Progress of research on quantitative techniques for trace amount of crystals in solid state drugs

It is well-known that crystal form of a drug is a key factor impacting the physicochemical properties of the drug, which in turn affects its in vivo efficacy, safety and stability. The study on crystal forms of solid-state drugs is crucial for drug quality control, selection of production process and evaluation of clinical efficacy. The combination of chemometric and analytical techniques exhibited its great ability to analyze a large amount of multidimensional data, providing the possibility for quantification of trace amount of crystals (< 1%). Meanwhile, using the process analytical technology (PAT) to monitor the crystal content real-time during prescription preparation process can further realize the control on formulation quality and serve as a core technology to support the patent protection of crystalline forms. In this review, the combined application of crystal analytical techniques and chemometric methods for the quantitative analysis of trace crystals were summarized, aiming to provide guidance for the manufacturing of pharmaceutical preparations and their quality control.