Identification of Degradation Products in the Phosphodiesterase (PDE-4) Inhibitor Roflumilast Using High Resolution Mass Spectrometry and Density Functional Theory Calculations

Roflumilast analogs are a group of drugs which act as selective photodiesterase (PDE-4) inhibitor for the treatment severe chronic pulmonary disease associated with chronic brochnonities. Structural identification of degradation products using high resolu- tion mass spectrometry and theoretical investigation by density functional theory have been successfully carried out on roflumilast to identify four degradation products namely, 3,5-dichloropyridin-4-amine, N-(3,5-dichloropyridin-4-yl)-4-(difluoromethoxy)-3-hydroxy benzamide, N-(3,5-dichloropyridin-4-yl)-3-(cyclopropylmethoxy)-4-(difluoromethoxy) benzamide and 3-(cyclopropylmethoxy)-N- (3,5-dichloro-1-oxidopyridin-4-yl)-4-(difluoro methoxy) benzamide, generated in alkali, acidic and oxidative conditions.