, 4 times/d. An 8-week placebo run-out period occurred between and after the 2 treatment periods. Outcomes: Morning PEFR. Secondary outcomes were spirometric values, evening PEFR, morning/evening PEFR variability, asthma symptoms, use of rescue medication, and adverse asthma control episodes. Patient follow-up: 86% (intention-to-treat analysis).