Antimutagenic activity of fluphenazine in short-term tests.

Fluphenazine, an antipsychotic drug that belongs to the phenothiazine family, reduced the genotoxicity of direct- and indirect-acting mutagens in the Ames test, both in the presence and in the absence of promutagen-activating S9 fraction. In short-term tests on human lymphocytes, the inhibitory effect of fluphenazine on the genotoxicity of standard mutagens was strongest in the cytokinesis-blocked micronucleus assay and in the thioguanine resistance test, and weakest in the sister chromatid exchange test. Fluphenazine also considerably reduced the level of free radicals estimated in in vitro samples of human granulocytes. The results suggest that, in the range of the tested concentrations, fluphenazine could be considered for use to prevent the genotoxicity of daunorubicin, methyl methanesulfonate, benzo[a]pyrene, and mitomycin C. Reduction in the level of free radicals appears to be an important mechanism of the antimutagenic action of fluphenazine.