title: Radiochemical synthesis of [123I]2-iodo-lisuride for dopamine D2-receptor studies.
abstract: By variation of reaction parameters iodination of 3-(9,10-didehydro-6-methyl-8 alpha-ergolinyl)-1,1-diethylurea (lisuride) was performed with the radiohalogen [123I]iodine (t1/2 = 13.3 h). For comparative experiments and stability studies the beta(-)-emitting radioisotope [131I]iodine (t1/2 = 8.04 d) was also used. Reaction occurs at the activated position 2 of the molecule, thus leading to [123I]3-(9,10-didehydro-2-iodo-6-methyl-8 alpha-ergolinyl)-1,1-diethylurea ([123I]2-iodo-lisuride, [123I]ILIS) or the analogous [131I]iodine-labeled compound, respectively. Electrophilic radioactive species were generated by oxidation of no-carrier-added (n.c.a.) iodide with IODOGEN (1,3,4,6-tetrachloro-3 alpha,6 alpha-diphenylglycouril) fixed on the glass wall of the reaction vial prior to iodination. After optimization of reaction parameters [123I]2-iodo-lisuride after HPLC-purification was obtained with radiochemical yields of 70 +/- 5% and a radiochemical purity of > 97%. In n.c.a. syntheses, specific activities of the product were in the range between 4440 and 7400 GBq/mumol (120-200 Ci/mumol) corresponding to 50-85% of the theoretical value.
authors.affiliation: Nuklearchemie und Radiopharmazie-Klinik für Nuklearmedizin Universitätsklinikum, Essen, Germany.
authors.forename: D
authors.initials: D
authors.lastname: Bier
authors.forename: K
authors.initials: K
authors.lastname: Dutschka
authors.forename: E J
authors.initials: EJ
authors.lastname: Knust
mesh_terms: D017357:Cyclotrons; D004355:Drug Stability; D007457:Iodine Radioisotopes; D007553:Isotope Labeling / Q000379:methods; D008090:Lisuride / Q000031:analogs & derivatives* / Q000138:chemical synthesis / Q000378:metabolism; D017448:Receptors, Dopamine D2 / Q000032:analysis / Q000378:metabolism*; D014508:Urea / Q000031:analogs & derivatives
chemical_list: D007457:Iodine Radioisotopes; D017448:Receptors, Dopamine D2; C075786:iodolisuride; C012385:1,3,4,6-tetrachloro-3 alpha,6 alpha-diphenylglycoluril; D014508:Urea; D008090:Lisuride