Synthesis of a Dopamine Transporter Imaging Agent, N-(3-18Ffluoropropyl)-2 -carbomethoxy-3 -(4-iodophenyl)nortropane.
- Author:
Yearn Seong CHOE
;
Seung Jun OH
;
Dae Yoon CHI
;
Sang Eun KIM
;
Yong CHOI
;
Kyung Han LEE
;
Byung Tae KIM
- Publication Type:Original Article
- Keywords:
Dopamine transporter;
Effective specific activity;
Positron emission tomography
- MeSH:
Chromatography, High Pressure Liquid;
Dopamine Plasma Membrane Transport Proteins*;
Dopamine*;
Ethanol;
Hydrogen-Ion Concentration;
Positron-Emission Tomography;
Solvents
- From:Korean Journal of Nuclear Medicine
1999;33(3):298-305
- CountryRepublic of Korea
- Language:Korean
-
Abstract:
PURPOSE: N-(3-[18F]Fluoroporpy)-2beta- carbomethoxy-3beta-(4-iodophenyl) nortropane ([18F]FP-CIT) has been shown to be very useful for imaging the dopamine transporter. However, synthesis of this radiotracer is some what troublesome. In this study, we used a new method for the preparation of [18F]FP-CIT to increase radiochemical yield and effective specific activity. MATERIALS AND METHODS: [18F]FP-CIT was prepared by N-alkylation of nor-beta-CIT (2 mg) with 3-bromo-l-[18F]fluoropropane in the presence of Et3N (5-6 drops of DMF/CH3CN, 140 degree C, 20 min). 3-Bromo-l-[18F]fluoropropane was synthesized from 5 microliter of 3-bromo-l-trifluoromethanesulfonyloxypropane (3-bromopropyl -l-triflate) and nBu4N18F at 80 degree C. The final compound was purified by reverse phase HPLC and formulated in 13% ethanol in saline. RESULTS: 3-Bromo-l-[18F]fluoropropane was obtained from 3-bromopropyl-l-triflate and nBu4N18F in 77-80% yield. N-Alkylation of nor-beta-CIT with 3-bromo-l-[18F]fluoropropane was carried out at 140 degree C using acetonitrile containing a small volume of DMF as the solvents. The overall yield of [18F]FP-CIT was 5-10% (decay-corrected) with a radiochemical purity higher than 99% and effective specific activity higher than the one reported in the literature based on their HPLC data. The final [18F]FP-CIT solution had the optimal pH (7.0) and it was pyrogen-free. CONCLUSION:: In this study, 3-bromopropyl-l-triflate was used as the precursor for the [18F]fluorination reaction and new conditions were developed for purification of [18F]FP-CIT by HPLC. We established this new method for the preparation of [18F]FP-CIT, which gave high effective specific activity and relatively good yield.
