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Rationale: Retrospective pharmacogenetic studies have questioned whether patients with asthma who are arginine homozygous at the beta(2-)adrenergic receptor (position 16) should use long-acting beta-agonists., Objectives: To examine whether the response to salmeterol alone or in combination with an inhaled corticosteroid is influenced by beta- receptor polymorphisms., Methods: Subjects using only as-needed albuterol were screened and completed two sequential open-label run-in periods (8 wk on as-needed albuterol; 8 wk on as-needed ipratropium). Five hundred forty-four subjects were randomized by Arg16Gly genotype to salmeterol alone or with fluticasone propionate for 16 weeks. Change from baseline in morning peak expiratory flow was the primary endpoint., Measurements and Main Results: Lung function responses were sustained over treatment and no statistically significant changes from baseline between genotypes within treatments were observed. Overall mean changes in morning peak flow for salmeterol with fluticasone propionate were 32.6 L/min (Arg/Arg vs. Gly/Gly, 95% confidence interval [CI], -6.3, 22.1), 25.9 L/min (Arg/Arg vs. Arg/Gly, 95% CI, -7.1, 21.3), and 24.9 L/min (Arg/Gly vs. Gly/Gly, 95% CI, -13.0, 14.6), and for salmeterol alone were 19.4 L/min (Arg/Arg vs. Gly/Gly, 95% CI, -1.7, 21.4), 24.6 L/min (Arg/Arg vs. Arg/Gly, 95% CI, -13.0, 10.6), and 12.4 L/min (Arg/Gly vs. Gly/Gly, 95% CI, -0.2, 22.3) for Arg/Arg, Arg/Gly, and Gly/Gly genotypes, respectively. Other measures of asthma control showed similar responses., Conclusions: The results showed no evidence of a pharmacogenetic effect of beta-receptor variation on salmeterol response. Clinical trial registered with www.clinicaltrials.gov (NCT 00102882).

The development of tolerance to the bronchodilator effects of beta2-agonists used in asthma therapy has been the subject of debate. We conducted two placebo-controlled crossover studies to assess the bronchodilator response to a short-acting beta2-agonist before and after chronic therapy with salmeterol. Patients in one study were corticosteroid-naive; patients in the other study were using inhaled corticosteroids. Changes in FEV1 after cumulative doubling doses of inhaled albuterol were assessed after a 2-wk beta-agonist washout period, before administering study medication on Day 1, and again after 28 d of therapy. Ipratropium bromide was provided as rapid-relief treatment for asthma, and use of any beta2-agonist except the study treatment was prohibited. On both assessment days for salmeterol, and during placebo administration periods, significant increases from predose FEV1 values were observed beginning with the lowest dose of albuterol and continuing throughout the dose-response assessment (p