One formulation of14C labeled and another of99mTc labeled 1-(2-chloroethyl)-3-cyclohexyl-1-nitrosourea (CCNU) were administered i.v. to tumor (glioma) bearing rats. The
radiopharmacokinetics of14C-CCNU were followed up to 24 hours post injection. On a per organ basis the blood, liver, small bowel, kidney cortex and
muscle contained most of the activity. Optimum tumor to organ ratios occurred at 4–12 hours. The99mTc-CCNU biodistribution was determined at 4 hours and compared to99mTc-NaTcO4. Tumor capsule to brain (29.5) and to muscle (10.59) ratios suggest99mTc-CCNU to be a potential tumor seeking agent.