Tuyển tập các báo cáo nghiên cứu về y học được đăng trên tạp chí y học 'Respiratory Research cung cấp cho các bạn kiến thức về ngành y đề tài: " Tolerance to bronchodilation during treatment with long-acting beta-agonists, a randomised controlled trial. | Respiratory Research BioMed Central Research Open Access Tolerance to bronchodilation during treatment with long-acting beta-agonists a randomised controlled trial Sarah Haney 1 and Robert J Hancox 2 Address 1Freeman Hospital Newcastle-upon-Tyne UK and 2Department of Respiratory Medicine Waikato Hospital Hamilton New Zealand Email Sarah Haney - sas_haney@ Robert J Hancox - Corresponding author Published 16 September 2005 Received 15 April 2005 Respiratory Research 2005 6 107 doi 1465-9921-6-107 Accepted 16 September 2005 This article is available from http content 6 1 107 2005 Haney and Hancox licensee BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License http licenses by which permits unrestricted use distribution and reproduction in any medium provided the original work is properly cited. Abstract Background Regular use of beta-agonists leads to tolerance to their bronchodilator effects. This can be demonstrated by measuring the response to beta-agonist following bronchoconstriction using methacholine. However most studies have demonstrated tolerance after a period of betaagonist withdrawal which is not typical of their use in clinical practice. This study assessed tolerance to the bronchodilator action of salbutamol during ongoing treatment with long-acting beta-agonist. Methods Random-order double-blind placebo-controlled crossover trial. After 1 week without beta-agonists 1 3 asthmatic subjects inhaled formoterol 12 pg twice daily or matching placebo for 1 week. Eight hours after the first and last doses subjects inhaled methacholine to produce a 20 fall in FEV1. Salbutamol 100 200 and 400 pg cumulative dose was then given at 5-minute intervals and FEV1 was measured 5 minutes after each dose. After a 1 week washout subjects crossed over to the other treatment. Unscheduled use of beta-agonists was not .
