Document Type: Original Article
Department of Radioisotope, Nuclear Research Center, AOEI, Tehran, Iran
Department of Medicinal Chemistry, Faculty of Pharmacy, Tehran University of Medical Sciences, Tehran, Iran
The high expression of somatostatin receptors in many tumours, have made receptor scintigraphy with 111In-DTPA-Octreotide a widly used procedure in nuclear medicine. Despite its clinical success, some limitation and drawbacks of radiolabelling with 111In remain, especially those concerned with the cost, availability and physical decay properties of this radionuclide. 99mTc-EDDA/HYNIC-Tyr3-TOC was studied as a new agent with the potential to replace Octreoscan in somatostatin receptor scintigraphy. This hydrazinonicotinic acid derivatized somatostatin complex contains ethylenediamine N,N diacetic acid ( EDDA ) as a co-ligand resulting in a high in vitro and in vivo stability. High labeling yields ( >90% ) were achieved at high specific activities. Charactrization via HPLC, biodistribution and receptor binding of the resulting complex are described. The formulation developed enables rapid and simple labeling of 99mTc-EDDA/HYNIC-TOC in a manner suitable for clinical setting.