Synthesis of an I-123 analog of A-85380 and preliminary SPECT imaging of nicotinic receptors in baboon

A radiosynthetic method to prepare the nicotinic acetylcholine receptor rad ioligand (S)-5 [I-123]iodo-3-(2-azetidinylmethoxy)pyridine, 5-IA, has been developed. The two-step sequence produced [I-123]-5-IA in high radiochemica l yield (52%), high radiochemical purity (98%), and high specific radioacti vities (>8,500 mCi/mu mol). Preliminary single photon emission computed tom ography studies with [I-123]-5-IA in baboon demonstrated the appropriate re gional localization for a high-affinity nicotinic radioprobe (thalamus > fr ontal cortex > cerebellum). Pretreatment with cytisine blocked [I-123]-5-IA uptake in all brain regions (78-59% reduction), demonstrating the specific ity of the radiotracer. NUCL MED BIOL 26;2:201-207, 1999. (C) 1999 Elsevier Science Inc. All rights reserved.