The importance of the device in asthma therapy.
Inhalation is the preferred route for drug delivery in asthma treatment. Successful management of asthma depends on achieving adequate delivery of inhaled drug to the lungs, and to this end the role of the device used for delivery is very important. Aerosolized anti-asthma medications have been available for more than 40 years as pressurized metered dose inhalers (pMDIs), but more recently dry powder inhalers (DPIs) have been developed as an alternative. Laboratory assessment of fine particle dose has been shown to correlate to pulmonary deposition if the assessments are performed with an in vivo-like set up. The DPI Turbuhaler delivers a high proportion of the dose as fine particles suggesting high pulmonary deposition. This finding has been confirmed by lung deposition studies, which indicate superior pulmonary deposition from Turbuhaler compared with a pMDI. This superior delivery to the lungs with Turbuhaler is reflected in a better clinical effect, as measured by greater improvements in lung function. The DPIs such as Turbuhaler are easy to use, and Turbuhaler has been shown to function well in a constrained situation such as an acute asthmatic exacerbation. Furthermore, the use of Turbuhaler in acute asthma will provide rapid clinical improvement. The in vivo variability in lung deposition obtained with Turbuhaler is lower than with pMDI, indicating that the performance of Turbuhaler is less dependent on patient competence. Thus, the development of Turbuhaler represents an important step forward in the effective management of asthma.