Orally inhaled drug performance testing for product development, registration, and quality control.

A DPI can be split into three different modules; device, formulation, process. These are developed in parallel, and together with the user they provide the performance of an inhalation product. During product development, these modules are evolving and changing, whereas the requirements on an inhalation product are always expressed in terms of the performance of the final commercial product. To do performance testing during development when the product is not finished presents many challenges and can be confusing and misleading. During development, the performance of the final product is typically being predicted by testing ever changing prototypes. This article describes methods and approaches to manage such development and to, during development, provide relevant predictions of the in vitro and in vivo performances of the final product.