[Metabolism of 123I-FP-CIT in humans].
The metabolism of N-(3-fluoropropyl)-2 beta-carbomethoxy-3 beta-(4-iodophenyl)nortropane (123I) (123I-FP-CIT) in healthy humans was studied. Plasma and urine samples, obtained after i.v. administration of 123I-FP-CIT, were analyzed using the two-dimensional thin-layer chromatography technique. Eleven radiochemical components were detected in both plasma and urine, and four of them were the parent 123I-FP-CIT and its metabolites, N-(3-fluoropropyl)-2 beta-carboxy-3 beta-(4-iodophenyl)nortropane (123I) (123I-acid), 2 beta-carboxy-3 beta-(4-iodophenyl)nortropane (123I) (123I-nor-acid) and 2 beta-carbomethoxy-3 beta-(4-iodophenyl)nortropane (123I) (123I-nor-CIT). These four identified radiochemical components occupied about 80% or more in ratio of the radiochemical components in the plasma and urine. In the metabolites of 123I-FP-CIT, the high polar metabolites--123I-acid and 123I-nor-acid--were found to be the major components, while lipophilic 123I-nor-CIT was a minor component. Free iodide (123I-) was not found in the plasma or urine. Thus, the main metabolic reactions which 123I-FP-CIT undergoes in humans seem to be hydrolysis of the ester bond and N-dealkylation. In vivo deiodination of 123I-FP-CIT was found to be minimum. Current results suggest that the metabolites of 123I-FP-CIT hardly influence evaluation of the dopamine transporter in the human brain.
Tanaka
A
A
Research Center, Nihon Medi-Physics Co., Ltd., Chiba.
Okano
K
K
Tamagami
H
H
Matsumoto
H
H
Tanifuji
S
S
Yamamichi
Y
Y
Yoshimura
H
H
Katoazuma
M
M
Takano
K
K
Matsumura
K
K
Takeda
K
K
D000328:Adult; D002352:Carrier Proteins / Q000378:metabolism; D003342:Corpus Striatum / Q000378:metabolism; D003640:Dealkylation; D050483:Dopamine Plasma Membrane Transport Proteins; D006801:Humans; D006868:Hydrolysis; D007457:Iodine Radioisotopes / Q000378:metabolism*; D008562:Membrane Glycoproteins; D026901:Membrane Transport Proteins; D009419:Nerve Tissue Proteins; D019275:Radiopharmaceuticals / Q000378:metabolism*; D014326:Tropanes / Q000378:metabolism*
D002352:Carrier Proteins; D050483:Dopamine Plasma Membrane Transport Proteins; D007457:Iodine Radioisotopes; D008562:Membrane Glycoproteins; D026901:Membrane Transport Proteins; D009419:Nerve Tissue Proteins; D019275:Radiopharmaceuticals; D014326:Tropanes; C087552:2-carbomethoxy-8-(3-fluoropropyl)-3-(4-iodophenyl)tropane