Alogliptin impurity J

Alogliptin impurity J is a structurally related degradation byproduct arising from oxidative stress conditions during API synthesis. It features a pyrazine core linked to a sulfoxide-functionalized sulfonamide moiety, with a retained guanidine side chain. This impurity results from S-oxidation of the parent sulfonamide group, introducing a chiral sulfoxide center. It serves as a critical HPLC reference standard for quantifying oxidative degradation pathways in alogliptin formulations under accelerated stability testing.