The radiosensitizing effect of ornidazole in hypoxic mammalian tissue: an in vivo study.
In this study the sensitizing effect of ornidazole is investigated in vivo. The selected test system is the acute killing effect of radiation within 4-6 days after abdominal irradiation ranging from 9 to 24 Gy, in groups of C57 black mice. Ornidazole is given intraperitoneally in 500 mg/kg, 100 mg/kg, 20 mg/kg doses prior to irradiation of animals breathing air, oxygen or nitrogen. A decrease of LD50 dose is observed from 24.39 +/- 5.66 to 16.38 +/- 1.86 and 18.04 +/- 2.48 Gy, respectively, in nitrogen breathing animals. No sensitizing effect was observed in doses of 20 mg/kg. Enhancement Ratio (ER) was found to be 1.48 +/- 0.25 and 1.35 +/- 0.27; relative sensitizing efficiency (RSE) was 40% and 29% respectively. No sensitizing effect was observed in animals irradiated in oxic conditions. These results showed that ornidazole (Ro-7-0207) has a sensitizing effect on hypoxic cells in vivo. It is worthwhile to try this drug in a clinical study.
D000693:Anaerobiosis; D000818:Animals; D004307:Dose-Response Relationship, Radiation; D005260:Female; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D009593:Nitroimidazoles / Q000494:pharmacology*; D009950:Ornidazole / Q000494:pharmacology*; D010100:Oxygen; D011833:Radiation Injuries, Experimental / Q000401:mortality; D011838:Radiation-Sensitizing Agents / Q000494:pharmacology*
D009593:Nitroimidazoles; D011838:Radiation-Sensitizing Agents; D009950:Ornidazole; D010100:Oxygen