The mutagenic action of nitroimidazoles. II. Tinidazole, ipronidazole, panidazole and ornidazole.

The 5-nitroimidazoles tinidazole (Fasigyn), ipronidazole (Ro-7-1554), panidazole and ornidazole (Tiberal, Ro-7-0207) in concentrations of 0.02--1 mM per liter increased the mutation frequency of Klebsiella pneumoniae. Escherichia coli K12 and Citrobacter freundii to streptomycin resistance, including streptomycin dependence, in Luria and Delbrück's fluctuation test. At low concentration (0.1 mM), the increase of the mutation frequency caused by each compound was nearly the same, i.e. 3--4 times the spontaneous mutation frequency. At higher concentrations, considerable differences between the mutagenic activities of the compounds occurred.