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4‐Fluoro‐N‐{2‐[4‐(6‐trifluoromethylpyridin‐2‐yl)piperazin‐1‐yl]ethyl}benzamide is a full 5‐HT1A agonist with high affinity (pKi=9.3), selectivity and a c log P of 3.045. The corresponding PET radioligand 4‐[18F]fluoro‐N‐{2‐[4‐(6‐trifluoromethylpyridin‐2‐yl)piperazin‐1‐yl]ethyl}benzamide was synthesized by nucleophilic aromatic substitution on the nitro precursor. The fluorinating agent K[18F]F/Kryptofix 2.2.2 was both dried (9 min, 700 W) and incorporated in the precursor (5 min, 700 W) using a commercially available microwave oven. In a total synthesis time of 60 min, an overall radiochemical yield of 18% (SD=5, n=7, EOS) was obtained. Radiochemical purity was always higher than 99% and specific activity always higher than 81.4 GBq/µmol (2.2 Ci/µmol). Initial brain uptake in mice was 2.19% ID (5.47% ID/g, 2 min) but decreased rapidly (0.17% ID, 0.45% ID/g (60 min)). During the first 20 min p.i., radioactivity concentration of the brain was significantly higher than that of blood demonstrating good brain entry of the tracer. Copyright © 2004 John Wiley & Sons, Ltd.

Schizophrenia is a devastating mental disorder characterized by relapsing psychotic episodes accompanied with emotional, professional and social decline. The classical dopamine hypothesis of schizophrenia postulates that hyperactivity of dopaminergic neurotransmission is responsible for the positive symptoms of the disorder. More exactly hyperactivity of the dopamine D3 receptor system is thought to be involved in the pathology of schizophrenia. Therefore, a new ¹²³I-labelled compound was developed which may allow in vivo visualization of the D3 receptor by SPECT. [¹²³I]-4-iodo-N-(4-(4-(2-methoxyphenyl)-piperazin-1-yl)butyl)-benzamide was synthesized and labelled by electrophilic aromatic substitution of the tributylstannyl derrivative. The radiochemical yield was 82–85% and the specific activity was >2.96 Ci/µmol. Copyright © 2003 John Wiley & Sons, Ltd.

4-[¹²³I]Iodo-N-{2-[4-(6-trifluoromethyl-2-pyridinyl)-1-piperazinyl]ethyl}benzamide (1. ¹²³I), a potential SPECT 5-HT1A radioligand, was synthesized by electrophilic iododestannylation of the tributyltin derivative with n.c.a. [¹²³I]NaI and chloramine-T under acidic conditions (20 min, ambient temperature). Radiochemical yield averaged around 60 % (sd = 8,n = 22). After HPLC purification, chemical purity was higher than 95 % and radiochemical purity higher than 99 %. Specific activity was always higher than 222 GBq/µmol (6 Ci/µmol). The calculated log P is 4.28. Initial brain uptake in NMRI mice was 1.16 % ID (2 min) and decreased slowly afterwards (0.51 % ID (2 h)). 60 min p.i., the majority of the radioactivity in plasma and brain was present as 1. ¹²³I, respectively 75.15 % and 96.48 %. Copyright © 2001 John Wiley & Sons, Ltd.

The synthesis of two ¹¹C labelled chromeno[3,4-c]pyridin-5-ones for the visualisation of the dopamine D4 receptor subtype has been developed. The production entailed an O-methylation of the O-desmethyl precursor with [¹¹C]iodomethane in the presence of tetrabutylammonium hydroxide. Subsequent purification by RP-HPLC and formulation by tracer enrichment on a C18 Sep Pak provided a solution which was suitable for human iv injection. Specific activity of the tracer averaged 37 GBq/μmol at EOS and the radiochemical yields were 65% (decay-corrected, based on [¹¹C]CH3I). Total activity obtained was 5·6–7·4 GBq. The preparations have been demonstrated to be chemically and radiochemically pure by HPLC. Copyright © 2000 John Wiley & Sons, Ltd.

Human recombinant annexin V was radiolabelled with iodine-123 by electrophilic substitution of the containing tyrosine residues using carrier-free sodium iodide-123 as the isotope source. The synthesis of ¹²³H-labelled annexin V was performed using IodoBeads as oxidative solid phase iodinating agent and reaction parameters were optimized and evaluated. Purification by straight-phase HPLC gave [¹²³I]annexin V in a maximum yield of approximately 70% with a radiochemical purity of more than 95% and a specific activity of about 10 MBq/μg of protein. Furthermore, in vitro stability experiments indicated that [¹²³I]-annexin V was stable for at least 8 hours in an aqueous phosphate buffer solution. In plasma however it decreased more rapidly. The biological activity of [¹²³I]-annexin V remained intact in comparison with FITC labelled annexin V as confirmed by in vitro binding experiments with apoptotic cells. Copyright © 2000 John Wiley & Sons, Ltd.