Biochemistry of metalocenes. I. Distribution of 59Fe or 103Ru-labeled metalocene carboxylic acid in mice.

Metalocene carboxylic acids labeled with 59Fe or 103Ru were administered to mice and the organ distributions and amounts of label excreted were determined. Both metalocenes were excreted approximately 90 times faster than the respective inorganic chlorides 59FeCl3 or 103RuCl3. The metalocenes showed an extremely high kidney-to-muscle ratio (up to 1,000). 99mTc-labeled renal agents, tested for comparison, showed lower ratios. Retention of radioactivity in blood and the presence of free iron in urine indicate that the ferrocene derivative is degraded in vivo, but the ruthenocene analog is not.