Isolation and structure elucidation of the main UV-A photoproducts of vandetanib

Exposure of aqueous solutions of the antitumor drug vandetanib to UV-A light results in the photochemical degradation. Two main photodegradation products were identified by HPLC-MS analysis and their structures were elucidated, after their isolation by HPLC, on the basis of LC-MS and NMR spectra. The photoproducts derived from a simple debromination (N-(2-fluorophenyl)-6-methoxy-7-((1-methylpiperidin-4 yl)methoxy)quinazolin-4-amine, FP3) or from the loss of the bromide atom followed by the solvent addition (N-(4-hydroxy-2-fluorophenyl)-6-methoxy-7-((1-methylpiperidin-4 yl)methoxy)quinazolin-4-amine, FP2). At our knowledge this is the first report about the photodegradation of vandetanib.