Biodistribution of 14C-lomustine in an animal tumor model.

A formulation of 14C-lomustine in propylene glycol-ethanol (4:1) was administered intravenously to rats infiltrated with glioma tumors of the astrocytic series (RT6). The organ and tumor distribution of this agent was followed at 1, 4, 12, and 24 hr. Rapid blood disappearance (0-1 hr) of the label concomitant with an increase in all organs except the lung, muscle, and brain was observed. Only the blood, liver, and muscle contained greater than 1% of the dose after 24 hr. The bladder, liver, small bowel, and kidneys concentrated the highest percentages throughout the study. The distribution of 14C-lomustine in the tumor relative to the brain, muscle, and blood showed a maximum 4-12 hr after administration.