Ketoconazole EP Impurity E

Ketoconazole EP Impurity E is a chlorinated aromatic derivative featuring a substituted pyridine ring fused to an imidazole core, with a 4-chlorophenyl substituent and a sulfonamide-linked hydroxybutyrate side chain. Its structure diverges from the parent drug by the absence of the terminal methyl group on the propionate chain and the incorporation of an additional hydroxyl functionality at the α-position of the sulfonamide moiety. This impurity arises during oxidative degradation pathways, specifically via hydroxylation of the ketoconazole backbone. Serves as a reference standard for HPLC-based quantification of process-related impurities in ketoconazole drug substance analysis.