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

In a recent clinical study we have demonstrated that the bronchodilator eff ect of 200 mu g salbutamol (Ventoline(R)) was spacer device-dependent in 10 0 tested asthmatic children, with the Babyhaler(R) providing greater effica cy for improving peak expiratory flow rate compared to Aeroscopic(R), Nebuh aler(R), Aerochamber(R) and Volumatic(R). The aim of this present study was to correlate our clinical results to in vitro determinations of the emitte d dose (ED) of Ventoline(R) administered via these five different plastic s pacer 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. Thre e pressurized metered-dose inhalers and three sets of spacer devices were u sed to obtain a total of 30 measurements per group. Inter-group results wer e compared by RM-ANOVA or Student-Newman-Keuls method when indicated. Babyh aler(R) delivered significantly (P < 0.05) more salbutamol than Nebuhaler(R ), Aerochamber(R) and Aeroscopic(R) (mean +/- standard deviation: 63.6 +/- 2.9 mu g/100 mu g actuation for Babyhaler(R) vs. 59.4 +/- 8.6 for Nebuhaler (R), 50.8 +/- 5.0 for Aerochamber(R) and 47.5 +/- 2.5 for Aeroscopic(R)). T he ED from Volumatic(R) (61.5 +/- 7.9 mu g/100 mu g actuation) was similar to that from the Babyhaler(R). The variability in the ED was greatest with the large volume spacers. Despite a greater ED from the Babyhaler(R), in vi tro results do not fully explain the in vivo results. However, the previous ly described clinical improvement seen with the Babyhaler(R) may be due to the quantitatively different aerosol production in a more 'useful' size ran ge, 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 phys iological outcomes. (C) 2000 Editions scientifiques et medicales Elsevier S AS.