A novel approach to the synthesis of [18F]flumazenil, a radioligand for PET imaging of central benzodiazepine receptors

Abstract

An express method of solid-phase extraction was proposed for the first time for isolation and purification of [¹⁸F]flumazenil, a radioligand used to quantify the density of central benzodiazepine receptors by positron emission tomography (PET). This novel approach afforded the radioligand with >97% radiochemical purity and a high chemical purity (nitromazenil content <1 μg mL^–1) and considerably reduced the time of the synthesis (from 90 to 50 min). The nonoptimized decay-corrected radiochemical yield was 8%, and the specific radioactivity was >37 GBq μmol^–1. The novel synthetic procedure easily can be integrated into automatic modules for the synthesis of clinically used PET radiopharmaceuticals.