Comparison of the bronchodilating efficacies of a novel salbutamol metered dose powder inhaler and a pressurised metered dose aerosol with a spacer

In a two-day, randomised, double-blind, double-dummy, cross-over multicenter study, the bronchodilating effect of 100 μg of salbutamol (CAS 18559-94-9) inhaled from a new metered dose powder inhaler (MDPI; Taifun®) was compared with that of an identical dose of salbutamol inhaled from a conventional pressurised metered dose inhaler connected to a spacer (pMDI+S). Thirty-six non-smoking, adult asthmatic outpatients with a baseline forced expiratory volume in 1 s (FEVI) between 35 and 70 % of the predicted value participated in the study. After inhalation of the study medication pulmonary function, FEV 1 and airway resistance (Raw), blood pressure (BP), and heart rate (HR) were measured up to 6 h. Area under the FEVI vs. time curve (AUC FEV1 ) was used as the primary efficacy parameter, and the 90 % confidence intervals (CI) were used to judge clinical equivalence. Other efficacy parameters were used in supportive analyses as secondary parameters. Both treatments produced a clear improvement in pulmonary function. The mean + SD AUC FEV1 were 893 + 281 and 889 + 276 1 min after MDPI and pMDI+S, respectively. The 90 % Cl for the relative efficacy of the MDPI is from 98 to 103 % of that of the pMDI+S. Also the other efficacy parameters gave similar results without significant differences: the mean + SD values of percent increase in FEV 1 were 47.2 + 19.3 and 44.7 + 20.8, the maximum absolute value of FEV 1 were 2.87 + 0.77 and 2.86 + 0.77, the maximum percent decrease in R aw 53.2 + 20.5 and 55.0 ± 19.1, and the minimum absolute value of Raw 0.27 ± 0.11 and 0.30 ± 0.12 kPas1 -1 for the MDPI and pMDI+S, respectively. The salbutamol doses had no significant effect on BP or HR, and were equally well tolerated. Furthermore, 57.5 % of the patients preferred the MDPI, 35 % the pMDI+S, and 7.5 % considered that there was no difference between the devices. In conclusion, this study demonstrates that the new MDPI is as effective and safe a device as a conventional pMDI connected to a spacer in administering inhaled salbutamol for asthmatic patients. Further, most patients considered the MDPI easier to handle, and preferred it over the pMDI+S.