Determination of free radicals generated from light exposed ketoprofen

Ketoprofen [(RS)-2-(3-benzoylphenyl)propanoic acid] has been widely used for the treatment of inflammatory diseases and musculoskeletal injury. However, there is concern over its phototoxicity and photosensitization potential as side effects. In the present study, we examined photodynamic action of ketoprofen, determined free radicals and active oxygen species generated from ketoprofen by photo-irradiation, which have been implicated as the phototoxicity and photosensitization. The generation of superoxide anion, hydroxyl radical and singlet oxygen were determined by electron spin resonance (ESR), chemiluminescence analyzer (CLA) and the on-line photo irradiated superoxide anion detection system, when ketoprofen was exposed by the ultraviolet lamp or the chemical lamp. The on-line light exposed superoxide anion detection system was developed to catch superoxide anions generated at an instant and estimate quantitatively risk of the light-sensitive disease of drugs. These radicals were maintained for 20 min at the ESR spectrum measurement using the spin trapping reagent, 5,5-dimethyl-1-pyrroline-N-oxide (DMPO), though these signals were declining gradually. The degradation products were analyzed to identify the chemical structures. The pathway of the photo degradation and generation of the active oxygen species was estimated by the experimental results obtained in this study.