[Biochemistry of metallocenes, II. Organ-distribution and thymus affinity of cinnamoyl-[103Ru]ruthenocene (author's transl)].

Metallocenes, labelled with 103Ru, are potential radiopharmaceuticals for use in nuclear medicine diagnosis. Ruthenocene derivatives with oxopropene side-chains were administered to mice and rats to study their biochemical properties. Excretion rates and organ distributions of 103RuCl3 and Cinnamoyl-[103Ru]ruthenocene were very different. While 103RuCl3 was relatively evenly distributed in the body, the metallocene derivative was concentrated in liver, lungs and spleen after intravenous (i.v.) injection. After i.p. injection however a high thymus affinity was observed and autoradiography proved that the site of 103Ru accumulation was in thymocytes. The thymus affinity can be diminished by corticoid pretreatment and raised by inhibition of phagocytosis (BeSO4). The mechanism of accumulation in the thymus and a possible clinical application are discussed.