Effect of beta2-adrenergic receptor polymorphism in asthma control of patients receiving combination treatment

Combination treatment of inhaled corticosteroid (ICS) plus long-acting beta2-agonist (LABA) is widely used as a maintenance regimen for the management of asthma. This study evaluated the effect of the beta2-adrenergic receptor (ADRB2) polymorphism on lung function and asthma control with regular use of combination treatment of an inhaled ICS plus LABA.

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 microg/day) plus terbutaline (5 microg prn). as needed. During the 24-week active treatment period, they received budesonide 160 microg and formoterol 4.5 microg 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.

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.

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.