Study of the Interactions with UV Light of Non Steroidal Anti-Inflammatory Drugs, the Selective Inhibitors of the Cyclooxygenase-2: Photostability and Photosensitizing Properties in vitro

In the last years, skin photosensitization is appearing in the most sensitive subjects with a greater number of drugs (Antibiotics, Antifungals, Diuretics and Cardiovascular agents, NSAIDs and Antipsychotics) either applied directly on the skin or administered systemically, and results in the risk of tumors of the skin. It’s likely that other drugs that induce moderate phototoxicity are not recognized as 'photosensitizers' since the induced cutaneous reactions are taken for mild sunburn or solar eczemas. The selective inhibitors of the cyclooxygenase-2 (CSIs), drugs entered recently the market, are here studied in terms of phototoxicity and photostability, since their chemical structure suggests their interactions with UV light. This reactivity could bring to changes of the molecule or to its activation, with induction of photosensitizing effects. Indeed, for the less recent Nimesulide, some phototoxic reactions have already been reported in humans. In fact, CSIs drugs are characterized by the presence of an aromatic structure with high degree of conjugation, of a sulphonamide moiety (similar to that of the Sulphonamides, the phototoxicity of which has been already demonstrated) and, in some of them, of a trifluoromethyl group highly unstable under irradiation (as in the case of Fluphenazine). The present study includes investigations on the photostability of PTPBS (4-[5-phenyl-3-(trifluoromethyl)-1H-pyrazol-1-yl]benzenesulfonamide), and the evaluation of its phototoxic potential in vitro on cellular models and on isolated biomolecules.