Development of [111]In-labeled porphyrins for SPECT imaging

ABSTRACT

The aim of this research was the development of [111]In-labeled porphyrins as possible radiopharmaceuticals for the imaging of tumors. Ligands, 5, 10, 15, 20-tetrakis [3, 5-dihydroxyphenyl] porphyrin] [TDHPP], 5, 10, 15, 20-tetrakis [4-hydroxyphenyl] porphyrin [THPP] and 5, 10, 15, 20-tetrakis [3,4-dimethoxyphenyl] porphyrin] [TDMPP] were labeled with [111]InCl3 [produced from proton bombardment of natCd target] in 60 min at 80[degree sign]C. Quality control of labeled compounds was performed via RTLC and HPLC followed by stability studies in final formulation and presence of human serum at 37[degree sign]C for 48 h as well as partition coefficient determination. The biodistribution studies performed using tissue dissection and SPECT imaging up to 24h. The complexes were prepared with >99% radiochemical purity [HPLC and RTLC], high stability in 48h. Partition coefficients [calculated as log P] for [111]In-TDHPP, [111]In-THPP and [111]In-TDMPP were 0.88, 0.8 and 1.63 respectively. Due to urinary excretion with fast clearance for [111]In-TDMPP, this complex is probably a suitable candidate for considering as a possible tumor imaging agent