Abstract: Provided herein is an impurity of eletriptan, eletriptan N-oxide, (R)-5-[2- (phenylsulfonypethyl]-3-[(1-methyl-2-pyrrolidinyl-N-oxide)methyl]-1H-indole, and a process for the preparation and isolation thereof. Provided further herein is a highly pure eletriptan or a pharmaceutically acceptable salt thereof substantially free of eletriptan N-oxide impurity, processes for the preparation thereof, and pharmaceutical compositions comprising highly pure eletriptan or a pharmaceutically acceptable salt thereof substantially free of eletriptan N-oxide impurity.

Abstract: The present invention relates to novel hemioxalate salt of eletriptan, process for preparation, pharmaceutical compositions, and method of treating thereof. The present invention relates to solid forms of eletriptan hemioxalate, processes for preparation, pharmaceutical compositions, and method of treating thereof. The solid form of eletriptan hemioxalate is useful for preparing eletriptan free base or a pharmaceutically acceptable salt thereof, particularly eletriptan hydrobromide, in high purity. The present invention also provides a process for preparing substantially pure eletriptan hydrobromide using eletriptan hemioxalate.