Inhibition of thiazide photohemolysis in vitro by antioxidants and a nitrogen atmosphere.

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 screened in vitro for phototoxic effects by means of a photohemolysis test. In all, 19 out of the 25 test substances revealed phototoxic hemolytic properties after irradiation with either solar stimulating irradiation, UVA and/or visible light. Addition of the antioxidants ascorbic acid, alpha-tocopherole or superoxide dismutase significantly inhibited the phototoxic hemolysis, as well as did investigations carried out in a nitrogen rich atmosphere, findings which indicate the involvement of reactive oxygen species in the phototoxic process.