N-Desmethyl Levofloxacin

N-Desmethyl Levofloxacin is a structurally related impurity derived from Levofloxacin via N-demethylation at the piperazin-1-yl moiety. It retains the quinolone-4-carboxylic acid core, fluorine substitution at C-6, and a methoxy group at C-8, but features a dealkylated piperazine ring. This modification alters its hydrophobicity and hydrogen-bonding capacity compared to the parent drug. It arises as a synthetic byproduct during Levofloxacin production or via oxidative degradation pathways. It serves as a critical HPLC reference standard for quantifying process-related impurities in Levofloxacin active pharmaceutical ingredients.