The efficacy of a new salbutamol metered-dose powder inhaler in comparison with two other inhaler devices

An open cross-over and randomized study was carried out in order to compare the efficacy and safety of inhaled salbutamol delivered from a new 50 microg dose(-1) metered-dose dry powder inhaler Taifun, and a commercially available 50 microg dose(-1) dry powder inhaler Turbuhaler, and a conventional 100 microg dose(-1) pressurized metered-dose inhaler with a spacer (pMDI+S). Twenty-one patients, aged 21-70 years, with stable asthma and with demonstrated reversibility upon inhalation of salbutamol were included in the study. On three separate study days, the patients received a total dose of 400 microg of salbutamol from the dry powder inhalers and a dose of 800 microg from the pMDI+S in a cumulative fashion: 1,1, 2 and 4 doses at 30 min intervals. The percent change in forced expiratory volume in 1 sec (FEV1), was used as the primary efficacy variable. Salbutamol inhaled via the Taifun produced greater bronchodilation than the other devices. The difference in percent change in FEV1 between the Taifun and the other devices was statistically significant at the two first dose levels, but diminished towards the higher doses when the plateau of the dose-response curve was reached. The estimated relative dose potency of the Taifun was approximately 1.9- and 2.8-fold compared to the Turbuhaler and the pMDI+S, respectively. The Taifun caused a slight, but clinically insignificant, decrease in serum potassium concentration. There were no significant changes in the other safety parameters (blood pressure, heart rate and electrocardiogram recordings) with any of the used devices. In conclusion, this study indicates that salbutamol inhaled via the Taifun is more potentthan salbutamol inhaled from the other devices tested. In practise, a smaller total dose of salbutamol from theTaifun is needed to produce a similar bronchodilatory response. All treatments were equally well tolerated.