Pharmaceutical powder technology - from art to science: the challenge of the FDA's Process Analytical Technology initiative

-This paper describes with typical examples the state of art. The list of examples includes the problems of non-robust formulations and critical processes. The paper demonstrates the necessity and the challenge of the FDA's Process Analytical Technology initiative, which is an important stimulus to develop a rigorous scientific framework in the area of pharmaceutical powder technology. The paper suggests a kind of 'road map' to achieve as fast as possible the top of the 'knowledge pyramid'. The road map includes the extensive use of a multivariate design of experiments, the use of artificial neural networks (ANN), the use of the laws of physical pharmacy and percolation theory, and, last but not least, tries to 'translate' the existing laws of physical chemistry into the area of pharmaceutical powder technology, where we have the problem that the number of particles involved is much lower than the Avogadro number NA. For this reason it will be of interest to monitor closely the progress in nanoscience, especially in the area of mathematical modeling of the fascinating special physical properties of nanoparticles, which again consist of a finite number N of atoms, respectively molecules, with N ≪ NA.