Photohemolysis Due to Oral Antidiabetic Drugs

The oral hypoglycemic sulfonamides carbutamide, chlorpropamide, glibenclamide, glibornuride, gliclazide, glipizide, gliquidone, glisoxepide, glymidine, tolazamide, and tolbutamide were investigated for photohemolytic properties in vitro. Irradiation with a solar simulator revealed hemolysis in the presence of chlorpropamide, glipizide, gliquidone, glymidine, and tolbutamide (all at a concentration of 10−3 mol/L). Except for glymidine, which exerted photohemolysis at the concentration 10−4 mol/L, no hemolytic effects were seen in the concentration of 10−4 mol/L or 10−5 mol/L. Irradiation with light sources emitting mainly ultraviolet B (UVB), ultraviolet A (UVA), or visible light did not induce phototoxic hemolysis with any of the test substances. Tolbutamide and chlorpropamide have previously been described as a cause of clinical photosensitivity, whereas the other drugs so far have not shown phototoxic effects in humans.