The frequency of sister chromatid exchanges in cultured human peripheral blood lymphocyte treated with metronidazole in vitro.

5-Nitroimidazoles are a group of antiprotozoal and antibacterial agents. Thanks to their antimicrobial activity, these chemotherapeutic agents inhibit the growth of both anaerobic bacteria and certain anaerobic protozoa. One of the useful drugs used in the treatment of infections caused by Trichomonas vaginalis, Entamoeba histolytica, and Giardia lamblia is metronidazole (MTZ). The mutagenicity of metronidazole [1-(hydroxyethyl)-2-methyl-5-nitroimidazole] has been previously shown in different prokaryotic systems but not in eukaryotic systems. The objective of this study is to determine the mutagenic and cytotoxic effects of MTZ at plasma concentration and higher in vitro. In this study, we evaluated the mutagenicity and cytotoxicity of MTZ in cultured human peripheral blood lymphocytes. Doses were selected according to plasma concentration of drug. End points analyzed included mitotic index (MI), replication index (RI), and sister chromatid exchange (SCE). An analysis of variance test (ANOVA) was performed to evaluate the results. A significant decrease (p < 0.001) in MI and RI as well as an increase in SCE frequency (p < 0.001) was observed compared with control cultures. Our results indicate the genotoxic and cytotoxic effect of MTZ in cultured human peripheral blood lymphocytes at plasma concentrations slightly higher than encountered therapeutically.