Simple and Efficient Automated Radiosynthesis of 1-[18F]-IPA Using Solid-Phase Extraction Cartridges Purification

Abstract

1-[¹⁸F]Fluoroethyl-indole propionic acid (1-[¹⁸F]-IPA), a fluorinated analogue of indole-3-propionic acid (IPA), shows considerable promise as a PET tracer for imaging BxPC-3 pancreatic cancer xenografts. In the present study, we report a straightforward automated synthesis protocol that employs cartridge-based purification, providing 1-[¹⁸F]-IPA in a form suitable for human use. This method was developed in compliance with good manufacturing practice (GMP) guidelines, and the final product meets the established release specifications for radiopharmaceuticals. The automated synthesis was carried out via a two-step, one-pot procedure, which involved [¹⁸F]fluorination of methyl 1-(2-tosyloxyethyl)-1H-indole-3-propionate, subsequent hydrolysis with sodium hydroxide, and purification using a series of commercially available solid-phase extraction cartridges, thereby eliminating the need for preparative high-performance liquid chromatography (preparative HPLC). Using this one-pot approach on a modified commercial GE TRACERlab FX-FN radiosynthesis module, the final product was obtained with high uncorrected radiochemical yields (> 35 %) and radiochemical purity (> 95 %). Collectively, these results establish the GE TRACERlab FX-FN radiosynthesis module as a robust, flexible, and cost-effective platform for the routine clinical production of 1-[¹⁸F]-IPA.