Automated radiosynthesis of [¹⁸F]SPA‐RQ for imaging human brain NK₁ receptors with PET

Abstract

Abstract [ 18 F]SPA‐RQ is an effective radioligand for imaging brain neurokinin type‐1 (NK 1 ) receptors in clinical research and drug discovery with positron emission tomography. For the automated regular production of [ 18 F]SPA‐RQ for clinical use in the USA under an IND we chose to use a modified commercial synthesis module (TRACERlab FX F‐N ; GE Medical Systems) with an auxiliary custom‐made robotic cooling–heating reactor, after evaluating several alternative radiosynthesis conditions. The automated radiosynthesis and its quality control are described here. [ 18 F]SPA‐RQ was regularly obtained within 150 min from the start of radiosynthesis in high radiochemical purity (>99%) and chemical purity and with an overall decay‐corrected radiochemical yield of 15±2% (mean±S.D.; n =10) from cyclotron‐produced [ 18 F]fluoride ion. The specific radioactivity of [ 18 F]SPA‐RQ at the end of synthesis ranged from 644 to 2140 mCi/µmol (23.8–79.2 GBq/µmol). Copyright © 2005 John Wiley & Sons, Ltd.