Analytical tools for reliable in vitro and in vivo performance testing of drug nanocrystals

Abstract Drug nanocrystals are a versatile option for drug delivery purposes. They have mostly been utilized for improving poor solubility properties of drugs, but there are also controlled release applications, for example, based on nanocrystal technologies. In order to reach the desired formulation properties with drug nanocrystals, thorough physicochemical analyses both in vitro and in vivo are needed. In this chapter, drug nanocrystals and their benefits for drug delivery purposes are described. Then the techniques to produce drug nanocrystals are reviewed and the most important applications for drug delivery presented. The most emphasis in this chapter is put on the analytical techniques, and their utilization in nanocrystal characterization. Techniques analyzing particle size (dynamic light scattering (DLS), scanning electron microscopy (SEM), transmission electron microscopy (TEM)), morphology and shape (TEM, SEM, atomic force microscopy), zeta potential, physical state of the drug (X-ray powder diffraction (XRPD, differential scanning calorimetry (DSC), thermo gravimetry/thermo analysis (TG/TA), dissolution and solubility properties, as well as cell uptake studies (coherent anti-Stokes Raman scattering), and in vivo behavior are presented.