Active pharmaceutical ingredients (APIs) are capable of forming solids as crystalline or amorphous glasses. The various crystalline forms are composed of molecules arranged in a three-dimensional structure with a local pattern (i.e., structural unit or unit cell) that repeats periodically in all directions with a regular repeat distance that results in a well-defined lattice. Polymorphism, the potential of a crystalline material to exist in different crystalline phases with different molecular arrangements and/or conformations, is of critical interest in the development of pharmaceutical solid dosage forms. Variations in the crystalline forms of APIs may affect their physiochemical properties, which can significantly impact the therapeutic index, bioavailability, manufacturing processing, and marketability of the commercialized drug product.