ABSTRACT
Polymorphism of drug is known to influence the stability, dissolution, bioavailability and other performance characteristics of the products. Therefore, the crystal form of the drug must be identified and determined in order to ensure consistent product performance. Even if the identification and characterization of crystal forms are performed thoroughly and the effective crystal form is selected for preparation, it is important to ensure that the effective crystal form in the final product remains unchanged. Therefore, it is essential to quantitate the content of the effective crystal form in the product to control the quality and performance of them. X-ray powder diffraction, FT-Raman, mid-IR, near-IR, terahertz pulsed spectroscopy, solid-state NMR spectroscopy, and DSC are the quantitative methods of crystal form used in the recent 10 years. This review briefly highlights the basic principles and the progress of these methods and discusses the perspective as they apply to pharmaceutical research and development.