(23a) Microstructural Characterization and Dissolution Behavior of Drug/Semicrystalline Polymer Systems On Substrates

Solid dispersions have been used to improve the bioavailability of poorly water-soluble drugs. However, controlling the stability of the products can still be challenging. Recently, solidification on certain substrates can result in the control of polymorph and crystallization kinetics. The presence of  the substrate surface provides heterogeneous nucleation sites that enables the control and scale-up of solidification processes.

In this study, the Drop on Demand technique is used to dispense a solution of Naproxen (NAP) and polyvinylpyrrolidone (PVP) on Chitosan or HPMC films to investigate the role of the substrate surface on the crystallization of the solid dispersion. XRD curves show that NAP has higher crystallinity when crystallized on Chitosan film compared to the HPMC film. The SEM and SHG images also show that NAP forms larger crystal sizes on the Chitosan film. AFM was used to characterize the films and it shows that the Chitosan film has a rougher surface that may provide more sites for NAP to nucleate. The dissolution experiments of those samples on different substrates were also conducted and the results are correlated to their crystallinity and microstructure on the films.