Effect of mouthpiece washing on aerosol performance of CFC-free Ventolin

The prescribing information for chlorofluorocarbon (CFC)-free salbutamol metered-dose inhalers carries a strongly-worded instruction to wash the mouthpiece weekly, but patients rarely carry this out. This study investigated the effect of washing/not washing the mouthpiece on CFC-free Ventolin aerosol performance. Twelve CFC-free Ventolin inhalers were actuated two puffs four times/day, and assessed by unit dose sampler and cascade impactor on Days 1, 7, 8, 14, 15, 21, and 22 ("throughlife," i.e., over the entire content of the inhaler). The mouthpieces of six inhalers were washed after the last actuation on Days 7, 14, and 21. A single priming maneuver, as recommended by the manufacturer, was sufficient for fine particle mass. There were no significant through-life differences in delivered dose between washed and unwashed inhalers. Without washing, fine particle mass fell from 47 microg to 33 microg (Friedman p=0.002). Fine particle mass increased significantly after washing (median change + 11.2 microg, p=0.019 cf. unwashed). Large particle mass showed no significant through-life trend for washed or unwashed inhalers, but was significantly reduced after washing (p=0.04 cf. unwashed). This study shows a progressive through-life reduction in fine particle mass from CFC-free Ventolin inhalers, which is prevented by weekly mouthpiece washing. However, in view of the steep bronchodilator dose-response curve for salbutamol, further studies are needed to determine whether such device care is clinically necessary.