Automated one‐step radiosynthesis of the CB1 receptor imaging agent [18F]MK‐9470 |
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| Authors: | David Thomae Thomas J. Morley Terence Hamill Vincent M. Carroll Caroline Papin Nicole M. Twardy H. Sharon Lee Richard Hargreaves Ronald M. Baldwin Gilles Tamagnan David Alagille |
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| Affiliation: | 1. Institute for Neurodegenerative Disorders, New Haven, CT, USA;2. Molecular NeuroImaging, LLC, New Haven, CT, USA;3. Merck Research Laboratories, West Point, PA, USA |
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| Abstract: | The fluorine‐18‐labeled positron emission tomography (PET) radiotracer [18F]MK‐9470 is a selective, high affinity inverse agonist that has been used to image the cannabinoid receptor type 1 in human brain in healthy and disease states. This report describes a simplified, one‐step [18F]radiofluorination approach using a GE TRACERlab FXFN module for the routine production of this tracer. The one‐step synthesis, by [18F]fluoride displacement of a primary tosylate precursor, gives a six‐fold increase in yield over the previous two‐step method employing O‐alkylation of a phenol precursor with 1,2‐[18F]fluorobromoethane. The average radiochemical yield of [18F]MK‐9470 using the one‐step method was 30.3 ± 11.7% (n = 12), with specific activity in excess of 6 Ci/µmol and radiochemical purity of 97.2 ± 1.5% (n = 12), in less than 60 min. This simplified, high yielding, automated process was validated for routine GMP production of [18F]MK‐9470 for clinical studies. |
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| Keywords: | [18F]MK‐9470 CB1 Production Good Manufacturing Practice (GMP) |
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