Crystallization is one of the most common phase transformations in pharmaceutical production processes as 90% of the active pharmaceutical ingredients (APIs) are crystallized small molecules. Despite the popularity of crystallization, many aspects concerning the creation of solid particles from solutions are not fully mastered, leading often to an empirical approach. Two separate phrases from trustworthy scientists that can be heard at crystallization conferences are: “never trust a spontaneous nucleation event, it will run out of hand” and “that is where the magic happens”. Both are related to shortcomings understanding of the crystallization mechanisms and provoke quotes like: “In industrial crystallizers, however, homogeneous nucleation is usually not desired at all and, for the production of large crystals in particular, it has to be avoided. Only for the crystallization of very fine or even nano-sized materials may this mechanism be useful.”
This paper reviews the basics of the crystallization transformation and explains more specifically how the theory is implemented to master nucleation for a successful intensified crystallization of small molecules… Read more on our White Paper on continuous crystallization processes.