Application of LC-MS/MS for the identification of a polar impurity in mosapride, a gastroprokinetic drug.

In the impurity profile of mosapride a polar impurity (0.1%) was detected in HPLC with respect to mosapride. Based on the mass spectral data obtained by LC-MS/MS analysis this impurity structure was characterised as 4-amino-5-chloro-2-ethoxy-N-[[(4-benzyl)-2-morphinyl] methyl] benzamide. It is interesting to note that this impurity is potent analogue of mosapride, which will have much higher gastroprokinetic activity than metoclopramide. This impurity was synthesised from an unambiguous route and confirmed the structure by collecting various spectral data and the formation is discussed. To our knowledge this compound was not reported as process impurity elsewhere.