A view on the less-than-rational development of drug delivery systems - the example of dry powder inhalers

This review is about the meandering course of science. It uses the research on, and development of, dry powder inhalations (DPIs) as a case study. It suggests that the influences can be classified as bottom-up (reductionist, specific) and top-down (whole-system - gestalt). Based on information in the public domain, it seems that DPI research has taken a meandering course being influenced by historical and cultural beliefs, communication and debate, serendipity and chance comment and regulation. It has also been strongly influenced by the availability of highly sophisticated equipment which has been used to characterize particles and their interactions, as well as their deposition in the lung. DPI research has been influenced by closely related (e.g. oral drug delivery) or distantly related (mineralogy, industrial hygiene) disciplines and now it influences other disciplines. Sometimes the time period for inter-disciplinary knowledge transfer has been surprisingly long. The primary aim (or outcome) of DPI research is improved healthcare for people through efficient pulmonary drug delivery. A fundamental aim is improved mechanistic understandings of the behaviour of particles in DPIs to give increased predictive ability.