Thepresentpopularityofnoveldrypowde

Thepresentpopularityofnoveldrypowderinhaler(DPI)devel- opment commenced at the time that CFC replacement became an issue. These devices are now much more sophisticated than used to be the case when only single-dose, capsule-loading sys- tems existed (e.g., Spinhaler and Rotahaler from Aventis and GlaxoSmithKline, respectively). From a user perspective, the numberofdifferentdesignsthataremarketedorindevelopment will itself create problems for physicians and patient educators. We already have difficulty teaching patients to use MDIs; imag- ine the increasing complexity as the variety of inhaler options increases further. Importantly, from the point of view of DTL variance, most DPIs only deliver drugs when the patient inhales through them. As a consequence, the issue of “coordination” between actuation and inhaling disappears. However, because smallvolumepowdermeteringisneveraspreciseasthemeasure- ment of liquids, and because DPIs are generally less robust than MDIs, there are many alternative (and often inhaler-specific) ways in which patients can misuse these inhalers. As a result, patients may fail to receive therapy for a variety of reasons (e.g., exhalation into the device, loading the device in incorrect orientations and inappropriate storage conditions may affect different DPIs in different ways)