자동합성장치를 이용한 [¹⁸F]Fallypride의 합성

Automated Synthesis of [¹⁸F]Fallypride for Routine Clinical Use

Purpose: [¹⁸F]Fallypride plays an effective radiotracer for the study of dopamine D2/D3 receptor occupancy, neuropsychiatric disorders and aging in humans. This tracer has the potential for clinical use, but automated labeling efficiency showed low radiochemical yields about 5∼20% with relatively long labelling time of fluorine-18. In present study, we describe an improved automatic synthesis of [¹⁸F]Fallypride using different base concentration for routine clinical use. Materials and Methods: Fully automated synthetic process of [¹⁸F]Fallypride was perform using the TracerLab FXFN synthesizer under various labeling conditions and tosyl-fallypride was used as a precursor. [¹⁸F]Fluoride was extracted with various concentration of K2.2.2./K2CO3 from 18O-enriched water trapped on the ion exchange cartridge. After azeotropic drying, the labeling reaction proceeded in CH3CN at 100 °C for 10 or 30 min. The reaction mixture was purified by reverse phase HPLC and collected organic solution was exchanged by tc-18 Sep-Pak for the clinically available solution. Results: The optimal labeling condition of [¹⁸F]Fallypride in the automatic production was that 2 mg of tosyl-fallypride in acetonitrile (1 mL) was incubated at 100 °C for 10 min with K2.2.2./K2CO3 (11/0.8 mg). [¹⁸F]Fallypride was obtained with high radiochemical yield about 66±1.4% (decay-corrected, n=28) within 51±1.2 min including HPLC purification and solid-phase purification for the final formulation. Conclusion: [¹⁸F]Fallypride was prepared with a significantly improved radiochemical yield with high specific activity and shorten synthetic time. In addition, this automated procedure provides the high reproducibility with no synthesis failures (n=28).