Evaluation of phototoxic properties of oral antidiabetics and diuretics. Photohemolysis model as a screening method for recognizing potential photosensitizing drugs.

The oral hypoglycemic drugs carbutamide, chlorpropamide, glibenclamide, glubornuride, gliclazide, glipizide, gliquidone, glisoxepide, glymidine, tolazamide and tolbutamide, and the diuretics acetazolamide, bemetizide, bendroflumethiazide, benzthiazide, benzylhydrochlorothiazide, bumetanide, butizide, chlorazanile, chlorothiazide, chlortalidone, clopamide, cyclopenthiazide, cyclothiazide, diazoxide, etozoline, furosemide, hydrochlorothiazide, hydroflumethiazide, indapamide, mefruside, metolazone, piretanide, polythiazide, trichlormethiazide, and xipamide were investigated for photohemolytic properties in vitro. Irradiation with a SOL 3 apparatus (solar simulating irradiation) revealed hemolysis in the presence of five oral hypoglycemic agents and in the presence of 19 out of the 25 tested diuretics. Photohemolysis was induced in the presence of three substances, respectively, after exposure to UVA or visible light. UVB alone did not induce phototoxic hemolysis in the presence of the tested drugs. Compared to clinical reports on photosensitivity reactions, the photohemolysis model seems a good predictive model in recognizing potential photosensitizing sulfonamides.