EFFICACY OF CUMULATIVE DOSES OF SALBUTAMOL ADMINISTERED VIA TURBUHALER(R) OR DISKHALER(R) IN PATIENTS WITH REVERSIBLE AIRWAY-OBSTRUCTION

The study aimed to estimate the relative dose potency of salbutamol in haled via Turbuhaler(R) and Diskhaler(R). The 24 adult patients partic ipating had chronic reversible airway obstruction. The study was of a double-blind, double-dummy, crossover, randomized design. Five doses o f salbutamol Turbuhaler, 50, 50, 100, 200, and 400 mu g, were given on one study day at intervals of 30 min. On another study day, five dose s of salbutamol Diskhaler? 200, 200, 400, 800, and 1600 mu g, were giv en with the same interval. The treatment days were separated by a wash out period of at least 24 h. The inhalation technique was standardized and supervised. Efficacy variables were recorded before and after eac h study dose. The primary efficacy variable was forced expiratory volu me in Is (FEV1). When parallel and linear cumulative dose-response cur ves were statistically compared on a logarithmic scale, the dose poten cy of salbutamol Turbuhaler vs salbutamol Diskhaler was 1.99 (95% conf idence interval 1.52-2.54). This study indicates that only half the do se of salbutamol is required via Turbuhaler as via Diskhaler for the s ame bronchodilating effect.