Tropolone: a lipid solubilizing agent for cationic metals.

Lipid soluble agents which chelate radioactive cations have several potential uses in nuclear medicine including: brain imaging, labeling of blood elements, and identifying fatty infiltration of organs. A tropolone-gallium complex has been characterized by the determination of in vitro partition ratios correlated with in vivo organ distribution in the rat. Partition ratios were determined for gallium-67 citrate, indium-114m chloride, and iron-59 chloride cations complexed with tropolone in chloroform + water, octanol + water, olive oil + water, and olive oil + plasma two-phased systems. Tropolone proved to be highly effective in the lipid solubilization of these metal cations. Distribution studies in animals of these cations complexed with tropolone demonstrated an increased concentration of these cation complexes in tissues of high lipid content when compared with appropriate controls.