Investigation of the photochemical properties and in vitro phototoxic potential of bumetanide

The photophysical and photochemical properties of bumetanide, a sulfonamide diuretic drug, have been investigated and the photodegradation of the drug on exposure to UV-B and UV-A radiation monitored by fluorimetric and chromatographic ( HPLC) methods. The main photoproducts were isolated by solid-phase extraction and liquid chromatographic procedures, and their structure elucidated by H-1-NMR and mass spectrometry. Bumetanide generates only extremely small quantities of singlet oxygen (O-1(2)) upon irradiation in the presence of oxygen. The in vitro 3T3 NRU phototoxicity test yielded no evidence of phototoxic action.