MOLECULAR-BIOLOGICAL PROBLEMS OF DRUG DESIGN AND MECHANISM OF DRUG ACTION

Phosphonates labeled with beta-emitting radionuclides are widely used in nuclear medicine for palliative therapy of bone metastases. This work was aimed at studying the biodistribution of a new osteotropic antitumor agent based on N,N,N',N'-ethylenediaminetetralds(methylenephosphonic acid) labeled with Lu-177 (Lu-177-EDTMP) in intact animals. The biodistribution in vivo in intact Wistar rats of free Lu in the form of (LuCl3)-Lu-177 was also investigated to assess the stability of Lu-177-EDTMP. It was found that Lu-177-EDTMP accumulated mainly in the skeleton (22.67 - 54.89% of the injected dose) with minimal uptake in other organs and tissues. The amount of (LuCl3)-Lu-177 in bone did not significantly differ from Lu-177-EDTMP uptake but the concentration of (LuCl3)-Lu-177 in soft organs was significantly higher (p < 0.05) as compared to that of Lu-177-EDTMP. The results indicated that further studies of Lu-177-EDTMP in clinical application for therapy of skeletal metastases had good prospects.