Breath-actuated inhalers in chronic asthma: comparison of Diskhaler and Turbohaler for delivery of beta-agonists.

An open, randomized, cross-over study was performed to compare the efficacy and acceptability of two breath-actuated inhalers, the Turbohaler (T) and Diskhaler (D), for delivery of beta-agonists. Thirty six adults with chronic asthma requiring beta-agonists four times daily were treated with terbutaline 500 micrograms via T and salbutamol 400 micrograms via D four times daily, each period lasting four weeks. Additional bronchodilator via pressurized aerosol was permitted as required. Peak expiratory flow (PEF) was recorded in the morning (before and after beta-agonist) and in the evening. The mean morning PEF was higher during the first two weeks using T (295 l.min-1) than whilst using D (281 l.min-1, p < 0.01), but this difference did not persist during the second two weeks and there were no differences in post-bronchodilator PEF or rescue beta-agonist use. After four weeks, > 90% of patients used both inhaler devices efficiently and they were equally acceptable in terms of ease of use and convenience to carry. The Diskhaler and Turbohaler achieve similar clinical efficacy for delivery of beta-agonists.