Preparation via coligand exchange and characterization of [99mTc-EDDA-HYNIC-D-Phe1,Tyr3]Octreotide (99mTc–EDDA/HYNIC–TOC)

✍ Scribed by Elisabeth von Guggenberg; Bettina Sarg; Herbert Lindner; Laura Melendez Alafort; Stephen J. Mather; Roy Moncayo; Clemens Decristoforo

• Book ID: 102373195
• Publisher: John Wiley and Sons
• Year: 2003
• Tongue: French
• Weight: 119 KB
• Volume: 46
• Category: Article
• ISSN: 0022-2135
• DOI: 10.1002/jlcr.672

✦ Synopsis

Abstract

[^99m^Tc‐EDDA–HYNIC‐D‐Phe^1^,Tyr^3^]octreotide (^99m^Tc‐EDDA/HYNIC–TOC) is a promising new agent with the potential to replace [^111^In‐DTPA‐D‐Phe^1^]‐octreotide in somatostatin receptor scintigraphy. This hydrazinonicotinic acid derivatized somatostatin complex contains ethylenediamine N,N′ diacetic acid (EDDA) as a coligand resulting in a high in vitro and in vivo stability. Since direct ^99m^Tc‐labelling of HYNIC–TOC with EDDA results in low labelling yields, in this study we describe the preparation of ^99m^Tc‐EDDA/HYNIC‐TOC via coligand exchange from Tricine for EDDA. Exchange of coligands is achieved at elevated temperature and under optimized conditions of pH, EDDA concentration and stannous ion. High labelling yields (mean 95.9%) were achieved at high specific activities (>37GBq/µmol). Characterization via HPLC, receptor binding and LC–MS of the resulting complex is described. The formulation developed enables rapid and simple labelling of ^99m^Tc‐EDDA/HYNIC–TOC in a manner suitable for a clinical setting. Copyright © 2003 John Wiley & Sons, Ltd.