title: Isolation, identification and characterization of novel process-related impurities in flupirtine maleate.
abstract: Flupirtine maleate is a centrally acting, non-opioid, nonsteroidal antiinflammatory analgesic. During the manufacturing of flupirtine maleate, two unknown impurities present in the laboratory batches in the range of 0.05-1.0% along with the known impurities in HPLC analysis. These unknown impurities were obtained from the enriched mother liquor by column chromatography. Based on the complete spectral analysis (MS, (1)H, (13)C, 2D NMR and IR) and knowledge of the synthetic scheme of flupirtine maleate, these two new impurities were designated as diethyl 5-((4-fluorobenzyl)amino)-2-oxo-1H-imidazo[4,5-b]pyridine-1,3(2H)-dicarboxylate (impurity-I) and diethyl(6-((4-fluorobenzyl)amino)pyridine-2,3-diyl)dicarbamate (impurity-II). Impurity isolation, identification, structure elucidation and the formation of impurities were also discussed. Preparation and structure elucidation of impurity-III were also first reported in this paper.
authors: Department of Pharmacy, Food and Pharmaceutical Engineering College, Hubei University of Technology, 430068 Wuhan, Hubei, China.
authors: Dengfeng
authors: D
authors: Zhang
authors: Department of Pharmacy, Food and Pharmaceutical Engineering College, Hubei University of Technology, 430068 Wuhan, Hubei, China.
authors: Xin
authors: X
authors: Song
authors: Department of Pharmacy, Food and Pharmaceutical Engineering College, Hubei University of Technology, 430068 Wuhan, Hubei, China. Electronic address: jiangtsu@126.com.
authors: Jiangtao
authors: J
authors: Su
mesh_terms: D000631:Aminopyridines / Q000032:analysis* / Q000592:standards; D000700:Analgesics / Q000032:analysis* / Q000506:poisoning; D002851:Chromatography, High Pressure Liquid / Q000379:methods*; D004340:Drug Contamination; D009682:Magnetic Resonance Spectroscopy; D013058:Mass Spectrometry; D013055:Spectrophotometry, Infrared
chemical_list: D000631:Aminopyridines; D000700:Analgesics; C034161:flupirtine
keywords: Characterization; Flupirtine; Identification; Impurity; Isolation