Fenofibrate EP Impurity D

Fenofibrate EP Impurity D is a degradation byproduct arising from the hydrolytic cleavage of the glycerol ester moiety in fenofibrate, resulting in the exposure of a free carboxylic acid group. Its structure retains the core phenoxyphenylpropanoic acid scaffold with an isopropyl substitution at the γ-position, while lacking the triazole linkage characteristic of the parent API. This impurity exhibits enhanced polarity due to the de-esterified carboxylate, facilitating distinct chromatographic behavior. It serves as an HPLC reference standard for quantifying degradation pathways in fenofibrate formulations.