title: Control of radioactivity pharmacokinetics of 99mTc-HYNIC-labeled polypeptides derivatized with ternary ligand complexes.
abstract: An enhancement of the target/nontarget ratio of radioactivity levels enables reliable diagnosis and therapy using polypeptide radiopharmaceuticals in nuclear medicine. In the present study, we investigated the effects of the physicochemical properties of radiometabolites on the radioactivity pharmacokinetics after administration of 99mTc-labeled polypeptides using 6-hydrazinopyridine-3-carboxylic acid (HYNIC). Four ternary ligands (L) [3-benzoylpyridine (BP), 3-acetylpyridine (AP), 3-nicotinic acid (NIC), pyridine (PY)] with different lipophilicity were selected as coligands for the preparation of 99mTc-HYNIC-polypeptides. Each of the ternary ligands tested provided 99mTc-HYNIC-labeled galactosyl-neoalbumin (NGA) and Fab fragments of high stability with high radiochemical purity. Moreover, after administration of each 99mTc-HYNIC-labeled NGA into normal mice, the respective ternary ligand [99mTc](HYNIC-lysine)(tricine)(L) complexes were generated as final radiometabolites in the hepatic lysosome. The partition coefficients of [99mTc](HYNIC-lysine)(tricine)(BP), [99mTc](HYNIC-lysine)(tricine)(AP), [99mTc](HYNIC-lysine)(tricine)(NIC), and [99mTc](HYNIC-lysine)(tricine)(PY) were determined to be -2.21, -2.37, -2.93, and -2.73, respectively. Elimination rates of these radiometabolites from the lysosome were enhanced in the order of increasing lipophilicity of the radiometabolites. After injection of the four 99mTc-HYNIC-labeled Fab fragments into normal mice, blood clearances of radioactivity were similar while radioactivity elimination rates from the kidney were enhanced in the order of increasing lipophilicity of the radiometabolites. The present study indicated that the lipophilicity of the radiometabolites constitutes one important factor affecting their elimination rates from the tissues. Thus, as ternary ligands facilitate alteration of the physicochemical properties of radiometabolites, the use of ternary ligand complexes might be applicable for controlling the pharmacokinetics of 99mTc-labeled polypeptides.
authors: Department of Patho-Functional Bioanalysis, Graduate School of Pharmaceutical Sciences, Kyoto University, Yoshida Shimoadachi-cho, Sakyo-ku 606-8501, Japan.
authors: Masahiro
authors: M
authors: Ono
authors: Yasushi
authors: Y
authors: Arano
authors: Takahiro
authors: T
authors: Mukai
authors: Tsuneo
authors: T
authors: Saga
authors: Yasushi
authors: Y
authors: Fujioka
authors: Kazuma
authors: K
authors: Ogawa
authors: Hidekazu
authors: H
authors: Kawashima
authors: Junji
authors: J
authors: Konishi
authors: Hideo
authors: H
authors: Saji
mesh_terms: D000418:Albumins / Q000737:chemistry / Q000493:pharmacokinetics*; D000818:Animals; D005998:Glycine / Q000031:analogs & derivatives* / Q000737:chemistry; D006801:Humans; D006834:Hydrazines / Q000737:chemistry*; D007140:Immunoglobulin Fab Fragments / Q000737:chemistry; D007275:Injections, Intravenous; D007668:Kidney / Q000378:metabolism; D008024:Ligands; D008099:Liver / Q000378:metabolism; D008239:Lysine / Q000737:chemistry; D008297:Male; D051379:Mice; D008819:Mice, Nude; D009536:Niacinamide / Q000031:analogs & derivatives* / Q000737:chemistry; D009539:Nicotinic Acids / Q000737:chemistry*; D015609:Organotechnetium Compounds / Q000737:chemistry / Q000493:pharmacokinetics*; D012516:Osteosarcoma / Q000000981:diagnostic imaging / Q000378:metabolism; D010455:Peptides / Q000737:chemistry / Q000493:pharmacokinetics*; D011485:Protein Binding; D011877:Radionuclide Imaging; D019275:Radiopharmaceuticals / Q000138:chemical synthesis / Q000493:pharmacokinetics*; D012513:Sarcoma, Experimental / Q000000981:diagnostic imaging / Q000378:metabolism; D014018:Tissue Distribution
chemical_list: C120392:6-hydrazinopyridine-3-carboxylic acid; D000418:Albumins; D006834:Hydrazines; D007140:Immunoglobulin Fab Fragments; D008024:Ligands; D009539:Nicotinic Acids; D015609:Organotechnetium Compounds; D010455:Peptides; D019275:Radiopharmaceuticals; C117288:hydrazino nicotinamide; C036586:technetium Tc 99m neogalactoalbumin; D009536:Niacinamide; D008239:Lysine; D005998:Glycine; C100184:tricine