Radiosynthesis of [18F]-flumazenil Using an Isotopic Approach.

Abstract

Background: Fluorine-18 (¹⁸F) flumazenil (FMZ) has been synthesized using various precursors, and its role has been explored in imaging Gamma-aminobutyric acid-A receptors.

Aim and objective: The main objective was to synthesize (¹⁸F) FMZ using isotopic substitution.

Materials and methods: Around 18 ± 2 GBq was added to the module, dried, and radiolabeling was standardized with 3.0 mg of the FMZ precursor at various temperatures (110°C -160°C) for 10-30 min. The product was finally eluted with 20% ethanol (in phosphate buffer). The final product was characterized by high-performance liquid chromatography (HPLC). The stability was evaluated in water, saline, and phosphate-buffered saline for 4 h.

Results: The radiolabelling efficiency of cartridge-based purification was 16 ± 4% (n = 10) with a radiochemical purity of 96.5 ± 1.8%, whereas in HPLC-based purification, the yield was 10 ± 4% (n = 5) with a radiochemical purity of 97.3 ± 1.4%. The specific activity was 120 ± 20 GBq/μmol.

Conclusions: (¹⁸F) FMZ was successfully synthesized using an isotopic approach and could be used as an alternative cheaper option for the synthesis.