An industrial perspective on co-crystals: Screening, identification and development of the less utilised solid form in drug discovery and development.

Active pharmaceutical ingredients are commonly marketed as a solid form due to ease of transport, storage and administration. In the design of a drug formulation, the selection of the solid form is incredibly important and is traditionally based on what polymorphs, hydrates or salts are available for that compound. Co-crystals, another potential solid form available, are currently not as readily considered as a viable solid form for the development process.

Dynamic Crystallization Pathways of Polymorphic Pharmaceuticals Revealed in Segmented Flow with Inline Powder X-ray Diffraction.

Understanding the transitions between polymorphs is essential in the development of strategies for manufacturing and maximizing the efficiency of pharmaceuticals. However, this can be extremely challenging: crystallization can be influenced by subtle changes in environment, such as temperature and mixing intensity or even imperfections in the crystallizer walls. Here, we highlight the importance of in situ measurements in understanding crystallization mechanisms, where a segmented flow crystallizer was used to study the crystallization of the pharmaceuticals urea: barbituric acid (UBA) and carbamazepine (CBZ).