COMPARISON OF THE BRONCHODILATING EFFICACIES OF A NOVEL SALBUTAMOL METERED-DOSE POWDER INHALER AND A PRESSURIZED METERED-DOSE AEROSOL WITH A SPACER

In a two-day, randomised, double-blind, double-dummy, cross-over multi center study, the bronchodilating effect of 100 mu g of salbutamol (CA S 18559-94-9) inhaled from a new metered dose powder inhaler (MDPI; Ta ifun (R)) was compared with that of an identical dose of salbutamol in haled from a conventional pressurised metered dose inhaler connected t o a spacer (pMDI+S). Thirty-six non-smoking, adult asthmatic outpatien ts with a baseline forced expiratory volume in 1 s (FEV1) between 35 a nd 70 % of the predicted value participated in the study. After inhala tion of the study medication pulmonary function, FEV1 and airway resis tance (R-aw), blood pressure (BP), and heart rate (HR) were measured u p to 6 h. Area under the FEV1 vs. time curve (AUC(FEV1)) was used as t he primary efficacy parameter, and the 90 % confidence intervals (CI) were used to judge clinical equivalence. Other efficacy parameters wer e used in supportive analyses as secondary parameters. Both treatments produced a clear improvement in pulmonary function. The mean +/- SD A UC(FEV1) were 893 +/- 281 and 889 +/- 2761 . min after MDPI and pMDI+S , respectively. The 90 % CI for the relative efficacy of the MDPI is f rom 98 to 103 % of that of the pMDI+S. Also the other efficacy paramet ers gave similar results without significant differences: the mean +/- SD values of percent increase in FEV1 were 47.2 +/- 19.3 and 44.7 +/- 20.8, the maximum absolute value of FEV1 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 R-aw 0.27 +/- 0.11 and 0.3 0 +/- 0.12 kPa.s.l(-1) for the MDPI and pMDI+S, respectively. The salb utamol doses had no significant effect on BP or HR, and were equally w ell tolerated. Furthermore, 57.5 % of the patients preferred the MDPI, 35 % the pMDI+S, and 7.5 % considered that there was no difference be tween the devices. In conclusion, this study demonstrates that the new MDPI is as effective and safe a device as a conventional pMDI connect ed to a spacer in administering inhaled salbutamol for asthmatic patie nts. Further, most patients considered the MDPI easier to handle, and preferred it over the pMDI+S.