NEWLY DISCOVERED PHOTODEGRADATION PRODUCTS OF NIFEDIPINE IN-HOSPITAL PRESCRIPTIONS

New photodegradation products of nifedipine (1) have been isolated. Th ey were found in tablets dispensed in the pulverized form by hospitals . 1 decomposed concurrently into six components after storage of 30 da ys under exposure to normal room light. The main photoproduct was a ni troso derivative (2) and others were minor. Preparative thin-layer chr omatography has been used to isolate the six photodegradation products . The chemical structures of these isolated compounds were identified or estimated by comparison with authentic samples and/or using UV, IR, H-1 NMR, mass spectroscopy, melting point determination, and elementa ry analysis. From these analyses, it was found that 1 was converted in to a cis-azoxy derivative (4), a trans-azoxy derivative (5), a N,N'-di oxide derivative (6) and a lactam derivative (7) in addition to 2 and a nitro derivative (3). Furthermore, it is proposed that 2 is mainly r esponsible for the formation of these new products (4-7) by photochemi cal condensation.