In vitro and in vivo evaluation of p-Boc-Trp-Trp-NH(CH2)6 NH-PO(ONH4)-O-Ph131I

Stability in vitro, lipophility and acute toxicity of p-B oc-Trp-Trp-NH(CH2)6NH-PO (ONH4)-O-Ph131I are studied in this work. The complex, with labeling yield of around 85%, was obtained using sealed-tube method. Stability of the complex was obtained by measuring labeling yield at different time. Its lipophility was studied through swaging-flask method, and its impacts to liver function and peripheral blood of the experimental animals were also studied. The results indicate the complex is lipophilic and less toxic, and the iodine removal rate was about 13% three days later. The rabbit model with VX2 liver tumor was established successfully. The organ and tissue uptake and retention of p-Boc-Trp-Trp-NH(CH2)6NH-PO(ONH4)-O-Ph13'1I were studied in a model subject. Blood, liver, lungs, kidneys, spleen and tumour tissue samples were assayed in a well counter for radioactivity and the results were compared with the biodistribution studies in five normal mice. The complex trends to concentrate into adipose tissues in tumour-bearing and normal animals, and the uptake rate in tumor tissue is relatively high, hence its potential possibility as radiopharmaceuticals. But it cleared quickly. Further researches are underway to improve the stability of complexes to prolong concentration time in target tissue. (authors)