Comparison of Intravenous and Intra-arterial Pyrimidine Infusion as a Means of Radiosensitizing TumorsIn Vivo

Abstract

The halogenated pyrimidine analog 5-bromo-2-deoxycytidine (BCdR) was infused into BALB/C mice bearing EMT-6 [mammary] tumors via the i.v. or intraarterial route. Hepatic dehalogenation of the drug was blocked by 5-diazouracil (DAZU) to ascertain its relative importance in the degradation of i.v. administered analogs. Increased radiosensitization was noted with higher i.v. pyrimidine concentrations, but DAZU blockage of dehalogenation had little effect. Following i.v. infusion, enough BCdR apparently bypasses the hepatic vessels to permit tumor radiosensitization despite dilution of the drug by the systemic circulation.