Preferential tumor radiosensitization by analogs of nicotinamide and benzamide.
The effects of a range of different analogs of nicotinamide and benzamide on the X ray response of the EMT-6 tumor in vivo was investigated. Using an in vivo/in vitro survival assay, sensitization was seen at a dose of 2 mmole/kg for all but one of the analogs tested. The enhancement ratios (ER's) ranged from 1.0 to 1.5. Of particular interest were nicotinamide and SR-4350 which gave large ER's (1.5 and 1.4 respectively) at doses which were only about 12% of the LD50 values. In one normal tissue studied (skin reaction) a large single dose of nicotinamide (8 mmole/kg) only gave an ER of 1.1. These results will be discussed with reference to the mechanisms involved and the clinical implications.
D000818:Animals; D001549:Benzamides / Q000627:therapeutic use* / Q000633:toxicity; D003131:Combined Modality Therapy; D051379:Mice; D009374:Neoplasms, Experimental / Q000188:drug therapy / Q000532:radiotherapy*; D009536:Niacinamide / Q000031:analogs & derivatives / Q000627:therapeutic use* / Q000633:toxicity; D011838:Radiation-Sensitizing Agents / Q000627:therapeutic use* / Q000633:toxicity
D001549:Benzamides; D011838:Radiation-Sensitizing Agents; D009536:Niacinamide