Emitted doses of salbutamol pressurized metered-dose inhaler from five different plastic spacer devices

Abstract

In a recent clinical study we have demonstrated that the bronchodilator effect of 200 μg salbutamol (Ventoline®) was spacer device-dependent in 100 tested asthmatic children, with the Babyhaler® providing greater efficacy for improving peak expiratory flow rate compared to Aeroscopic®, Nebuhaler®, Aerochamber® and Volumatic®. The aim of this present study was to correlate our clinical results to in vitro determinations of the emitted dose (ED) of Ventoline® administered via these five different plastic spacer devices. ED was determined from the mean of single doses collected in unit dose sampling tubes using a constant suction flow of 28.3 L/min. Three pressurized metered-dose inhalers and three sets of spacer devices were used to obtain a total of 30 measurements per group. Inter-group results were compared by RM-ANOVA or Student-Newman-Keuls method when indicated, Babyhaler® delivered significantly (P < 0.05) more salbutamol than Nebuhaler®, Aerochamber® and Aeroscopic® (mean ± standard deviation: 63.6 ± 2.9 μg/100 μg actuation for Babyhaler® rs. 59.4 ± 8.6 for Nebuhaler®, 50.8 ± 5.0 for Aerochamber® and 47.5 ± 2.5 for Aeroscopic®). The ED from Volumatic® (61.5 ± 7.9 μg/100 μg actuation) was similar to that from the Babyhaler®. The variability in the ED was greatest with the large volume spacers. Despite a greater ED from the Babyhaler®, in vitro results do not fully explain the in vivo results. However, the previously described clinical improvement seen with the Babyhaler® may be due to the quantitatively different aerosol production in a more 'useful' size range, as well as the different breathing patterns of the children tested. The results of this present study question the relevance of mouthpiece filter collection studies using a constant sampling in predicting clinical or physiological outcomes. (C) 2000 Editions scientifiques et medicales Elsevier SAS.