Automated radiosynthesis of [¹⁸F]FMPEP-d₂ for cannabinoid receptor PET imaging

The cannabinoid subtype 1 receptor (CB1R) is highly expressed in the central nervous system and abnormalities in regional CB1R density are associated with neurodegenerative disorders. The PET tracer [¹⁸F]FMPEP-d₂ is an inverse CB1R agonist which was shown to be suitable for non-invasive PET imaging. In this work, we reported the fully automated radiosynthesis of [¹⁸F]FMPEP-d₂ on a Synthra RNplus research module. In a total synthesis time of 70 min, [¹⁸F]FMPEP-d₂ was obtained in 2.2 ± 0.1 GBq (n = 3) with excellent radiochemical and chemical purity. Quality control test showed that [¹⁸F]FMPEP-d₂ product meets all the release criteria for clinical patient use.