Metronidazole (“Flagyl”). A radiosensitizer of hypoxic cells

Abstract

The radiosensitizing properties of metronidazole have been studied using bacteria, bean roots, and mammalian cells in vitro as test systems. Metronidazole has been shown to sensitize only anoxic cells in a concentration-dependent manner, a maximum enhancement ratio of 1·9 being obtained at 8 mmol/1. metronidazole concentration for mammalian cells. The effect of added SH compounds on the sensitizing effect of metronidazole was studied in bacteria and bean roots. Metronidazole sensitized bacteria to the effects of neutron irradiation by a factor of only 1·4. The mechanism of sensitization by metronidazole is discussed in the light of pulse radiolysis and ESR data, and its action compared with that of oxygen. Pharmacological data presented suggest that in vivo testing of metronidazole should be possible and that any radiosensitizing effects shown may be related to measured serum concentrations.