POTENTIAL GA-67 RADIOPHARMACEUTICALS FOR MYOCARDIAL IMAGING - TRIS(1-ARYL-3-HYDROXY-2-METHYL-4-PYRIDINONATO)GALLIUM(III) COMPLEXES

A series of highly lipophilic complexes of 1-aryl-3-hydroxy-2-methyl-4-pyridinones with gallium(III)-67 has been evaluated in vitro and in vivo as potential radiopharmaceuticals. The pyridinones have different substituents at the para -position of the phenyl ring: R = H, CH3, OCH3 and NO2. Biodistribution studies of Ga-67 complexes have been carried out in rabbits, mice, rats and a dog. High heart uptake of the radionuclide has been shown in rabbits and the dog. The different biodistribution patterns in mice and rats indicate that there is a species difference in the biodistribution of these complexes. Rabbits and the dog show rapid heart uptake and blood clearance. The speciation of the Ga3+ ion in vivo is simulated in vitro with a simple blood plasma model based on the available thermodynamic data.