Comparison of I-bleomycin prepared by two methods stability and pharmacokinetics in tumor-bearing mice

Bleomycin, a chemotherapeutic antibiotic agent, was radio-iodinated by the ICI and chloramine-T methods; the radiochemical stabilities and pharmacokinetics of the two I-bleomycins in tumor-bearing mice were compared. The ICI preparation was more stable with respect to deiodination in vitro. Both products were sufficiently stable in vivo that high body background due to free isotope, a disadvantage of 111In- and 99mTc-bleomycin, was not encountered. Tumor uptake of the ICI preparation was constant from 2 to 24 hrs., and the tumor/blood ratio increased with time; with chloramine-T, this ratio decreased, and was less than that for ICI. The two preparations are chemically and biologically different; the ICI product is the superior tumor radiodiagnostic agent.