Identification and quality control strategy of impurities in Zhengqing Fengtongning injection

Zhengqing Fengtongning injection is the sterile aqueous solution of Sinomenine Hydrochloride extracted from the root and stem of Sinomenium acutum, and is widely used to treat rheumatoid arthritis. Due to the processes of extraction, separation, purification, preparation and storage, some related impurities might be formed, which may cause side effects on patients. It is important to rapidly separate and identify the related impurities to ensure the safe use of Zhengqing Fengtongning injection. However, there are few literatures about the impurity in Zhengqing Fengtongning injection. In this work, ultra-high performance liquid chromatography- quadrupole time-of-flight mass spectrometry (UPLC-QTOF/MS) was developed to analyze impurities in both Zhengqing Fengtongning injection and its drug substance, with Sinomenine Hydrochloride as its active pharmaceutical ingredient (API). Six impurities of the Zhengqing Fengtongning injection were found. Structures of impurities 1 and 6 were confirmed by NMR and other impurities were identified from the fragmentation pattern of Sinomenine, the similarity of molecular weight and fragment ions in references. Finally, the HPLC analytical technique was developed to achieve the quantification of impurities 1 and 6. In addition, some reasonable suggestions are put forward on the quality control of Zhengqing Fengtongning injection and its drug substance based on the processes and structural characteristics of the related substances. The technical system established in this paper is helpful to strengthen the quality control of Zhengqing Fengtongning injection and improve production, and can also provide references for the production and quality control of similar drugs.