A new approach toward a pancreas-seeking zinc radiopharmaceutical. II. 62Zn-EDDA (ethylenediamine-N,N'-diacetic acid) for pancreas PCT imaging.

The functionality of various zinc complexes of amino acid derivatives as a zinc radiopharmaceutical for pancreas PCT imaging was tested using 65Zn, which has a long half-life, and 62Zn, which has a short half-life. Because of the favorable results obtained in previous in vitro pancreas section studies, the ability of those Zn complexes to retain their integrity in the presence of blood serum or in living organisms was screened using Sephadex column chromatography and mice biodistribution studies. A relationship between the structure and stability of Zn complexes played a determining role on the in vivo availability of Zn for the pancreas or liver. Among the Zn complexes tested, the tetra-coordinated structure of the Zn-EDDA complex at an equimolar ratio showed proper accumulation in the pancreas, inducing an appropriate pancreas PCT image in the dog with the positron emitter 62Zn-EDDA administered at 1 mg Zn/kg body weight.