Microfluidic Radiosynthesis of the Muscarinic M2 Imaging Agent [18F]FP-TZTP*

Abstract 3-(4-(3-[18F]Fluoropropylthio)-1,2,5-thiadiazol-3-yl)-1-methyl-1,2,5,6-tetrahydropyridine ([18F]FP-TZTP) is a selective 18F-radiotracer for the muscarinic acetylcholine receptor subtype M2, which can be used to perform positron emission tomography (PET) scans on patients with neurological disorders such as Alzheimer’s disease. [18F]FP-TZTP was produced using continuous-flow microfluidics, a technique that uses reduced amounts of chemical reagents, shorter reaction times and in general, results in higher radiochemical yields compared to currently used techniques. The optimal 18F-radiolabelling conditions consisted of a total flow rate of 40？μL？min？1 and 190°C, which produced [18F]FP-TZTP in 26？±？10？% radiochemical yield with a molar activity of 182？±？65 GBq μmol？1 and >99？% radiochemical purity.