Effectiveness of nitrofuran derivatives in sensitizing hypoxic mammalian cells to x rays

Various nitrofuran derivatives have been tested with Chinese hamster cells growing in vitro to determine their toxicity and radiosensitizing effectiveness. All nitrofurans tested displayed a greater radiosensitizing potential than p-nitroacetophenone for hypoxic cells at concentrations producing no acute toxicity. The most effective compound tested to date is nifuraldezone which at 250 μm in complete medium gives the same extent of radiosensitization (ER∼2·85) as oxygen in air-saturated medium. Additional nitroheterocyclic compounds in current clinical usage have also been characterized. The chemical and pharmacological properties of the various compounds are discussed in relation to their application in animal tumour studies. High water solubility appears to be an important property for radiosensitizers to be used in animal tumour studies. A positive demonstration of radiosensitization in vivo with nitroheterocyclic drugs will depend upon whether or not a sensitizing concentration of the drugs can be established in the hypoxic cells of a solid animal tumour for the duration of the radiation treatment.