The metabolism of rhodium(II) acetate in tumor-bearing mice.

Rhodium(II) acetate has been shown to have carcinostatic activity in Swiss mice bearing Ehrlich ascites tumors. For metabolic studies, single therapeutic doses of rhodium(II) [1-14C]acetate that had been given i.p. implantations 3 days previously of 50-fold 10(6) Ehrlich ascites tumor cells. The tissue distribution and excretion of the rhodium (measured by atomic absorption spectrometry) and the acetate (measured by 14C label) were followed at designated time intervals up to 24 hr after injection. Rhodium(II) acetate, a neutral cage complex, breaks down to rhodium and acetate ionic species within 2 hr after i.p. injection, as measured by the rapid exhalation of 14CO2. Both the rhodium and 14C label disappear rapidly from the ascites fluid, with a small but variable amount of each species being incorporated into the tumor cells. Both species were detected mainly in the blood plasma, and the primary organ of deposition was the liver. No measurable quantity of rhodium was found in the brain tissue. During the first 24 hr following drug administration, only 5% rhodium was eliminated in the urine.