PHOTODEGRADATION PRODUCTS OF SULFONAMIDE-DERIVED ORAL ANTIDIABETICS AND DIURETICS ARE NOT PHOTOTOXIC IN-VITRO

The oral antidiabetics glibenclamide and glipizide, and the diuretics bendroflumethiazide and furosemide, all sulphonamide derived drugs, we re investigated in vitro for phototoxic properties. Irradiation with b road-band UV induced phototoxic inhibition of colony forming ability i n cell cultures. During irradiation, the substances lost one absorptio n maximum in the UVA region, demonstrated by UV spectroscpoy. These fi ndings correlate well with the UV applied, the action spectrum being i n the UVA region. Photoproducts detected during and after irradiation showed a decomposition of the substances due to ionization and fragmen tation. Incubation of these preirradiated drugs with the cell cultures revealed no phototoxic effects.