A high-yield automated radiosynthesis of the alpha-7 nicotinic receptor radioligand [18F]NS10743

[18 F]FTC-146 was introduced as a very potent and selective sigma-1 receptor radioligand, which has shown promising application as an imaging agent for neuropathic pain with positron emission tomography. In line with a multi-laboratory project on animal welfare, we chose this radioligand to investigate its potential for detecting neuropathic pain and tissue damage in tumor-bearing animals. However, the radiochemical yield (RCY) of around 4-7% was not satisfactory to us, and efforts were made to improve it. Herein, we describe an improved approach for the radiosynthesis of [18 F]FTC-146 resulting in a RCY, which is sevenfold higher than that previously reported. A tosylate precursor was synthesized and radio-fluorination experiments were performed via aliphatic nucleophilic substitution reactions using either K[18 F]F-Kryptofix®222 (K2.2.2 )-carbonate system or tetra-n-butylammonium [18 F]fluoride ([18 F]TBAF). Several parameters affecting the radiolabeling reaction such as solvent, 18 F-fluorination agent with the corresponding amount of base, labeling time, and temperature were investigated. Best labeling reaction conditions were found to be [18 F]TBAF and acetonitrile as solvent at 100°C. The new protocol was then translated to an automated procedure using a FX2 N synthesis module. Finally, the radiotracer reproducibly obtained with RCYs of 41.7 ± 4.4% in high radiochemical purity (>98%) and molar activities up to 171 GBq/μmol.

Radiosynthesis

Radioligand

PET Imaging

10.1002/jlcr.4018

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Citations (2)

Radiosynthesis of [O-methyl-11C]viqualine through an N-trityl protected intermediate for evaluation as a PET radioligand for 5-HT re-uptake sites

Journal of Labelled Compounds and Radiopharmaceuticals (1991)

Claudio Pascali David R. Turton S.P. Hume Victor W. Pike

Radiosynthesis

Radioligand

Source

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Citations (0)

Radiosynthesis and characterisation of a potent and selective GPR139 agonist radioligand

RSC Advances (2015)

Sebastiaan Kuhne Anne Cathrine Nøhr Aleš Marek Tomáš Elbert Anders B. Klein

Compound 1 is a selective and potent agonist of the G protein-coupled receptor GPR139 (EC₅₀ = 39 nM).

Radiosynthesis

Radioligand

10.1039/c5ra21326f

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Citations (7)

Radiosynthesis of the adenosine A3 receptor ligand 5-(2-[18F]fluoroethyl) 2,4-diethyl-3-(ethylsulfanylcarbonyl)- 6-phenylpyridine-5-carboxylate ([18F]FE@SUPPY)

Radiochimica Acta (2008)

Wolfgang Wadsak Leonhard‐Key Mien Karem Shanab Karl Weber Bernd M. Schmidt

Since to date very limited information on the distribution and function of the adenosine A 3 receptor is available, the development of a suitable radioligand is needed. Such a selective radioligand can then be used for quantitative autoradiography, preclinical studies in animals and subsequent human PET applications. Recently, a promising candidate compound, 5-(2-fluoroethyl) 2,4-diethyl-3-(ethylsulfanylcarbonyl)-6-phenylpyridine-5-carboxylate (FE@SUPPY), has been presented. The successful preparation of a suitable labelling precursor and the evaluation and optimization of the radiosynthesis of [ 18 F] FE@SUPPY is presented herewith. For satisfactory yields, a reaction temperature of 75 °C has to be applied for at least 20 min using 8–10 mg of precursor. Until now, 15 complete high-scale radiosyntheses were performed. Starting from an average of 51±12 GBq (average ±SD; range: 30–67 GBq) [ 18 F]fluoride, 9.4–3.6 GBq of formulated [ 18 F]FE@SUPPY (32.3±12.4%, based on [ 18 F]fluoride, corrected for decay) were prepared in <105 min.

Radiosynthesis

Radioligand

Carboxylate

10.1524/ract.2008.1467

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Citations (7)

The radiosynthesis of [18F]PK 14105 as an alternative radioligand for peripheral benzodiazepine binding sites

Journal of Labelled Compounds and Radiopharmaceuticals (1991)

S. K. Luthra Claudio Pascali Victor W. Pike Gary Price R. G. Ahier

Radiosynthesis

Radioligand

Radioligand Assay