LAUSR

Impurity investigations are important in pharmaceutical development to ensure drug purity and safety for the patient. The impurities typically found in drug products are degradants or reaction products of the active pharmaceutical ingredient (API), or leachable compounds from the container closure system. However, secondary reactions may also occur between API degradants, excipient impurities, residual solvents and leachables to form adduct impurities. We hereby report an adduct-forming interaction of API (Moxifloxacin) with a leachable compound (ethylene glycol monoformate) in Moxifloxacin ophthalmic solution. The leachable compound originated from a low density polyethylene (LDPE) bottle employed in the packaging of drug products. The adduct impurity was tentatively identified as 1-cyclopropyl-6-fluoro-7-(1-(2-(formyloxy)ethyl)octahydro-6H-pyrrolo[3,4-b]pyridin-6-yl)-8-methoxy-4-oxo-1,4-dihydroquinoline-3-carboxylic acid (C24H28FN3O6, MW= 473.19621) using accurate mass LC-QTOF analysis. The mass accuracy error between the theoretical mass and the experimental mass of an impurity was found to be 0.2 ppm. An MS/MS analysis was utilized to provide mass spectrometry fragments to support verification of the proposed structure.