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. 2016 Oct 17;84(4):671–687. doi: 10.3390/scipharm84040671

Table 1.

Chemical structures of linagliptin (LGP) as well as metformin hydrochloride (MET HCl) and their impurities.

Structure Chemical Name/Molecular Weight/Formula
graphic file with name scipharm-84-00671-i001.jpg Linagliptin: 8-[(3R)-3-aminopiperidin-1-yl]-7-(but-2-yn-1-yl)-3-methyl-1-[(4-methylquinazolin-2-yl) methyl]-2, 3, 6, 7-tetrahydro-1H-purine-2,6-dione (472.55) C25H28N8O2
graphic file with name scipharm-84-00671-i002.jpg S-isomer: (S)-8-3(-aminopiperidin-1-yl]-7-(but-2-yn-1-yl)-3-methyl-1-((4-methylquinazolin-2-yl) methyl)-1H-purine-2, 6 (3H, 7H)-dione (472.55) C25H28N8O2
graphic file with name scipharm-84-00671-i003.jpg Metformin HCl: 1,1-Dimethylbiguanide hydrochloride (165.63) C4H12ClN5
graphic file with name scipharm-84-00671-i004.jpg Impurity-A (MET HCl): 1-Cyanoguanidine (84.08) C2H4N5