Fast and very fast MAS solid state NMR studies of pharmaceuticals

In this chapter we show the application of solid state NMR spectroscopy to study active pharmaceutical ingredients (APIs) in different solid forms, as pure components and as parts of more complex systems. The chapter is divided into the sections. After the preface, 2 Very fast MAS solid state NMR, 3 Studies of APIs by means of 2D and 3D very fast MAS solid state NMR techniques present a comprehensive introduction to the modern NMR techniques which are used in structural studies of pharmaceutical products. Techniques employing fast and very fast magic angle spinning with sample rotation over 40 kHz are reviewed. The problem of resolution, sensitivity and N-dimensional NMR is discussed. The application of DNP techniques to study APIs is shown. Section 4 reviews methodologies which are employed to the analysis of structure, polymorphism and molecular dynamics of APIs in the solid state. The NMR crystallography approach for the determination of crystal structure of compounds without or with doubtful X-ray data is reviewed. Section 5 is devoted to the problem of drug delivery systems (DDS) studies. Pharmaceutical cocrystals and salts are discussed in Section 6. The results presented in this chapter demonstrate that by adjusting the sample spinning speed and selecting dedicated solid state NMR sequences, general and specific problems covering various aspects of drug design and therapeutic applications can be solved, described and explained.