Identification and characterization of new impurities in rivastigmine
Srinivasa Rao, M.; Rao, S.V.; Srinivasa Rao, D.V.N.; Bharathi, C.; Rajput, P.; Sharma, H.K.
Die Pharmazie 65(5): 336-338
2010
ISSN/ISBN: 0031-7144 PMID: 20503924 Document Number: 644985
Rivastigmine is a drug against Alzheimer's disease, and is a non-pharmacopoeial compound. During the preparation of rivastigmine in our laboratory, two impurities were detected and identified with a simple and sensitive reversed-phase liquid chromatography coupled with electrospray-mass spectrometry. The same impurities were also observed in commercial batches. These impurities were isolated by preparative HPLC and co-injected with rivastigmine sample to confirm the retention times in HPLC. These impurities were characterized as N,N-dimethyl-3-[1-dimethylaminoethyl]phenylcarboxylate (dimethyl-rivastigmine) and N,N-diethyl-3-[1-dimethylaminoethyl]phenylcarboxamide (diethyl-rivastigmine). Structural elucidation of these impurities by spectral data (1H NMR, 13C NMR and MS) is discussed.