In vitro photosensitized lysis of red blood cells by an antifungal drug griseofulvin.

Human red blood cells (RBCs) were lysed by in vitro irradiation in the presence of the antifungal drug griseofulvin (GF). Effects of UVA fluence and GF concentration on photohaemolysis were examined under aerobic conditions. The photohaemolysis occurred at much lower fluence than that necessary for oxidation of the membrane lipids. UVA-irradiated solution of GF did not cause haemolysis. The photohaemolysis was colloid osmotic in nature because it was preceded by K+ leakage from the cells and was delayed in the presence of 30 mM sucrose in the medium. Even under anaerobic conditions, RBCs were lysed by irradiation with higher fluence than that required for aerobic photohaemolysis. Therefore, some phototoxic mechanism other than photosensitized oxidation is also involved in the photohaemolysis.