title: Carbon-11 choline: synthesis, purification, and brain uptake inhibition by 2-dimethylaminoethanol.
abstract: We report an improved method for the synthesis and purification of [11C]methylcholine from the precursors [11C]methyliodide and 2-dimethylaminoethanol (deanol). Preparation time, including purification, is 35 min postbombardment. Forty millicuries of purified injectable [11C]choline were produced with a measured specific activity of greater than 300 Ci/mmol and a radiochemical purity greater than 98%. The decay corrected radiochemical yield for the synthesis and purification was approximately 50%. Residual precursor deanol, which inhibits brain uptake of choline, is removed by a rapid preparative high performance liquid chromatography (HPLC) method using a reverse phase cyano column with a biologically compatible 100% water eluent. Evaporation alone did not completely remove the deanol precursor. Brain uptake of the [11C]choline product was six times greater after HPLC removal of deanol because doses of less than 1 microgram/kg significantly inhibit [14C]choline brain uptake.
mesh_terms: D000818:Animals; D001921:Brain / Q000000981:diagnostic imaging / Q000378:metabolism*; D002250:Carbon Radioisotopes; D002794:Choline / Q000031:analogs & derivatives* / Q000138:chemical synthesis / Q000378:metabolism; D002851:Chromatography, High Pressure Liquid; D003642:Deanol / Q000378:metabolism / Q000494:pharmacology*; D004983:Ethanolamines / Q000494:pharmacology*; D006847:Hydrocarbons, Iodinated / Q000378:metabolism; D008297:Male; D011876:Radionuclide Generators; D051381:Rats; D014055:Tomography, Emission-Computed
chemical_list: D002250:Carbon Radioisotopes; D004983:Ethanolamines; D006847:Hydrocarbons, Iodinated; C017506:methylcholine; D003642:Deanol; C014055:methyl iodide; D002794:Choline