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

Abstract

A14‐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%; t1/2=4.15 days) to provide a radiotracer for imaging with positron emission tomography (PET). Several reagents were compared for conversion of cyclotron‐produced [124I]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]. [124I]A14‐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 tC18‐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.

Radiochemistry, Production Processes, Labeling Methods, and ImmunoPET Imaging Pharmaceuticals of Iodine-124

“…Numerous studies were conducted since the first report by Kondo et al in 1977 [ 70 ]. The results from these studies suggested that 124 I can be successfully produced for research and clinical use by using low-energy cyclotrons that are available routinely for production of 11 C and 18 F-labeled imaging pharmaceuticals for standard care [ 71 , 72 , 73 , 74 , 75 , 76 , 77 , 78 , 79 , 80 , 81 , 82 , 83 , 84 , 85 , 86 ]. Consequently, the 124 Te(p,n) 124 I production process is being used extensively in the research and clinical environments worldwide.…”

“…Additionally, tellurium tends to blow up upon heating. The tellurium target for proton irradiation has been prepared by the three different methods: (1) filling 124 Te in an aluminum capsule under He atmosphere [ 70 , 84 ], (2) introducing melted enriched tellurium onto a support plate [ 71 , 72 , 73 , 74 , 75 , 76 , 77 , 78 , 79 , 80 , 81 , 82 , 86 ], and (3) electroplating tellurium on a nickel-coated copper substrate [ 45 , 48 , 97 , 98 ].…”

124,125Te(p,xn)123,124I ve 123,124Te(d,xn)123,124I İçin Reaksiyon Tesir Kesitleri

“…A minimum contamination can be seen starting around 10 MeV, peaking around 13 MeV and decreases with increasing energy. So, it is clear that the elimination of radionuclidic impurities is not always possible even with a wide energy selection and high enrichment as stated by Glaser et al, (2001), Sheh et al, (2000 and Michael et al, (1981). The production of 123 I were found appropriate for small, medium-sized cyclotrons and is convenient for economical and availability purposes.…”

“…The use of 124 I radioisotope has extended in medicine recently due to its diagnostic and therapeutic potential. Since its half life is 4.2 days and it has 23% positron decay (IAEA, 2009); it is possible to use 124 I for positron emission tomography (PET) radiopharmaceuticals (Glaser et al, 2001;Sheh et al, 2000;Michael et al, 1981). 124 I isotope were formerly considered as an impurity in 123 I production, since it has diagnostic and therapeutic potential the production of 124 I is becoming more widespread (Herzog et al, 2002;Pentlow et al, 1996).…”

Radiohalogens for PET Imaging

“…In addition, insulin has been labeled with 124 I on the fourteenth amino acid residue (tyrosine) using electrophilic radiolabeling conditions [119]. The nucleoside analog 2′-fluoro-2′-deoxy-1β-D-arabinofuranosyl-5-iodouracil (FIAU) has also been labeled using Na[…”