title: Comparison of [82Br]4-bromoantipyrine and [125I]4-iodoantipyrine: the kinetics of exchange reaction and biodistribution in rats.
abstract: Kinetics and mechanism of isotope exchange reaction between [82Br]bromide anion and 4-bromoantipyrine (BrAP), and the iodine-bromine exchange reaction between [125I]iodide anion and BrAP were studied. The preparation of [82Br]BrAP followed by exponential exchange law, the kinetics of the exchange reaction is a second-order reaction with an activation energy of 23.3 kcal/mol. The optimal exchange condition for halogen exchange between [125I]iodide and BrAP was by a hydrothermal melt method at 110 degrees C and 5 min reaction time. The partition coefficient at pH 7.0 for IAP and BrAP was 20.9 and 13.5, respectively. However, BrAP, which displayed the lower partition coefficient, showed higher brain uptake in rats than that for IAP (2.0% dose/organ vs 1.74% dose/organ), at 2 min after an i.v. injection.
mesh_terms: D000818:Animals; D000983:Antipyrine / Q000031:analogs & derivatives* / Q000378:metabolism; D001966:Bromine / Q000378:metabolism; D007457:Iodine Radioisotopes / Q000378:metabolism; D007474:Ion Exchange; D007700:Kinetics; D008297:Male; D011868:Radioisotopes / Q000378:metabolism; D051381:Rats; D011919:Rats, Inbred Strains; D014018:Tissue Distribution
chemical_list: D007457:Iodine Radioisotopes; D011868:Radioisotopes; C052632:4-bromoantipyrine; D001966:Bromine; D000983:Antipyrine; C008135:iodoantipyrine