Preparation and biodistribution of -[125I]Iodo-4-aminophenyl)ethyl]-4-[3-(trifluoromethyl)phenyl]piperazine and -[125I]Iodo-4-azidophenyl)ethyl]-4-[3-(trifluoromethyl)phenyl]piperazine

Article abstract of DOI:10.1021/jm00123a006

The iodinated analogue of 1-[2-(4-aminophenyl)ethyl]-4-[3-(trifluoromethyl)phenyl]piperazine (PAPP), IPAPP (4), and the corresponding azido compound azido-IPAPP (5) were synthesized. The corresponding no-carrier-added ¹²⁵I (T( 1/2 ) = 60 days, 35-60 keV) labeled compounds were also prepared. High specific binding was observed from in vitro binding studies using rat brain tissue preparation; K(i) = 20 and 17.5 nM against [³H]-5-HT. In vivo biodistribution studies in rats showed that azido-[¹²⁵I]IPAPP passed through intact blood-brain barrier and localized in the brain. Ex vivo autoradiography of rat brain sections exhibited a diffuse uptake pattern, which may be due to specific and nonspecific binding. The results indicate that IPAPP and azido-IPAPP may not be suitable to image the serotonin receptor in the brain.