Preparation of no-carrier-added [124I]A14-iodoinsulin as a radiotracer for positron emission tomography

✍ Scribed by Matthias Glaser; David J. Brown; Marilyn P. Law; Patricia Iozzo; Stephen L. Waters; Keith Poole; Markus Knickmeier; Paolo G. Camici; Victor W. Pike

• Publisher: John Wiley and Sons
• Year: 2001
• Tongue: French
• Weight: 155 KB
• Volume: 44
• Category: Article
• ISSN: 0022-2135
• DOI: 10.1002/jlcr.482

✦ Synopsis

Abstract

A~14~‐Iodoinsulin is a close biochemical and pharmacological mimic of insulin. Human insulin was labelled in its A chain tyrosine‐14 residue by direct iodination with the positron‐emitter iodine‐124 (β^+^=25.6%; t~1/2~=4.15 days) to provide a radiotracer for imaging with positron emission tomography (PET). Several reagents were compared for conversion of cyclotron‐produced [^124^I]iodide into a reactive species for the labelling reaction. Radiochemical yields from the use of Iodo‐Gen^®^, Chloramine‐T, N‐bromosuccinimide or lactoperoxidase–hydrogen peroxide were similar [35% (n=1), 33±9% (n=10), 32±11% (n=25) or 33% (n=2), respectively]. [^124^I]A~14~‐Iodoinsulin was separated from unreacted insulin and radioactive by‐products by tandem reverse phase HPLC and rapidly formulated for intravenous injection by adsorption on a Sep‐Pak ^t^C18‐Plus^®^ cartridge, followed by elution with 10 mM hydrochloric acid–ethanol (1:1 v/v, 1 ml). This radiotracer can now be obtained in useful radioactivities at high effective specific radioactivity and is now being applied to PET studies of its biodistribution in living subjects. Copyright © 2001 John Wiley & Sons, Ltd.