Hans J.C. Buiter, Josée E. Leysen, Robert C. Schuit, Abraham Fisher, Adriaan A. Lammertsma and Albert D. Windhorst
[11C]AF150(S) was successfully synthesized, yielding 69 ± 9%, with radiochemical purity >99%. The measured logDoct,7.4 was 0.05. Autoradiography showed binding in M1 muscarinic acetylcholine receptor (M1ACh-R)-rich brain areas and selective inhibition by muscarinic agents in conditions promoting agonist binding. Biodistribution studies revealed high brain uptake, to levels exceeding five times that in blood. In addition, rapid metabolism was observed. In M1ACh-R-rich areas, specific uptake versus cerebellum was observed. It provides an interesting lead for the development of an M1ACh-R-agonist positron emission tomography ligand meant to explore the active receptor state.