Synthesis, Characterization, and Biological Evaluation of [188Re(N)(cys~)(PNP)]+/0 mixedligand complexes as prototypes for the development of 188Re(N)-based target-specific radiopharmaceuticals

We report on an efficient procedure for the preparation of [188Re(N)(PNP)] - based complexes (where PNP is diphosphinoamine) useful in the development of target-specific radiopharmaceuticals. The radiochemical yield of the compounds was optimized considering such reaction parameters as nature of the nitrido nitrogen donor, reaction times and pH level. The chemical identity of the 188Re agents was determined by high-performance liquid chromatography comparison with the corresponding well-characterized cold Re compounds. 188Re(N) mixed compounds have been evaluated with regard to stability toward transchelation with GSH and degradation by serum enzymes. The clearance of selected radiocompounds from normal tissues and their in vivo stability were evaluated in rats by biodistribution and imaging studies. ....................