Dry powder inhalation, part 2: the present and future

Introduction: The manufacture of modern dry powder inhalers (DPIs), starting with the Spinhaler (Fisons) in 1967, was only possible thanks to a series of technological developments in the 20^th century, of which many started first around 1950. Not until then, it became possible to design and develop effective, cheap and mass-produced DPIs. The link between these technological developments and DPI development has never been presented and discussed before in reviews about the past and present of DPI technology. Areas covered: The diversity of currently used DPIs with single dose, multiple-unit dose and multi-dose DPIs is discussed, including the benefits and drawbacks of this diversity for correct use and the efficacy of the therapy. No specific databases or search engines otherwise than PubMed and Google have been used. Expert opinion: Considering the relatively poor efficacy regarding lung deposition of currently used DPIs, the high rates of incorrect inhaler use and inhalation errors and the poor adherence to the therapy with inhalers, much effort must be put in improving these shortcomings for future DPI designs. Delivered fine particle doses must be increased, correct inhaler handling must become more intuitive and simpler to perform, and the use of multiple inhalers must be avoided.