2-Oxazolidinone, 4-[[3-[2-(dimethyloxidoamino)ethyl]-1H-indol-5-yl]methyl]-, (4S)-, (4S)-4-[[3-[2-(Dimethyloxidoamino)ethyl]-1H-indol-5-yl]methyl]-2-oxazolidinone, Zolmitriptan N-Oxide, Imp. B (EP), Zolmitriptan Related Compound E, Zolmitriptan Impurity