Reproducibility of bronchodilator response for a reservoir dry powder inhaler following routine clinical use

The performance of dry powder inhaler (DPI) devices, particularly reservoir DPIs, may be influenced by environmental conditions. This study compared the bronchodilator efficacy and in vitro aerosol characteristics of salbutamol, delivered via a novel reservoir DPI (Clickhaler) and a conventional pressurized metered-dose inhaler (MDI) before and after use of the DPI in clinical practice. Following a screening visit, patients received cumulative doses of salbutamol (100, 200, and 400 microg) via DPI or MDI on separate days in a double-blind, crossover design before and after a 4-week period, during which the DPI was used as the patients' first-line bronchodilator. Lung function responses (forced expiratory volume in 1 sec [FEV1], forced vital capacity [FVC], and peak expiratory flow [PEF]) to salbutamol delivered by DPI and MDI and in vitro aerosol characteristics were not significantly different before and after the period of DPI patient use. DPI performance, assessed in vivo and in vitro, is maintained following an extended period of patient use.