Control of radioactivity pharmacokinetics of 99mTc-HYNIC-labeled polypeptides derivatized with ternary ligand complexes.
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.
Ono
Masahiro
M
Department of Patho-Functional Bioanalysis, Graduate School of Pharmaceutical Sciences, Kyoto University, Yoshida Shimoadachi-cho, Sakyo-ku 606-8501, Japan.
Arano
Yasushi
Y
Mukai
Takahiro
T
Saga
Tsuneo
T
Fujioka
Yasushi
Y
Ogawa
Kazuma
K
Kawashima
Hidekazu
H
Konishi
Junji
J
Saji
Hideo
H
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
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