Fenofibrate EP Impurity F

Fenofibrate EP Impurity F is a chlorinated aromatic ester derived from the parent drug's synthetic pathway, featuring a substituted phenoxyacetic acid core with a para-chloro substituent on the benzene ring and an isopropyl ester moiety. Its structure incorporates a conjugated diene system and a ketone functionality, distinguishing it from fenofibrate through a positional isomerism in the chloro group and altered ester linkage. This impurity arises via side-chain oxidation during fenofibrate synthesis, forming a stable, thermally resistant byproduct. It serves as a critical HPLC reference standard for quantifying this specific impurity profile in fenofibrate drug substances and dosage forms.