Rabeprazole Carboxylic Acid Impurity

Rabeprazole Carboxylic Acid Impurity is a structurally related degradation product derived from the proton pump inhibitor Rabeprazole, featuring a 5-substituted pyridine ring linked to a sulfinyl bridge and a terminal carboxylic acid moiety. The compound retains the benzimidazole core of the parent drug but exhibits a hydrolyzed carboxylic acid group in place of the sulfenyl ester functionality, resulting from oxidative degradation pathways. This impurity arises during API synthesis or storage under elevated temperature/humidity conditions. It serves as a critical HPLC reference standard for quantifying process-related impurities in rabeprazole formulations.