Effect of β2-Adrenergic Receptor Polymorphism in Asthma Control of Patients Receiving Combination Treatment

PURPOSE: Combination treatment of inhaled corticosteroid (ICS) plus long-acting β2-agonist (LABA) is widely used as a maintenance regimen for the management of asthma. This study evaluated the effect of the β2-adrenergic receptor (ADRB2) polymorphism on lung function and asthma control with regular use of combination treatment of an inhaled ICS plus LABA. MATERIALS AND METHODS: 43 Korean asthmatics who were symptomatic despite regular ICS use for at least 3 months were enrolled. For a 2-week run-in period, they received ICS (budesonide 800 µg/day) plus terbutaline (5 µg prn). as needed. During the 24-week active treatment period, they received budesonide 160 µg and formoterol 4.5 µg b.i.d. as maintenance and rescue medication. Pulmonary function and quality of life scores were monitored every 8 weeks; morning/evening peak expiratory flow meter (PEFR) was recorded daily. Patients were genotyped for ADRB2 Arg16Gly using single base extension methodology. RESULTS: During the run-in period, there were no significant between-group differences in lung function; after 8 weeks of active treatment, Arg/Arg patients had significantly higher forced expiratory volume in 1 secord (FEV(1)) and maximal mid-expiratory flow (MMEF) (p = 0.023 and p = 0.021, respectively), and better asthma control and quality of life after 24 weeks (p = 0.016 and p = 0.028, respectively). During treatment, there was a greater improvement in morning/evening PEFR in Arg/Arg patients. CONCLUSION: Asthmatic patients with the Arg/Arg genotype at codon 16 of ADRB2 achieve better asthma control with long-term regular use of combined budesonide and formoterol treatment, suggesting that the ADRB2 genotype may dictate choice of treatment strategy.