Carbon-11 epidepride: a suitable radioligand for PET investigation of striatal and extrastriatal dopamine D2 receptors

Nuclear Medicine and Biology
O LangerL Farde

Abstract

Epidepride [(S)-(-)-N-([1-ethyl-2-pyrrolidinyl]methyl)-5-iodo-2,3-dimethoxybenza mide] binds with a picomolar affinity (Ki = 24 pM) to the dopamine D2 receptor. Iodine-123-labeled epidepride has been used previously to study striatal and extrastriatal dopamine D2 receptors with single photon emission computed tomography (SPECT). Our aim was to label epidepride with carbon-11 for comparative quantitative studies between positron emission tomography (PET) and SPECT. Epidepride was synthesized from its bromo-analogue FLB 457 via the corresponding trimethyl-tin derivative. In an alternative synthetic pathway, the corresponding substituted benzoic acid was reacted with the optically pure aminomethylpyrrolidine-derivative. Demethylation of epidepride gave the desmethyl-derivative, which was reacted with [11C]methyl triflate. Total radiochemical yield was 40-50% within a total synthesis time of 30 min. The specific radioactivity at the end of synthesis was 37-111 GBq/micromol (1,000-3,000 Ci/mmol). Human postmortem whole-hemisphere autoradiography demonstrated dense binding in the caudate putamen, and also in extrastriatal areas such as the thalamus and the neocortex. The binding was inhibited by unlabeled raclopride. PET studies in a...Continue Reading

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Citations

Apr 12, 2003·Brain : a Journal of Neurology·Nicola PavesePaola Piccini
Oct 5, 2010·Human Brain Mapping·Mouna EsmaeilzadehJoakim Tedroff
Apr 29, 2015·Frontiers in Human Neuroscience·Kayo TakahashiYasuyoshi Watanabe
Dec 5, 2006·NeuroImage·Miguel Angel García-CabezasCarmen Cavada
Feb 24, 2015·European Journal of Medicinal Chemistry·Ashish Radadiya, Anamik Shah

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