Fenofibric acid

Fenofibric acid is a chlorinated aromatic carboxylic acid derivative characterized by a 4-chlorophenyl ring linked to a branched aliphatic chain terminating in a carboxylic acid group. Its structure incorporates an isopropyl substitution at the β-position relative to the acid functionality, distinguishing it from the parent drug, Fenofibrate, which contains an esterified counterpart of this acid. The compound arises as a degradation byproduct during Fenofibrate synthesis or storage, particularly under hydrolytic conditions. The presence of the chlorine substituent enhances metabolic stability while introducing a key structural divergence from the parent molecule. This impurity serves as a critical HPLC reference standard for quantifying process-related degradation products in Fenofibrate formulations.