Nicorandil-N-Oxide

Nicorandil-N-Oxide is an oxidation derivative of Nicorandil, featuring an N-oxide functional group on the piperazine nitrogen. This impurity forms via oxidative degradation of the parent drug's secondary amine, introducing a positively charged oxygen atom that alters the molecule's polarity and hydrogen-bonding capacity. The core structure retains the 4-nitrophenyl ring and ethyl ester linkage, but the N-oxide introduces steric and electronic perturbations compared to the native amine. It serves as an HPLC reference standard for monitoring oxidative degradation pathways in Nicorandil drug substance.