Clinical science
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Randomized Controlled Trial Clinical Trial
Beta2-adrenoceptor polymorphism and bronchoprotective sensitivity with regular short- and long-acting beta2-agonist therapy.
The aim of the present study was to investigate bronchoprotective sensitivity in patients receiving regular treatment with short- and long-acting beta2-agonists and to evaluate any possible association with genetic polymorphism. Thirty-eight patients with stable mild to moderate asthma and receiving inhaled corticosteroids were randomized in a parallel group, double-blind, double-dummy fashion to receive 2 weeks of treatment with either formoterol (12 microg once daily, 6 microg twice daily or 24 microg twice daily) or terbutaline (500 microg four times daily). Bronchoprotection against methacholine challenge (as a provocative dose to produce a 20% fall in forced expiratory volume in 1.0 s: PD20) was measured at baseline (unprotected) after an initial 1 week run-in without beta2-agonist, and at 1 h after the first and last doses of each treatment. ⋯ M.) for percentage desensitization according to each genotype (pooled treatments): Gly-16, 66+/-11%; Het-16, 53+/-8%; Arg-16, 69+/-18%; Glu-27, 68+/-12%; Het-27, 58+/-8%; Gln-27, 52+/-12%. The results of this preliminary study showed that bronchoprotective desensitization occurred readily in response to short- or long-acting beta2-agonist exposure irrespective of beta2-adrenoceptor polymorphism at codon 16 or 27. Further studies with larger patient numbers are required to further evaluate the effects of polymorphisms with lower doses of regular formoterol.